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plunger
11-14-2011, 04:31 PM
My first lathe I bought was a 13x40 Chinese lathe . I got caught real bad and have spent more money trying to fix it than what a new one would have cost. Any way it has been reground and has turcite under the saddle . Feels real smooth .I have to learn to scrape the toolpost and crosslide in. I hope this is not beyond me. There are no scraping schools in s africa. Anyway I hope someone could help me out .The aluminum gear chart is so worn I cant make it out. I got some gears with it but am not sure if they are the right ones as the lathe had parts mixed up with a lathe next to it. I see a couple of photos of this type of lathe and wonder if they all have the same gearing I am hoping someone could help me out with a photo or copy of a manual if it is not to much trouble. How would I be able to get a new gear chart made up? Do you think there are printing companies that could do this on aluminum.I would love to get this lathe running as I hate incomplete projects Thanks.http://i941.photobucket.com/albums/ad254/eugeneeman/054.jpg

The Artful Bodger
11-14-2011, 04:44 PM
I imagine there are a lot of ways of printing on aluminium and no doubt Evan can help you out there.

Regarding the gears you need, considering your lathe is somewhat similar to the more common(?) CQ6230A I expect 24,48 and a compound 120/127 will get you almost all metric thread pitches, if the compound is not there you will need something of about 120 as the intermediate idler in the chain.

For inch threads you need also 38,22,26 and the 120/127 compound gear.

It is not too difficult to figure out your thread table and that might be a bit more reliable than finding a chart to copy from a similar, but maybe different, machine.

If your machine is like mine one of those controls on the quick change gear box will switch between driving the feed screw and driving the carriage feed. Another will have a ratio of 2:1 which makes it easier when making your table.

plunger
11-14-2011, 04:58 PM
I have the 120/127 gear. The workshop is all closed now so tomorrow I will check to see what smaller gears I have I soppose its a good start at least.I am seriously mathamatically challanged . Sounds scary hard to work out. Does this lathe look similer to yours. Mine is quite old so it might even be taiwanese although when the headstock came off the bed under the headstock had been ground in with a angle grinder.Those chinese are highly skilled They can do with an angle grinder what other fitters do with a scraper

The Artful Bodger
11-14-2011, 08:05 PM
Yes, it does look like mine although they have tried to make it look quite different. For instance where you have two levers mine has two knobs but it is a fair bet that inside the box would look much the same.

Obviously the two levers at the top set the spindle speeds, mine has two knobs to do that. On the lower gear box you have two levers and 2 knobs, mine has four knobs.

It is not difficult to work out the threads...

... Set spindle to highest speed (not crucial but this makes it easy to turn the machine by hand, which you will be doing)

....Set the small lever on the top box to one side, centre position will be 'neutral' and not driving the lower box.

....Put you smallest gear on the position closest to the spindle. 24 tooth is preferred.
....Put another gear on the lower position which is the input to the lower gear box. 48tooth is preferred.
....Adjust your intermediate gear so that both these gears mesh with the 127 gear, you might have to flip the compound gear over or pull off spacers on the other positions.
.....Turn the spindle by hand and watch if the feed screw or the carriage drive rod is turning, only one or the other should be turning.
.....You want the feed screw to turn so experiment with the two knobs and levers on the lower gear box until the feed screw turns when you turn the spindle. There will be two controls that have only two positions and this will be one of them, I think these controls will be the two levers.
.....Look at the direction of rotation of the feed screw, you want it so that turning the spindle will move the carriage towards the headstock when the half nuts are engaged. If the carriage moves the other way reverse the position of the small lever on the top gear box, this lever reverses the drive to the change gears and would be used for cutting left hand threads or feeding towards the headstock.
....Engage the half nuts and turn the spindle, the carriage should move towards the head stock.

....Check the controls on the lower gear box until you find another control with only two positions, I think it will be one of the levers, try both positions, turning the spindle and observing the movement of the carriage, one position will be twice as fast as the other, leave this control in the slowest carriage movement position.

There is not much further to go!:p

You now have two controls on the lower gear box that are used to set a whole range of ratios, maybe 25 or more, but you dont have to manually identify each one!:) I expect these controls are the two knobs.

On my lathe these two knobss are labelled 1..5 and A..E.,


... set the two controlls both fully leftwise which I would call position 'A1'.
....mark the lathe chuck with sticky tape or something so that you can keep tracks of turns.
....use your DTI or other reliable method of measuring 10mm of carriage travel.
....turn the spindle forward to take up any slack and backlash.
....set your DTI, or whatever, and turn the spindle forwards counting revolutions until the carriage has moved 10mm. Divide 10 by the number of spindle revolutions to get thread pitch in metric.


I have to go and dig a post hole now and put in a new gate post, I will continue when the post is in the ground.....:D

Robin R
11-14-2011, 08:15 PM
Will that be the post post,post?

The Artful Bodger
11-14-2011, 09:35 PM
[later]

The post is in the ground and the concrete will be set very soon...


Now then, to continue....

... now draw up a sheet of paper or better still, open a spreadsheet on your computer.
... label your spreadsheet 1..5 by A..E.
...enter the pitch you found in the first cell ("1A") of your spreadsheet.
...move the letter knob to the 'B' position and repeat, finding the pitch and recording it in your spreadsheet.
...continue until you have values for 1A through 1E
...return the knob to the 'A' position.
...move other knob to the '2' position then find and record the pitches until you reach the 'A5' position.
...you can now fill in the blanks for all the other 15 pitches by calculation.


You will then have a table of 25 pitches, if you move your high low lever on the lower gear box you will have another 25 pitches, twice as coarse which gives 50 pitches, if thats not enough swap the 24 and 48 pinions you will have another 50 pitches which will be four times as coarse as the first set.

There will be a lot of duplications....

Sorry, I dont know anything about spread sheets but if you post your first ten pitches maybe someone will be kind enough to run a spread sheet and post the results.

Sparky_NY
11-15-2011, 07:38 AM
I have that exact lathe. My gear charts are in excellent condition and I will attempt to take a close up picture of them for you. I have the manual also but there is nothing in there of much use, its pretty generic.

Shoot me a PM with your email and I will send the pics direct.

Edit: I am going to cnc my lathe soon and so there will be lots of parts I will be removing.

plunger
09-24-2013, 07:46 AM
http://i941.photobucket.com/albums/ad254/eugeneeman/SDC12883_zpsaa62da54.jpg (http://s941.photobucket.com/user/eugeneeman/media/SDC12883_zpsaa62da54.jpg.html)I hope to finish this lathe project off. I cannot believe how fast time goes. Anyway I got this lathe up and running except for the compound.I will need to learn to scrape. But my first problem is the gearing. I hope someone has the exact same lathe.I am using a block instead of the compound but I find the feeds on this lathe too fast.I will try to get my head around the feeds before I understand the threading feeds. I am also waiting for the artfull bodger to finish his post.
I cannot read the feed chart so i tried to do what The Artfull Bodger described but I am needing time to take it all in.
This is the question I would like to ask. The slowest feed I can achieve is if I put my smallest gear on near the spindle.Then I am using an 85 immediate or idler gear. I have a 100 gear on the bottom and this seems to give me the slowest feed.Would this make sence and does the idler have no bearing on the speed of the feed.I am trying to understand the two levers on the bottom right of the gearbox. This seems to control the feed but has little bearing on things. I notice that if I put the top lever through its range all the letters which I think are marked J K L and I think m will controll the feed and lead screw except for L which only controls the feed and not the lead screw as well.
Also is there a easy way to know if my lead screw is metric or imperial. Being S Africa I would have thought it is metric and if I use a pitch guage it seems to be three millimeters.The gears that I have are 127/120 85 idler and 100,60,52,46,45,44,40,33,and 30

tlfamm
09-24-2013, 08:53 AM
re scraping:

If you're not familiar with them, a couple of sources for scraping instruction materials:


http://www.metalscraping.com/
http://www.machinerepair.com/

The Artful Bodger
09-24-2013, 03:40 PM
Hi Plunger


The concrete is well cured on my post and the neighbours sheep are where they should be.;)

Yes, the slowest feed is with the smallest gear doing the driving and the biggest gear being driven, you are correct in that the idler has no bearing on the ratio. It is obvious that your gearbox had quite different internals to mine and that gearing you show would be very slow on my lathe.

The easiest way to check your lead screw is to measure off a distance along the lead screw and count the threads, it will probably be either 3mm or 8TPI.

One of those levers probably switches between lead screw and feed drive. Move the lever to one position and see which rod can be turned by hand.