To harden or not to harden that is the Question

[Dell]

But what is the answer
hi all

spent the afternoon milling some long small long T nuts ready to fit the Multifix QCTP they are 50mm long 6mm thick , had to file the last 1/2 mm because I couldn’t get enough meat above the vice and get a good grip, once fitted they should not have to be removed the only bit that will be undone fairly regularly will be the 10 mm bolt in centre of the 8mm plate that is going on to the T’s so do I need to harden and temper them.

thanks Dell

 

[tom2207]

Depends on what they are made from ? you may not have the option.

 

[frank horton]

nah...the T nuts on my milling machine are quite soft......
if u use a standard studding u can get higher tensile......
I judge
8.8 = soft as shxte.....
12.9=tough as old boots....
so if u make/buy ur studding I'd get the higher strength and just use the norm nuts.....
even over time the studs wont stretch....
this is similar to the kits I use.....but mine are a prop manufacturer not Chineseum....
I guess this is similar to what ya making.....?

 

[My Old Landy]

I don't harden my home made ones. This is a commercial hardened one that broke

 

[Arc Tourist]

Make sure you dimple the thread on the bottom of the T-nuts, so that the studs are not allowed to protrude. Its the reason you see chunks broken out of T-slots due to upward pressure by the studs pushing against the bottom of the slots.

 

[My Old Landy]

These were the ones I made for the Centec. Not hardened and are all good

 

[Screwdriver]

That looks like regular hot rolled steel, aka mild steel. You can't (easily) harden them anyway...

If they had been a medium carbon steel I would say yes, harden for sure because as part of the process, you can also give them a nice black oxide finish.

 

[Dell]

Thanks everyone my thinking was no need to harden either.
Dell

 

[Dell]

Make sure you dimple the thread on the bottom of the T-nuts, so that the studs are not allowed to protrude. Its the reason you see chunks broken out of T-slots due to upward pressure by the studs pushing against the bottom of the slots.

Yes as the T nuts are only 6mm thick I will have to cut bolts down anyway.
Dell

 

[Kram]

From the pic they look a bit tall and could do with having 1mm shaved off the top. If they protrude above the slot it will not clamp tight.

 

[Dell]

From the pic they look a bit tall and could do with having 1mm shaved off the top. If they protrude above the slot it will not clamp tight.

That’s an optical illusion they are just below.

 

[Dell]

Next stage complete, I put an 8mm block on top but in hindsight I think I would be better with a 12mm block, that is something I will probably do it a bit later, next job is to set all the tool bits to centre, for the moment I will have to have the tool bits on top of the spacer block that the reason why I think 12mm would be better because then the tool bit can go on the bottom of the tool holder, as I mainly work on very small parts I don’t think it will be a problem for now, at least now I will be able to use it because I have a few jobs to do.
I do most to my turning using a graver anyway but it’s now ready to do things that need to be a bit more closer tolerance.

 

[My Old Landy]

Next stage complete, I put an 8mm block on top but in hindsight I think I would be better with a 12mm block, that is something I will probably do it a bit later, next job is to set all the tool bits to centre, for the moment I will have to have the tool bits on top of the spacer block that the reason why I think 12mm would be better because then the tool bit can go on the bottom of the tool holder, as I mainly work on very small parts I don’t think it will be a problem for now, at least now I will be able to use it because I have a few jobs to do.
I do most to my turning using a graver anyway but it’s now ready to do things that need to be a bit more closer tolerance.View attachment 325111
View attachment 325113

Looks good to me!

 

[Dell]

Finally up and working, it had a leaver missing so that was the first job, very pleased how it turned out and the industrial sewing machine motor is amazing so much torque even very slow.