adjustable motor mounts

Hi, just been relocating my 1929 Ideal lathe onto a new bench and thought I would resurrect the original motor mountings. They consist of slide rails upon which the motor sits, with t-nuts to hold it in place and horizontal bolts to adjust belt tension and pulley alignment, similar to the photo below but about 100 years older. I'm missing the t-nuts and wondered if anyone had some suggestions on what to use. The dimensions don't match any of the current metric t-nut sizes. I have made steel t-nuts previously (a bit tedious without a milling machine, just a bandsaw and files) so I'm not afraid to make them myself out of steel bar but wondered if something a bit easier to work with would suffice. I've got a decent lump of aluminium I could use. Other option is to modify some old square nuts which I have. Any suggestions greatly appreciated.

If the underside of the rails is open you could fit a square plate with a setcrew inserted through the drilled plate and head welded to the plate, fit a washer and nut as in the picture. The plate will be free to slide within the rail.
To prevent the setscrew dropping out when the nut is removed fit a compression spring to the head a llittle longer than needed to reach the surface on which the rail is fitted.

If you can fit the motor to the rails before fixing the rails no need for any springs.

Emgee

Depending on the size of your slots would a zebeddy c-channel fixing be any good?

Zebeddy

From your photos, you appear to have a lathe, so rather than making T nuts, why not make T bolts.

A bit of square bar, to suite the size of the internals of the channel, turned down to appropriate diameter and threaded at the end.

Bill

Thanks for those suggestions. I've since found some square nuts which are a good-enough fit and managed to get them tightened up. If this does not work in the long term then I might try the square plate method with threaded holes as I already have a piece of rectangular bar the right size.

I don't have a piece of square bar of suitable size to make T bolts, but if the square plate method doesn't work then I can weld extensions onto the heads of some bolts to make them lock in place like T-bolts.

Zebeddy not available in Australia, similar local products like Unistrut, Ezystrut etc have channel nuts that might suit if the 'home brew' doesn't work.

Zebeddy is a slang term for Unistrut channel nuts...........said Florence. Used by those awful electricians ......said Dougal.

True, but only the nuts with springs attached.

Boing!