PDA

View Full Version : Tailstock chucks?



japcas
04-16-2006, 06:08 PM
I though I would ask this question here because it seems some of you have some really good resources for finding things. At the shop I work in we run a lot of heavy and long shafts. Some out of stainless and some out of 4140 and mild steel. We use rotating 4 jaw independant tailstock chucks to indicate the shaft in and get the steady rest spots turned so we can face the shaft to length and get it centered. The problem is all of the ones we have are used and abused and worn out. We would like to buy some new ones but are not having any luck finding them. This is where you guys come in. If anyone knows of a vendor or supplier selling these could you post them here? We are looking for 8, 10, and 12 inch sizes. These are used mostly on American Pacemaker lathes in the 14 to 18in size on up to a couple of 24in machines. I think the tailstock taper is MT4 or MT5 but I can check on that to be sure. Anyone know what the tailstock taper is can chime in? Any help would be appreciated.

John Stevenson
04-16-2006, 06:30 PM
Can't help with an off the shelf solution but I run a 6" 4 jaw in a No 4 morse tailstock.
The first one I had was only 4 or 5" and came secondhand but was a poor design, the bearing weren't man enough.

I made the one I have at the moment and fitted three bearings, one into the back of the chuck and two in the backplate.
I got the one in the chuck as big as it would go and the backplate ones half as big again.
The two rear paired bearing on mine are 40mm bore.
I want to build one for the bigger lathe that's on 5morse but I reckon I need about 50 or 60mm bore races on this one.

.

JCHannum
04-16-2006, 06:54 PM
What is the diameter of the shafts? Would a large cup type live center work?

The other question is how worn out are the existing chucks? I know of no manufacturers that might have an off the shelf item like that, and it would most likely be made to order. How much would be involved in rebuilding the existing units? It would possibly be more economical than buying new.

Where are you located?

jh
04-16-2006, 07:32 PM
Bison brand chucks also sells something like this thou I don't know if they go big enough. Sold by Toolmex in the states. Check it out. James

japcas
04-16-2006, 09:50 PM
We do breakdown repair work for the company that I work for. We have Monarch 10EE's up to a monarch with a 34 inch chuck and everything in between. Our work varies everyday. I doubt if a cup center would do it. The chuck jaws seem to be sprung and the bearings are getting to be in rough shape. We may be able to go through them but we were hoping to buy some new ones but aren't having much luck. What I would like to know is why nobody makes these? How do other shops go about prepping large shafts so they can be turned with a center in the tailstock? I know we aren't the only shops using these so it seems that there would be a need for them.

JCHannum
04-16-2006, 11:08 PM
I sent an e-mail with a contact to try.

Rebuilding still may be the most economical approach, new chucks and bearings will need to be purchased regardless. If the bearing shafts and housings are not damaged, much machining and attendant cost can be avoided.

japcas
04-17-2006, 03:38 AM
Thanks JC. I'll check my mail.

John Stevenson
04-17-2006, 05:10 AM
Japcas.

Going on what you say the chucks and bearings more than likely need replacing so all you are left with is a Morse taper shaft which may or may not be worn on the bearing surfaces.

My take would be to buy in a new chuck then sketch up the layout, buy some decent bearings and make a new Morse arbor and backplate to suit.

Given on what you have stated you have the machines and skill necessary to do this and you will have a custom steady that will last.

You ask:
"How do other shops go about prepping large shafts so they can be turned with a center in the tailstock? I know we aren't the only shops using these so it seems that there would be a need for them."

Here's how I handle built up shafts that have no centre hole and can't be run in a steady.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/hidden/steady1.jpg

And in use.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/hidden/steady2.jpg


.

japcas
04-17-2006, 07:42 AM
Thanks John. We use "catheads" on occasion also but the tailstock chucks see a lot more use. I was thinking of just getting some plain back chucks and build a new rotating chuck. I just figured that somewhere out there someone was making and selling these things. The biggest thing bison sells is a 6 inch model and that usually wouldn't be big enough. By the way, we use 4 jaw tailstock chucks because a lot of times our shafting material may be bent and oversize just enough to make the part so we have to throw the shaft out to get the biggest fit on the shaft we are making to run true. We have one with a 3 jaw chuck but it very rarely gets used. We may just have to look into repairing ours.