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I want to cut wooden disks from a wood board. I bought what I thought was the right bit for my drill. However, the bit seems to be solely for the hole, not for the disk, as it comes with a centering drill. The drill will drill a hole in my disks, making them useless for my purpose. It tried to tighten the centering drill further in, but that did not work. The tightening screw seems to only work on the flattened part of the drill and (not surprisingly, when you think about it) on the thread part of the drill. When I push the drilling machine down, the cutting part will push up along the drill.

How do I solve this? Is there a spare part I'm likely to get at a DIY store? Do I have any chance of re-purposing some other drill bit for this?

Edit: I have a stand for my drill, so I don't think I actually need the centering drill.

enter image description here

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  • Are you using a drill press or a hand-held drill? If using a hand-held drill then the drill-bit in the middle is essential since it's what prevents the hole saw from just running all over the workpiece as soon as it touches down - the drill-bit going through 1st holds the hole-saw in place.
    – brhans
    Nov 20 '20 at 17:32
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All you need to do is cut 1 hole in a 1/2" or thicker piece of wood then use that hole you just drilled as a guide by clamping that board to the good board. You can remove the center guide drill since you now have a hole saw guide. Cut as many discs as you like just by moving the pilot hole piece you just made.

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Use TWO hole saws. One with the standard pilot bit and one with the standard pilot bit replaced with a much shorter bit such that it can drill the large hole without the pilot bit getting into your piece of wood.

Get a scrap piece of wood, at least 1/2" thick, maybe thicker. Clamp it on top of the piece you are trying to cut.

Start each hole using the regular hole saw. Drill into the top piece of wood until you have a good "starter circle". Switch to the second hole saw and drill through both pieces of wood.

Lather, rinse, repeat.

Easier if you have a second drill. If not, be careful as hole saws can get really hot in use.

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Use the hole saw to make a template piece of wood.

Just as it sounds, You want a thicker board, 2"x 6" would work, for your template so that the walls of your hole are high enough to guide the hole saw when it does not have the centering bit installed. You could have many holes in your template so you do not have to keep UN-clamping and clamping.

Once you have a template piece you can clamp it, very well, or screw it to the piece you are cutting discs out of.

You want your template fastened securely to your work piece and your work piece securely fastened to a work bench to keep every thing from moving. Mark your template piece so you do not toss it out with other scraps.

Remove the centering bit from the hole saw and now you can put the hole saw into the hole in the template and slowly start to cut your hole. It may want to grab a little, keeping the drill steady and straight and starting slow will help until you get going.

EDIT:

I formulated my answer with out looking closely at the hole saw in your photo. I am unfamiliar with that type of hole saw as it seems that it requires the pilot bit in place to operate it properly. (chuck it into a drill)

I am used to the kind of hole saw that has an arbor that the saw part threads onto and the bit can be removed, the arbor is chucked into the drill, not the pilot bit.

You can probably come up with a hack to use the one you have, such as find a steel rod of the same diameter of the bit and secure it to the hole saw (grind a flat spot for the set screw to sit against) without the rod sticking into the space of the hole saw.

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    Don't try to clamp the hole saw onto the flutes of the pilot drill. Instead, reverse the drill completely, and clamp the fluted part into the drill chuck. Nov 20 '20 at 22:31
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Option 1

It looks like your plywood is pretty thin. Try finding a shorter bit of the same diameter as the pilot bit provided with your hole saw. This way, you can replace the pilot with the shorter one, get the set screw to hit the unfluted portion of bit and not have the tip of the bit hit the plywood when you've cut all the way through.

Option 2

Find a set of pilotless hole saws. It seems they're made, but a quick search didn't turn one up (I didn't look very hard). This would be essentially the same as above, but wouldn't have a pilot at all, just a "handle" to chuck into your drill.

Option 3

Get a plug cutter set and cut plugs out of your plywood to glue into the holes left by the pilot bit. This will take a fair bit of extra work and time (cutting, gluing, drying time) but would get you the end result. You may need to do some sanding to get the surfaces flush if the initial gluing isn't quite precise.

Be Aware!

Both options 1 and 2 will make it difficult to control the hole saw and are probably best reserved for use in a drill press where you can clamp the wood down, and the bit is spinning in a heavy, very secure chuck that will allow for a very minimum of wandering. Also, with a drill press, you can move the bit very slowly into the wood for the first mm or two of cutting, allowing the saw to take its time and make a clean cut.

I imagine that it would be very difficult to get a clean start to the hole using a hole saw without a pilot in a hand-held drill of any sort. The hole saw would want to wander around the surface and it would be difficult to get it perfectly vertical, leaving you with a potentially oblong cutout instead of a perfectly round one.

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Use a circle cutter. You can remove the centering drill. Be careful though these are difficult to control even with the centering bit. There's no way it would work without the centering drill unless used in a drill press with your work piece securely clamped. If your "stand" is anything other than a drill press I would advise against using this. enter image description here

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I solved this by actually sawing off the centering drill.

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