I’ve been cutting a bunch of parts lately out of ~1/16" delrin and abs. The cutting itself (speeds, feed and depths) are all going great but I’m struggling with work holding. The material itself is flexible enough that no matter how well I clamp the exterior edges of the stock, the middle still lifts enough to make fine partial-depth cuts impossible.
Any ideas? Maybe combine mechanical clamps like I have with some double-sided tape? What are you all using?
I would use a layer of sacrificial plywood or hardboard — probably 1/4" plywood.
Thin material clamped on top and cut through you mean? I already back it with 1/4 board.
masking tape and superglue?
Tell me more of this super glue and masking tape…
vacuum holding
masking tape and superglue, as by Luke
double sided tape? should release well.
Depending on the cuts, span clamps- bars that span the work with hold-down points in the middle. Only really good if they can be set up so that they don’t interfere with the cut or can be removed before final cuts. I have used destaco type for this a few times, but there is probably not clearance on a shapoko
Screw through the material at a waste spot. Just cut around it at the end of the job, and avoid cutting through it. VERY handy method
It should would really well on your stock
Is it possible to divide up the job into several sections and cut one section completely at a time? You could then move the clamps around as you complete each section.
I have used two methods for holding down PCBs to cut that may work for you. PCBs are somewhat thin and need to be held down everywhere very firmly to prevent high and low spots, somewhat similar to your needs.
As mentioned above, there is the masking tape and superglue (CA) method. I used blue painters tape, and it worked great. I think this is probably your best bet.
A little easier is this double-sided tape, which isn’t too sticky and removes very nicely: https://www.amazon.com/Nitto-Permacel-Double-Coated-Kraft/dp/B000QDL9GK
I’ve done double sided tape, plus some strategically placed wood screws into the supplemental waste board to hold some thin UHMW I cut a month or two ago. Really can’t clamp thin floppy material well, double sided tape or the superglue/tape tricks are your friends(except maybe a vacuum table?).
Dan
Masking tape super glue method is really quite good.
Masking tape the bottom of your stock, press it on firmly (I use an old credit card etc), masking tape to you wasteboard or sacrificial stock that is clamped down (again pressing down firmly), then i put a few lines of superglue to the wasteboard masking tape, align the two and press firmly till it holds.
Sometimes this method holds too well just use less glue if that is the case you will get an idea of the amount of hold you will need.
If you go w/ the super-glue method, you can use baking soda as an activator.
Apply the super glue to the tape on your bed. Dip your finger in some baking soda (you know, the powdered stuff from Arm and Hammer) and wipe it on the tap on the back of your material.
When you apply pressure, the baking soda will cause the glue to kick-off and set very quickly.
You don’t need a ton, the fine residue left behind by wiping the tape w/ your finger is all that is required.
I’ve been using double sided tape between the masking tape layers instead of CA glue. It works well.
I second the Nitto double-sided tape recommendation. I use it all the time. Very grippy. Once the job is done a little shot of Isopropyl alcohol, wait a few seconds, and it releases like magic.