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View Full Version : can threaded spindle be converted into D1-4?



grinch
02-15-2002, 06:47 PM
I wondering specifically about a south bend 13in lathe spindle.

Thanks in advance

JIM DEWOLF
02-15-2002, 09:36 PM
Well, that is a bit of a problem, Grinch. If you make an adaptor to thread on the spindle nose, it will project out too far and increases machining chatter, plus it is a big job. I would suggest an even bigger job! Pull the spindle out of the lathe, make an accutate drawing of it, with nose modifications for the D-1 nose, reassemble the spindle, buy a piece of 4140 and now you have a great project to finish off the winter. Also you have a much improved lathe. Anyone who has a D-1 spindle would not willingly go back to threads. A real pain.
Good luck and there could be someone has a better idea. I always come up with the hard ways to do something (because I don't want to do it again).
Jim

Thrud
02-15-2002, 11:18 PM
Jim

The easy way is just get a machine with the desired spindle.

Your hard way is a great idea if build a lathe from scratch, but by the time he gets it hardened and ground properly by a jobber it would be cheaper to get a new machine.

There is nothing wrong with threaded spindles - okay, SOMETIMES they unscrew when the machine is thrown in reverse. My machine has a split collar that goes on a shoulder machined in the backplate, backplate is slotted, clamp puts death grip on lathe spindle. GIMME REVERSE, Scotty!

dave

KenS
02-16-2002, 03:53 AM
Call South Bend to see if the 13" was changed to D-1 in a year later than yours. I know that the Heavy 10 went from threade to L00 to D-1 over the years with little change to the machine, so a later spindle could be fitted into an earlier model. I haven't heard any statement that it wouldn't work. I am sure that a part change made with new SB stuff would be prohibitive (how DO they set their parts prices?), but there's plenty of other sources for used and even new parts that are excessed from some inventory.

Personally, I wouldn't bother. Threaded spindles aren't THAT bad if you can take the time to keep their threads and seating surfaces really clean, and the improvement in precision wouldn't be large considering that the 13" has plenty of other little built in losses. In fact I had once gotten a bug to changeover my Heavy 10 to a camlock mount but I took a testcut over an 18" span that came up .00011" difference one end from the other and came to my senses. How tight a tolerance does bumpkin home know nothing machinist wannabe NEED? As it is, or even were it much less than it is, this lathe has capabilities that far exceed my own.

JIM DEWOLF
02-16-2002, 08:21 PM
Gee whiz guys, I thought it would be a real chalange to make your oun spindle. And Dave, I don't think you would have to harden it. 4140 would be plenty tough enugh. I was stupid enough to make my own percision boring head for the mill/drill. sprnt 5 months on it off and on. Could buy one for 200 bucks but that was no fun. My little head is bang on and I had a ball making it. I would'nt hesitate making a spindle but you are all correct re threaded spindles. I never run a lathe with a D-1 spindle till I got my own lathe 3 years ago. If your not adventurus, stay with the thread.
Jim

Thrud
02-16-2002, 09:01 PM
Jim

I did the same thing - spent a ton of time making a duplicate of my lathe spindle so I could interchange tooling. Great Idea. Did a faboo job right upto threading that 1-1/2"x8TPI nose (perfect job on the mt#3 socket too!) only to thread it some bastard thread betwixt the 8TPI and metric. I got so upset I threw that spindle in the scrap. I double checked the gearing too - or, so I thought - and did a light test cut. I was in a hurry to get somewhere else and was not paying attention. I was a bad boy....

kap pullen
02-17-2002, 07:07 AM
Dave,
I feel your pain, been there ,done that.
Turned a crank shaft for my 1/2 size Case between centers. 2 1/4" by 30 some inches long within .001" Only problem was it was about 3" too short.

Did a job before Christmas, .0002 tolerance in sone bored holes. The plater etched them oversize in the plating operation.

Oh well, It took two more weeks to do them over again. Good thing the inspector checked each one as I finished it. Finished the holes after plating this time. The boss paid for that one.

That's life in the big city.

I've got a dumpster full.

But there's a warehouse full of good parts
out there somewhere.

That's the way it is with this job.
One moment of inattention at the end of a job, can spoil days, or weeks worth of work and materials.

That can spoil your whole day!

Can't erase our mistakes like some jobs.
Just a piece of steel. We have a lifetime to do it right (tell the boss that one).

Kapullen



[This message has been edited by kap pullen (edited 02-17-2002).]