Someone asked a while back about cutting thick materials with a hole saw. This is a trick I learned a long time ago, and really works well, especially on aluminum. This is a flange for a set of headers I am building, which in this case is a 3 1/2" hole. If my pictures are in order, you can see the first scribe line I made with my dividers at the 3 1/2'' dimension. The next pic , I made another circle 1/8'' smaller. Then I very carefully center punch 5 holes at somewhat equal distances apart, and drill them with a 1/4'' drill bit. This will give the chips somewhere to go, instead of wadding up under the teeth, You can see what it should look like in the pic where it is cut half way through. If your layout was reasonably acurate, you should not have any trace of the five holes, and it will cut through very quick. Doing it this way, you can keep steady pressure on the saw without it binding up. You should also hang on to your saws that have teeth missing. On thicker metals, they actually work better!
wow - we must be psychically connected. I just posted the same trick under another forum!!!! Someone was boring holes in an axle and I was thinking how much work that would be with a regular hole saw without using this trick.. I learned it about two weeks ago from a airplane fabricator.. It works awesome and you'll save your hole saws! Good post!
Also, drill your pilot hole with the hole saw OFF the arbor. Then re-install the saw on the arbor and have at it. Anytime you use a hole saw, drill that pilot hole first, if you just drill through with the saw on the arbor, when you break through with the pilot bit, you'll jam the saw teeth into the material and it'll grab. That will lead to broken teeth, broken pilot bits, chewed up material.
I did something similar when cutting the hole in the body to put my fuel filler tube thru.. I started the hole saw to get my groove, then took a small drill bit and went around and drilled holes in the groove all the way around, until there was not room between the holes to drill another one. Then went back to work with my hole saw (it was getting dull so I tried to minimize the metal I had to cut..
Awsome tech tip... Sure beats drill ,pull back, blow out, several hundred times. I'll will definitely remember that one. Thanks
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