C0630 Lathe Restoration Shanghai 11th machine works

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ysyang
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C0630 Lathe Restoration Shanghai 11th machine works

Post by ysyang »

Hi guys, I just bought this chinese lathe recently for $300 and I'm in the middle of taking it apart and cleaning it now.
The machine ways looks decent and it isnt binding up much. I'm gonna hand scrape every sliding surface and maybe even put some 0.03mm thick teflon in between the bed ways coz its hard to get turcite here.

Theres some scoring and grooves on the bed ways but it doesnt look too bad. You could still see the milling marks from the factory near the two ends of the bed ways.
Cross slides and compound table moves nicely.
However all the original scraping marks have been worn away, so I've got to scrape in new oil grooves on the sliding surfaces.
It uses a spindle busing and 2 thrust bearing in the spindle, which is a bit different from the tapered roller bearings.

im gonna try replaceing the lead screws with ballscrew to make it turn smoother.
maybe even add in a 1 shot oiler to oil all 6 dove tail surfaces at once.

The specs are:

Spindle busing instead of spindle bearings.
300mm swing over bed
550mm distance between centers
300kg weight
6 speed gearbox
automatic comound and crossslide feeding
Solid cast iron tray
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Last edited by rmac on Sat Apr 30, 2022 1:53 pm, edited 1 time in total.
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Bill Shields
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by Bill Shields »

Teflon on the bed ways?

Ball screws?

Have you given this a lot of thought?
Too many things going on to bother listing them.
ysyang
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Joined: Sat Apr 30, 2022 11:36 am

Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by ysyang »

Bill Shields wrote: Sat Apr 30, 2022 12:51 pm Teflon on the bed ways?

Ball screws?

Have you given this a lot of thought?
Yep teflon or turcite on the saddle
replace 13mm leadscrews with 1204 ball screws, 12mm diameter 4mm pitch.
The pitch is too high for manual turning,
so Add a stepper motor in for that 1.8 deg 200 steps/360 deg and I'll get 0.02mm resolution per step
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Harold_V
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by Harold_V »

ysyang wrote: Sat Apr 30, 2022 2:50 pm The pitch is too high for manual turning,
so Add a stepper motor in for that 1.8 deg 200 steps/360 deg and I'll get 0.02mm resolution per step
Hmmm.
I'm just thinking out loud.

.02 mm step on a cross slide equates to a diameter change of .00157", which would make it virtually impossible to do any precision work (like produce a bearing fit).

Personally, I'd give this idea a lot more thought. You'd probably be better served to invest the money in a more conventional machine, one that is already equipped with acceptable feed screws and dials.

Just sayin', of course. Each of us march to the drummer we hear.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
ysyang
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by ysyang »

Harold_V wrote: Sat Apr 30, 2022 4:19 pm
ysyang wrote: Sat Apr 30, 2022 2:50 pm The pitch is too high for manual turning,
so Add a stepper motor in for that 1.8 deg 200 steps/360 deg and I'll get 0.02mm resolution per step
Hmmm.
I'm just thinking out loud.

.02 mm step on a cross slide equates to a diameter change of .00157", which would make it virtually impossible to do any precision work (like produce a bearing fit).

Personally, I'd give this idea a lot more thought. You'd probably be better served to invest the money in a more conventional machine, one that is already equipped with acceptable feed screws and dials.

Just sayin', of course. Each of us march to the drummer we hear.

H
well its 0.02mm on a lathe cross feed/saddle, not a interpolated circle on a XY table, so it will always be fully round for the bearing fit
Guess u were thinking about 0.02mm on a 3 axis cnc.
Theres also 0.9 deg stepper motors which makes it 0.01mm with 1 full step, i think u can get more steps than 360/0.9=400 steps using half steps
ysyang
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by ysyang »

Woops. yeah i guess 0.02mm increments is a bit too high for bearing fits. I guess i will have to use 0.9 deg steppers with half steps that give 4mm/400/2= 0.005 mm increments
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Bill Shields
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by Bill Shields »

Have you ever before converted an old used manual lathe to CNC?
Too many things going on to bother listing them.
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Harold_V
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by Harold_V »

ysyang wrote: Sat Apr 30, 2022 6:58 pm
well its 0.02mm on a lathe cross feed/saddle, not a interpolated circle on a XY table, so it will always be fully round for the bearing fit
The point you're missing is that a half thou spells the difference between a slip and press fit. You're talking more than that. Also, does it mean that it advances the cross slide the .02mm, or does it mean that it alters the diameter by .02mm?

For rough work it most likely won't matter, but you will be very unhappy if you have to do any tight tolerance work. Some folks think they won't have to. I beg to differ. I've already mentioned a bearing fit. If you can't work to a couple tenths, you're not going to enjoy your attempts, and you're bound to have to fit a bearing at some point in time.

Roundness: Roundness is a function of the headstock bearings, not the cross feed nor its stepper motor. One generally does not interpolate a (small) hole on a lathe.
Theres also 0.9 deg stepper motors which makes it 0.01mm with 1 full step, i think u can get more steps than 360/0.9=400 steps using half steps
That would be far better (assuming the reading implies that the change is on the diameter, not the radius), although you still may not have the option to alter a diameter by a half thou if it designates a radius change instead of a diameter change. Again, I suggest you rethink your decision.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
ysyang
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by ysyang »

Harold_V wrote: Sun May 01, 2022 1:51 am For rough work it most likely won't matter, but you will be very unhappy if you have to do any tight tolerance work. Some folks think they won't have to. I beg to differ. I've already mentioned a bearing fit. If you can't work to a couple tenths, you're not going to enjoy your attempts, and you're bound to have to fit a bearing at some point in time.
Yep I get what you're saying now, and I realised 1mm move on the crossfeed= 2mm change in diameter.

I guess i will have to do some 5:1 reduction with a HTD 5mm belt drive to get that 4 micron or 0.15 thou steps in diameter
ysyang
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by ysyang »

Bill Shields wrote: Sat Apr 30, 2022 9:57 pm Have you ever before converted an old used manual lathe to CNC?
Not yet but I've watched rotarySMP's videos on his chinese mini lathe cnc conversion which should be a good starting point
https://www.youtube.com/watch?v=NVBC9Vz ... =RotarySMP
armscor 1
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by armscor 1 »

Hi Harold, you say roundness is a function of the headstock bearings.
My lathe has 8/10 of a thou runout measured in the spindle taper and on the D1, 4 external taper.
I took a very light cut on a piece of 2" aluminium bar and measured at different locations on the circumference and measured with a tenth resolution micrometer and no deviation.
Can I assume the spindle is not machined true or not seating true on the inner race of the bearing or worse the spindle is bent?
I think the course of action is to replace the bearings and grind the spindle true if required.
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Bill Shields
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Re: C0630 Lathe Restoration Shanghai 11th machine works

Post by Bill Shields »

QUESTION:

are you sure you have room inside the cross slide /compound for ball screw nuts?

Typically they are larger in diameter than conventional 'nuts'

we have an expression in North America involving silk purses and sow's ears.
Too many things going on to bother listing them.
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