View Full Version : Holding down sheet material.

28-06-2013, 01:56 AM
So I have some 1.5mm aluminum sheet that I want to machine. The problem I have is that the tool pulls the sheet up.

I could screw it to a bit of MDF but it won't be very flat or well cooled. Clamping it down to my t-slot bed makes it very viby and gives a bad finish.

Any ideas? Thanks.

02-07-2013, 09:05 PM
Have you tried some double sided tape? Surprisingly strong.

Or super glue and tap sideways to get the material off.

02-07-2013, 11:43 PM
Is your table flat? shouldn't be a problem clamping it to the table, mounting on something like MDF would be OK but you would be best to surface the board first to ensure it is flat, as for cooling the heat should be removed in the chips so it shouldn't get to warm anyway.
Double sided tape works well as well, just make sure you clean the table & sheet before sticking anything down, something like IPA, Industrial Meths (not the purple stuff) or even lighter fluid will work well for cleaning as it evaporates quickly & doesn't leave any residue behind.

John S
03-07-2013, 12:11 AM
Get a bit of MDF or ply and mill a pocket out same size as the sheet of alloy.
Then smear a bit of PVA in the bottom, then a sheet of cartridge paper, then more PVA and then the sheet, clamp down with a heavy weight until the glue dries.
The pocket and the PVA will prevent it moving. Hot water will release it.

One thing to note with thin alloy sheet. Most is just decorative and is 99% pure which means it sticks like sht to a blanket or even the tools.
Try to obtain what is called half hard, or even hard alloy sheet, this machines a lot better.