2" hole in a 3x2x1/8 rectangular tube

I need to drill 4 2" holes in a 3x2x1/8 steel rectangular tube. I
bought a 2" bi-metal hole saw and managed to drill 1 hole and half of
the second one until the tips of the teeth were all flat. I went back
to the hardware store and I bought a "better" 2" bi-metal hole saw and
I was able to finish the second hole I have started and half of the
3rd one before the teeth were flat again.
I don't know what to do... Is there any better hole saw/technique to
do this properly? I need to drill one more hole now and finish the 3rd
one that I started.
Are bi-metal hole saw not the proper bit for this job? In the
instructions says that it should be ok to handle 1/8 thickness at 160
Any ideas?
Thanks in advance.
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Are you using cutting oil on the saw?
I've made many cuts similar to this, and I lube the saw liberally and continuously with the heavy dark cutting oil I use on my mill for steel.
I also run the saw pretty slow, probably a lot slower than 160 rpm, and go easy on the feed if you want the blade to last. I pull the blade up every few seconds to clear out the swarf with an oil brush and re-lube it. I would guess you're building up too much heat from the combination of no cutting oil and spinning the saw too fast.
Its also possible that even the "better" bi-metal blade you bought is a piece of junk from you know where. I only buy hole saws from name brand suppliers, typically from MSC. I've never had a blade go dull yet, and I don't use them every day but some of them have lots of cuts in steel on them.
Good luck-
Paul T.
Reply to
Paul T.
Look for Lennox, Morse, or Milwaukee. You do have a 1/4" lead bit in the center of the arbor that holds the hole saw don't you?
are you in a drill press or freehand drill motor?
I suspect you are not giving it enough pressure and are just spinning the teeth on the metal. It should be making chips. Slow, steady pressure and make every effort to keep it running flat without tipping. Are your 2" holes going all the way through? You may do better by drilling all the way through with just a 1/4" bit and then drilling from each face with the hole saw/arbor/pilot bit combo.
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Reply to
These are all important points, but one other thing you can do to help things go a little smoother is the drill a couple of small holes on the circumference of the hole to allow the chips to escape from the cut. This helps a lot when using a holesaw on thicker (more than 1/8") material.
Reply to
Peter Snell
One technique to consider is a trammel cutter. This has a pilot bit and a single point tool that you can sharpen and change the cutter geometry should you need to.
On cuts like you are making these tools work well.
Reply to
Roger Shoaf
the ultimate for these holes is an annular{spelling} cutter
hougen , jancy, dewalt and others make them
work great cut fast and last forever
Reply to
Most other people have mentioned most of the potential problems. I have found that using hole saws ( starrett brand ) on the side where the weld seam is located is the kiss of death. Randy
Reply to
Randy Zimmerman
I have drilled thousands of holes in material similar to what you are describing (its one of our 'bread & butter' jobs at work) and we use a cutter that is like a 'heavy duty' hole saw. Basically a shell cutter.
For the small quantity of holes that you are doing, your method sounds to me like it should work just fine.
I would highly recommend FLOOD COOLANT. OK, its messy, but it makes a BIG difference.
Reply to
Lewis Campbell

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