Need Vacuum/ spoil board suggestions for small thin alum. Labels!

Hello!

I am currently using sheets of MDF (milled on both sides + edges sealed) with my Multicam Apex3r Router and 24HP Becker vacuum pump.

It's doing an ok job holding my thin .020 aluminum sheets down, but the vacuum releases when the through cut holes and cuts are made.. enough for the small 1.0 inch x 3/4 inch parts to move.

I have heard that LDF is better than MDF? Can anyone weigh in on this? And also... Where the heck do i find it?

Any other tips on holding small thin aluminum parts down without tape or anything id have to peel off the finished parts?

-Nicole

Hi Nicole - No matter what spoilboard you use when you cut holes in your job you are going to loss vacuum. What you need to do is cut a groove in the board and place a gasket it in so the gasket isolates the vacuum when it breaks thru. If they are repeat parts then you make custom aluminium, pads that have an o ring in them. You have a problem with size as they are small parts so have a small air pressure on them. If they are one off parts then you need to think about serial clamping. This means the part is clamped and you have to put a program stop in so you can release a clamp , place a clamp and keep going. But I think a custom vac mount is what you need. This can be as simple as a thin rubber sheet or as complex as an o-ring designed thingy depending on part numbers. If they are one offs and being thin and small double sided tape is the go to solution.

Another strategy I use is to clamp the plate or sheet down on a thick spoil board then cut the holes first. Then screw through the holes and then cut the profiles (remove the clamps if needed to, but you do need to hold the "rest" of the material as when it comes free it can move around spoiling your work! Sometimes I add holes to parts just for this purpose. May not be possible in your part. But you need at least two holes in a part to hold it properly. You can also break your "rest" cutting into stages so each bit can be removed by hand as it happens. Cheers Peter

rereading your note I think these are nameplates so they will have two holes in them. I'd go the drill holes first, screw it down, do rest path.

Not sure it will help you... but... I've heard of people using ice to do fixturing. The idea is to have a plate that gets cold (vortex tube, perhaps? Or maybe Peltier devices? Or both?) when the part is being held down; and when you flip a switch/valve the plate gets hot; melting the ice and releasing the part.

If I'm reading this right,you are holding 1"X3/4" parts with a vacuum.That seems very ambitious given that a perfect vacuum would generate less than 12 lbs force on that area.This would be reduced by leakage through the MDF and won't be a whole lot better,if any, with LDF.Can your CAM program generate hold down tabs?It does create more work to clean the tabs off,but it ought to hold the pieces in place.The only use of ice for this sort of thing that I have encountered was for holding down Nomex or aluminium honeycomb for composite cores.

Painters tape + cyanoacrilate, perhaps?

Quote:

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Painters tape + cyanoacrilate, perhaps?

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Well, it seems to work for John Saunders...

:)

Holding tabs would be the first idea. A bit of work to clean them up but better than a trashed part.
Another method might be a custom spoil-board "cover sheet" with several small (3 mm) vacuum holes carefully positioned underneath the parts and within their outline profile to concentrate and maximise suction on the part when it is cut.

Cover sheet could be anything suitable such as MDF, acrylic, plastic, paper or whatever to allow concentration of suction via the holes.

Thank you for the response! I dont really want to have to go the clamp route... but i like your idea of screwing through the holes. I may try that if it is feasible with the quantity!

- - - Updated - - -

whoa! this is interesting. Might have to youtube that!

Ive heard of this trick, and i may have to give it a try. The only thing is i cut all the way through the metal, therefore im pretty sure cutting the painters tape.
So id have to peel tape off the back of every part when finished...
I think.

Thank you for the ideas!
Holding tabs arent an option for 5000+ parts unfortunately, too much filing to finish them :(
I like the cover sheet idea to concentrate the vacuum... going to definitely see what i can do with this.

Thank you for your response!
Yes... 1 inch x 3/4 inch pieces. Super small.
Ambitious, yes. But that's my core business, so unfortunately i cant change that LOL.
For 5,000 parts in a run i cant take the time to clean up hold down tabs :(

So you dont think LDF would get me any better suction?

I would expect the difference in holding force to be trivial if you switch to LDF.Seems that you have a job that would be better accomplished with a simple tool in a fly press.That is if the parts are all the same shape.If they were to need engraving it wouldn't be too hard to make a fixture and add simple toggle clamps.

5000 nameplates, that's quite a lot. So is 10000 screws in and out :-(

Ignoring costs (some homework for you) I'd consider the following:

1. Make a cover sheet from acrylic, pocket the sheet to take the plates at a about 50% to 75% depth (to allow for easier removal) and have several suction holes with countersinks positioned in the pockets under the work pieces
2. Get a machine shop to stamp out the blanks to the required size
3. Load up the pockets with the blanks
4. Fire up the vacuum
5. Engrave away

Around each pocket edge you could also have a dimple hole on a center-line to get a tool to help with plate removal. Hummm, slots rather than pockets might be an idea but harder to align the blanks I guess...

YMMV :-)

Hi Nicol - For 5000 make a custom vac jig and use an O-ring (hole thru to a passageway) to hold each piece down. Don't try to pull vac thu a material. Say 200-500 pieces to a board each with an oring. The back of the board has grooves to communicate the vac to the holes and O rings. Then glue a board to the back of that to create passageways vs grooves. I'd do it in aluminium and screw the backboard on and use sealant. But an MDF or melamine board will be a good prototype, this way you can do the lot on one hit. You can also glue a thin soft rubber or foam sheet to the face and drill the holes. Then the first pass will custom cut the gasket. Peter

I've used a pierson workholding smart vac 2 system in the past. I would assume you could do the same with your Becker but you would have to make a aluminum fixture or comparable. Then use a o-ring like method for each part but it should work i would think. Your parts are very small.

Something like this. https://www.youtube.com/watch?v=ZpDq_q3JX1c