Bridgeport or Knee Mill, VMC, Surface Grinder Owners.

ddickey said:
@Eddyde perhaps if you relieve the middle section a small amount.
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Perhaps if the tee nut was concave and spring tempered it would help a bit but the contact pressure rapidly drops off as you move away from the bolt.
 
Eddyde said:
Interesting problem but I don't think longer tee nuts will make a difference. The pressure from the screw will not be effectively transferred to the ends of a longer nut. Probably not even 100% pressure dispersion getting out to the ends of the 1"nuts, either.
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Agree.
 
Yes, material compliance means the pressure distribution is limited to cone; but that depends on a flat interface and a relief can extend the area as desired. The potential to bend a table is interesting though, assuming it’s accurate.
 
I suggest we do some experimenting. Next time you tighten your vise on your mill table, mount a mag base on the side of the quill and put a .0001" indicator on the side of the T slot next to the T-nut and tighten it. See how much it moves. I am telling you this happens and with my 50+ years of experience I say it happens. You can take it or leave it.
 
Richard King 2 said:
You can take it or leave it.
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Nobody has questioned that, Richard. We have, however, questioned whether a longer T-nut without a top relief near the threads does anything helpful. I’m sure your long experience includes deformation near threads, which limits the pressure applied at the interface. It’s common (or should be) to heavily countersink the interface side of female threads for that reason.

The T-nut shape makes this more difficult, as it’s the central portion of the wide flange that requires a relief/contour. I think it’s a neat idea to design a T-nut with concave flanges to achieve a uniform pressure at design torque.
 
Thanks for all the Likes everyone. I wanted to share a tip to the members from my years of experience and what a College Professor shared with me. I am going to stop writing on this thread. I hope if others who want to discuss this they go on another thread and not in my forum. Thanks
 
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Charles scozzari said:
I now have a better understanding and respect for the little thing that holds things together. Charlie
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I learned a lot about pressure distribution back in the mid 90's, when I was tasked to make a heated press for veneering wood panels, for the tops of cigar humidors. The panels were roughly 12" x 10". The "glue" was a polyester film only a couple of thou thick and required a pressure of approximately 100 psi so about 6 tons for the given area. I made a heated platen from two pieces of .75 MIC-6 screwed together at the perimeter with a thin heating mat sandwiched between. On top of that I had a 1" thick steel plate, slightly larger than the aluminum platen, on top of that I placed a 6" square of .75" thick steel. all of this was placed in a ton hydraulic press, its 3' diameter cylinder bearing on the 6" plate. The initial results were terrible. Peeling off the veneer showed the adhesion was achieved only in a 5-6 diameter area in the center of the panel. I added more steel plates on top of the platen in an effort to distribute the pressure more evenly, not much improvement. I theorized heat distortion might be the problem, so I purchased pressure indicating film and tried pressing cold. The film revealed a clear, radial, pattern of pressure dropping off from the center outward, even through all that metal. That's when I researched pressure distribution and learned the pressure is transmitted in a conical path, at roughly 30° from center. I ended up making a tapered wooden block of cross laminated layers solid maple,12" square at the bottom 6" square at the top and almost 16" thick (it was a primarily a wood shop so that's what I had to work with). The block was placed on top of the steel plate and the 6" plate on top of the block. That did the trick, the veneers were finally adhered evenly.
Richard King 2 said:
I suggest we do some experimenting. Next time you tighten your vise on your mill table, mount a mag base on the side of the quill and put a .0001" indicator on the side of the T slot next to the T-nut and tighten it. See how much it moves. I am telling you this happens and with my 50+ years of experience I say it happens. You can take it or leave it.
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To be clear, I am not challenging your theory of the vise bolts warping the table. Only that a longer tee nut will probably not significantly distribute the bolts pressure over a larger area. However, I am only going from my knowledge & experience, some experimentation is a great idea. I need to move my vise in a few days, I will do some tests and publish my results.
 
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