Thread: BSA Motor repair.

Hello Jordan,
I have not had a great amount of experience in reaming which is why I asked the question and looked up various references.

My Machinery's Handbook (19th ed., P1598) quotes the following:

'The minimum practical amount of reaming stock allowance will often improve finish by reducing the volume of chips and the resulting heat generated on the cutting potion of the chamfer. Too little reamer stock , however, can be troublesome in that the reamer teeth may not cut freely but will actually deflect the work material out of the way. When this happens, excessive heat, poor finish and rapid reamer wear can occur.'

The text does not differentiate between hand and machine reaming, I suspect also that the thickness of the component being reamed and the sharpness of the reamer would also play a considerable part in getting a satisfactory result.
If I had ten to do I could fiddle with the reaming variables and probably get what I want, with only one to do I will follow your advice.

Regards, Phillip

I see the idea now, Phil, thanks. The theory makes sense, but if you can't creep up to size with an adjustable reamer it isn't much use. It's a good reason to use the honing method instead.

Jordan

Even with an adjustable reamer you should find it easier to get a decent finish and bite on your cutting edges if you have a few thou to remove.
If you leave to little in the hole it is hard to start the reamer without it chattering and biting in.
Also if you dont have enough meat to take out you will put a lot of load on only a small area of the reamer rather than over most of its length.

Probably why it's so hard to get perfect results with a hand reamer. I make tiny adjustments to the nuts on an adjustable reamer - like about an eighth of a turn - when I want to finish at a certain size. I don't expect it to be perfectly round though.
It sounds like a more round hole could be possible with more metal to remove. But how to be certain you'll end up at the exact desired size?

Jordan

Dont you set your adjustable reamers with a micrometer.

No, although it sounds like a good idea. When fitting a bush, I've always had the thing that goes into it to use as a gauge. I've got lots to learn.

Jordan