Tee Nuts, To Harden Or Not?

[Tony Wells]

For one thing, not knowing the material would leave you guessing as far as how to treat them. Plus if they are hardener than the cast table and you really torque them down they will indent the underside of the slot. Granted, the studs and hex nuts that come from the high end suppliers are hardened, but the idea of sacrificial tee nuts makes sense to me.

When I have made nuts for this general purpose, I will stake the underside of the hole to prevent the stud from going all the way through, or simply stop the thread short of a complete thread through the nut.

btw, I have a couple of new 5/8" roughers and a used 3/4" in fair shape. We can get together sometime and I'll hand them off to you.

 

[turnitupper]

When I started my apprenticeship in the days before electricity, this is what we used to put holes in masonry. The pointed triangular bit is perfect for deforming the threads in the bottom of tee nuts. Perhaps an old 3 or 4 flute end mill suitably sharpened would do the same job.
John.

 

[Tony Wells]

Yep, a star drill would do nicely. I normally use a cold chisel and hit them a few times radially, inclined from center about 30° towards the far side of the thread.

 

[cathead]

Even brass or maybe even hardened aluminum would make perfectly usable T-Nuts for general use I would think. I have a chunk of square brass rod so might
try making one or two just for fun and see if they hold up to some use.

 

[astjp2]

several of the machinists at work put the studs all the way through the T-nuts to keep them from moving if doing multiple parts, keeps the setup almost the same. Tim

 

[Tony Wells]

I've seen that, and done that myself, Tim.....but can't recommend it for fear of someone getting carried away and breaking out the top of the slot. Cast iron is good in compression, not so much in tensile....sort of like concrete. I don't like to see it stressed in that direction.

 

[JimDawson]

several of the machinists at work put the studs all the way through the T-nuts to keep them from moving if doing multiple parts, keeps the setup almost the same. Tim

I try to avoid doing that for the same reason that Tony stated. When I want to keep the studs in position for a setup, I use a nut/washer on the stud, below the clamp, to keep the stud anchored to the table. This keeps the table in compression with t-nut/nut combination. There is of course the tension on the assembly from the clamping forces, but it is not exaggerated by running the stud into the bottom of the t-slot.

 

[GLCarlson]

I picked up some unknonium this morning to make some "t" nuts for my mill. Should I attempt to harden them or not? If so what are the advantages, besides a longer service life?

Sent from somewhere in East Texas Jake Parker

Nah. Waste of time.

I make all my own (usually double hole, 3/8 & 1/2 in same tee nut)...out of aluminum. OK, it's 7075 equivalent (FortAl), so it's a lot closer to mild steel for strength, but it's still softer than anything else on the miil. Intentionally. Service life so far is 30+ years and counting. In fact, most of my "furniture" on the mill is aluminum. If I happen to hit it with a rogue move, the cutter usually survives, and the clamp, nut, or whatever is generally still usable too. I use brass allthread for the posts. Hardened jigs, fixtures, clamps, and the like are fine in a production shop; in the small shop, making your own is cheap, fun, and chances are you'll be giving them to yuor grandkids, in like-new condition.

BTW- personally, I roll these out in 12" or longer length tee shapes, and then cut, drill, and tap to order as needed. The other thing I really like for mill furniture is Kanttwist clamps. And, yes, my fixture plate is a big chunk of Blanchard ground aluminum, too.

 

[turnitupper]

Made tee nuts for my X2 mill out of 20mm x 12mm x 600 mm mild. Measured length needed for nuts + kerf width of cut off blade, drilled 1/4" holes in center of where nuts would be after cutting. Drilled and tapped 4, 16mm x 5mm x30 bars to take 1/4" bolts. Slid the tapped bars into the tee slots and fastened one end of the drilled 20mm x 12mm x 600 with 1/4" cap screws every 2-3 holes with washers underneath between the work and the table. Wound the table to it's extremity and positioned the material just short of a 12mm roughing mill. Lined it up [roughly] and tightened up. Cut the top slot out, then cut the bottom to size. [This is where the washers come in handy as they avoid the dreaded trench in your table]. Moved the stock along the table by rotating bolts/holes. When finished, flipped work to sit in slots, reclamped, facemilled it's bum a bit, all good! P.S. Battery Drill on x handle a godsend and I'm not a religious man!
John.

 

[turnitupper]

Yep, a star drill would do nicely. I normally use a cold chisel and hit them a few times radially, inclined from center about 30° towards the far side of the thread.

Done the same Tony but with the star drill you only need a hard surface to put the nut on and give it smack. With a cold chisel, if you don't put it in a vise, and elect to go freehand, it might slip and move around the shop, possibly causing the destruction of the cat's good eye!