posted
This is driving me crazy. I am trying to drill 5/8" metal for my windows in the db drag car and it is not going well. I have tried cobalt bits and predrilling with tapping oil. What is the low down on getting this done. I have about half of the 75 holes left to drill. Is there a better bit to us. Should I not be using a highspeed air drill?
posted
I would use a drill press if I were you. And do the predrilling as well. Start out with a small bit and keep moving up a size or two until you have the correct size hole in it, and be sure to use the oil. If you don't have a drill press mark all the holes and their diameters and take the plates to a machine shop that has a drill press and see if they will do it for you. It shouldn't cost much but will probably take longer cause most of them are very busy.
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posted
Here is the scoop for everyone I got the holes finished last night.
Use cobalt bits; very slow speed and the kicker... do NOT use oil. Use ice water to cool the bits. The lubrication was not a important factor and was helping the holes polish out and not drill through. The drill speed was my biggest downfall at first. The high speed drill was heating the bits up to much and not allowing them to cut into the metal before they got to hot and lost there edge. Now with the ice water I am drilling a pilot hole with my 14.4 dewalt cordless and slow speed. Then using a variable speed elctric drill to size the final hole.
To bad I didn't drill them on a press before the pieces were welded into the car ;-)
posted
Cobalt bits last longer than carbide or titanium carbide. My suggestion was that you were drilling at too high a speed but you found that out already!
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quote:Originally posted by Dukk: Cobalt bits last longer than carbide or titanium carbide. My suggestion was that you were drilling at too high a speed but you found that out already!
yep, with metal slower = faster i work in a metal fab shop we drill up to 1 1/2 inch on the jig bore, then from there on up we use the CNC plasma/torch (it'll cut up to 14" thick plate with the torch going!!!)
posted
plus, you could have rented a mag drill, (almost like a small drill press) only it has a STRONG magnet for base. that would have worked pretty good, take all this into account next time
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