How To Thread in Chinese (not an instruction manual but a question)

Logan Novice

Logan Novice

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Braking the Code
My PM 1127 lathe came with a manual which, like most import equipment instructions, leaves something to be desired. I have some of it interpreted but I'm stuck, VERY stuck, on the gear change routine for threading. I figured out the"L" is for lowest gear (not in terms of gear ratio but in terms of where it is positioned in the gear chain) and that "H" represents a spacer, but what "spacer" means remains a mystery. Is it a gear put into place to act as a spacer or a shim of some sort? (even though my lathe didn't some with a set of "spacers") Oh yes, "Z" appears to be a Chinese abbreviation for "gear".
At the moment I am setting up to thread a rifle barrel, (1.0625 x 16tpi) The four jaw chuck is centered and the recoil lug is fitted. I am ready to thread. Anyone got a guide that makes sense? And, while I'm at it, if the setup for a 16tpi thread has "Z1" on the backside of Z2 then Z4 can't be on the back side of Z3.
Help .... anyone ...

ADDENDUM:
OK; success. My sincere thanks to all of you who took the time to offer guidance. You reduced my level of frustration immensely and I appreciate it more than I can say here.
This project is a rifle barrel mock up on which I have practiced before actually tackling an actual barrel. Mock ups are cheap, barrels are expensive. The threads are a little rough (I used a HSS cutter and probably cut a bit faster than I should have) but the action and pseudo recoil lug fit beautifully. Thanks again to all who contributed to helping me over this hump.
For those who may not have tried it, I used Joe Pieczynski's method of reverse cutting (lathe spindle and lead screw in reverse with cutter inverted) and it works like a charm.
 

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I can not help with your gear issues. But since you are not sure of the setup I would try that thread on a piece of scrap before I tried a real barrel.
 
Spacer, from what I have seen on these lathes is one of the smaller loose gears, simply used as a placeholder. It's not an "active" gear and plays no part in the chain other than as a placeholder, keeping the other active gear on the shaft in position.
If you can post a picture of the chart it would help. Definitely don't try an important threading job until you are certain you are set for 16tpi by doing a scratch pass on a piece of sacrificial stock
-Mark
 
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You can use a small gear as a spacer, but the lathe should have come with little rings that are intended for the job. They look like just the hub of the gear, about 1/4" wall.

The lines in the chart show which gears mesh.

Let me pull up the manual and I'll try to get the setup for your thread.
 
Gear box to A. And threading mode.

From the headstock, looking at the side, you have a spacer then an 80T.

Middle is 30T then 40T. 40 is meshed with the 80 above.

Leadscrew end is a 60T then a spacer. The 60 meshes with the 30 in the middle.

Make sure you test on scrap or at least a scratch test to make sure you have the right gears setup.
 
Thanks to all who posted .... I think y'all put a light on the path to success; and I appreciate it very much. I'll do my best to work with the advice you've given and make a test run as recommended before making the cut. Thanks ttabbal for the outline. I'll use that as an decode the entire coding system on the charts. Also, my lathe came with only one "little ring" spacer that already had a home on the end of the shaft that powers the carriage. I'll see if PM has that part available and add some to my OEM parts collection. :encourage:
 
You could probably make some, great Saturday morning project with a cup 'o coffee :)
-M
 
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You might find my online program useful for calculating gear trains. The help files have an extensive discussion about the Chinese method of labeling gears. If you choose a Chinese mini lathe and click help (Then click Return to Menu or Help) it should take you to the section. This includes diagrams showing how to interpret the Chinese labels.

For one thing they do not include the spindle/stud gear in their tables, but it is essential if you need to calculate the gear train ratio GTR! Instead of the traditional tumblers and stud gear they use a gear machined into the end of the spindle shaft (which has the chuck on the opposite end). This gear does the same job as a stud gear with one difference - it cannot be changed. My software takes note of the fact that it is not "changeable". It usually has 40 teeth. I tend to call it the stud gear but it is really a spindle gear.

I found the Chinese labeling of gears very confusing at first. In the program https://RideTheGearTrain.com I label the gears according to the way power is transmitted through the gear train. ie the order in which each gear meshes with the next. This makes sense if you are calculating the gear train gear ratio (GTR). But the Chinese method (which may have been copied from an Austrian /German method), labels the gears by the order in which you put them on the stud shafts. There is no easy way to translate between their method and mine, so If you use my program I would suggest ignoring the Chinese method.

I hope this helps. Evan.
 
I've always stayed away from threading on my G4000 lathe, simply because of the hassle and mess associated with change-gears. No more! ......I've recently implemented the @clough42 Electronic Leadscrew and now threading is a breeze. :grin:
 
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