Sharpening/dressing a chamber reamer

[270 totheend]

I recently came by some chamber reamers from an old gunsmith's estate. Some of them could stand to be sharpened. What is the recommended way to sharpen or dress a high speed steel reamer? I know not to touch the outer edge/face but can you sharpen a reamer by stoning the flute face of the cutting edge? I was thinking of making a jig to hold the reamer in place and a guide to maintain the angle of a stone. Clymer will sharpen ones made by them for a fee but most of the reamers I have do not have a manufacturers name.

270 totheend

 

[guntech]

Stoning the flat of the flute with a fine India stone is acceptable. Usually that 'cleans' any build up off. Stoning the relief on the diameter is tricky.

I have chambered probably 100 7mm Rem Mags with my reamer and I have lightly stoned the flats once or twice.

 

[trevj]

If you can get hold of a copy of the Guy Lautard books, The Machinist's Bedside Reader series 1,2, and 3, one of them has the drawings that would lead you to end up with a stoning jig which will maintain the angles and clearances that your reamers will need to keep cutting. The First, I am pretty sure, but you can check the index on his site.

Not really rocket science, mostly careful work and some trig to work out the angles.

Essentially a jig which can be adjusted to be parallel with the section of the reamer you wish to stone, as well as being adjusted for the height required, to maintain the angle. Having a decent tenths reading dial indicator, is handy for checking the drop as the reamer is rotated (a function of the clearance angle).

Might consider whether they are worth the effort to send to one of the reamer makers for a resharp. Pretty much going to boil down to their condition. Might be best used as roughers, or such similar work. Reamers that have been used and stored with care, may well be able to have their life extended, but if they were all just chucked into a drawer...

Cheers
Trev

 

[BCRider]

TECHNICALLY anything you remove from the face will also result in a slight reduction in diameter due to the clearance rake angle. But doing this with a stone and a jig to freshen up the edge is going to remove so little metal that in practical terms it isn't an issue when done with care and consideration a few times. Angles and trig and all that. Particularly if your touch up will be the first time it is being done.

I like the idea of a guide or jig. I'd want to support the stone so that it can't move inwards and catch on the gullet of the flute. And it should not be allowed to ride outwards and fall off the edge either. That would result in a bad spot on the edge. So some sort of block that the stone file or slip stone is clamped into so it is fully guided.

Perhaps treat it like sharpening a wood saw where you do 5 or 10 strokes on each edge for consistency and then check it for sharpness? And if any single edge needs more then again teh same number of strokes is used on each edge to keep things consistent?