Looking for t-nuts

[Ulma Doctor]

The slots, and by default , the t nuts are metric , 14mm

 

[ChazzC]

You might also see if a 5/16" carriage bolt will fit after trimming the head, then you would have threaded "T" studs.
With T nuts you have to be careful not to run the bolts in too far and hitting the bottom, possibly damaging or cracking the slot

The nominal size of a 5/16" carriage bolt will fit, but the square would need to be ground to fit the slot as well as the head:



More importantly, the available clamping area is greater for the t-slot nut (= less load on the slot for an equal applied clamping force), and given the profile of the domed head of the carriage bolt, the t-slot nut would be stronger. There's a reason that t-slot nuts are rectangular, and it's not to keep the nut from spinning in the slot.

 

[graham-xrf]

There may be some advantage to getting T-Nuts into place under a clamp bolt from the top, but expanding on the modified carriage bolt concept, why not a full T-Bolt instead of T-Nut? Something nicely fitting with a full strength rectangular head, strong enough, and large enough to spread the load. There would never be any danger of a bolt from the top hitting the bottom of the T-slot, and jacking very breakable bits.

The notion is so obvious that I think such stuff would probably have been around since the beginning of threaded anythings.

 

[WobblyHand]

There may be some advantage to getting T-Nuts into place under a clamp bolt from the top, but expanding on the modified carriage bolt concept, why not a full T-Bolt instead of T-Nut? Something nicely fitting with a full strength rectangular head, strong enough, and large enough to spread the load. There would never be any danger of a bolt from the top hitting the bottom of the T-slot, and jacking very breakable bits.

The notion is so obvious that I think such stuff would probably have been around since the beginning of threaded anythings.

Threaded studs, at least for me are better. Easy to make, along with the tee nuts. I don't have to worry about hitting bottom because I bought the right kind of tee nuts. The one's I made also are not fully threaded. So I never have to worry about it. Even the tee nuts I made for my rotary table are goof proof. Thread the stud by hand until it stops, install clamp and nut and tighten. Works every time, despite any other screw ups I make.

 

[ChazzC]

There may be some advantage to getting T-Nuts into place under a clamp bolt from the top, but expanding on the modified carriage bolt concept, why not a full T-Bolt instead of T-Nut? Something nicely fitting with a full strength rectangular head, strong enough, and large enough to spread the load. There would never be any danger of a bolt from the top hitting the bottom of the T-slot, and jacking very breakable bits.

The notion is so obvious that I think such stuff would probably have been around since the beginning of threaded anythings.

You can make T-Slot Bolts by Loctiting a stud into a T-Slot Nut - a solid/one-piece bolt could be machined, but it would involve a large amount of material removal. Such a “bolt” would be useful for securing a vise it rotary table, but traditional studs & nuts are more flexible and a full set of them would be significantly less expensive than a set of bolts.

 

[7milesup]

I would not use carriage bolts unless I absolutely had to. There is a lot less surface area on a carriage bolt vs a T-Nut.

 

[Ulma Doctor]

you can make t nutz from other materials with custom anchor bolt sizes.
i made a couple sets of aluminum t nuts and i have plans to make some from aluminum bronze
we own machines that can make tools, if we let em'

 

[OTmachine]

I would not use carriage bolts unless I absolutely had to. There is a lot less surface area on a carriage bolt vs a T-Nut.

And carriage bolts are usually only grade 2. A recipe for disaster.

 

[erikmannie]

Sometimes even after taking the most careful measurements, I end up buying the wrong size T-nuts. You can buy 1 each of the 2 possibilities that you have narrowed it down to, & test fit.

I would bet that you will need a metric size for that machine.

 

[jmkasunich]

Make em! We're machinists after all.

I understand that there can be ac chicken/egg problem: how do you mount the vise when you are making your t-nuts? That's where the carriage bolts might come into play. Grind or file flats on the sides of the heads so they fit your t-slots. But once you rig something temporary, making a set of t-nuts from a length of bar is a very good first milling project. Usually you take a bar say 4-5" long (for four t-nuts), and mill the correct slot profile on it. Then drill and tap the holes and finally cut the four nuts apart using a bandsaw or hacksaw. Cleaning up the cut ends is optional; the mill can do that too.

One advantage of making your own is that you can fit them to your machine slots and you get to choose the stud threads. For example I use 3/8-16 on my 3-in-1. You can get 3/8-16 all-thread at home depot (the crappy grade 2 stuff, but good enough), or McMaster has what they call B7 grade threaded rod (similar to grade 5 bolts) or grade 8. You can make a wide variety of different stud lengths cheaply with nothing more than a hacksaw.