[FuriousGeorge]

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.

[popspipes]

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.

If the soft jaws are machined to the actual parts size they would work reasonably well. If the parts are of slightly different sizes they wont as it will clamp on the larger part or parts and leave the others loose.
I would make one jaw rigid (aluminum), the other of delrin uhmw or similar so that they give slightly to take up any discrepancy in the different sizes within reason.
Personally I use UHMW for that, say drilling several pieces of stock at once etc.

You would have to experiment and see what works in your situation.

Another idea is to split each v block on one jaw so that they can be clamped separatey, that would work, I also would beef up both jaws as well unless they are going to be used in a vise

[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.

[MikeC8]

Have you looked into Mitee bites machinable uniforce clamps?

[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.

[amish_rabbi]

the piece in the middle is either going to be the only part clamped well or totally loose. Depending on if it is bigger than the side parts or smaller its either going to be a pivot point or just missed period.

why talon clamps though? make it with individual "v-blocks" for each part and use one excentric hex per part so that each part has the proper pressure. more parts to it but better clamping

[BIG IGG]

the piece in the middle is either going to be the only part clamped well or totally loose. Depending on if it is bigger than the side parts or smaller its either going to be a pivot point or just missed period.

why talon clamps though? make it with individual "v-blocks" for each part and use one excentric hex per part so that each part has the proper pressure. more parts to it but better clamping

I agree with amish_rabbi

If one is to small are to big it will not be clamped. I would try to make them individual clamps for each one or break it up maybe. Like amish_rabbi said with a pivot point

[SCzEngrgGroup]

I handle round parts with a small, and cheap, 3-jaw lathe chuck, bolted to a flat plate, with the jaws opening up. It's mounted centered on a 4"x4" plate, so for quick jobs I can toss it in the vise and use the vise corner as my origin, knowing the work is centered at X2 Y-2 (for non-critical work). For more critical work, I can get it centered to the exact center of the workpiece in about 30 seconds using a coaxial indicator. And it will hold any round piece up to about 3" in diameter, with enough clamping force to even do very heavy high-speed roughing. In your case, bolt three of them to a single plate, bolt the plate to the table, and you're in business. It'll cost a little but more up-front, but you'll have a MUCH more versatile setup, with no worries about clamping force, and no adaptor plates to make for new parts.

Regards,
Ray L.

[AUSTINMACHINING]

I have a 3 jaw chuck mounted to the table next to my vise for round stock. I recently made a part (tube) with a very thin wall. The trick in my case was having enough force to hold the part, without crushing it (second op to remove carrier stock )Next time I would make vise soft jaws to increase surface area for clamping in stead of the 3 pressure points of the chuck method. Depends on wall thickness and how aggressive you want to cut I guess.

Food for thought.

[Steve Seebold]

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.

The idea is good BUT I would make the fixture fit the part. Round parts on round holes. I' use a lot of Mitee-Bite products in my little machining business. I use mostly the brass hex clamp. I do have some Uniforce clamps and even some pit bulls.