Ideas for workholding / fixture please!

CoertHFT · Sep 16, 2021

Hi all,

First post for me, so Hi again!

I'm running out of ideas for a fixture/workholding of a part.

In this part I need to mill three 'bayonet lockings'(?), 120 degrees apart (at the circumference).
The part dimensions are Ø170mm (6.7") by 85mm (3,4"), I added a picture also.

Now the question is what do you think is the best fixture for this part, I need to make 50 of them.

Hope to hear from you,

Coert

deltap · Sep 16, 2021

Is it hollow? 3 jaw chuck internal grip mounted on rotary table. Bolt to mill table so chuck is horizontal.

CoertHFT · Sep 16, 2021

Thanks for the reply.

Yes it's hollow with a wall thickness of 2mm.

Your option is one of the options, but the minimal wall thickness is a bit of a problem I think. A 6-jaw chuck would be better, but unfortunately we don't have that.

An extra option with this solution is to use a tailstock with a delrin ring.

gregormarwick · Sep 16, 2021

Make a spider that fits inside, put in three jaw chuck clamping on the spider so the chuck does not collapse the part. Machine the bayonets between the jaws.

boslab · Sep 16, 2021

Vacuum Chuck suggests itself,
Mark

CoertHFT · Sep 16, 2021

gregormarwick said:
Make a spider that fits inside, put in three jaw chuck clamping on the spider so the chuck does not collapse the part. Machine the bayonets between the jaws.

That's a possibility for sure. Thank you!

CoertHFT · Sep 16, 2021

boslab said:
Vacuum Chuck suggests itself,
Mark

Thanks for your suggestion. We have a vacuum chuck already but the part does not stay perpendicular to the machine axis. Already tried to correct it with a corner plate, but it doesn't work.

CoertHFT · Sep 16, 2021

thermite said:
Punch it then. That's how this sort of goods are usually done for volume production.

Simply support the hollow rim on a curved arc of a shoe, mating pair of arced shoes....or even rollers.

The section of it you need to work on is functionally the same as a 2 mm wall tube, the closed "spinner" part of the shape is not involved.

Or mill it, but same deal. You don't NEED to grip the entire part and spin it.
Only grip and reinforce the rim where the cutting force is to be applied.

Shouldn't be rocket science to index off the first slot cut?

"Worried?" Go to the delron form (or shiney-wood) concept - and rig it for internal expander WITH an external "cinch" band, too. All you need is a narrow cylinder. External band needs cut-outs, Internal should have clearance pockets as well.

Mating clamping so you neither stretch nor shrink it.

Thanks for your idea. Punching isn't one of the possibility's since we don't have punching machines.

I don't really get your last idea, it is pretty stiff to compress

NewGunPlumber · Sep 16, 2021

Make an acetal or ply disk 1" thick that fits the ID. 3 jaw chuck from the outside on a rotary table?

CoertHFT · Sep 16, 2021

NewGunPlumber said:
Make an acetal or ply disk 1" thick that fits the ID. 3 jaw chuck from the outside on a rotary table?

gregormarwick said:
Make a spider that fits inside, put in three jaw chuck clamping on the spider so the chuck does not collapse the part. Machine the bayonets between the jaws.

I think you both mean the same. That's what I'm going to try now. Thank you very much!

fciron · Sep 16, 2021

thermite said:
This is not a new challenge.

Put yourself in the shoes of an ancient armorer making helms and riveted features for battles when "high tech weaponry" was still Bronze swords and a whole army had to be equipped, faster and better than the other side.

Sounds like you're recommending a hammer and chisel.

boslab · Sep 16, 2021

Dividing head, with ring, foot stock with ball, do it between centres, you might have to plug the middle with timber or uhw to stop chattery resonance, assuming vertical mill to cut the bayonet slots, reminds me of a Harley pan head headlight I once repaired ( rust ) that had the same bayonet slots, if it was original I don’t know, the metal spinning my mother in law worked used similar “ cup and ball” fixturing on round bowls
Mark

Scottl · Sep 16, 2021

Is the part a stamping/pressing (ie hollow)?

If so, I'm thinking sacrificial soft jaws on a chuck, turned to the ID, on a simple indexing fixture. Mill slightly into the jaws with a larger diameter first, then mount the parts and mill them.

charlie gary · Sep 16, 2021

Am I the only one curious about what kind of machine he's got to do the work? If it's a vertical mill, you could get away with making a triangle plate that has a round protrusion that fit inside the part. Set up an angle plate on the mill, clamp the part/fixture plate against the angle plate with the fixture sitting on one of the three triangle flats and mill your feature. Turn it to the next flat for the next feature. Repeat until done.

Superbowl · Sep 17, 2021

You don't tell us what machines you have to work with. In my shop I would use my Bridgeport right angle adapter and a rotary table.

To fixture it on the rotary table I would use a sacrificial round piece of aluminum plate slightly larger in diameter than the open end of the work piece. To that piece attach another sacrificial round piece of aluminum plate exactly the inside diameter of the work piece. Then you can clamp down from the bullet nose end of the work piece. The bottom aluminum plate would have to be very thick or spaced high enough above the top of the rotary table to avoid interference with the right angle head.

Search

Largest Manufacturing Technology Community on the Web

Search

Ideas for workholding / fixture please!

CoertHFT

Plastic

Attachments

deltap

Cast Iron

CoertHFT

Plastic

gregormarwick

Diamond

boslab

Titanium

CoertHFT

Plastic

CoertHFT

Plastic

CoertHFT

Plastic

NewGunPlumber

Aluminum

CoertHFT

Plastic

fciron

Stainless

boslab

Titanium

Scottl

Diamond

charlie gary

Stainless

Superbowl

Hot Rolled

Similar threads