Hi there, Martin,

I suggest that you research tapered D-bits.

Best regards,

Swarf, Mostly!

Would a google with "D-bit reamer", "D taper reamer" or "D bit chambering reamer" help?

I ocassionally stumble upon on D-bit type taper reamer instructions, but can't remember bookmarkking any right away.

I have made several too from silversteel/dil rod and they seem to work reasonably well, require quite a bit effort to use though.

**LINK**

There is one rather compilicated, but good method:

**LINK**

Pekka

Martin, I have made many tapered 'D bit' reamers over the years all of which have produced good holes and surface finish mainly in steel but also brass and aluminium.

The big problem with tapers is that to be effective they have to match the corresponding part exactly and this is usually achieved by making sure the hole is done at the same setting as the cutter without moving the topslide.

When this can't be done ie in your case – if its possible you need the magneto shaft as you do it. Turn a tapered hole in a piece of scrap (I usually use brass) to match the shaft as best you can and then check the shaft in this using engineers blue to see where it fits – slightly moving the topslide and recutting if required to improve the fit until it's satisfactory and mating its full length. It's surprising how little it has to be moved to make quite a big difference in fit. Once you have the taper right you can then proceed to make the cutter reasonably confident that it will match the shaft

Hope this helps – Ramon

If you can set the shaft between centers you can then set the topslide with a dial gauge, should be spot on. Difficulty I have is cutting down to exact center without a mill.

From memory:- the taper will be 1 in 6 or 1 in 7.