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Pot Holes

10/20/2000 6:28 PM
Matthew Springer
Pot Holes
No not the kind in poorly maintained streets, but those ones you drill in the chassis.  
What is the standard size? It looks like 3/8" for both pots and jacks. Is a stepper drill bit the easiest thing to use? Or just buy one good drill bit for 3/8"?  
10/20/2000 7:43 PM
Jim Jones

Hey Matthew,  
I use 3/8" for pretty much everything. All I have is a hand drill and I'm sick of triangular crappy looking holes. Next time I'm going with a Unibit. Beautifully round holes everytime.  
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10/20/2000 8:07 PM
Bryan James

yes 3/8" don't forget if you use a drill bit to clamp a piece of wood behind the metal so you drill into the metal then into the wood. though messy and a pain will give you round holes each time. if you use a steper bit i found it easier to drill pilot holes first then use the steper bit. goes much faster.  
10/20/2000 9:04 PM

You get triangular shaped holes because your drill bit isn't set up for sheet metal. You are using the standard rake bit.  
Go look at those drill bits that are sharpened like a wood bit, i.e., they have a narrow web point in the center, are flat until the edge, and then have a small 'lip' for an edge. This is an old sheet-metal mechanic's trick that Black & Decker patented (jeesh, they'll run a patent on anything, I guess).  
What happens is that the outside edge breaks through the sheet metal creating a little 'doughnut' that you've just plugged. This is instead of your standard bit that starts in the center and works it's way out, to the point where the drill bit grabs, and spins the chassis all over the place . . .  
Good luck, let me know if you need any pictures or drawings of what I'm trying to describe. I made mine myself with standard high-speed drill bits and a dressing wheel/grinder. Have the standard sizes, i.e., 5/16", 3/8", 7/16", and 1/2". They work great and leave round holes . . . jrem.
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