[CadRhino]

Nice complex fixture idea. I am not sure if it will be any more accurate than just clamping in machined soft jaws. My experience is that there is always a little tolerence gap when clamping from one side on a round part.
The most accurate clamping in my opinion is when the center can remain the same as in a collet holder or drill/chuck.
How about lining up some small chucks?
Just an idea

I make many round parts that are similar in shape but not quite identical. My idea is to make a fixture plate with a solid angle block for one “jaw” and a detachable “soft jaw” to account for various shaped parts of similar (but not the same) form. The detachable jaw would be held vertically in place by shoulder bolts with accompanying slots to allow for some play in the horizontal plane. The jaw would then be tightened horizontally by 2 mitee-bite pitbull clamps per 3 parts. I would end up making several soft jaws for various parts, but they would all be pretty similar.

I’ll start off parts as 1.25” round aluminum stock, machine them down to am OD of 1.15” inches (with flats for locating) and place them in a stepped jaw.


Would a fixture like this work? Or would there just not be enough clamping force? Pictured is a smaller test part that I would make as a final proof of concept. In the end, I would make a much larger plate of similar design to take full advantage of the Tormach’s travel. I would bolt it directly to the table. This prototype is 6” long and would simply be held in a vice.

[FuriousGeorge]

Mike,

That is a great idea trying to machine the non-rigid jaw out of delrin. In the past, I have made soft jaws and machine little grooves and stuck some o-ring stock in there (just like this: Tips for operating a CNC mill | Practical Machinist), but that migh be a better solution in this case. I was HOPING that by having two clamps, I would eliminate play. I'm just thinking out loud here, so please correct me if I'm wrong. By having two clamps, you essentially have a second area to apply pressure. So you tighten the first one, and exactly what you said happens: the oversized part is rigidly clamped but the undersized part has some wiggle. By tightening the second clamp, you are now slightly twisting your jaw, making up the slack and tightening the loose piece. So this MIGHT work with two metal jaws (hopefully). I'll definitely have to experiment a bit.

CadRhino,

Thanks! I definitely agree that soft jaws in a vice would be easier. In this situation tho, I'm hoping to ultimately expand this idea to making a full fixture plate that could do 20-30 pieces in one setup. I was thinking about making a plate with some expanding collets (https://www.mscdirect.com/product/de...?item=68082940) but I really can't justify the cost at this point.