[Sonicmook56]

Hi-

Sorry if this has already been covered, my search on this form rendered nothing I was looking for.


I mill out small chassis panels for my electronics business on a Taig mill.


I made a fixture that works very well, except the time it takes to remove the work, and put a new piece in takes longer than the milling process.



You can see here I used a square bolted onto a sub plate.

A close up shows the screws I use to hold the work down


and with the work in place



Is there a product or something I can make that can speed up my process?

[donwayne]

Have you thought about a vacuum fixture. They are fairly simple to make.

[Med-Pac]

Some toggle clamps from Reid might work; clearance may become an issue, but they have many different styles and it would definately speed up the process.

Mike

[Sonicmook56]

I've never thought about building my own vacuum table, but I am familiar with there operation. Are the pumps required to operate noisy?

Toggle clamps look great, but I don't think they will work for this application. Regardless, I think I might order one or two to play with around the shop for other applications. Thanks for the tip.

I'm somewhat answering my own question here, but I found some thumb screws with the same thread that I have taped on the fixture plate that I think might work. Part of my current problem is I need a tool to loosen the screws, and a the loose washers I use need to be lifted off the fixture plate and over the work piece. I think these thumb screws would fix both problems.

http://www.keyelco.com/pdfs/p56.pdf

Look for "thumb screws" on the bottom right of the .PDF

Still interested in hearing about solutions from others as well on this subject.

~B

[LeeWay]

I use toggles for some aluminum sheet that I make parts out of. I use a mag chuck mainly. The tooling plate for this process is 1/8" steel sheet with some left over 3/16 phenolic as a spoil board. Two pieces of angle iron keep it from slipping on the mag chuck. It holds pretty well, but I put these type things on where possible just in case.
These are HF toggles and are fairly big. They have some nice tiny ones I use on my router table from Mcmaster Carr. Maybe 1/4 of the size of these.
I just used all thread and ground a point on them. They don't move.





Here is also a video, but turn your sound down. The camera is almost on top of the router.

[ame="http://www.youtube.com/watch?v=fswDGVjeZPc"]YouTube - Milling aluminum sheet[/ame]

[Geof]

We have a similar job in ABS plastic and made a fixture that clamps the part with compressed air; the unique thing about it is the fixture is 'upside down.

We have two fairly thick aluminum plates bolted together along two opposite edges with a gap of about 1-1/2" between the plates and these bolt down onto the table of the machine.

The ABS workpiece slides in under the top plate and a large diameter but very short air cylinder goes underneath; the air pressure clamps the ABS up against the underside of the top plate.

All the machining is done through holes in the top plate; the holes were machined using the part program with tools slightly larger than used for the part.

Reload time is a matter of a few seconds; turn the air off, slide out the finished part, slide the next piece in and turn the air on.

[Sonicmook56]

Geof, Very interesting about your compressed air fixture. Can you post pictures and/or links, design ideas for a fixture of this type? Did you fab your cylinders or are they commercial off the shelf type?

Best
~Ben

[Geof]

Everything was made in-house.

It is at the business, I will see if I can dig it out early next week.

[jimc]

Ben,

Like everything, whatever you do should depend upon the volume of parts processed, the tolerances of the parts put into the fixture, the amount of chips produced and your budget.

The problem with air cylinder clamping is the large size of cylinders required. Hydraulic clamping is a good option - if you can fabricate your own cylinders- because the hydraulic lines and cylinders can be very small, yet exert enormous force instantly.

Eccentric cams are also a good option as are destaco clamps.

I don't like using long stops- like your square- I would use 4 pins instead so I didn't have to fight the chips. I also like to elevate the stock above the fixture plate for the same reason. When I do have to use a long stop - or it is just easier - I like to have a space under it for chips to go.

All the lateral stress on your plates is concentrated on one end, and I wouldn't think you would need more than 6 pins a couple of flat bar standoffs and one "push" type destaco (possibly 2 ) and you'd be in business.

The hydraulic route is really a good one. I picked up a never-used, air-operated hydraulic unit on ebay for a hundred bucks a while back. I'd be happy to take some pics if you're interested.

It is used for two separate clamping operations - one on a shuttle fixture that travels a couple feet back and forth between two separate operations. And for a bending operation to minimize the bend ID deformation so I don't have to machine it again after bending.

I use 500lbs total force for the former and 4,500 llbs for the latter. All that's required is a couple turns on the air regulator.

I actually have a video of that one on the computer at the shop.

Another advantage to that type of clamping is that you can use pressure switches on both air and hydraulic lines to disable, or run a shut down program on your computer or PLC if the operator forgets to clamp the part, the air compressor isn't turned on, etc. etc. This functionality has saved me a great deal of money in broken tooling, flying parts and so on. Most of my help has been either friends' college kids or my nephews. Need I say more?

My memory ain't so good either.

Cheers,
Jim

[Sonicmook56]

Jim, thank you for the reply.

Have you posted the video on YouTube? I would be interested in seeing it.

~B

[lkenney]

Use a good quality double sided tape and no coolant, air instead. Make sure the base and material are clean from oil or grease. I have also used super glue and popped them off with heat from a torch and a thin piece of metal. I try to mill an edge and end in to the base to align the material for either tape or glue down. You can also program in small web links about 0.005" thick on the last pass so the parts are still connected to the material but easily snapped out after removal from the machine. Make your cut out contour cuts but stop 0.005 from going through the material. Segement the contour line leaving short sections uncut and make the final pass. Does not take long if you are using a CAM program.

Have a Great Day

Eagle

[ImanCarrot]

Superglue. A light tap with a brass hammer will "unglue" it. Acetone will disolve the superglue from your parts and fixturing.

I too use double sided tape and made the fatal mistake of using flood coolant... which turned the tape into mush.

Other stuff I've used is Tippex (typing correction fluid- sets like concrete and again disolvable in acetone).

UV curing epoxy worked good as well- get the stuff that you can peel off with your fingernails (can't recall it's name at the moment).

But really, vacuum fixturing is the way to go for full production. Make sure you got a moisture trap if you're using coolant though.