Those funny drill saw things...

I'm guess that, like me, you've probably bought sets of bits that include a weird one that resembles a drill on the end but is studded with coarse rectangular teeth.

My understanding was always that they are for drilling a hole then working sideways like a crude saw.

I finally used one today and it worked very well.

The material was the 305mm very heavy density plastic pipe that is the tube for my dobsonian telescope. I had to enlarge the focuser hole to about 100mm, bigger than my largest holesaw and anyway no centre to guide one.

It was actually fairly easy to cut a neat hole and just tidy it up with a rasp. The focuser has a cover plate so a perfect hole was not needed although it came out much tidier than I expected.

Even on plastic it cut rather than melted (it was a TiN coated one) and I found gently working it up and down sped things up, presumably by keeping the teeth clear.

Nice to know they work, wonder if I will ever use one again?

Neil

I have a few kicking around, will have to give them a go.

mike

I should say I used it in a hand drill - I coldn't fit a 1' by 5'8" tube on my mill...

If they are what I think then I use them a lot when doing piercing work on my woodturning great tools and remove material very fast

How fast were you winding the handle to worry about it melting the plastic?

Brian

That's because you have a Fisher Price toy mill

I think Neil used a hand held power drill, hand power doesn't work too well sideways.

Ian S C