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student mod

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...

Reply to
Austin Shackles
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On or around Tue, 22 Jan 2008 14:20:57 +0000, Austin Shackles enlightened us thusly:

which isn't in the handbook, FFS.

BTW, pictures of the mod:

formatting link
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 ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯| ______________ | ¯¯¯¯¯¯¯¯//¯¯¯|| |b _______//____||____|

saddle gib slide body

Reply to
Austin Shackles

thusly:

slackening

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

Reply to
Andrew Mawson

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.

That'll be what's going wrong then :-)

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

Reply to
Mark Rand

On or around Tue, 22 Jan 2008 23:28:50 +0000, Mark Rand enlightened us thusly:

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.

Reply to
Austin Shackles

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