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Posted by Austin Shackles on January 22, 2008, 9:20 am
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Been working on the crossfeed on the Student. Took it apart and studied the
nut, which is about 40mm long and made of what seems to be bronze, it fits
in a groove on the underside of the cross-slide, where it's retained by a
hollow bolt (which I guess originally had a grease or oil nipple on the top,
as the nut has a matching hole.
Basically, I've cut it in half and arranged for one half to be fitted in
such a way that it has a small amount of length-wise adjustment. Each half
is retained by an M6x1 stainless bolt. The fixed half is fixed through a
new 6mm hole in the cross-slide, while the adjustable half if fitted with a
bush in the old (7/16") mounting hole, with a reducing bush with an 8mm
hole, and a 6mm bolt with penny washer. Adjustment is a touch problematic,
it'd be better with some shims in between the 2 halves. I'll test it a bit
and see how it works, and possibly add shims later.
none of this precludes fitting a normal single nut back to it (except I
don't have one).
Now, to look up the proper way to adjust the gibs in the slide, rather than
guessing...
--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------
>> http://www.schlockmercenary.com/ << ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!
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Posted by Austin Shackles on January 22, 2008, 2:59 pm
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On or around Tue, 22 Jan 2008 14:20:57 +0000, Austin Shackles
>
>Now, to look up the proper way to adjust the gibs in the slide, rather than
>guessing...
which isn't in the handbook, FFS.
BTW, pictures of the mod:
http://www.ddol-las.net/lathe
the white bits are squirty grease, no pigeon guano.
As for the cross-slide gibs, they're held from above by screws (a) which
screw into the strip, and moved laterally by other screws (b) in the cross
slide body. I've formed the impression that you adjust 'em by slackening
the top screws and moving the lateral ones, but if you get it too tight
laterally, it then locks up when you re-tighten the top ones. Once you get
it right, there should be no scope for it moving, at least.
I was hoping for an official technique...
a
ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ|
______________ |
ŻŻŻŻŻŻŻŻ//ŻŻŻ|| |b
_______//____||____|
saddle gib slide body
--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------
>> http://www.schlockmercenary.com/ << ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!
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Posted by Andrew Mawson on January 22, 2008, 3:28 pm
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> On or around Tue, 22 Jan 2008 14:20:57 +0000, Austin Shackles
thusly:
>
> >
> >Now, to look up the proper way to adjust the gibs in the slide,
rather than
> >guessing...
>
> which isn't in the handbook, FFS.
>
> BTW, pictures of the mod:
>
> http://www.ddol-las.net/lathe
>
> the white bits are squirty grease, no pigeon guano.
>
> As for the cross-slide gibs, they're held from above by screws (a)
which
> screw into the strip, and moved laterally by other screws (b) in the
cross
> slide body. I've formed the impression that you adjust 'em by
slackening
> the top screws and moving the lateral ones, but if you get it too
tight
> laterally, it then locks up when you re-tighten the top ones. Once
you get
> it right, there should be no scope for it moving, at least.
>
>
> I was hoping for an official technique...
>
> a
> ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ|
> ______________ |
> ŻŻŻŻŻŻŻŻ//ŻŻŻ|| |b
> _______//____||____|
>
> saddle gib slide body
> --
> Austin Shackles. www.ddol-las.net my opinions are just that
> Travel The Galaxy! Meet Fascinating Life Forms...
> ------------------------------------------------
> >> http://www.schlockmercenary.com/ << ...and Kill
them.
> a webcartoon by Howard Tayler; I like it, maybe you will too!
There is a version of the Student crossfeed nut cut in two like yours,
but removing a wedge of material (ie two cuts at an angle) the wedge
sits on the upper face, and a set screw presses down from above
forcing the wedge into the two parts and parting them.
AWEM
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Posted by Mark Rand on January 22, 2008, 6:28 pm
Please log in for more thread options On Tue, 22 Jan 2008 19:59:38 +0000, Austin Shackles
>On or around Tue, 22 Jan 2008 14:20:57 +0000, Austin Shackles
>
>>
>>Now, to look up the proper way to adjust the gibs in the slide, rather than
>>guessing...
>
>which isn't in the handbook, FFS.
>
>BTW, pictures of the mod:
>
>http://www.ddol-las.net/lathe
For next time I would suggest drilling and tapping for a couple of 8BA or M2
screws axially through the bottom half of the nut. Then cutting a slot in the
nut about 3/16" from the end, most of the way through. After fitting a couple
of allen screws, you can nip up the slot to give backlash control.
>
>the white bits are squirty grease, no pigeon guano.
That'll be what's going wrong then :-)
>
>As for the cross-slide gibs, they're held from above by screws (a) which
>screw into the strip, and moved laterally by other screws (b) in the cross
>slide body. I've formed the impression that you adjust 'em by slackening
>the top screws and moving the lateral ones, but if you get it too tight
>laterally, it then locks up when you re-tighten the top ones. Once you get
>it right, there should be no scope for it moving, at least.
>
>
>I was hoping for an official technique...
>
> a
> ŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻŻ|
> ______________ |
> ŻŻŻŻŻŻŻŻ//ŻŻŻ|| |b
> _______//____||____|
>
>saddle gib slide body
The same setup as the Myford S7 and long-bed ML7 then. Basically they're a
bugger to adjust. If you are enthusiastic, you could scrape the bottom surface
of the cross-slide and the top face of the gibs to eliminate rocking. Then
only just take the tension of the top screws whilst adjusting the side ones.
One thing that I found useful on the Myford was to adjust one end of the gib
at a time, with the other end reasonably firmly clamped. This, again, reduces
the chance of the gib dropping down whilst moving sideways.
Of course, if you want a locking screw, you'll probably need to drill through
the whole lot and have a brass/copper plug driven by the locking screw, since
the gibs ain't going to move!
Have a nice day :-)
Mark Rand
RTFM
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Posted by Austin Shackles on January 23, 2008, 5:24 am
Please log in for more thread options On or around Tue, 22 Jan 2008 23:28:50 +0000, Mark Rand
>For next time I would suggest drilling and tapping for a couple of 8BA or M2
>screws axially through the bottom half of the nut. Then cutting a slot in the
>nut about 3/16" from the end, most of the way through. After fitting a couple
>of allen screws, you can nip up the slot to give backlash control.
It's a thought. The underside of the nut is quite thin, material-wise. The
only thing I've thought of that's really a problem with how I've done it is
that it has to be dismantled to adjust it, on the plus side, that gives a
good chance to clean it properly.
The squirty grease was mainly 'cos it was to hand. I'll use better stuff
when I re-assemble it.
--
Austin Shackles. www.ddol-las.net my opinions are just that
Travel The Galaxy! Meet Fascinating Life Forms...
------------------------------------------------
>> http://www.schlockmercenary.com/ << ...and Kill them.
a webcartoon by Howard Tayler; I like it, maybe you will too!
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>Now, to look up the proper way to adjust the gibs in the slide, rather than
>guessing...