T Nuts: What if any treatment?

Looking to make my own T Nuts and wondering if they are just plain mild steel or are they hardened/tempered please?

I've made T Nuts for a couple of mills over the years out of plain mild steel. Not heard of anyone hardening them before but you could do I suppose if you wanted to.

Thanks Vic, I don't want to harden them, plain mild steel is ok by me if that's the usual

If you tighten them enough for hardening to help, they will be too tight!

However, when I made some out of some square BMS bar, I started by milling down one dimension to suit, and when I took it out of the vice it had developed a banana-like bend due to stress relief! So you may find it a good idea (if you use BMS) to get it red hot for a minute or two and let it cool slowly before starting to machine it. Or use black bar.

Thanks John. I have heard of BMS 'unstressing' when it is machined, Ill try for black bar when I come to it

And bash the bottom thread with the ball of a hammer to deliberately damage it so that you can't run the bolt all the way through and possibly damage the slot.

Dave
The Emerald Isle

Made a handful by milling two corners of a strip of mild steel then chopped it into short lengths and drilled and tapped them.

Edited By Roger Provins 2 on 05/07/2017 21:13:19

If you make T nuts of the small size needed for Myford lathes and such, then hardening them can be useful to avoid thread tearout. I ended up case hardening all but one of the ones I made. Tthe other one didn't have any threads left...

I make my own, Myford size, and never harden them. No problems.

Don't forget that you can turn T-Nuts if it's more convenient - stepped diameters; drill/tap; cut off; then mill flats on the larger dia. I generally find it less fiddly. Probably gets around any BMS distortion issue too.

If you don't mind interrupted cuts, you can even put flats on a length of bar, turn the barrel dia and part/saw off. Repeat as necessary.

Edited By Bandersnatch on 06/07/2017 01:28:51

I have a dozen in a row at the moment, machined, drilled and tapped, waiting to be cut into separate pieces.

A dozen because my mill only has 12 1/2" traverse and they will be milled to ~22mm long (if the cuts are all square). There will be more as both mills use the same 3/8" size.

I would have preferred a hardenable steel as the threads would be less likely to get damaged (tight studding in the threads is a bear), but these are from black iron bar and I am likely not going to case harden them (my wife complains when I use the kiln for hours on end - no, every time I use it, if she knows!).

If you use studs and not bolts in to the tee nut the life of simple mild steel will outlast you.

Do you use 1/4" or 5/16" threads? I use 5/16" and there isn't much meat left on the top part of the nut at that diameter.

I leave T nuts soft. I don't want them harder than the bed or slide they are being used on. If they wear over time, just replace or use helicoils to recover the threads. I make them fairly long to spread the load over the most area that is reasonably possible. Neil

This site gives a clamp load of 700 odd pounds for a 1/4 inch bolt.

**LINK**

Myford boring tables are a little on the slender side so gently does it. Milling tables are much more robust.

regards Martin

All the industrial T-nuts I've used have been as hard as a landlord's heart. When I wanted to shorten one by a few thou to stop it projecting proud of the table and defeating a clamp, I had no option but to grind it.

I'd imagine gauge plate would probably work well unhardened for most ME uses, but I think you might need to remake MS ones quite often.

Edited By Mick Burmeister 1 on 06/07/2017 13:49:15

Yes, I've made them like that as well.

I have to admit that I only ever make the "specials". I buy standard T-Nuts .... they are so inexpensive and I have more than enough jobs in progress and planned that the time can be better spent on.

Most of the ones I buy don't seem to be particularly hard. At least I've milled/filed them down for other purposes occasionally.

Edited By Bandersnatch on 06/07/2017 14:40:51

Resigned to having to make T Nuts as I am finding it difficult to find them to fit my Myford ML4; all the commercially available 3/8 threaded ones seem to be too deep in the base as the bottom slot is only 5/32 'thick'. 8mm versions seem to have the same problem.