T nuts, bear with me

[snoopdog]

So , I would like some input. Would there be a strength/holding disadvantage to a circular t nut? Would the holding surface be less than the standard? Would it be sufficient for a benchtop mill? I ask because I need to make some for accessories, and I have roundstock of sufficient dimension, not so much square or rectangular.

 

[john.oliver35]

Strength may not be the issue - if the nut is round, then it will spin when you try to tighten it.

 

[benmychree]

Strength may not be the issue - if the nut is round, then it will spin when you try to tighten it.

The nut can be round without loss of clamping surface if it is made with a large enough diameter for sufficient surface area and then trimmed down to fit the T slot width, also if made that way, it will not spin.

 

[ttabbal]

I think if I were to try to make T-nuts from round stock, I'd aim for the large OD to be slightly too big to fit in the slots. Then use a V-block, collet block or whatever you have that will hold round stock on the mill and trim two sides parallel-ish to fit in the slots. It doesn't have to be perfect. So you can tighten without spinning. You could do the smaller diameter to fit the slot on the lathe and thread on the lathe if you like. I have a few I made on the lathe using a 4-jaw with flat bar, face the smaller diameter into it, drill and tap and they work great. I didn't have a mill at the time and was building them to hold parts on the face plate.

If you don't mind parting on the lathe, you could do the small diameter, thread, then part. Drop it in the mill vise, trim one side, flip it and hold the now flat bit on a parallel and cut the other side. More setups per part, but it depends on what tooling you have available.

 

[Shotgun]

It would necessarily be less area, so could not support as much clamping force, but I would think you'd break your arm trying to tighten it before it would be enough to make a difference.
I would think the biggest drawback would be trying to slide them through swarf/chip filled slots. I often use a t-nut to help clean the slots on my mill. I would think that the round ones would pack the chips into the sides instead of pushing them out the end.

 

[brino]

@snoopdog

Also remember to "damage" the first two threads at the bottom of the t-nuts.
Without that a bolt that gets tightened thru the hole could damage the table t-slots.

It's usually done with a cold chisel and making a heavy X shape over the hole after tapping.

Brian

 

[ChazzC]

@snoopdog

Also remember to "damage" the first two threads at the bottom of the t-nuts.
Without that a bolt that gets tightened thru the hole could damage the table t-slots.

It's usually done with a cold chisel and making a heavy X shape over the hole after tapping.

Brian

I just use a plug tap and stop 2 threads before the bottom.

 

[snoopdog]

I think if I were to try to make T-nuts from round stock, I'd aim for the large OD to be slightly too big to fit in the slots. Then use a V-block, collet block or whatever you have that will hold round stock on the mill and trim two sides parallel-ish to fit in the slots. It doesn't have to be perfect. So you can tighten without spinning. You could do the smaller diameter to fit the slot on the lathe and thread on the lathe if you like. I have a few I made on the lathe using a 4-jaw with flat bar, face the smaller diameter into it, drill and tap and they work great. I didn't have a mill at the time and was building them to hold parts on the face plate.

If you don't mind parting on the lathe, you could do the small diameter, thread, then part. Drop it in the mill vise, trim one side, flip it and hold the now flat bit on a parallel and cut the other side. More setups per part, but it depends on what tooling you have available.

This was basicly my plan, right down to the t, pun intended. I enjoy working on the lathe moreso than the mill, and I have all the time, so not discou

I just use a plug tap and stop 2 threads before the bottom.

raged about an extra setup, thanks.

 

[snoopdog]

It would necessarily be less area, so could not support as much clamping force, but I would think you'd break your arm trying to tighten it before it would be enough to make a difference.
I would think the biggest drawback would be trying to slide them through swarf/chip filled slots. I often use a t-nut to help clean the slots on my mill. I would think that the round ones would pack the chips into the sides instead of pushing them out the end.

I don't know, I know I have seen similar hardware

 

[Chips O'Toole]

I had to make T-nuts that were long with semicircular ends. Very weird.