12" Sebastian Geared Head Lathe Info Hunt and Compound Rest Repair

[hiluxindustries]

Howdy everyone,

I recently acquired an older Sebastian lathe - #31480 with a "Gold Seal" tag on it - which I've since cleaned up and gotten into decent running condition. I'm now in the process of fabricating an adjustable base with (6) 7/8-14 jack bolts (I'll post photos once complete) as the previous base only has 1/2" holes for miniscule hold down bolts. Once I've got it leveled out I'd like to start dialing it in by cutting some test bars but presently my compound tool rest has some excessive back play I can't get out of it causing chatter and inconsistent depths of cut on heavier passes. Threading and feeding .001" can result in .005 - .07 and a spring pass could be the same making it a guessing game hahaha.

Here's a few photos, it's been brought into this century with a new 3 phase 3 HP motor controlled via VFD and a quick-change tool post holder. If anyone has the manual for this particular machine I'd greatly appreciate it. I've been apprehensive to buy the other manuals I've found online because I haven't seen one that looks like mine in any of the sample pictures. Other than some standard wear, typical repaired parts and homemade repairs she runs decently quietly thru the gears and seems to have a solid head stock. The cross slide will probably need some love next but one thing at a time.

If anyone has any other advice for getting this one in order that would be great. One job I think I'm going to perform is cutting a new drive pulley (double v-belt design) to get some additional RPMs out of it, the Timken bearing should be able to handle things up to 1100 RPM which would be ideal. Right now, I can push it to 9ish00 RPM without issue but max out the revs on VFD frequency at 60hz. Looking forward to hearing some thoughts!

 

[johnoder]

Howdy everyone,

I recently acquired an older Sebastian lathe - #31480 with a "Gold Seal" tag on it - which I've since cleaned up and gotten into decent running condition. I'm now in the process of fabricating an adjustable base with (6) 7/8-14 jack bolts (I'll post photos once complete) as the previous base only has 1/2" holes for miniscule hold down bolts. Once I've got it leveled out I'd like to start dialing it in by cutting some test bars but presently my compound tool rest has some excessive back play I can't get out of it causing chatter and inconsistent depths of cut on heavier passes. Threading and feeding .001" can result in .005 - .07 and a spring pass could be the same making it a guessing game hahaha.

Here's a few photos, it's been brought into this century with a new 3 phase 3 HP motor controlled via VFD and a quick-change tool post holder. If anyone has the manual for this particular machine I'd greatly appreciate it. I've been apprehensive to buy the other manuals I've found online because I haven't seen one that looks like mine in any of the sample pictures. Other than some standard wear, typical repaired parts and homemade repairs she runs decently quietly thru the gears and seems to have a solid head stock. The cross slide will probably need some love next but one thing at a time.

If anyone has any other advice for getting this one in order that would be great. One job I think I'm going to perform is cutting a new drive pulley (double v-belt design) to get some additional RPMs out of it, the Timken bearing should be able to handle things up to 1100 RPM which would be ideal. Right now, I can push it to 9ish00 RPM without issue but max out the revs on VFD frequency at 60hz. Looking forward to hearing some thoughts!

Here is a scan though not exactly as yours.

 

[4GSR]

From your description of trying to hold tolerances tells me you lathe has wear in the bed ways and cross slide. This is typical on most all lathes of this vintage. Need to study the ways and means of scraping for accuracy to improve the condition of your lathe so it will cut more accurately.
Try some high speed steel for cutting tools instead of carbide. This may give you better results. Believe me, I've run lathes in my past that were so worn out that you learned how to cut and hold tolerances by many unorthodox methods not written in any school books out there! Files and emery cloth are your best friends.
BTY- Welcome to the forum!

 

[hiluxindustries]

Thanks for the info guys, I'll do just that. I have some scraper blades on order and have been watching people like Keith Rueker work their magic compounds for a while so it should be a fun starter project.

I was able to procure the 8" 4 jaw chuck and a bunch of HSS blanks so I'll get to work shaping tools and start having some fun