| Gallery, Projects and General > How do I?? |
| machine an eccentric |
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| andyf:
Is it something like the top end of this you're after, John? I made that in the 4-jaw by centring up a round bar a bit bigger than the diameter at the fat end with the lever on it. The middle bit and the bit which would eventually form the off-centre stub was turned to the diameter of the middle bit (16mm in my case), and the end was faced. With a threading tool set dead on centre height, but with the toolpost at an angle to the lathe bed, I touched on the 16mm diameter, zeroed my cross-slide dial and then moved carriage to the right, taking the tool off the end of the work. Using the dial, I ran the cross-slide in by 4mm (half the diameter of the stub) and used the tool to scribe a light circle with the tool on the faced end. I then centre-popped a mark on the circle (the scribing located the punch). I could then use a wobbler located in the tailstock and a DTI to centre up the punch mark in the 4-jaw, and turn the peg down to 8mm. As I recall, I then reversed the job and gripped it in a 16mm collet to tidy up the fat end before adding the lever. Its function is to lift a plate carrying a motor and idler gear in and out of mesh with a gear on my mill's feedscrew, so absolute accuracy wasn't needed; the idler was positioned later with the lever in the "meshed" position, and it didn't really matter where the idler ended up when the lever was turned to "unmesh". Andy |
| Chuck in E. TN:
--- Quote from: mklotz on December 29, 2012, 11:42:26 AM --- a far safer technique than the redneck shim approach. --- End quote --- Marv, I resemble that remark... Chuck |
| John Rudd:
Lew, Your answer makes perfect sense to me...I need to find a 2mm thick shim..else go the 4j route. :scratch: Andy, The cam shaft is for a cam lock arrangement for a mini lathe tail stock...I'm trying to replicate the one on my Sieg... :coffee: Marv, Thanks for the info and the approach using a 4jaw with the pump centre...might give that a try... :dremel: |
| Pete.:
I used my 4-jaw. Turned the OD true using a light cut as the jaws were lightly snugged, then put my dial indicator on the No1 jaw and wound it out 1mm. Spun the chuck round and wound the No2 jaw in 1mm. Now I had an eccentric with 2mm throw with some very minor adjustment using the DTI. |
| Lew_Merrick_PE:
John, The attached document may help you.... |
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