To All:
Just saw this mentioned over in PM, and thought I'd relay it here.
First you have to have T-nuts with the threads going all the way through, (run a tap through them if need be). Get a some short 1/2-13 set screws, put them into your T-nuts, position the T-nuts where you want them, then tighten the set screws until they contact the bottom of the T-slot groove. Just make sure your bolts don't hit the set screws when tightening your fixture plates or whatever.
Out of the last 110 posts to alt.machines.cnc this is the only one which didn't get dropped by my filters.
Any attempts at keeping this group alive and semi on topic are noble, but apparently futile.
The set screws would have to be pretty short. A few threads long maybe? Enough to shorten the socket enough to make loosening difficult after a period of time. Not too bad of an idea though, but I prefer using t-bolts with integral nuts of the forged kind.
BD: My "Westec Cruising" should have gotten through, but that was probably
600 political posts ago. LOL
I'm optimistic that the pendulum will eventually swing back to more on-topic posting. Without going into great detail (which would turn THIS thread to the darkside), people are frustrated and angry right now, so they are expressing that. And a note to Cliff & Gunner - PLEASE do me a favor and not reply to this thread.
Different brand machines sometimes have different depths of T-slot grooves. Our Haas has deep ones and our Fadal's grooves are shallower. I suppose if this particular feature was of great utility someone could mill the top of the "T" part on either side of the T-nuts to bring it up higher in the slot.
Do you mean like the following?
With enough wall thickness on the T-Nut you could drill & tap for screw.
BottleBob wrote in news:O_ydnW4RRYKol0rUnZ2dnUVZ snipped-for-privacy@earthlink.com:
Bob, A simple (cheap) way is to take metal pallet banding, cut in to pieces about 1-1/4 long, drill a 4 mm hole in one end, taper the other. (May have to narrow it down based on your T-nut size), bend at about 3/8" from end with hole, bow the long side. Sort of like a curve with a leg. Use the hole to spot em to the end of the T-Nut. They will act like a spring and hold the nuts in place, without defeating the non-finished threads.
Tom:
I was going to suggest making longer T-nuts so they could be tapped on either side, BUT, I didn't think that would be an optimum idea. Part of the advantage of the center set-screw idea is that you can put your T-nuts in the slots, lay your fixture plate on top (against stops in X & Y), insert your 1/2-13 allen bolts through the plate into the T-nuts to align them, take the bolts out and then tighten the set-screws to keep them from moving, then reinsert your bolts. I think this would mainly be beneficial in a production type setup where you were milling a number of identical plates that had numerous T-nuts in the table that might accidentally move when you were blowing off the chips the plate was finished.
My concern using setscrew in center is thread engagement. Too little thread engagement and it may strip the T-Nut. Too long of a bolt will bottom out against the set screw without clamping fixture properly.
Set the T-nuts to the bolt pattern using scale or other measure. Or you can still do similar as you describe above, instead of allen bolt to line it up use stud/s. Position fixture plate, insert stud/s and bottom out thru T-nut (like your setscrew) snug enough to hold T-nut in place, remove fixture plate, tighten screws on T-nut, remove stud, replace fixture and use allen bolts.
Tom
You guys could just buy and use quarter turn T-Nuts you know.
JC
It is another option as long as its easy/quick to set and maintain quarter turn T-Nuts alignment while loading and un-loading blanks (if I understand BottleBob's use correctly).
Tom
Tom:
Well it would only take a little snugging up to keep the T-nut from moving - it don't need 60 ft lbs of torque.
The bolt only needs 6 threads of engagement, that's like .460 for a
1/2-13 thread. So there should theoretically be plenty of clearance.That would be a pain, and possibly inaccurate, especially if you're trying to measure from a stop a couple of T-slots away.
Now that's an EXCELLENT idea.
Anthony:
Spring steel holders sounds like a good idea.
The non-finished threads seem to serve a semi-useful purpose for studs
- so you don't tighten the studs into the table. But IMO, they are less than useless for allen bolts being screwed into T-nuts.
John:
What's going to keep your quarter turn T-nuts from moving any better than regular T-nuts?
BTW Is THIS the ONLY semi on-topic thread in here? Cripes, time for a survey or something. LOL
BottleBob wrote in news:WK2dnTQQEbymYkrUnZ2dnUVZ snipped-for-privacy@earthlink.com:
The purpose is to keep you from running a bolt into the table too, and to ensure that the t-nut is pulled up properly and that the bolt is not just rammed into the table with the nut holding nothing.
Anthony:
If a stud hits the incomplete threads it's no biggie, since tightening the nut on top will still clamp your part. BUT, if an allen bolt hits the incomplete threads it will SEEM like it's tightened but WON'T be. Not exactly what I'd call an advantageous situation, eh.
Had you looked carefully at the two sets of the things on my end box you'd have seen that one end was drilled and tapped with 1/4" detents installed and the sliding drawer has a handful of wrenches for them in it. That's why I have my own studs, BTW. Well, that and most shops don't take very good care of their stuff once the boss is off the floor.
As far as I've seen, the political stuff has all been cross posted up the wazoo. Maybe you can get Gunner and Cliff to go in together on a glob or something
JC
John:
Spring loaded detents? I LIKE that idea, if fact that's probably the best idea yet for this purpose. Quarter turn T-nuts or not. That would still let a T-nut be aligned into position by the bolt, yet keep it from being blown away by the inadvertent use of the air hose or blasting coolant flow.
Well maybe I'm confused here..but...
Almost never will I end up with a situation where a tee nut is going to be repeatedly loosened/ tightened...and so almost never would it be an import factor to not have one slide...
I guess maybe if one is using mitee bites or some shit directly against the table and there is no through holes I suppose otherwise I'm stumped here.
Waxear:
Well, say you had to face & pocket 10 flat plates that were 15" X 20" and had 9 counterbored holes to hold them down flat. It's two few parts to bother wasting time to make a subplate for. So in the process of installing & removing them (and blowing off chips in between) a few of the T-nuts "could" move out of position. I'm not saying this is a frequent occurrence, just one of those times where keeping the T-nuts from moving might be helpful and save time.
Well Bob, You weaken the stud when you modify it. I have yet to break one but it probably wouldn't be that hard to do. I tested them at 80 ft/lbs when I made them up and didn't break one but that might be because the T-nuts are "tall" compared to most. They nearly flush mount to a HAAS or FADAL table but on the older European machines they are well below the table.
JC
John:
OK, I misunderstood just where the detents were. I thought they were in the "Half-Turn T-nuts", not the studs themselves.
So what I think would be the best of both worlds would be to take Tom's idea of outboard tapped holes in T-nuts (like his drawing showed)
Somebody ought to market these puppies, "Detent-T's", "Spring-a-Nut", or whatever. LOL
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