On Tue, 29 Dec 2009 10:33:25 -0800, stans4 wrote:

On Dec 28, 11:31Â*pm, Tim Wescott wrote:
Well, my delightfully high-quality Smithy lathe turned up a new defect
this week.

One of the T-bolts that hold the compound slide to it's base stripped.
Now, I could order a pair from Smithy, and get the same crap that they
sold me in the first place, or I could fabricate something and maybe
have a chance of it lasting for a while.

My challenge is that I want something that'll last, and I need to do it
without my lathe (boo hoo).

The bolts are M8x1 or so, maybe coarser thread. Â*I'm thinking of going
to the farm store and getting some good old 'merican grade-8 5/16"
bolts, then cutting off the threaded parts for the T-bolts. Â*Then I'll
take some stock about as thick as the heads on the old ones and I'll
fabricate new heads (or I'll use the old bolt heads). Â*I'll thread them
to match the bolts, and I'll screw and braze the new heads onto the
bolts.

This would be absolutely bullet-proof, except that the heat of the
brazing will ruin the temper of the bolt. Â*I'm pretty sure that neither
peening the head onto the bolt, nor soft-soldering the head onto the
bolt, will have enough strength to hold together through one of those
"damn but this is tight" experiences one occasionally has with screws.

I'm also pretty sure that attempting to heat treat the bolts after
brazing won't get me a grade-8 bolt. Â*I suspect that a 5/16" grade-8
bolt isn't going to be made from the fanciest steel, so I can probably
just heat it up and chuck it into water, temper, and have something no
worse than without heat treating at all, but that's not exactly the
most scientific way to get 'er done.

Thoughts? Â*Suggestions? Â*It'd be fun to turn these out of drill rod,
except (a) I don't have any that big, and (b) I don't have a lathe
right now (boo hoo).

I'd kinda like to do this on the cheap, but if McMaster has just the
right thing (they don't) I'd at least like to know so I can feel
virtuous about the money I'm saving.

--www.wescottdesign.com

Why not make t-nuts instead? Whack a suitable strip of steel to width,
file to fit, drill and tap holes and use the bolts of your choice. Or
studs. Bugger the last couple of threads on the bottom so they don't
bust the slot flanges off. Seems to me I bought a similar t-slot
clamping kit from Enco or the like for about $20 with all the studs
you'd ever need, but your slots may not be standard.

My slots are way not standard. I _may_ be able to do the T-nut thing if
I go fully custom, but I may not have enough clearance for the bolt to
tighten satisfactorily.

Good idea, though -- I will investigate.

--
www.wescottdesign.com