What kind of parting off tool are you using?

I know nothing about Emma Victoria so have no idea of diameter, width, material etc but I assume that your tool width is a lot less than the groove width?

Chatter is due to lack of rigidity, of the job. as well as the cutter. If your groove is in the middle of a long shaft or a long way out from the chuck, it will make things difficult.

After roughing out most of the material I would grind the profile of the cutter twice whilst finishing to size. Angle the front edge so that it effectively becomes a single point tool. That allows one inside face and half, at least, of the diameter to be finished. Regrind the tip to do the opposite face and carefully machine the diameter to match the first cut.

Definitely don't try and cut the groove to the same width as the cutter unless you have an extremely rigid setup and you know the the tip of the tool is parallel to the main axis.

Ian P

You may have more luck grinding up a tool that is 1/16" wide, make two plunge cuts almost to depth and then traverse back and forth while slowly advancing the tool the last few thou' . Use the slowest speed you have and some cutting fluid.

J

If you have enough height to centre the tool try it in reverse IMHO you should see a difference.

Once the tool has started to vibrate and cause chatter then getting rid of it especially in a groove by machining is a bit tricky. In the past I've achieved a passable result by turning the chuck by hand, or with the chuck key, against the tool, obviously only very small cuts of 0.001'' or so can be taken, but with a razor sharp tool and a little cutting oil you should be able to improve the situation.

Too high a speed can cause chatter also.

Tony

Neil,

you've worried me now. I made mine to fit the bottom of the groove. With the screws done up tight there is a nice running fit. Where should the strap bear on the eccentric ???

John

Sorry John,

I had in mind the design where the strap has a tenon all round or sometimes a peg that engages the groove in the eccentric. In these designs the eccentric runs on the shoulders of the groove.

Neil

Bill, I'd tend to go for cast iron. Which ever way you go use slow back gear, On my lathe 60rpm (some times I'd like a bit slower), and grind the HSS tool as Ian Phillips wrote. Ian S C

Henry, Pleased you've joined the forum at last. I'm itching to start the boiler. I'm miles behind,still at the pump stage.

Bill, I made my eccentric out of free cutting mild steel with a cutter thinner than the groove. I also ground a 'V' in the top rake .. something someone mentioned on here. Got a lovely smooth finish by traversing the last few thou out the bottom. .. John