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Old 9th July, 2008, 10:47 PM
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Azriel Azriel is offline
Join Date: September 2001
Location: Clifton, Illinois
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Metal blades should have a neutral rake. I would only recommend a negative rake for glass. Plastics can't take the heat. Some blades are labeled as being suitable for materials they aren't really ideal for. I've been a machinist for 12 years, and experience has taught me well.

Avoid the wavy blades, they will snag in butter.

For the future, you may want to pick up a sample piece of white UHMW Polyethylene plastic from mcmaster. (you'd think I worked for them the way I plug them)
You can cut out the shape of the base of your jigsaw, and screw it on with countersunk flatheads. It will keep you from marring material with the steel jigsaw base. (UHMW means Ultra high molecular weight)

If you are driling holes for case screws, and want them to self-tap:
The coarse case screws are 6-32 and a 1/8" drill is perfect for forming threads with the screw. They require a #27 (.144) clearance hole in the panel. I usually clamp the plastic, drill all the .125 holes, and then open them up to .144 in the case side.

As a general rule thread forming hole dia in plastic is roughly the average of the tap and clearance sizes.
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Contest: What can you do with a  case*?-thread-tap-and-clearance-chart.jpg  
A64 3800+ Dual Core/GF8800GT-512/2gig DDR/10,000 RPM Raptor SATA 36gig HDD, 250gig 1394b/28" LCD

Last edited by Azriel; 9th July, 2008 at 11:01 PM.
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