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General Metalworking - All aspects of working with metal.
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Posted by DoN. Nichols on June 2, 2008, 10:13 pm
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>
[ ... ]
>> >> O.K. Then perhaps I could use one as well.
>>
>> O.K. Harbor Freight's web site is back up -- and this is
>> designed to mount via four socket head cap screws to a flange, not to be
>> bolted with nuts and flanges directly on the spindle.
>
> True. It's a knock-off of the Baldor carbide tool grinder.
It really says that it is a carbide grinder -- yet it uses the
nuts and flanges which have been making your stones wobble?
>
>> I see no RPM listed.
>>
>> And I *do* see the following:
>>
>> For Baldor & Other Popular *CARBIDE* Bench Grinders
>> ^^^^^^^
>>
>> My emphasis on the "carbide" part. I know that the carbide grinders
>> have driving faces instead of just clamp flanges. I *don't* know what
>> the RPM is.
>
> The nameplate on mine says 3400 rpm, 1/2 hp.
>
> I don't understand the part about driving faces and clamp flanges.
A grinder made to fit the wheel which you pointed me to does not
have the wheel clamped between two flanges by a step on the motor shaft
and a nut run down against the outer flange.
Instead -- it has a permanently mounted hub which includes a
face something like half the diameter of the wheel or so. The hub is a
nice slide fit for the hole in the diamond wheel, and the face is
drilled and tapped in four places for socket head cap screws which
secure the metal body of the wheel to the hub.
Given the problems which you were having with the wheels
wobbling thanks to drunken threads on the shaft or the nuts, I would not
even *want* to consider trying to mount a diamond wheel like the one
which you pointed me to on it.
It *was* you who was talking about the problems with your
grinder, wasn't it?
> With HF, I find it best to download and read the users manual.
>
> What grinder do you have, that you would be mounting a diamond wheel on?
I have two grinders -- one (a 6" one) which has been in the
family since about 1956 or so -- and it was obviously old even then. My
father accepted it in trade for a spare anchor for his sailboat. His
other tools consisted of a rusty pair of pipe pliers, a couple of rusty
straight blade screwdrivers, and two tiny claw hammers with one or bot
claws broken off -- so obviously I wound up with it. :-) I don't
remember the brand, other than it being one which I found unfamiliar.
The other is an 8" Jet -- which runs very nicely true.
Neither are made to mount that diamond wheel.
>> >> > Although when I replaced one gray wheel with aluminum oxide, I had to
>> >> > modify the wheel housing so the Norton wheel would fit, using a die
>> >> > grinder that often outran my compressor.
>> >>
>> >> *That* would worry me -- because it would reduce the wall
>> >> thickness needed to protect the operator when the wheel shatters.
[ ... ]
>> > Actually, are plated diamond wheels likely to burst at all? Aren't they
>> > made of metal?
>>
>> But you thinned the housing to fit a stone, not a diamond wheel
>> from what I read above.
>
> True, but how is that relevant to the question?
You asked whether the diamond wheels were likely to burst, and I
was pointing out that my worry was because *you* intended to put stone
wheels in it -- not the diamond one.
> And both wheels are the
> same nominal diameter, 6". With the HF carbide tool grinder, all the
> action happens on a flat face, like a cup wheel, and the cylindrical
> outer edge is not used.
Yes -- do you actually have such a grinder, or is yours purely a
stone wheel grinder?
[ ... ]
>> >> > I'm curious - why is carbide dust any worse than say HSS or stainless
>> >> > steel dust?
>> >>
>> >> I *think* that it is the Tungsten matrix in which the carbide is
>> >> embedded.
>> >
>> > Actually, the matrix is cobalt, which glues tungsten carbide particles
>> > into a solid mass, like cement gluing stones into a solid mass called
>> > concrete.
>>
>> O.K. But there are MSDS sheets which come with each carbide
>> tool from MSC which warn about grinding them.
>
> I get from MSC a MSDS every time I buy a steel bar, telling me of the
> dangers of iron.
:-)
[ ... ]
>> > I don't recall ever seeing such a number except in textbooks on the
>> > design of machine tools.
>>
>> O.K. Then those should give you the ability to calculate the
>> deflection -- if you take the time to measure everything carefully. :-)
>
> I'm also hoping to motivate people to test and publish the results.
You didn't *say* that until now -- assuming that anyone else is
still reading this thread. :-)
[ ... ]
>> Does it? I don't have the formulas to hand, but I would expect
>> only a factor of four.
>
> Time to look into Roark, Formulas for Stress and Strain, 1954.
[ ... ]
> So we are both wrong. Doubling the diameter of a round bar will
> increase the stiffness (decrease the max deflection) by a factor of 2^4=
> 16, while doubling the depth of a rectangular beam (the width remaining
> constant) will increase the stiffness by a factor of 2^3= 8.
O.K. You have a reference book which I don't, obviously.
[ ... ]
>> > True enough, but the objective here is to measure the stiffness of the
>> > machine tool holding the HSS or carbide bit, and not to measure the
>> > stiffness of the boring bar. The use of a BXA-4D boring bar holder is
>> > fortuitous - the holder accepts a 1" bar, and a 6' length of 1" CRS bar
>> > fits perfectly and can be clamped as if it were a boring bar.
>>
>> Hmm ... that would not work on *my* lathe. The bed is not long
>> enough to support a 6' bar by the middle without it having to pass
>> through the spindle. (Hmm ... 1" bar, 1-3/8" bore -- I guess that you
>> could do that a bit at least.
>
> I see. I have confused things by talking of boring bars. In the
> present test, the boring bar holder is clamped to the left side
> dovetail, and the bar is perpendicular to the bed ways.
But I feel that there will be more give on a bar parallel to the
ways, which will represent the off-center load from a tool on the
quick-change toolpost. Your right-angles measurement would be more
meaningful for tools in a lantern style toolpost -- which is also
probably what the Clausing test cut was done with originally.
> I have also done the test with a shorter bar parallel to the bed ways.
> For this, I removed the tailstock so the bar could project out off the
> end of the bed, with the weight dangling just beyond the end.
O.K. My bed is shorter (only 24" between centers), and there is
a weird table right off the end of the bed to accept the bed turret, so
I don't have to lift it. It would be a major hassle to try to measure
that on my lathe -- even assuming that I had a 6-foot 1" steel bar,
which I don't. The 6' 416 SS rod has long since been cut shorter as it
has been used in projects. The same for the 6' of 1" diameter aluminum.
>> But -- I am interested in seeing the difference when you run that
>> test at right angled to the bed and parallel to the bed. I'll bet that
>> it is a lot worse parallel to the bed, which is the kind of load you
>> would have with the offset of the tool holder on the BXA toolpost.
>
> What is reported above is the perpendicular-to-bedway value. I will
> repeat the parallel-to-bedway test.
O.K. I think that will show a greater deflection.
>> > I do have some Criterion solid carbide boring bars (bought used for a
>> > few dollars each), and they do a really nice job.
>>
>> Solid carbide with non-interchangeable cutting surfaces? Mine
>> is a Kennametal, with the bar 1/2" diameter (with a pair of opposed
>> flats for clamping it in the tool holder) with the very end steel brazed
>> on, and triangular inserts. I know that they are Kennametal, because I
>> had to dig through the overstuffed drawer beside the lathe to find them.
>> I finally wore out the third point on the insert which I have been using
>> for some years. :-)
>
> They are solid carbide, cutting tip and shank, with a cylindrical steel
> shank sleeve brazed to the carbide.
This sounds strange. Where is the cylindrical sleeve in all of
this?
What I was trying to describe is similar to this (but smaller):
ebay # 250252780188
unfortunately, the part where the inserts mount is covered in wax in the
photos.
O.K. Here is mine -- even the same size. The price is not too
bad for what it is -- but you will need more inserts over time. At
least it describes the proper inserts to order. It is amazing how
little chatter I get with a lot of extension with that bar. :-)
>> I've got a two-pan balance with beam weights (picked up at a
>> hamfest) plus the set of weights (picked up at an estate sale. I wish
[ ... rest of list snipped ... ]
> Those are real scientific scales. Perhaps a bit fussy for cooking,
> though.
Especially with a wife who prefers to toss in unmeasured amounts
which "look right". I can't complain about the results, however.
But she did get min pink stone mortar and pestle set. :-(
[ ... ]
>> > A question: On your Clausing, if you pull the backgear pin, so the
>> > spindle can turn freely, when you turn the spindle by hand, how much
>> > drag do you encounter? And, is there an initial resistance to turning,
>> > which resistance lessens once the spindle is turning? I'm wondering if
>> > I over-tightened the spindle preload adjustment nut, but have no
>> > comparison.
>>
>> Mine may not be truly equivalent, since mine has three belts
>> applying stress to the side of the shaft. But I get what feels like a
>> 3:1 or perhaps 4:1 ratio of starting force vs moving force. It pegged
>> the force gage which I was able to find -- at about 1.5 KG applied at a
>> point 3.125" from the center (on a chuck jaw at the OD of a 6-1/4"
>> chuck.)
>
> Ah! That sounds exactly how it now feels like when turning the spindle
> by hand. It sounds like I did not over-tighten it.
O.K. Note that when I had the spindle out to change belts, I
tightened it until it fit the manual's spin test. But after using it a
while, it developed chatter. I had to go back, overtighten the collar
on the back, and then loosen it and re-tighten it after I had set the
bearings properly. :-)
>> The heavier force gauge has gone into hiding for the moment. I
>> last used it to check the match of a newly purchased clock weight to the
>> original one (time was still there, gong was missing, but I remembered
>> them as being the same dimensions.)
>
> Use a fish scale and a cord?
A good idea -- if I had a fish scale. Since I don't go fishing,
that isn't one of the things around here. :-
[ ... ]
> I'm just looking for a simple fix for the X-axis power feed, and the
> circuit diagram isn't available. (A diagram did come with the unit, but
> the provided diagram makes no sense electronically, and has no
> connection to what's on the circuit board.)
O.K. That makes things more difficult.
[ ... ]
>> > Wirewound sounds workable. For instance, CTS 026TB32, like DigiKey
>> > CT2159-ND, for $3.60 each, which is a 10K 5-watt wirewound in the
>> > standard form factor of the traditional molded carbon pots.
>>
>> That sounds as though it would work -- other than eliminating
>> the finest of the control -- but you don't need that fine a control. ;-)
>
> A 10K wirewound will use *very* fine wire.
Thus making it easier to fry the wire near the bottom setting.
[ ... ]
>> > Making a regulator to handle 10 psi should not be hard. The only thing
>> > I would worry about is if a failure in the regulator can cause full
>> > inlet pressure to appear at the facemask. The design should be such
>> > that failure causes zero output.
>>
>> If you get full inlet pressure to the facemask, it would simply
>> float clear of the face with lots of air escaping all around -- which
>> would *still* keep the undesirable components out. If you had straps
>> tight enough to build up a pressure dangerous to the lungs, you would
>> probably also be limiting blood circulation to the scalp. :-)
>
> OK.
And that would keep you breathing as you walked out of the
danger zone.
[ ... ]
>> > OK. Why is lapping any more likely to yield parallel faces than a
>> > surface grinder?
>>
>> It isn't -- but it can produce both a better finish (You can't
>> wring blocks which are just surface ground together), and it can remove
>> very small amounts of material at a time -- allowing approaching the
>> final dimension with less chance of overshooting. (And remember that
>> the grinding increases the temperature a lot more than lapping does.
>
> OK. It all comes down to some kind of precise machine.
Yes.
>> Does anyone finish lenses by grinding? All that I know are
>> finished by lapping. The surface finish is an important part, as well
>> as the final dimensions.
>
> In the IR, lenses can be machined with a diamond point. But in the
> visible, lapping is required. Except for molded lenses. But this only
> makes the lapping once removed - one laps the mold.
The lenses which I have used in the deep IR were made from
either silicon or germanium -- neither of which would turn very nicely,
even with a diamond. They are very brittle substances.
[ ... ]
>> > I'm not visualizing this. The angled faces would not find flat surfaces
>> > to rest upon in all those bored circular holes, so it would be hard to
>> > know the effective spacings between jaws as tightened.
>>
>> Apparently, it is close enough so the deformation of the points
>> left by the joining of the holes allows the jaws to all reach the same
>> preload force (which may or may not be with equal spacing between the
>> faces, BTW).
>>
>> Do a web search on "truing chuck jaws" and you will find several
>> mentions of this system. Maybe one of them can answer your questions
>> better than I can.
>
> Is this it: <http://www.loganact.com/tips/chuck-jaw.htm>?
That is, indeed.
[ ... ]
>> > Probably ground in a fixture that has been lovingly tweaked over the
>> > years.
>>
>> Not sure of that. The proper positioning is also dependent on
>> the scroll plate, so they may be finished in a chuck body with the
>> scroll plate with which they are to be used.
>
> Using a fancy fixture to hold the jaws in plane but under pressure as
> for actual use.
Note that a slight error in the angular placing of the jaws
on the chuck body will introduce an error in the advance of the jaws.
[ ... ]
>> >> > Hardhat?
>> >>
>> >> Just makes it more likely that I will hit something. My
>> >> hardhat adds at least another inch to the top of my head. :-)
>> >
>> > But reduces the impact-induced IQ decrement.
>>
>> I tend to learn quickly for things like that. I am tall enough
>> so I tend to spot things likely to hit my head, while shorter people are
>> not accustomed to looking for overhead hazards. Not that I am *really*
>> tall, but tall enough. :-)
>
> Stay away from warships. A 5' zip Chinese female colleague of mine told
> me how she rung her bell a few times while installing systems in US Navy
> ships. This was a great surprise to her - she is not at all used to
> running out of headroom.
Which is *why* she is more vulnerable. Taller people are
accustomed to checking for head clearance. (Of course your friend is
still taller than my wife. :-)
[ ... ]
[ ... ]
>> I used to lose a Frame Relay CSU/DSU about every other year,
>> when lightning struck either the power line or the phone lines not too
>> far from the house. Since they replaced the wiring, I have not had a
>> repeat of that problem -- so far. But since I went to a T1 line, there
>> is a board of electronics at the demark (just outside the house) with is
>> the phone company's responsibility, and (so far) that has not gone out
>> either.
>
> So far, I have not had such dramas.
Perhaps you are more in the city, instead of in the suburbs
where there are more exposed wires to be hit by lightning or falling
trees. (More trees available for that matter. :-)
>> I am temped by the FIOS fiber optics -- but until they can offer
>> me things like a Class-C static IP block, I won't play. I'm not that
>> interested in the cable service which they are pushing, and I like the
>> copper-based phone system still -- it keeps working during a five-hour
>> power outage. I'm not sure how long the charge on the FIOS battery
>> backup will last.
>
> They are pushing FiOS up here as well, but I doubt that they are quite
> ready for prime time. And, if you get FiOS, they tear the copper line
> out, thus burning the bridges. So, maybe in ten years.
If I get FIOS, it will be *purely* a net feed -- meeting my
requirements. The phone service will remain copper for as long as I can
manage it.
[ ... ]
>> That looks good. Do you need two to protect the typical 240 V
>> US service, or does one unit protect both sides? It sounds as though
>> you only need one -- but you mention having two.
>
> It's one per branch circuit, so if a sufficiently large hit shorts the
> protector, the branch breaker will pop.
O.K. That means that I will have a few more to buy, once I
trace down where the power is coming from to the critical outlets.
>
>> And where is it mounted? It looks as though you poke the wires
>> in through a knockout and route the wires to the incoming power point --
>> perhaps after the main breaker so you can shut off while you connect.
>> :-) Is it intended to be visible so you can easily detect if it has been
>> hit hard enough to take it out of service?
>
> As you surmise, they are mounted to the panel using knockouts, but they
> are wired to branch circuits, not directly to the bus bars.
O.K.
[ ... ]
> Well, I haven't worried about outages, so long as the equipment isn't
> damaged. The power here has been pretty reliable.
Running servers, I try to keep them up 24/7.
One of the web based comics which I follow "Schlock Mercenary"
got hit bad. A transformer in the data center's power room blew, taking
out three of the four walls. Luckily, nobody was near at the time.
[ ... ]
>> They sound a like a good idea for the things which I can't hang
>> on the UPS. The two client computers (my wife's and mine), and the two
>> laser printers (you really don't want a fuser hung on the UPS. :-)
>
> Don't forget TVs and stereos. I have them protected as well, as they
> can be expensive.
Well ... the TV is scheduled for replacement anyway. It still
works, but has a "warm-up" time until it gets the tuner locked in to the
cable box. And the broadcast signals are going digital soon enough
anyway, so it is time to pick up something new.
>
>> Anyway -- the power went down just as we were leaving for a
>> get-together with someone from out of the area -- so we had to trust to
>> the UPS and its software to shut the computers down cleanly. Apparently
>> they worked as desired.
>
> So far, Macs have been pretty successful in shutting themselves off
> gracefully when the power fails.
I have *one* Mac -- an Intel based Mac Mini. The rest of the
machines are mostly Sun Workstations and servers, with one in the shop
which is an Intel box ("Shuttle" small computer) with OpenBSD installed.
Some of the Suns are running OpenBSD as well -- the rest a mix of
Solaris 2.6 and Solaris 10.
Enjoy,
DoN.
--
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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Posted by DoN. Nichols on June 4, 2008, 1:36 am
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[ ... ]
> Ah. I have two grinders, one the sad-sack Rypobi, the other a perfectly
> competent HF knockoff of a Baldor carbide tool grinder.
>
> Ryobi: <http://www.homediscussion.com/showthread.php?t=173029>.
>
> HF:
><http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=46727>
Aha! -- I can trim a lot of what follows then.
I note that it claims to be good for both Carbide and HSS. I
presume that this means that it does not come with diamond wheels, since
diamond does *not* like high speed grinding of ferrous metals.
[ ... ]
>> >> > Actually, are plated diamond wheels likely to burst at all? Aren't they
>> >> > made of metal?
>> >>
>> >> But you thinned the housing to fit a stone, not a diamond wheel
>> >> from what I read above.
>> >
>> > True, but how is that relevant to the question?
>>
>> You asked whether the diamond wheels were likely to burst, and I
>> was pointing out that my worry was because *you* intended to put stone
>> wheels in it -- not the diamond one.
>
> The diamond wheel would be only for the HF unit, and should fit without
> fiddling, although I may have to sculpt the blade guard a bit.
O.K.
[ ... ]
>> > I'm also hoping to motivate people to test and publish the results.
>>
>> You didn't *say* that until now -- assuming that anyone else is
>> still reading this thread. :-)
>
> I think there are a few diehards out there.
O.K. I hope so. But I find *myself* skipping re-reading what
I've posted. :-)
[ ... ]
>> But I feel that there will be more give on a bar parallel to the
>> ways, which will represent the off-center load from a tool on the
>> quick-change toolpost. Your right-angles measurement would be more
>> meaningful for tools in a lantern style toolpost -- which is also
>> probably what the Clausing test cut was done with originally.
>
> It's plausible that there will be more give if the toolpost is rocked
> side-to-side (parallel to the bed ways), versus to-and-fro. But I'll
> try to measure this today.
>
>
>> > I have also done the test with a shorter bar parallel to the bed ways.
>> > For this, I removed the tailstock so the bar could project out off the
>> > end of the bed, with the weight dangling just beyond the end.
>>
>> O.K. My bed is shorter (only 24" between centers), and there is
>> a weird table right off the end of the bed to accept the bed turret, so
>> I don't have to lift it. It would be a major hassle to try to measure
>> that on my lathe -- even assuming that I had a 6-foot 1" steel bar,
>> which I don't. The 6' 416 SS rod has long since been cut shorter as it
>> has been used in projects. The same for the 6' of 1" diameter aluminum.
>
> A 3' aluminum bar 1" in diameter would probably work well enough, as
> would a thicker bar with a 1" diameter stub machined into it to allow
> clamping in the boring bar holder. I used the 6' bar held in the middle
> to balance the weight of the steel bar, but aluminum is a bit lighter.
I don't want to waste larger aluminum by turning a stub on what
is intended as working stock. :-) (Of course, my larger aluminum is
something like 3" diameter -- and not long enough for a good test
anyway. :-)
[ ... ]
>> > What is reported above is the perpendicular-to-bedway value. I will
>> > repeat the parallel-to-bedway test.
>>
>> O.K. I think that will show a greater deflection.
>
> Seems plausible.
I'll await the results -- but not with bated breath. :-)
[ ... ]
>> This sounds strange. Where is the cylindrical sleeve in all of
>> this?
>
> The sleeve goes in the bar holder. The Criterion model numbers are
> SBT-250A and ABT-250A:
><http://www.criterionmachineworks.com/Catalog/brazed%20carbide.htm>.
O.K.
> A better picture of how they are constructed is here, upper right
> diagram: <http://www.criterionmachineworks.com/Catalog/micrograin.htm>.
>
> I got them used for $1.00 each, but they look perfect to me. No idea
> why they were excessed.
That sounds like a good price.
>> What I was trying to describe is similar to this (but smaller):
>>
>> ebay # 250252780188
>>
>> unfortunately, the part where the inserts mount is covered in wax in the
>> photos.
>
> This one uses inserts, whereas the boring tool bits I have are solid.
> But I see that the insert bar is made by Circle, and I've seen them in
> catalogs.
By Circle, and by Kennametal, depending on your luck. Both are
good.
[ ... ]
>> > Those are real scientific scales. Perhaps a bit fussy for cooking,
>> > though.
>>
>> Especially with a wife who prefers to toss in unmeasured amounts
>> which "look right". I can't complain about the results, however.
>>
>> But she did get min pink stone mortar and pestle set. :-(
>
> What triggered her annexation of my utility scale was the reading of
> French and Italian cookbooks, which universally specify quantities by
> weight, not by volume. Not that I in the slightest protested the
> annexation, as this act of unprovoked aggression inured to my benefit.
Understood. If I were still mixing photochemicals, I might
object, but otherwise, no. :-)
[ ... ]
>> >> Mine may not be truly equivalent, since mine has three belts
>> >> applying stress to the side of the shaft. But I get what feels like a
>> >> 3:1 or perhaps 4:1 ratio of starting force vs moving force. It pegged
>> >> the force gage which I was able to find -- at about 1.5 KG applied at a
>> >> point 3.125" from the center (on a chuck jaw at the OD of a 6-1/4"
>> >> chuck.)
>> >
>> > Ah! That sounds exactly how it now feels like when turning the spindle
>> > by hand. It sounds like I did not over-tighten it.
>>
>> O.K. Note that when I had the spindle out to change belts, I
>> tightened it until it fit the manual's spin test. But after using it a
>> while, it developed chatter. I had to go back, overtighten the collar
>> on the back, and then loosen it and re-tighten it after I had set the
>> bearings properly. :-)
>
> Hmm. I may have to do much the same, as the spindle bearing was
> probably too loose for years, and may need to re-adjust to its new
> circumstances.
Perhaps -- but I think that I simply didn't pre-tighten over the
spin test point, when I should have. A bit of use pushed the bearings
deeper into their mounts.
>> >> The heavier force gauge has gone into hiding for the moment. I
>> >> last used it to check the match of a newly purchased clock weight to the
>> >> original one (time was still there, gong was missing, but I remembered
>> >> them as being the same dimensions.)
>> >
>> > Use a fish scale and a cord?
>>
>> A good idea -- if I had a fish scale. Since I don't go fishing,
>> that isn't one of the things around here. :-
>
> But fish scales are easily obtained, and cheap.
Not on Sunday evening when I'm sitting here typing away. I'll
go down to check something in the shop which does not take too much
time, but I will not go out hunting for a store which is still open at
1:00 AM. :-)
[ ... ]
>> >> That sounds as though it would work -- other than eliminating
>> >> the finest of the control -- but you don't need that fine a control. ;-)
>> >
>> > A 10K wirewound will use *very* fine wire.
>>
>> Thus making it easier to fry the wire near the bottom setting.
>
> Yes. I plan to measure the wiper current the control circuit imposes.
O.K.
> But even fine resistance wire is far more robust than thin carbon film
> on epoxy.
Or on phenolic, as they used to be made.
> Resistance wire is usually a form of nichrome.
Yep.
> One problem is that many datasheets fail to specify a maximum wiper
> current.
Figure the maximum current total for the wiper and the upper
terminal to be defined by the resistance and the voltage needed to get
the maximum power. As you are pumping more current into the full
resistance, you can draw/source less from/to the wiper.
[ ... ]
>> > In the IR, lenses can be machined with a diamond point. But in the
>> > visible, lapping is required. Except for molded lenses. But this only
>> > makes the lapping once removed - one laps the mold.
>>
>> The lenses which I have used in the deep IR were made from
>> either silicon or germanium -- neither of which would turn very nicely,
>> even with a diamond. They are very brittle substances.
>
> I have read of such substances, and even glass, being machined with a
> diamond point. The trick is to take a very shallow cut at very high
> speed, so the material acts ductile. Brittle materials still have an
> elastic range, albeit a short range. I recall seeing a micrograph of
> the cut made by such a tool in glass: as the tool dug deeper, there was
> a smooth-sided groove that abruptly transitioned into a rough-sided
> scratch at some critical (and microscopic) depth of cut.
O.K. I don't think that I will try that with my PCD inserts,
even once I get a holder for them. :-)
[ ... ]
>> > Stay away from warships. A 5' zip Chinese female colleague of mine told
>> > me how she rung her bell a few times while installing systems in US Navy
>> > ships. This was a great surprise to her - she is not at all used to
>> > running out of headroom.
>>
>> Which is *why* she is more vulnerable. Taller people are
>> accustomed to checking for head clearance. (Of course your friend is
>> still taller than my wife. :-)
>
> Yes, it never occurred to her. Until the day.
>
> (Sounds serious. So, the wife hits her head on the chip pan while
> running under the lathe?)
Not likely, because there is a shelf between the pedestals, I
think designed to hold the sump and pump.
[ ... ]
>> > So far, I have not had such dramas.
>>
>> Perhaps you are more in the city, instead of in the suburbs
>> where there are more exposed wires to be hit by lightning or falling
>> trees. (More trees available for that matter. :-)
>
> We have no shortage of trees here, and they are forever falling on
> things. But they quickly grow back.
Hmm ... if they grow back quickly, they are probably not the
heavy oaks which we have -- running 80' to 100' tall. When those fall,
they do some damage to whatever they hit.
> Our power is more reliable for a non-technical reason - the town owns
> the electric distribution system, and seems to do a pretty good job of
> keeping it maintained.
Is the power also mostly underground? That makes a difference.
>
>> >> I am temped by the FIOS fiber optics -- but until they can offer
>> >> me things like a Class-C static IP block, I won't play. I'm not that
>> >> interested in the cable service which they are pushing, and I like the
>> >> copper-based phone system still -- it keeps working during a five-hour
>> >> power outage. I'm not sure how long the charge on the FIOS battery
>> >> backup will last.
>> >
>> > They are pushing FiOS up here as well, but I doubt that they are quite
>> > ready for prime time. And, if you get FiOS, they tear the copper line
>> > out, thus burning the bridges. So, maybe in ten years.
>>
>> If I get FIOS, it will be *purely* a net feed -- meeting my
>> requirements. The phone service will remain copper for as long as I can
>> manage it.
>
> Read the fine print, for sure. They really want to be rid of copper.
> Nor can one negotiate with a company the size of Verizon, so the
> agreement will prove to be immutable (except at Verizon's whim).
If I get FIOS *only* as a net feed, not as a phone, how can they
rip out the copper for the phone? I can understand them ripping out the
copper for the T1 once it is replaced -- but I've got two T1s (one
retired) and one phone in a six-pair copper wire buried from the street
to the house. Ripping up the T1 copper would get the phone as well, and
I will *not* be buying FIOS phone service for some time -- especially
with the prices going *up* instead of down. :-)
>
>> [ ... ]
>>
>> >> That looks good. Do you need two to protect the typical 240 V
>> >> US service, or does one unit protect both sides? It sounds as though
>> >> you only need one -- but you mention having two.
>> >
>> > It's one per branch circuit, so if a sufficiently large hit shorts the
>> > protector, the branch breaker will pop.
>>
>> O.K. That means that I will have a few more to buy, once I
>> trace down where the power is coming from to the critical outlets.
>
> There may be bigger units available, that can be hooked to the bus bars
> (but after the main breakers).
The individual ones will do -- but I'll have to cut away some
drywall to gain access to the mounting points. :-) It will give me a
chance to put in an extra (nearer) 240V outlet for the lathe, and a
spare 120V one with a switch for the compressor.
[ ... ]
>> Well ... the TV is scheduled for replacement anyway. It still
>> works, but has a "warm-up" time until it gets the tuner locked in to the
>> cable box. And the broadcast signals are going digital soon enough
>> anyway, so it is time to pick up something new.
>
> Yep. But if you have cable, analog signals will still be available.
> It's over-the-air analog signals that will disappear.
Yes -- but the news programs are playing nasty teasing tricks
with the digital format -- the weather reporter pointing past the edge
of the screen and saying "And for those of you who have digital, you can
see the likely tornado clouds out here".
>> >> Anyway -- the power went down just as we were leaving for a
>> >> get-together with someone from out of the area -- so we had to trust to
>> >> the UPS and its software to shut the computers down cleanly. Apparently
>> >> they worked as desired.
>> >
>> > So far, Macs have been pretty successful in shutting themselves off
>> > gracefully when the power fails.
>>
>> I have *one* Mac -- an Intel based Mac Mini. The rest of the
>> machines are mostly Sun Workstations and servers, with one in the shop
>> which is an Intel box ("Shuttle" small computer) with OpenBSD installed.
>> Some of the Suns are running OpenBSD as well -- the rest a mix of
>> Solaris 2.6 and Solaris 10.
>
> Well, the solution is obvious - simplify your life by replacing that
> cat-and-dog collection with Macs.
When they will do all that *I* want -- maybe. But they won't be
Macs then, since I don't like the Mac GUI. I like running arrays of
Fibre Channel drives as RAID arrays using Sun's ZFS (more reliable than
standard RAID), and I run web servers, mail servers, file servers and
other things -- plus a lot of limiting of access for other ports. I
know how to turn off more services on a Mac than I do on Windows, but I
still know more in detail about the Sun boxen, thank you.
And the Sun boxen are also very good at recovering from an
unplanned outage -- which is why I don't bother with a UPS for the
machines which my wife and I use -- just for the servers. It is amazing
how well the ZFS raidz2 arrays deal with outages -- or failed drives.
Enjoy,
DoN.
--
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
|
|
Posted by Joseph Gwinn on June 4, 2008, 11:04 am
Please log in for more thread options
>
> [ ... ]
>
> > Ah. I have two grinders, one the sad-sack Rypobi, the other a perfectly
> > competent HF knockoff of a Baldor carbide tool grinder.
> >
> > Ryobi: <http://www.homediscussion.com/showthread.php?t=173029>.
> >
> > HF:
> ><http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=46727>
>
> Aha! -- I can trim a lot of what follows then.
>
> I note that it claims to be good for both Carbide and HSS. I
> presume that this means that it does not come with diamond wheels, since
> diamond does *not* like high speed grinding of ferrous metals.
The HF 46727 tool grinder came with two plate-mounted 6" mystery gray
wheels that I presume to be silicon carbide. I replaced one wheel with
a white aluminum oxide wheel for HSS, which didn't fit until I sculpted
the wheel guard a bit.
> [ ... ]
>
> >> > I'm also hoping to motivate people to test and publish the results.
> >>
> >> You didn't *say* that until now -- assuming that anyone else is
> >> still reading this thread. :-)
> >
> > I think there are a few diehards out there.
>
> O.K. I hope so. But I find *myself* skipping re-reading what
> I've posted. :-)
Likewise.
I've posted my findings in a separate thread. And there was a discovery
- the front hold-down plates were worn, and had never been adjusted,
allowing the carriage to lift off the front bed way rail under
sufficiently large cutting force.
> [ ... ]
>
> >> But I feel that there will be more give on a bar parallel to the
> >> ways, which will represent the off-center load from a tool on the
> >> quick-change toolpost. Your right-angles measurement would be more
> >> meaningful for tools in a lantern style toolpost -- which is also
> >> probably what the Clausing test cut was done with originally.
> >
> > It's plausible that there will be more give if the toolpost is rocked
> > side-to-side (parallel to the bed ways), versus to-and-fro. But I'll
> > try to measure this today.
> >
> >
> >> > I have also done the test with a shorter bar parallel to the bed ways.
> >> > For this, I removed the tailstock so the bar could project out off the
> >> > end of the bed, with the weight dangling just beyond the end.
> >>
> >> O.K. My bed is shorter (only 24" between centers), and there is
> >> a weird table right off the end of the bed to accept the bed turret, so
> >> I don't have to lift it. It would be a major hassle to try to measure
> >> that on my lathe -- even assuming that I had a 6-foot 1" steel bar,
> >> which I don't. The 6' 416 SS rod has long since been cut shorter as it
> >> has been used in projects. The same for the 6' of 1" diameter aluminum.
> >
> > A 3' aluminum bar 1" in diameter would probably work well enough, as
> > would a thicker bar with a 1" diameter stub machined into it to allow
> > clamping in the boring bar holder. I used the 6' bar held in the middle
> > to balance the weight of the steel bar, but aluminum is a bit lighter.
>
> I don't want to waste larger aluminum by turning a stub on what
> is intended as working stock. :-) (Of course, my larger aluminum is
> something like 3" diameter -- and not long enough for a good test
> anyway. :-)
Ah, well, a suitable steel bar will no doubt turn up one day. It's not
as though we are strangers to steel.
> [ ... ]
>
> >> > What is reported above is the perpendicular-to-bedway value. I will
> >> > repeat the parallel-to-bedway test.
> >>
> >> O.K. I think that will show a greater deflection.
> >
> > Seems plausible.
>
> I'll await the results -- but not with bated breath. :-)
The crosswise stiffness and longitudinal stiffness turned out to be
about the same. On reflection, I guess that Clausing would have to
design the stiffnesses to be roughly equal, or the lathe would be unable
to do both cylinder turning and face turning equally well. One
consequence is that the footprint of the carriage is almost square.
> [ ... ]
>
> > A better picture of how they are constructed is here, upper right
> > diagram: <http://www.criterionmachineworks.com/Catalog/micrograin.htm>.
> >
> > I got them used for $1.00 each, but they look perfect to me. No idea
> > why they were excessed.
>
> That sounds like a good price.
I thought so too. Nor did I want to be learning just how hard I can
push things using $40 tool bits.
> [ ... ]
>
> >> >> Mine may not be truly equivalent, since mine has three belts
> >> >> applying stress to the side of the shaft. But I get what feels like a
> >> >> 3:1 or perhaps 4:1 ratio of starting force vs moving force. It pegged
> >> >> the force gage which I was able to find -- at about 1.5 KG applied at a
> >> >> point 3.125" from the center (on a chuck jaw at the OD of a 6-1/4"
> >> >> chuck.)
> >> >
> >> > Ah! That sounds exactly how it now feels like when turning the spindle
> >> > by hand. It sounds like I did not over-tighten it.
> >>
> >> O.K. Note that when I had the spindle out to change belts, I
> >> tightened it until it fit the manual's spin test. But after using it a
> >> while, it developed chatter. I had to go back, overtighten the collar
> >> on the back, and then loosen it and re-tighten it after I had set the
> >> bearings properly. :-)
> >
> > Hmm. I may have to do much the same, as the spindle bearing was
> > probably too loose for years, and may need to re-adjust to its new
> > circumstances.
>
> Perhaps -- but I think that I simply didn't pre-tighten over the
> spin test point, when I should have. A bit of use pushed the bearings
> deeper into their mounts.
I perhaps may see the same effect. The bearings in my 5914 may well
have walked a tad out of their mounts, and will now walk right back,
under pressure.
> >> >> The heavier force gauge has gone into hiding for the moment. I
> >> >> last used it to check the match of a newly purchased clock weight to the
> >> >> original one (time was still there, gong was missing, but I remembered
> >> >> them as being the same dimensions.)
> >> >
> >> > Use a fish scale and a cord?
> >>
> >> A good idea -- if I had a fish scale. Since I don't go fishing,
> >> that isn't one of the things around here. :-
> >
> > But fish scales are easily obtained, and cheap.
>
> Not on Sunday evening when I'm sitting here typing away. I'll
> go down to check something in the shop which does not take too much
> time, but I will not go out hunting for a store which is still open at
> 1:00 AM. :-)
There must be shops for night fishermen.
> [ ... ]
>
> > One problem is that many datasheets fail to specify a maximum wiper
> > current.
>
> Figure the maximum current total for the wiper and the upper
> terminal to be defined by the resistance and the voltage needed to get
> the maximum power. As you are pumping more current into the full
> resistance, you can draw/source less from/to the wiper.
And use the smallest allowed pot resistance. The problem with the power
feed speed control pot is that I have no idea what resistance values are
allowed, so I'll just have to brute-force it.
> [ ... ]
>
> >> > In the IR, lenses can be machined with a diamond point. But in the
> >> > visible, lapping is required. Except for molded lenses. But this only
> >> > makes the lapping once removed - one laps the mold.
> >>
> >> The lenses which I have used in the deep IR were made from
> >> either silicon or germanium -- neither of which would turn very nicely,
> >> even with a diamond. They are very brittle substances.
> >
> > I have read of such substances, and even glass, being machined with a
> > diamond point. The trick is to take a very shallow cut at very high
> > speed, so the material acts ductile. Brittle materials still have an
> > elastic range, albeit a short range. I recall seeing a micrograph of
> > the cut made by such a tool in glass: as the tool dug deeper, there was
> > a smooth-sided groove that abruptly transitioned into a rough-sided
> > scratch at some critical (and microscopic) depth of cut.
>
> O.K. I don't think that I will try that with my PCD inserts,
> even once I get a holder for them. :-)
Yes. Nor do I think that any standard lathe is both fast enough
(spindle speed) and deft enough to achieve ductile machining of glass.
Here is an interesting presentation:
<http://unit.aist.go.jp/amri/group/finemfg/ogu/postersession1.pdf>
<http://unit.aist.go.jp/amri/group/finemfg/ogu/postersession2.pdf>
If memory serves, I first read about ductile machining of brittle
materials in a book on precision machinery.
> [ ... ]
>
> >> > So far, I have not had such dramas.
> >>
> >> Perhaps you are more in the city, instead of in the suburbs
> >> where there are more exposed wires to be hit by lightning or falling
> >> trees. (More trees available for that matter. :-)
> >
> > We have no shortage of trees here, and they are forever falling on
> > things. But they quickly grow back.
>
> Hmm ... if they grow back quickly, they are probably not the
> heavy oaks which we have -- running 80' to 100' tall. When those fall,
> they do some damage to whatever they hit.
Maples can grow quite rapidly, but fall hard. We are always having
trees trimmed or even removed, precisely to protect things, and for
looks.
> > Our power is more reliable for a non-technical reason - the town owns
> > the electric distribution system, and seems to do a pretty good job of
> > keeping it maintained.
>
> Is the power also mostly underground? That makes a difference.
No, it's mostly standard poles and hanging wires, although the feed from
street pole to my house is buried.
> >> >> I am temped by the FIOS fiber optics -- but until they can offer
> >> >> me things like a Class-C static IP block, I won't play. I'm not that
> >> >> interested in the cable service which they are pushing, and I like the
> >> >> copper-based phone system still -- it keeps working during a five-hour
> >> >> power outage. I'm not sure how long the charge on the FIOS battery
> >> >> backup will last.
> >> >
> >> > They are pushing FiOS up here as well, but I doubt that they are quite
> >> > ready for prime time. And, if you get FiOS, they tear the copper line
> >> > out, thus burning the bridges. So, maybe in ten years.
> >>
> >> If I get FIOS, it will be *purely* a net feed -- meeting my
> >> requirements. The phone service will remain copper for as long as I can
> >> manage it.
> >
> > Read the fine print, for sure. They really want to be rid of copper.
> > Nor can one negotiate with a company the size of Verizon, so the
> > agreement will prove to be immutable (except at Verizon's whim).
>
> If I get FIOS *only* as a net feed, not as a phone, how can they
> rip out the copper for the phone? I can understand them ripping out the
> copper for the T1 once it is replaced -- but I've got two T1s (one
> retired) and one phone in a six-pair copper wire buried from the street
> to the house. Ripping up the T1 copper would get the phone as well, and
> I will *not* be buying FIOS phone service for some time -- especially
> with the prices going *up* instead of down. :-)
OK. But I'm wary, and they have been pushing FiOS around here, and the
war stories are circulating at work.
The good news is that we are at last beginning to get some competition
between COMCAST and Verizion. They are monopolies now, and it shows.
One of the major developments of the present day is that the advance of
technology has caused many of what had been natural monopolies to become
ordinary competitive markets, with telephones and cable being the
example du jour.
> >> [ ... ]
> >>
> >> >> That looks good. Do you need two to protect the typical 240 V
> >> >> US service, or does one unit protect both sides? It sounds as though
> >> >> you only need one -- but you mention having two.
> >> >
> >> > It's one per branch circuit, so if a sufficiently large hit shorts the
> >> > protector, the branch breaker will pop.
> >>
> >> O.K. That means that I will have a few more to buy, once I
> >> trace down where the power is coming from to the critical outlets.
> >
> > There may be bigger units available, that can be hooked to the bus bars
> > (but after the main breakers).
>
> The individual ones will do -- but I'll have to cut away some
> drywall to gain access to the mounting points. :-) It will give me a
> chance to put in an extra (nearer) 240V outlet for the lathe, and a
> spare 120V one with a switch for the compressor.
I don't know if it's needed, but if so this might be the best time to
replace the power panel itself.
> [ ... ]
>
> >> Well ... the TV is scheduled for replacement anyway. It still
> >> works, but has a "warm-up" time until it gets the tuner locked in to the
> >> cable box. And the broadcast signals are going digital soon enough
> >> anyway, so it is time to pick up something new.
> >
> > Yep. But if you have cable, analog signals will still be available.
> > It's over-the-air analog signals that will disappear.
>
> Yes -- but the news programs are playing nasty teasing tricks
> with the digital format -- the weather reporter pointing past the edge
> of the screen and saying "And for those of you who have digital, you can
> see the likely tornado clouds out here".
If it's that far off-screen, it's someone else's problem? Hmm. Unless
one's town is also always off screen.
> >> >> Anyway -- the power went down just as we were leaving for a
> >> >> get-together with someone from out of the area -- so we had to trust to
> >> >> the UPS and its software to shut the computers down cleanly.
> >> >> Apparently they worked as desired.
> >> >
> >> > So far, Macs have been pretty successful in shutting themselves off
> >> > gracefully when the power fails.
> >>
> >> I have *one* Mac -- an Intel based Mac Mini. The rest of the
> >> machines are mostly Sun Workstations and servers, with one in the shop
> >> which is an Intel box ("Shuttle" small computer) with OpenBSD installed.
> >> Some of the Suns are running OpenBSD as well -- the rest a mix of
> >> Solaris 2.6 and Solaris 10.
> >
> > Well, the solution is obvious - simplify your life by replacing that
> > cat-and-dog collection with Macs.
>
> When they will do all that *I* want -- maybe. But they won't be
> Macs then, since I don't like the Mac GUI. I like running arrays of
> Fibre Channel drives as RAID arrays using Sun's ZFS (more reliable than
> standard RAID), and I run web servers, mail servers, file servers and
> other things -- plus a lot of limiting of access for other ports. I
> know how to turn off more services on a Mac than I do on Windows, but I
> still know more in detail about the Sun boxen, thank you.
>
> And the Sun boxen are also very good at recovering from an
> unplanned outage -- which is why I don't bother with a UPS for the
> machines which my wife and I use -- just for the servers. It is amazing
> how well the ZFS raidz2 arrays deal with outages -- or failed drives.
Yeah, Sun does make good stuff. But it's still a menagerie there.
As for the Mac GUI, you can bypass that and use the command line for
many things. BSD lurks, hiding under the eye candy.
Joe Gwinn
|
|
Posted by DoN. Nichols on June 5, 2008, 10:01 pm
Please log in for more thread options >
[ ... ]
>> I note that it claims to be good for both Carbide and HSS. I
>> presume that this means that it does not come with diamond wheels, since
>> diamond does *not* like high speed grinding of ferrous metals.
>
> The HF 46727 tool grinder came with two plate-mounted 6" mystery gray
> wheels that I presume to be silicon carbide. I replaced one wheel with
> a white aluminum oxide wheel for HSS, which didn't fit until I sculpted
> the wheel guard a bit.
O.K. so those wheels will work on HSS -- but the diamond one
should not be so used.
[ ... ]
>> > I think there are a few diehards out there.
>>
>> O.K. I hope so. But I find *myself* skipping re-reading what
>> I've posted. :-)
>
> Likewise.
:-)
> I've posted my findings in a separate thread. And there was a discovery
> - the front hold-down plates were worn, and had never been adjusted,
> allowing the carriage to lift off the front bed way rail under
> sufficiently large cutting force.
O.K. I'll be zapping a lot because I just went through 24 hours
without power -- after a tornado wandered past a couple of blocks from
my house. :-( Not much sleep, because power came back around 3:30 AM, I
got ready to bring the systems back up, and it went down again. Power
returned again about 5:30 AM, and I got all the systems up and all the
windows logged into them all (40+ windows, most of which require
username and password to access other systems -- especially the ones
with me logged in as root to administer the machines).
And then, about 11:30 (just before I was going to get up and
start catching up on email and such) the power started playing yo-yo
again (one second on, BZAAAPPP BOOM, five seconds off, rinse and repeat)
and finally the lines gave up and let the UPS run out of battery reserve
again and shut everything down cleanly. Power finally was restored at
3:30 PM -- and one glitch just long enough to reset my desktop machine
before I got too far into my logins.
No bets what will happen in the next few days. :-(
But I was finally able to get some SPL readings:
Everything off: 44 dB C scale
Servers only: 58 dB C scale
Add clients and their disks: 60 dB C scale
(before shutting down the 12 older drives, and adding some foam rubber
to reduce the bouncing sound off the walls behind the computers and
disks.
[ ... ]
>> I'll await the results -- but not with bated breath. :-)
>
> The crosswise stiffness and longitudinal stiffness turned out to be
> about the same. On reflection, I guess that Clausing would have to
> design the stiffnesses to be roughly equal, or the lathe would be unable
> to do both cylinder turning and face turning equally well. One
> consequence is that the footprint of the carriage is almost square.
O.K. This says that the cross-slide dovetails and gibs are in
better shape than was feared. That is where I would have expected the
give.
>
>> [ ... ]
>>
>> > A better picture of how they are constructed is here, upper right
>> > diagram: <http://www.criterionmachineworks.com/Catalog/micrograin.htm>.
>> >
>> > I got them used for $1.00 each, but they look perfect to me. No idea
>> > why they were excessed.
>>
>> That sounds like a good price.
>
> I thought so too. Nor did I want to be learning just how hard I can
> push things using $40 tool bits.
Indeed -- though you may still not know how hard you can push a
real $40.00 tool bit. :-)
[ ... ]
>> >> O.K. Note that when I had the spindle out to change belts, I
>> >> tightened it until it fit the manual's spin test. But after using it a
>> >> while, it developed chatter. I had to go back, overtighten the collar
>> >> on the back, and then loosen it and re-tighten it after I had set the
>> >> bearings properly. :-)
>> >
>> > Hmm. I may have to do much the same, as the spindle bearing was
>> > probably too loose for years, and may need to re-adjust to its new
>> > circumstances.
>>
>> Perhaps -- but I think that I simply didn't pre-tighten over the
>> spin test point, when I should have. A bit of use pushed the bearings
>> deeper into their mounts.
>
> I perhaps may see the same effect. The bearings in my 5914 may well
> have walked a tad out of their mounts, and will now walk right back,
> under pressure.
O.K. At least you know to watch for that problem. The main
trick seems to be to over-tighten the nut, back it off, and then tighten
to the desired spin test.
[ ... ]
>> > But fish scales are easily obtained, and cheap.
>>
>> Not on Sunday evening when I'm sitting here typing away. I'll
>> go down to check something in the shop which does not take too much
>> time, but I will not go out hunting for a store which is still open at
>> 1:00 AM. :-)
>
> There must be shops for night fishermen.
Maybe -- but since I don't fish -- night or day -- I don't know
where they are. And I would not want to east anything caught in the
Potomac river. :-)
>
>> [ ... ]
>>
>> > One problem is that many datasheets fail to specify a maximum wiper
>> > current.
>>
>> Figure the maximum current total for the wiper and the upper
>> terminal to be defined by the resistance and the voltage needed to get
>> the maximum power. As you are pumping more current into the full
>> resistance, you can draw/source less from/to the wiper.
>
> And use the smallest allowed pot resistance. The problem with the power
> feed speed control pot is that I have no idea what resistance values are
> allowed, so I'll just have to brute-force it.
Or an active double-ended emitter follower so the current from
the wiper is a lot less than what the controller requires.
[ ... ]
>> > I have read of such substances, and even glass, being machined with a
>> > diamond point. The trick is to take a very shallow cut at very high
>> > speed, so the material acts ductile. Brittle materials still have an
>> > elastic range, albeit a short range. I recall seeing a micrograph of
>> > the cut made by such a tool in glass: as the tool dug deeper, there was
>> > a smooth-sided groove that abruptly transitioned into a rough-sided
>> > scratch at some critical (and microscopic) depth of cut.
>>
>> O.K. I don't think that I will try that with my PCD inserts,
>> even once I get a holder for them. :-)
>
> Yes. Nor do I think that any standard lathe is both fast enough
> (spindle speed) and deft enough to achieve ductile machining of glass.
:-)
Well ... the Taig can reach really scary speeds with the little
3" or 4" chucks. :-)
>
> Here is an interesting presentation:
>
><http://unit.aist.go.jp/amri/group/finemfg/ogu/postersession1.pdf>
>
><http://unit.aist.go.jp/amri/group/finemfg/ogu/postersession2.pdf>
>
>
> If memory serves, I first read about ductile machining of brittle
> materials in a book on precision machinery.
I'm too tired to download and read that now -- and I've got too
much newsgroup to catch up with. Something like 650 articles in
rec.crafts.metalworking, down to about 250 after the killfile did its
job. Maybe more trimming as I find things to add to the killfile. :-)
But this comes up first (along with other threads in which I am
participating) thanks to the scoring feature of slrn.
[ ... ]
>> > We have no shortage of trees here, and they are forever falling on
>> > things. But they quickly grow back.
>>
>> Hmm ... if they grow back quickly, they are probably not the
>> heavy oaks which we have -- running 80' to 100' tall. When those fall,
>> they do some damage to whatever they hit.
>
> Maples can grow quite rapidly, but fall hard. We are always having
> trees trimmed or even removed, precisely to protect things, and for
> looks.
Maryland gets it worse than Virginia because the power company
is not allowed to trim trees which threaten the power lines -- and then
they get blamed for all of the power outages.
Here we may have people without power for another 24 hours, so
we got off better than some. And at least without power, while we lose
the air conditioning, we also lose the heat contributions of nine
computers and 53 disk drives (until I get through transferring the
contents of 12 older drives to a RAID array of six drives plus a spare
146 GB Fibre Channel drive to play with for big things.
>> > Our power is more reliable for a non-technical reason - the town owns
>> > the electric distribution system, and seems to do a pretty good job of
>> > keeping it maintained.
>>
>> Is the power also mostly underground? That makes a difference.
>
> No, it's mostly standard poles and hanging wires, although the feed from
> street pole to my house is buried.
Maybe the trees are kept trimmed clear of threating the wires
where you are. Yesterday, after the first storm came through, and we
had no power, we went off to do some shopping, and I saw a *big* limb
hanging from a bunch of phone and cable TV cables between poles. And
judging by the leaves on that limb, it was at least 100 feet (and more
likely 300 feet) from the nearest tree of the same type. I don't want
to know how that limb got there. :-)
And we did lose someone -- a big tree fell on a passing pickup
truck about a couple of miles from here and killed the driver. The
wind also took the roof off a commercial building in that area.
[ ... ]
>> >> If I get FIOS, it will be *purely* a net feed -- meeting my
>> >> requirements. The phone service will remain copper for as long as I can
>> >> manage it.
>> >
>> > Read the fine print, for sure. They really want to be rid of copper.
>> > Nor can one negotiate with a company the size of Verizon, so the
>> > agreement will prove to be immutable (except at Verizon's whim).
>>
>> If I get FIOS *only* as a net feed, not as a phone, how can they
>> rip out the copper for the phone? I can understand them ripping out the
>> copper for the T1 once it is replaced -- but I've got two T1s (one
>> retired) and one phone in a six-pair copper wire buried from the street
>> to the house. Ripping up the T1 copper would get the phone as well, and
>> I will *not* be buying FIOS phone service for some time -- especially
>> with the prices going *up* instead of down. :-)
>
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