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Posted by DoN. Nichols on October 13, 2008, 6:00 pm
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> On Mon, 13 Oct 2008 16:00:36 +0000, the infamous Christopher Tidy
>
>>Larry Jaques wrote:
>>> On Sun, 12 Oct 2008 17:15:30 +0000, the infamous Christopher Tidy
[ ... ]
>>>>I never knew the space bar did that. I've always used "Page Down" and
>>>>"Page Up".
>>>>
>>>>I just figured out that backspace does the opposite, too. Cool!
>>>
>>>
>>> Hmm, it doesn't for me in Firefox. Backspace on a second or further
>>> page acts as a back button in the browser.
>>
>>Well it does on Firefox 2.0.0.3 for Solaris SPARC, which is what I'm using.
>
> Windows XP Home/FF 2.0.0.17 here. Does anyone else on a different
> platform find different behavior? Please pipe up.
I get page-up from backspace in Opera 9.60 on SPARC running
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 Steve Lusardi on September 16, 2008, 9:17 pm
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It is no big problem to remove the headstock and reinstall it, but the use
of a test bar is best for alignment. Machining a test bar indicates error
but not direction of error, where a proper predision test bar does. Most
hobbyists will not own one, but after having done this job using both
methods, the use of a test bar is much easier and more accurate. They can be
found on ebay from time to time. I now have a set of them.
Steve
>I was quoted about 400-500 dollars if I bring in my lathe bed, to have
> it reground. The bed is relatively worn (carriage drops about 0.002 inch
> near headstock), and the rest of the lathe is not.
>
> I am ending my ebay selling soon, so I will have some more time.
>
> If applying turcite and re-scraping the saddle is not too much, I will
> have them do it too. My thinking is that after this, I will have a
> lathe that is as good as a new one.
>
> My current question is, how hard is it to take the headstock off this
> clausing colchester master, and, no less important, how to align it
> again once I get the bed casting back home.
>
> --
> Due to extreme spam originating from Google Groups, and their
> inattention
> to spammers, I and many others block all articles originating
> from Google Groups. If you want your postings to be seen by
> more readers you will need to find a different means of
> posting on Usenet.
> http://improve-usenet.org/
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Posted by Terry Coombs on September 16, 2008, 10:10 pm
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Steve Lusardi wrote:
> It is no big problem to remove the headstock and reinstall it, but
> the use of a test bar is best for alignment. Machining a test bar
> indicates error but not direction of error, where a proper predision
> test bar does. Most hobbyists will not own one, but after having done
> this job using both methods, the use of a test bar is much easier and
> more accurate. They can be found on ebay from time to time. I now
> have a set of them. Steve
>
A description of your test bars , please ? Precision ground between
centers bar ?
--
Snag
I've learned a couple of ways to test accuracy , but always open for a new
idee !
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Posted by Jon Elson on September 17, 2008, 12:13 pm
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Terry Coombs wrote:
> Steve Lusardi wrote:
>> It is no big problem to remove the headstock and reinstall it, but
>> the use of a test bar is best for alignment. Machining a test bar
>> indicates error but not direction of error, where a proper predision
>> test bar does. Most hobbyists will not own one, but after having done
>> this job using both methods, the use of a test bar is much easier and
>> more accurate. They can be found on ebay from time to time. I now
>> have a set of them. Steve
>>
> A description of your test bars , please ? Precision ground between
> centers bar ?
Really, a piece of hardened and ground shafting (like Thompson glide
rails) works very well with the types of indicators the typical home
shop would have. There is a tiny bit of sag due to weight, but it isn't
real bad. The indicator with the lightest touch is best to avoid
deflecting the shaft. (Oh, you have to verify the straightness of the
shaft with indicator and surface plate, first. You can't assume any
shaft is straight.)
Jon
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Posted by Steve Lusardi on September 17, 2008, 4:40 pm
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Setting up a lathe is not high tech. You must be careful, keep everything
spotlessly clean and make multiple measurements with every step. Regrinding
the bed of a lathe rarely produces increased accuracy, but what it does do
is allow tight carraige adjustments which reduces chatter and adds overall
machine stiffness. This increases consistancy making every step more
repeatable. A worn out, loose lathe is capable of accuracy, but takes a lot
of patience and experience to do that. When you service a lathe bed, every
surface on the bed should be remachined to original specs. Any attempt to do
otherwise is a waste of money. For those folks that have never done this,
let me assure you that lathe beds look massive and enormously stiff, but
they are not. They can and do bend and twist quite easily. That is why the
bed leveling operation is so critical. Please do not misunderstand that
statement, a level lathe is NOT important. They are quite successfully
installed on ships. What is important, is bed straightness and reference to
a water level is nothing more that a common base line reference. All lathe
beds will twist with the weight of the carraige simply sliding across them.
A lathe carraige is not balanced. It is much heavier on the apron side and
when moved to the center between bed supports, will exert a twist as much as
.004" worst case. Contrary to popular opinion, this will not cause an
observable change to the dimensions of the cut because the position change
of the tool rotates about the bed center. This is the reason a worn bed does
not cause inaccuracy.
Head alignment does effect the lathe's accuracy. It is critical, so getting
the spindle line parallel to the lathe bed is the second step in setting up
a lathe. That is why a precision test bar is so important, because it easily
shows these position errors. Every spindle comes with a precisionly ground
inside cone. Typically it is a morse taper and the test bar seats there and
provides a spindle extension on which a simple dial indicator is placed. The
top of the bar has a ground flat which is positioned during testing,
parallel to the bed. Observed deviation is vertical head misalignment. When
the indicator is positioned 90 degrees away at the horizontal center any
deviation along the bar's length indicates horizontal deviation. This
deviation can be compensated with shims under the headstock.
These statements are verifyable with two tools, a precision machine level
and a test bar and if you don't have access to them, get access or buy them.
These are necessary to install a lathe, let alone repair one.
Steve
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