Milling flat/cutting thin delrin

[macpod]

I have to mill out a shape in delrin that is 1.5mm thick. I have tried cutting this in two manners sofar:
1. Mill down a .25" block of delrin and use holding tabs
- This works, but you have to go very slowly and slight bowing of the piece is inevitable.

2. Clamp a piece of delrin underneath the piece you are cutting and use holding tabs
- This works fine, but requires me to remove the tabs still


I'm considering using double sided tape for my next piece so I don't have to remove holding tabs. What have your experiences been with tape? Do you have a favorite brand/etc?

[mfgbydesign]

Buy a vacuum chuck. Or make your own and hook up a vacuum generator that runs off compressed air.

[macpod]

I have to cut this 1.5mm shape too. Is that possible with a vacuum setup?

[WATERJET71]

Do you have a drawing of the part and also how many pcs you are making???

[macpod]

I'm only making one piece. I just wanted to experiment with different ways to make it to learn.

The shape is a rectangle with 3 small arcs cut into one side (roughly 3" x 2") ... very simple. I would upload a picture, but my mill and cad computer are not hooked up to the internets.

Think of this as how you would cut out a 3x2" rectangle from a piece of 1.5mm material. .. and mill it down from a piece of .25" stock.

[Togliatti]

I would start out with .060, or 1/16" sheet. Delrin is notorious for warping, so the less material removed, the better. IOf 2" x 3", there's sufficient surface area, so I would use tape without coolant. I've used 3M #444 double-coated paper tape for years for milling all kinds of materials, including Delrin, and if anything, it holds too well. You may have to use a solvent to get it loose to avoid breaking a thin Delrin part. It's also very uniform in thickness.

[mfgbydesign]

If you want to try the vaccum method, here's a $80 clamp that works from shop air:
V-Clamp, Vacuum clamps powered by compressed air.
Take a piece of MDF, paint it on all but the bottom, load it on the clamp, and mill a shallow pocket to fit your raw material. The vacuum will pull thru the MDF and the paint will minimize loss to the sides & top outside the stock. Machine the stock down, then when you machine the form out the extra pieces will hold in place until you turn off the air.

[macpod]

Oh I see, the porous nature of mdf will allow the table to suck the part down through and the paint improves efficiency. Huh, that's clever

For the paper tape, do you have to worry about coolant killing the tape?

[Togliatti]

Not necessarily. If you have extra material to spare, and feel you really need to use coolant, you might find that the milling operations will finish before the coolant seeps into the tape. Tape is a lot cheaper and quicker than making a fixture.

[diyengineer]

Originally Posted by macpod Oh I see, the porous nature of mdf will allow the table to suck the part down through and the paint improves efficiency. Huh, that's clever For the paper tape, do you have to worry about coolant killing the tape?

Use a light mist instead of a solid stream of coolant.

Look into the vacuum jig. its amazing.