The backing plate fits on the taper just like a drill chuck fits in the tailstock and locks on the taper. If it's hitting the flat section instead of the taper you will have a problem. The chuck you ordered, per your link above, is a standard accuracy chuck, not a high accuracy one, so if you have it running within .001 t.i.r. then you have a pretty good chuck. I don't see an issue here.
Bison chuck question
- Thread starter dskogman
- Start date
If you set your chuck up , as you have done, so there is little runout, you can then check with a feeler gauge to determine how much shim you want. If a .002" feeler goes and . .003 does not, I would try a .003 shim. Check for repeatability. If concentricity does not repeat reliably, go to a .002 shim. Ideally the chuck (or backing plate) should, as someone already stated, contact the face and taper at the same time. WH
Dusty Stevens
Shiner
I cant believe they even sell plain scroll chucks without being on a set tru backplate
Set True chucks are mostly just something else to fiddle with, my opinion. They wear pretty fast ( set screws) if you do any heavy turning. For general turning and most work a decent flat back three jaw chuck will do fine. With a direct mount chuck you have to live with what you got. They're pretty decent but you can't take the chuck off and true up the backplate if it decides to warp a little. If you can't live with .001-003 runout then you need a four jaw. Hot Roll steel isn't made to size and often isn't truly round so you have to turn to size anyway.
Set True chucks are fine if that's what you like but you set it for something out of round and the next thing you chuck will have to be reset and that wears out screws and threads. They're expensive and usually heavier. It's something you have to constantly fiddle with and cannot truly take the place of a good four jaw anyway.
The usual comeback is "do you own a set true chuck"? The answer is yes, two of them. An old Buck 6" set true and an 8" Pratt. They're ok for what they are but just in my humble opinion a good flat back three jaw is my go to. As for the OP, the chuck indexes on the taper. There's a reason why industry went to D series to replace the old long taper. They're lighter and work just as good. I would check the cam pins to make sure they're not set too long or too short before I'd suspect anything else. I sure wouldn't try to remanufacture the spindle.
Set True chucks are fine if that's what you like but you set it for something out of round and the next thing you chuck will have to be reset and that wears out screws and threads. They're expensive and usually heavier. It's something you have to constantly fiddle with and cannot truly take the place of a good four jaw anyway.
The usual comeback is "do you own a set true chuck"? The answer is yes, two of them. An old Buck 6" set true and an 8" Pratt. They're ok for what they are but just in my humble opinion a good flat back three jaw is my go to. As for the OP, the chuck indexes on the taper. There's a reason why industry went to D series to replace the old long taper. They're lighter and work just as good. I would check the cam pins to make sure they're not set too long or too short before I'd suspect anything else. I sure wouldn't try to remanufacture the spindle.
dskogman
Gold $$ Contributor
Success!!! I checked with a feeler gauge and there was a .0015 gap between the spindle and chuck. I figured with the shallow taper on the spindle nose it was only a tenth or two too small as Alan suggested. I turned it around and chucked it up in the four jaw and polished the taper in the chuck with some 400 grit and a block. After a couple of try’s it lock’s up with <.0005 runout. Thanks for all the suggestions everyone!
https://giphy.com/gifs/runout-iFCPfopaIw9fg6htNu
https://giphy.com/gifs/runout-iFCPfopaIw9fg6htNu
Good job! WH
My 6 jaw set true is too heavy for the old man. I used it one time and put it up.
Butch;
If you pleases, have your grandson pick it up, put it in a strong wood box and send it to me. I will take good care of it.
Dusty Stevens
Shiner
Your old pal in arkansas needs one too butch
butchlambert
Site $$ Sponsor
I want one too!!!
Dusty Stevens
Shiner
I'll gladly exchange it for the next custom die you'd like.
butchlambert
Site $$ Sponsor
I will get some plywood and 1X4 and build a box. I will send you an email.
dskogman
Gold $$ Contributor
Don't have a big ground rod to test but a barrel showed .0003-.0004 or so. I have not pulled it off and back on to see how repeatable it is yet.
Fixed it for you...lol
I have seen that chuck, brand new condition, too heavy even for this young 67 yo.
ridgeway
Silver $$ Contributor
Just curious as to your setup and how you go about indicating.
If you are simply chucking up on a blank OD and just going to town on turning a tenon and chambering, this is not ideal. I've seen custom cut rifled barrels vary in OD to ID concentricity by a rather large amount. If you truly plan on doing barrels, the chuck you have is not what you are looking for...
dskogman
Gold $$ Contributor
I have a spider mounted on a backplate for barrel work. The 3 jaw is just for simple stuff.
I am glad the 10" Buck Chuck is gone, but I keep making cradles to lift them onto the ways and store them on the floor.
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