Sshire
Well-Known Member
- Joined
- Jun 29, 2011
- Messages
- 936
- Reaction score
- 259
Lucky Accident
Somewhere, on virtually every forum having anything to do with machining and small lathes or mills, you'll find something like this.
"Chinese machines are a kit and will require some level of tuning, adjusting, remaking parts, etc. to get them to a workable state."
I've seen that and so have you. So what do we do?
Clean off the shipping gunk. Lubricate them. Replace 4 way tool posts with the quick change variety. Add a DRO. Better live centers. Better chucks, etc. I've done that.*
Finding endless belt changing a PITA (turn and face at one speed, change the belts to different pulleys for parting, change back, change to yet a different speed for center drilling and reaming, change back), I replaced the 120 V single speed motor for a 220 V Leeson motor and Teco VFD to give me variable speed with lots of low end torque. Spectacular.
So all of the above made my lathe much better than it was out of the crate. But...
I was never happy with the lack of smoothness of the cross slide and compound slide. It seems as if I was forever adjusting the gibs. A bit tight but no wiggle in the slides. A bit loose, easier to turn the handwheels but movement in the slides. Sometimes I got lucky and hit a sweet spot but after a few days that was gone.
I had read a number of articles about lapping the slide dovetails and figured why not? The "professional" machining forums screamed, "NO!! Never lap the gib and dovetails!" Most of the "amateurs" who had done it said "big improvement". What to do.*
Removed toolpost, compound, crossslide screw and nut and applied Timesaver lapping compound. This starts out at the stated grit and progressively becomes less effective until it won't cut at all. Put fresh Timesaver on, rinse and repeat. Move the compound by hand back and forth for about 45 minutes replacing Timesaver when it feels like nothing is happening. As the slide movement gets easier, tighten the gibs a bit and continue.
When I felt that the movement was pretty smooth (and my arms felt like they would drop off), I cleaned everything very well and started to reassemble everything.
I noticed that the gib strip had a curve in it. I really hadn't paid this any close attention but everything I had read indicated that this wasn't right.
Maybe it's supposed to have a slight spring but this seemed to spring in the wrong direction. Very little. Maybe 50 thou off the surface plate at the center.
I can bend that straight. Take that gib strip! *I laid it across two parallels at either end, and very gently lowered the handle of the press. It moved (honest) maybe 20 thou and SNAP. Now I have two gibs, evenly divided at the locating slot. NEW PROJECT.
.25 brass flat bar. Cut, faced, 30 degree bevels on each side, new locating slot milled. Done. (Uh, 2 1/2 hours later).
So how did this all work out.
Gib adjustment is no longer a PITA. Much easier to set and much less fiddling. And the cross slide movement. No wiggle and smooth as glass. It's like a new lathe. Can't wait to do the same for the compound slide. Timesaver and brass gib strip for sure
Somewhere, on virtually every forum having anything to do with machining and small lathes or mills, you'll find something like this.
"Chinese machines are a kit and will require some level of tuning, adjusting, remaking parts, etc. to get them to a workable state."
I've seen that and so have you. So what do we do?
Clean off the shipping gunk. Lubricate them. Replace 4 way tool posts with the quick change variety. Add a DRO. Better live centers. Better chucks, etc. I've done that.*
Finding endless belt changing a PITA (turn and face at one speed, change the belts to different pulleys for parting, change back, change to yet a different speed for center drilling and reaming, change back), I replaced the 120 V single speed motor for a 220 V Leeson motor and Teco VFD to give me variable speed with lots of low end torque. Spectacular.
So all of the above made my lathe much better than it was out of the crate. But...
I was never happy with the lack of smoothness of the cross slide and compound slide. It seems as if I was forever adjusting the gibs. A bit tight but no wiggle in the slides. A bit loose, easier to turn the handwheels but movement in the slides. Sometimes I got lucky and hit a sweet spot but after a few days that was gone.
I had read a number of articles about lapping the slide dovetails and figured why not? The "professional" machining forums screamed, "NO!! Never lap the gib and dovetails!" Most of the "amateurs" who had done it said "big improvement". What to do.*
Removed toolpost, compound, crossslide screw and nut and applied Timesaver lapping compound. This starts out at the stated grit and progressively becomes less effective until it won't cut at all. Put fresh Timesaver on, rinse and repeat. Move the compound by hand back and forth for about 45 minutes replacing Timesaver when it feels like nothing is happening. As the slide movement gets easier, tighten the gibs a bit and continue.
When I felt that the movement was pretty smooth (and my arms felt like they would drop off), I cleaned everything very well and started to reassemble everything.
I noticed that the gib strip had a curve in it. I really hadn't paid this any close attention but everything I had read indicated that this wasn't right.
Maybe it's supposed to have a slight spring but this seemed to spring in the wrong direction. Very little. Maybe 50 thou off the surface plate at the center.
I can bend that straight. Take that gib strip! *I laid it across two parallels at either end, and very gently lowered the handle of the press. It moved (honest) maybe 20 thou and SNAP. Now I have two gibs, evenly divided at the locating slot. NEW PROJECT.
.25 brass flat bar. Cut, faced, 30 degree bevels on each side, new locating slot milled. Done. (Uh, 2 1/2 hours later).
So how did this all work out.
Gib adjustment is no longer a PITA. Much easier to set and much less fiddling. And the cross slide movement. No wiggle and smooth as glass. It's like a new lathe. Can't wait to do the same for the compound slide. Timesaver and brass gib strip for sure
