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Old 07-09-2013, 02:14 PM
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Sir Crashalot
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Default CAD question

Hello all!
Just a quick question for those CAD users out there. I have a “tab A in slot b” type of question. How much room do you give for clearance? For example, for a tab that is 1/8” by 1”, how much larger would you make the slot to allow a tight but easy fit? This is only for a former which fits into a fuse doubler. Nothing fancy.
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Old 07-09-2013, 03:16 PM
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All Day Dan
 
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Default RE: CAD question

Before I use the "real thing" a few trial and error cuts gets me to the right size. I make them the same size and cut on the line. If that does not work I start enlarging the slot or reducing the tab until they fit. It is all dependent on the width of the saw blade and the type of wood. I do not use a laser cutter. Dan.
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Old 07-09-2013, 04:39 PM
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N1EDM
 
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Default RE: CAD question

Are you using the CAD file for laser cutting? If so, I wouldn't leave any clearance at all. If accurately drawn, the kerf from the laser cutting should be enough. That's been my experience with laser cutting.

Just my $.02

Bob
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Old 07-09-2013, 07:50 PM
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Chad Veich
 
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Default RE: CAD question

A generally allow .005" for the laser kerf on just about every type of material that I cut in order to get a snug fit on slots and tabs. Has been working for me for nearly a decade.
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Old 07-10-2013, 06:21 AM
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Sir Crashalot
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Default RE: CAD question

Hello all!
Thanks for all your replies. I made a guess at .004”, but I wasn’t sure if that was enough. I will change it to .005”. This is my first time trying a laser cutting company, so I’ll have to wait to see how things turn out. If this doesn’t work, I’ll change it. The guy I talked to said he would work out any problems I would have. So I don’t think I’ll have any issues. I just wanted to be as close to the ball park as possible.
Thanks again.
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Old 07-10-2013, 07:42 AM
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BMatthews
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Default RE: CAD question

Balsa is an amazingly supple material. If the goal is to have the parts snick together with a slight push fit I'd suggest that you size the slot so that with allowance for the kerf that the final slot width is a perfect match or even a couple of thou smaller than the thickness of the sheet part intended to fit in the slot.

This is actually something you can try yourself. Cut and sand a slot in some material and measure the width with a set of calipers. Then test fit some sheet stock into the slot and aim for the sort of light push fit you're after. You'll quickly get a feel for how you want to size the laser cut notches to allow for the laser kerf.
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Old 07-10-2013, 08:19 AM
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BMatthews
Thanks for your reply. That sounds like a good idea. I’ll try that first before I send the files off to the cutter and see what I come up with. The parts in question are ply. So I was more worried about having enough room. I’ve got a lot to learn about this aspect of our hobby.
Thanks again.
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