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Making tools to mend tools to make tools Mark Rand 04-16-2008
Posted by Mark Rand on April 16, 2008, 6:10 pm
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 Someone moaned about the amount of politics and calendars:-


I may have let slip (to the point of monotony) that I have been rebuilding an
Ebay basket case Hardinge HLV for the last 18 months.

At the start of March I started to work on improving the removable, hardened
dovetail way bed. Having removed the bed, I measured its thickness in a number
of places. The micrometer showed that there was at least 3.7 thou of wear. At
least, because the micrometer doesn't measure to the bottom of the roughness.

I could have sent the bed away to be reground. Trouble is that I'm cheap.
That's why I didn't just wait for a lathe to turn up in better condition to
start with...

I reasoned that I might be able to grind the bed on my £75 J&S 1400 grinder.

Because the bed is38" long and the table travel on the grinder is only 24",
the bed had to be ground in two sections. I got a bit of a visible furrow at
the point where the table stopped at the end of the cut in the middle of the
bed, but even after the roughing cuts, the bed thickness is now even to within
a couple of tenths outside of that narrow furrow, which the carriage will
ignore. I had to remove 6 thou to get rid of all of the wear marks.

Ok. That did for the thickness of the bed. Now I can think about the
dovetails. The dovetails have a 1/8" wide, unmachined, vertical section at the
top. I assume that I can measure from that to the dovetail on the opposite
side to get an indication of the wear.

While thinking of that, it was assumed that the way to grind the dovetails
would be to make a sine table. The old 6"x12" Humphrey's electromagnetic chuck
that I inherited off father could be pressed into use for that. A 15" long bit
of 1 1/4" square bar was milled into angle iron on the Myford and hinge pins
turned on the ends. A couple of lengths of 2" square were milled and ground
into L shapes for the sides. Holes could be bored in these for the hinge pins
before final grinding to get the height of the side at the exact level of the
bottom of the hinge pin. Something like this:-

|-----------------------------------|
| |
| |---| |
|-------|_______________________|___|_|
| /- | |/-|
| _/ |_________________________/___
| |
|______________________________________|

Boring the holes means that the boring head that I got some years ago needed
an adapter to fit the Myford headstock mandrel. Did that, got a set of taps
from RDG to finish the internal threads, having had problems with getting
these right before.

In the meantime, the junction box on the mag chuck needs sorting.The screws
holding it to the chuck have waled out heads and one of the screws holding the
cover on was sheared off before I was born by the look of it. No problem. Bit
of 3/8" silver steel for the cap head screws and 3/8" brass for the
countersunk screws. drill out the busted screw and run a 5/32"BSW tap down all
the holes to clean them up..

A jig had to be made to hold a tenths dial gauge at a variable, fixed height
and slide along the bed, measuring the variations in width. Just a bit of
sawing, milling, grinding, drilling, tapping and Loctiting. Job done.

The jig shows that the vertical bits at the top of the dovetails seem to be
parallel within a tenth, but that the dovetails have a reasonably steady 12
thou slope compared to the vertical bit. Bugger. The jig needs modifying so
that it can measure one dovetail against the opposite dovetail. If I make a
push tool to fit the boring head, I can use it with the Myford dividing head
to make a ball turning tool and make some ball ended pins to go on the jig to
bear against the dovetails. Haven't got any 1/2" round HSS. Never mind, make a
3/8" to 1/2" adapter to hold the 3/8" HSS that I've got.

To cut off the bit of round HSS to the right length, I can use one of the thin
cut off disks I got for the grinder. Bugger, the wheel arbours won't grip
something that thin. Never mind. Slice off a bit of 95mm bar and turn up a
spacer to fit the wheel arbour.




Now, What was it that I was trying to do...



Mark Rand
RTFM

Posted by Charles Ping on April 17, 2008, 4:52 am
Please log in for more thread options
> Someone moaned about the amount of politics and calendars:-
>
> I may have let slip (to the point of monotony) that I have been rebuilding=
an
> Ebay basket case Hardinge HLV for the last 18 months.
>
> At the start of March I started to work on improving the removable, harden=
ed
> dovetail way bed. Having removed the bed, I measured its thickness in a nu=
mber
> of places. The micrometer showed that there was at least 3.7 thou of wear.=
At
> least, because the micrometer doesn't measure to the bottom of the roughne=
ss.
>
> I could have sent the bed away to be reground. Trouble is that I'm cheap.
> That's why I didn't just wait for a lathe to turn up in better condition t=
o
> start with...
>
> I reasoned that I might be able to grind the bed on my =A375 J&S 1400 grin=
der.
>
> Because the bed is38" long and the table travel on the grinder is only 24"=
,
> the bed had to be ground in two sections. I got a bit of a visible furrow =
at
> the point where the table stopped at the end of the cut in the middle of t=
he
> bed, but even after the roughing cuts, the bed thickness is now even to wi=
thin
> a couple of tenths outside of that narrow furrow, which the carriage will
> ignore. I had to remove 6 thou to get rid of all of the wear marks.
>
> Ok. That did for the thickness of the bed. Now I can think about the
> dovetails. The dovetails have a 1/8" wide, unmachined, vertical section at=
the
> top. I assume that I can measure from that to the dovetail on the opposite=

> side to get an indication of the wear.
>
> While thinking of that, it was assumed that the way to grind the dovetails=

> would be to make a sine table. The old 6"x12" Humphrey's electromagnetic c=
huck
> that I inherited off father could be pressed into use for that. A 15" long=
bit
> of 1 1/4" square bar was milled into angle iron on the Myford and hinge pi=
ns
> turned on the ends. A couple of lengths of 2" square were milled and groun=
d
> into L shapes for the sides. Holes could be bored in these for the hinge p=
ins
> before final grinding to get the height of the side at the exact level of =
the
> bottom of the hinge pin. Something like this:-
>
> =A0 |-----------------------------------|
> =A0 | =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
|
> =A0 | =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 |---| |
> |-------|_______________________|___|_|
> | =A0/- =A0| =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 |/-|
> | =A0_/ =A0|_________________________/___
> | =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0|
> |______________________________________|
>
> Boring the holes means that the boring head that I got some years ago need=
ed
> an adapter to fit the Myford headstock mandrel. Did that, got a set of tap=
s
> from RDG to finish the internal threads, having had problems with getting
> these right before.
>
> In the meantime, the junction box on the mag chuck needs sorting.The screw=
s
> holding it to the chuck have waled out heads and one of the screws holding=
the
> cover on was sheared off before I was born by the look of it. No problem. =
Bit
> of 3/8" silver steel for the cap head screws and 3/8" brass for the
> countersunk screws. drill out the busted screw and run a 5/32"BSW tap down=
all
> the holes to clean them up..
>
> A jig had to be made to hold a tenths dial gauge at a variable, fixed heig=
ht
> and slide along the bed, measuring the variations in width. Just a bit of
> sawing, milling, grinding, drilling, tapping and Loctiting. Job done.
>
> The jig shows that the vertical bits at the top of the dovetails seem to b=
e
> parallel within =A0a tenth, but that the dovetails have a reasonably stead=
y 12
> thou slope compared to the vertical bit. Bugger. The jig needs modifying s=
o
> that it can measure one dovetail against the opposite dovetail. If I make =
a
> push tool to fit the boring head, I can use it with the Myford dividing he=
ad
> to make a ball turning tool and make some ball ended pins to go on the jig=
to
> bear against the dovetails. Haven't got any 1/2" round HSS. Never mind, ma=
ke a
> 3/8" to 1/2" adapter to hold the 3/8" HSS that I've got.
>
> To cut off the bit of round HSS to the right length, I can use one of the =
thin
> cut off disks I got for the grinder. Bugger, the wheel arbours won't grip
> something that thin. Never mind. Slice off a bit of 95mm bar and turn up a=

> spacer to fit the wheel arbour.
>
> Now, What was it that I was trying to do...
>
> Mark Rand
> RTFM

I like a workshop challenge as much as the next bloke who spends his
working bay in the white collar world of email and meetings and I
don't want to sound defeatist but wouldn't just have been easier to
give it to someone with a big enough surface grinder?

OK, I'll get my coat.......


Charles

Posted by Tony Jeffree on April 17, 2008, 5:29 am
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On Thu, 17 Apr 2008 01:52:56 -0700 (PDT), Charles Ping

>> Now, What was it that I was trying to do...
>>
>> Mark Rand
>> RTFM
>
>I like a workshop challenge as much as the next bloke who spends his
>working bay in the white collar world of email and meetings and I
>don't want to sound defeatist but wouldn't just have been easier to
>give it to someone with a big enough surface grinder?

Ah..but then he wouldn't have that nice furrow 2/3 of the way along
the bed...

Regards,
Tony

Posted by ravensworth2674 on April 17, 2008, 12:08 pm
Please log in for more thread options
> On Thu, 17 Apr 2008 01:52:56 -0700 (PDT), Charles Ping
>
> >> Now, What was it that I was trying to do...
>
> >> Mark Rand
> >> RTFM
>
> >I like a workshop challenge as much as the next bloke who spends his
> >working bay in the white collar world of email and meetings and I
> >don't want to sound defeatist but wouldn't just have been easier to
> >give it to someone with a big enough surface grinder?
>
> Ah..but then he wouldn't have that nice furrow 2/3 of the way along
> the bed...
>
> Regards,
> Tony

Mark,
In all honesty, I hadn't a clue about your Hardinge HLV but
lathes.co suggest that it is a flat bed.
Last year, I had my second or third flat bed Myford reground locally
on a Lumsden for =A330+ Vat. OK, this is not quite Myford works or so on
but it is a solution to get a pretty decent top which may only need a
few swirl marks removed.

Have you a guy with a big Lumsden?

Cheers

Norman

Posted by Mark Rand on April 17, 2008, 2:03 pm
Please log in for more thread options
On Thu, 17 Apr 2008 09:08:21 -0700 (PDT), ravensworth2674


>
>Mark,
> In all honesty, I hadn't a clue about your Hardinge HLV but
>lathes.co suggest that it is a flat bed.
>Last year, I had my second or third flat bed Myford reground locally
>on a Lumsden for £30+ Vat. OK, this is not quite Myford works or so on
>but it is a solution to get a pretty decent top which may only need a
>few swirl marks removed.
>
>Have you a guy with a big Lumsden?
>
>Cheers
>
>Norman


The flat bit's done apart from that cosmetically annoying furrow, that might
get another couple of finish cuts. The 11" wide saddle won't notice a 3/16"
wide, half thou deep furrow, but it might allow grit to get under the saddle.

The bit that all the current work is for is the dovetails. At the moment, I
don't even know accurately what the wear is on them.

I think that the point that I was failing to get across was that one job leads
to another. To the point that you end up having so much fun, you forget what
the original task was :-)


Mark Rand
RTFM

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