That one cost as much as the lathe. The Bison is a significant portion of the cost. I'm glad I got a relatively good one that isn't tru-set considering a large portion of the run out is in the crappy adapter plate.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
I just glued on my 3 jaw chuck...
- Thread starter Batmanacw
- Start date
That one cost as much as the lathe. The Bison is a significant portion of the cost. I'm glad I got a relatively good one that isn't tru-set considering a large portion of the run out is in the crappy adapter plate.
- Joined
- Sep 8, 2019
- Messages
- 4,392
I just went out & checked the TIR on my PM-1030V.
.0005” on the spindle:
.0022” on the backing plate:
.0046” on the 4J chuck:
.0005” on the spindle:
.0022” on the backing plate:
.0046” on the 4J chuck:
Last edited:
- Joined
- Dec 20, 2012
- Messages
- 9,422
Set-tru chucks are nice, and they offer the speed of a scroll chuck. You can dial a Set-tru in to pretty tight tolerances BUT it will only be super-accurate for the diameter you set it for. This really helps if you have a production run on a bunch of precision rod. However, once you change to a different diameter you have to re-set the chuck for that diameter to regain really low run out.
There is a misconception that a Set-tru can be dialed in and it will then be accurate for ALL diameters you put in the chuck. This is not so, again because of the nature of a scroll chuck.
I own a near mint Pratt Burnerd 6 jaw Set-Rite chuck that I can dial in to about 0.0001" TIR and it will repeat that run out if I chuck up the same diameter work piece but the run out changes significantly if I use any other diameter. I can bring it back in to ridiculous run out for another diameter but it takes time. If I just set it once and use it on everything, it has about 0.001" TIR or less. Still pretty accurate but do you really need a $2,000 chuck for first operations? I don't think so.
Personally, I use an Emco/Rohm 3 jaw the vast majority of the time for first ops and an Emco/Rohm 4 jaw for second ops. I rarely use the 6 jaw except for plastics or thin-walled pieces and I use an ER chuck even less often for polished/knurled/threaded parts.
There is a misconception that a Set-tru can be dialed in and it will then be accurate for ALL diameters you put in the chuck. This is not so, again because of the nature of a scroll chuck.
I own a near mint Pratt Burnerd 6 jaw Set-Rite chuck that I can dial in to about 0.0001" TIR and it will repeat that run out if I chuck up the same diameter work piece but the run out changes significantly if I use any other diameter. I can bring it back in to ridiculous run out for another diameter but it takes time. If I just set it once and use it on everything, it has about 0.001" TIR or less. Still pretty accurate but do you really need a $2,000 chuck for first operations? I don't think so.
Personally, I use an Emco/Rohm 3 jaw the vast majority of the time for first ops and an Emco/Rohm 4 jaw for second ops. I rarely use the 6 jaw except for plastics or thin-walled pieces and I use an ER chuck even less often for polished/knurled/threaded parts.
My lathe
Loosen the studs and then re-tighten and see how much the backing plate changes. Mine simply had too much play to make me happy. I fixed it.
My er40 is Set-tru. I'll most likely always need to dial it in each time I install it. I would like the fit to be better so I don't have to dial in so much.
- Joined
- Dec 20, 2012
- Messages
- 9,422
ER collet chucks are different. If you dial it in accurately and then mount it the same way every time then it should hold its run out provided you are consistent with torquing the nut and do not collapse the collet excessively.
My ER chuck is not a set tru but it is damned accurate for what it is (about 0.0001" TIR). That is fine for any turned and ground rod I am likely to use it on and it matters very little for threaded or knurled parts.
My adapter for the collet chuck has a couple thou of slop so there is no way to mount it perfect each time.....unless I can do something to remove the excess slop.
So now you get the entire point of the thread. Glad you are all caught up now.
