Those funny drill saw things…

[Neil WyattModerator @neilwyatt]

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

[Neil WyattModerator @neilwyatt]

[AJWParticipant @ajw]

I have a set of them.
Just need the telescope to use them!

Alan

[Mike PooleParticipant @mikepoole82104]

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

mike

[Neil WyattModerator @neilwyatt]

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

[DalboyParticipant @dalboy]

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

[Brian GParticipant @briang]

Posted by Neil Wyatt on 11/09/2018 21:33:09:

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

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

Brian

[David Standing 1Participant @davidstanding1]

Posted by Neil Wyatt on 11/09/2018 21:33:09:

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

That's because you have a Fisher Price toy mill

[Ian S CParticipant @iansc]

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

Ian S C

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