Ecentric on both ends

[jumpinjimmy]

Hi every one I am brand new to the forum, I am a maintenance mechanic/ machinist , I have been working with manual lathes and mill for the better part of 20 years, I make parts for the company I work for to cut costs and speed up repair time.
I have a bad shaft on a machine that has an ecentric on both ends that must be in time with each other or the same place ?
I can cut the ecentric on one end with no problem , my problem is how do cut the other and have the in time with each other?
My first thoughts are to build a split collar to put on the shaft and cut it with my first ecentric , so when I turn it around I can chuck the ecentric in a 3 jaw chuck and steady rest split collar to give me a true center line to center drill the other end.
any help would be very nice. thanks

[jumpinjimmy]

I am beginning to wonder if I have asked a totaly stupid question?
I am not a highly trained machinist , mostly I have learned from trial and error, I have never seen any one put 2 eccentrics on one shaft that must be the same on both ends, is their a simple way?

[mccolld]

You need to index the part in some way. Maybe you could make a lathe dog with the catch part (the part that inguages the drive plate) on both sides. Then you machine one end and turn the part around and machine the other.

Wouldn't that work?

[drylakemachine]

You didn't say how big the shaft is.But any way I'd cut a pieceof material 1 inch longer than the part ,about 1/4 oversize.Check the center distance or stroke and center drill that dim into one end of the material. thinking the ecc is the larger of the dia.you would rough the ends to about .060 over then offset and finish the center. now go and finish the ends.If the end are smaller you need to do the center first because the center drilled hole would cut out. Good luck. jim

[solarguy]

If you can't think of any other way, then make the shaft with one eccentric integral/fixed, and make the the other eccentric as a separate piece with a short section of shaft. Make a nice coupling with a good fit to join the two pieces of shaft, slide the 2nd eccentric into the coupling, get it dialed in to exactly the relationship you want, and weld the coupling to both parts of the shaft.

There are drawbacks to every method, this one could distort the shaft when you weld it. The shaft will be somewhat weaker at the coupling. How much power gets transmitted by this shaft? What kind of precision is needed? How is the shaft supported? How big is the shaft? Could you turn a reduced diameter on the ends to be joined so the coupling is the same diameter as the shaft?


There's always a way.

HTH,

troy