Leblond crossfeed screw

[bartthefarmer]

I am currently rebuilding a 1966 15" Leblond servoshift. The lead screw for for the cross feed is badly worn. The nut seems to be in useable condition. My first inclination after, pricing a new screw from Leblond ($762.00) was to get a length of 8 t.p.i. acme rod and machine a new screw. However, John from Leblond told me that they used a "modified" version of acme thread for these lathes. My question is: has anyone found a source for this rod, or used off the rack rod and made a new nut? I don't think I am up to the task of starting from scratch on a new leadscrew. Any advice is appreciated, Bart

 

[Mike C.]

I think at that price, I'd be looking into a length of standard Acme rod and a matching nut, which could be silver soldered into the existing cross slide nut, or somehow made to work. If you need a new leadscrew, the nut is probably toast, as well. No sense in replacing just one or the other.

 

[JHOLLAND1]

I think we have one in great shape for $80.00 plus $15.00 shipping.

jh

 

[gbent]

I bought a length of threaded acme from Green Bay Manufacturing. Rockwell hardness of 30C, pretty good accuracy. Keep in mind yours is left hand thread. I just cut the old threaded portion off and spiggoted the new threaded rod into the old stub. Heat shrink only, no solder or pins. My old nut was good enough I just reused it rather than making a new one. Worn nuts don't introduce pitch error like worn lead screws.

JHolland's offer sounds fair to me, I'd buy it if I needed one.

And one feature that seems to be undocumented from LeBlond. The cross slide nut is retained in the top of the cross slide by the large nut visible on top of the cross slide. There is a pipe plug in the center of this assembly you remove to lubricate the cross slide screw and nut assembly.

 

[bartthefarmer]

Thanks for the input guys. Jholland that sounds very fair. My cross feed screw has a single key where it slides in the dial end and I also have a taper attachement. The lathe is a 6 C. I presumed the nut would also be worn but when you thread it out to the edge there is very little play.

 

[JHOLLAND1]

i will take photos of leadscrew and post these. Also will post dimensions. Should be up be 6 pm pdt.

jh

 

[JHOLLAND1]

cross feed screw dimensions LeBlond servoshift
1-length over all 25.25 inches
2-threaded segment 10.25 inches
3. diameter of acme threaded segment 0.744" typical
4. if you want nut it is another $20.00.
5-from machine with taper attachment
pics
Picasa Web Albums - jacksonholland - LEBLOND CROSS...

thanks
jh

 

[MwTech Inc]

My Cinci 17" had the same problem.

Repair done:

Bought precision acme rod and matching nut, LH of course

Grafted new acme rod to old shaft at area in front of old threads,shrink fit

Made a "adapter" between crosslide body and new nut as old nut was flat sided.

Smooth as silk

(this method suggested from PM members)

 

[bartthefarmer]

Jholland, thanks for the quick response. Your lead screw is very similar with the following exceptions;
1 overall length is 26 inches
2 My screw has a single 1/8" keyway on the dial side vs. the splined shaft
3 the bearing surface on the taper attachement side outboard of the threads is larger diameter.
With that said I am still considering buying your screw with the chance that I could use it for the threads as others have suggested, or possibly buy the dial with the splined mate to your lead screw if you have that piece.
I am curious if any one else can confirm that Leblond had it's own version of left hand 8 t.p.i. acme.

thanks to everyone for the help-Bart

 

[JHOLLAND1]

Bart
for $20.00 more I will throw in crank handle, short shaft with internal splines and apron mount. this will allow use of splines which I believe are critical-- it allows free movement of taper attachment.

jh

 

[bartthefarmer]

Jholland- sounds like a deal, I would like to have all the parts you mentioned. P.m. me with your info and I will send you some money, Thank you- Bart

 

[JHOLLAND1]

Bart

new pic of remaining parts which should reduce replacement problems.

Picasa Web Albums - jacksonholland - LEBLOND CROSS...

jh