Quote:
Originally Posted by Mk.32
A more quick and dirty solution is, I have just taken 1/4 6061 and clamped it to the table of the machine with a hunk of 3/4 ply wood in between. Then drill my though holes, and wood screw the alum plate to the chuck of wood. Then do all the inside/outside cuts, pop the screws and you have your part.
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We run more or less the same setup, but we use acrylic as backing and double-sided tape instead of retaining tabs or screws on the part.
Just tape the part to roughly the same size scrap acrylic (we use 9mm), and strap clamp the part onto the table. We generally run a 1/4" 3 flute high helix end mill with 0.1" deep passes. With that you don't have to worry about chip evacuation in the slot, and it leaves a thin final pass (0.025" in 1/8" and 0.05" in 1/4"). Then just take the whole plate out of the mill, hit it with the heat gun until the tape releases, and then assign freshmen to a character building deburring/scotchbriting.
Mitee-bite sells a similar product that leaves less residue, but you have to heat the part to apply and release the compound. Double sided tape seems to be cheaper and faster when you have students to help. It's McMaster number 50245A21.
Otherwise just check out Mitee-Bite or Carr-Lane and poke around, they have lots of interesting stuff for fixturing. We tend to just do a lot of simple parts in the vice, the double sided tape method, and rarely a part using soft jaws. Two vices are helpful for long parts to minimize vibration/chatter, just indicate them in and clamp your part.