Adjustable hole cutter

I have one, its OK but it can be hard to keep level. I only did 50-70 mm holes with it, I would use a pillar drill if possible.

Not sure about that one. I have an Armeg one which I'm generally impressed with. The Toolstation one doesn't look nearly as well made but, since it's cheap and you only want to cut hardboard, it might be worth a punt.

I found mine works best in a big SDS drill running moderately fast. That way it doesn't tend to catch so much. You still need strong arms though. Approach the work very slowly and watch where the score mark starts to appear so you can adjust the angle to get it perfectly perpendicular.

Don't get carried away with it. I did, and this happened to my lounge ceiling.

Cheers,

Colin.

Eek ... that's some mouse infestation there

Looking at it setup of the two cutting points might be fun to get them both cutting at the same radius. Might not be that critical, just a small flag being waved. B-)

In article , fred writes

Thanks to all, reservations noted, I will prob give it a punt and report back on the results.

Particular thanks to Colin for the view of his Whack-a-mole[1] game :-)

flycutters work, but due to the inherent unbalance of the things should always be run at low RPM.

The one linked to is symmetrical so shouldn't be unbalanced when rotating in free air. Once it starts cutting though keeping it square so each cutter takes the same amount is going to be the hard bit. I think reasonable RPM will be needed but very little push.

"can be set up infinitely carefully to be *almost* symmetrical"

You are talking to a model aircraft man here, and we all know here how to balance a propellor by carefully sanding off a few microns here and there. Or how much difference an uneven coat of paint makes.

Less on a big cut

I have both made, and used these things on pillar drills.. if you want a clean cut keep the cutter speed slow.

I used one recently to cut a series of hardboard discs (don't ask!) and found that setting the blades slightly apart, so that one cutter was cleaning out the slot behind the other cutter, worked best for me.

Nick

PS Definitely loads easier in a pillar drill.

Nick

A low speed might work well in a pillar drill but if you have to use it hand-held as I did for my ceiling holes, then too slow-a-speed just makes for copious amounts of comedy snagging, arm wrenching, step ladder wobbling and swearing. Higher speeds cut that down *massively*.

After experimenting, I ended up using a big, Chinese, mains SDS drill set to around two-thirds full speed. Most of the holes were relatively painless then...

Cheers,

Colin.

I did wonder where all the cheese kept going :o)

Cheers,

Colin.