pipe drilling

I have to drill some 1/2 inch hole though some 3/4 inch thin wall brass
tube. Small drills do fine but when I reach the larger sizes I have
problems. I drill a small hole as a guide and then follow it up with a
larger bit. The larger bit does fine going through the first side of the
brass but when it reaches the second hole it just catches and freezes. It
will grab and really pull the pipe out of shape or if I hold the pipe
tightly the drill just stops.
I could drill one side and then turn it over but I am worried because I have
to run a pipe through the holes and they really have to line up.
Any suggestions on how to get a straight smooth hole though thin brass pipe?
(I am using twist drills made for meta in a cheap drill press)
Reply to
Leonard & Peggy Brown
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Going one step further I would also drill a block of wood for the tubing with it's dowel to go into and then drill through the block as a guide the brass it's dowel and into the block of wood again.
Reply to
Beecrofter
OK, non-rigid setup, regular drills, problems guaranteed with brass. Like the other fellow said, you'll need to modify your drills. The other problem is the thickness of the material and the size of the hole. One way to do this is to pour some low melting-point alloy into the tube and then drill, should cut down on burrs inside. I hope there's not going to be a lot of stress on that assembly, there's very little metal going to be left when you get done. You might want to consider soldering a sleeve on the outside to strengthen things up before drilling. If the hole's got to be smooth, you'll want to drill undersized and ream to finished size, too.
Stan
Reply to
Stan Schaefer
No surprise there. The lips are contacting the far wall first due to the curvature. One will grab before the other, and off you go.
If you can drill a pilot hole all the way through, the holes should still be in line when you enlarge them from either side. You can then pass a reamer completely through to ensure the holes are in line.
My best suggestion would be to use a holesaw.
Gary
Reply to
Gary Coffman
Drill a 3/4 inch hole through the center of a block of square wood. insert the tubing and retain with a little hot glue. Drill from each side with a slightly undersize drill then ream to size.
When your holes are done, melt the hot glue and go to the next piece.
-- Roger Shoaf If you are not part of the solution, you are not dissolved in the solvent.
Reply to
Roger Shoaf
Greetings,
Take a small sharpening stone and put a thin flat surface on the cutting edge (where the flute meets the tips). This will prevent the drill from grabbing in brass. You only need to flatten a few thou. Brass cuts better with zero rake, doesn't matter if it's a drill or a lathe bit.
If this isn't clear, take a look at:
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I have a set of drills with the tips done this way for brass, makes a world of difference.
Once you have done this, the bit isn't much good for other materials. Just figured I should warn you so you expect to have to either sharpen the bit back to original configuration for steel drilling or at least don't use your most expensive bit for this :-)
Cheers, Stan
Roger Shoaf wrote:
Reply to
Stan Stocker
This should be his first 'fix' and it will probably cure his problems.
Or, as you do, have one index that has "Brass Drills" written on it, if one does a lot of work in brass. And every time you need that size, flat the rake with the pedestal grinder. Eventually the index will be full of brass drills!
Jim
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Reply to
jim rozen

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