Eccentric turning

[desmotom]

Has anyone ever turned an eccentric on a lathe. The eccentric is turned from bar stock with concentric journal next to the eccentric one. Tolerance is not an issue, the part will be sent out for grinding. I was thinking of using a milling cutter and the c axis to interpolate it.

[Zoober]

Only other way I know is to bore collet or jaws off- center on a mill. But that would be 2 ops, 2 collets (or set of jaws), 1 for concentric, 1 for eccentric.

[FP1]

We make a part approx 2" OD X 2" long. It has a bore thru the face but eccentric to to the OD by .25 offset. We made a split bushing and wire EDM the hole in the bushing off center. We slip the bushing over the part then chuck on the bushind OD in a standard 3 jaw chuck. Works fine. Of course this is a very simple type eccentric part.

[desmotom]

I was hoping to get it done in one setup. That was they way I was going to go in two ops. I would save so much time in one op though.

[Guest]

I used to machine shafts, many, many shafts that has eccentrics on one end.

 

When had a sleeve machined and reamed off center and placed the shafts into the sleeves, held with set screws and machined the ends.

[FP1]

quote:

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I was thinking of using a milling cutter and the c axis to interpolate it.

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I have done this too. It was kind of like a stop collar with a set screw thru the OD and and eccentric cam shape on one face. Used an endmill mounted paralles to Z-axis to mill the cam. Worked very well.

[DavidB]

LINKY

HTH

[MCFELIX]

DESMOTOM maybe you will need a y axis for turning out center if you turning behind any shoulder examples shafts good luck

[desmotom]

I do have a y axis, I going to give it a try.

[crazy^millman]

I would try curve 5 axis for accomplish this task. There is alos a toolpath in the advanced 5 axis that might do it but not hasp tonight. If I get some time tommorrow I will see if I can make up an exmaple for you.

[Greg Williams]

Des,

 

This can be done with Y axis Milling.

[desmotom]

The machine I am doing it on has 8 axis.

[Jack Neelands™]

http://www.okuma.com/video/MACTURN350_02.wmv

 

Is this what you are looking for ...watch the final part of the video...this shows it cutting an eccentric fin using the b axis in the the last 30 seconds of the video

[JDowe]

Can you create a circle offset by the amount

of eccentricity then use c axis - c axis

contour to do a series of plunge cuts

I have never done it this way but it looks

to backplot and post to give the desired

effect

[JDowe]

Playing with it a bit more - create

a helix on the dia then offset the helix

by the eccentricity and use c axis contour

on the helix

[desmotom]

I'll try that thanks

[Tom Dorgan from American Precision]

Here is a crazy one for you guys. My old company made subsurface shutdown valves for oilfield. They had a lot of eccentric parts. They would chuck a smaller 4 jaw chuck in the 3 jaw and indicate the bar turned in the first op to the amount of eccentricity required and run the heck out of them. I am talking 6-10" monel, inconel, incoloy up to 3 or 4 feet in length.