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Chinese lathe

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Julian Newstead25/02/2021 14:17:22
8 forum posts
1 photos

Hi I am new to machine work have bought a 7x12 lathe CD 210V and need help, I am trying to find out what the original gear set up is for the power feed . Got in a bit of a muddle with the gears.🤔

Howard Lewis25/02/2021 16:44:26
4678 forum posts
10 photos

What gears do you have?

If it is like my Sieg C3 mini lathe the Manual lists, in various places, 2 x 20T, 30T, 35T, 2 x 40T, 2 x 45T, 50T 55T, 57T, 60T, 65T , and 2 x 80T

Against the time when I want to cut Imperial threads, I bought a 63T, (and an extra 45T for some reason. )

For the finest feed rate, the manual advises Driver 20T: Stud 80T/20T Leadscrew:80T

This gives a 16:1 reduction, so a 1.5 mm Leadscrew will produce a feed of 0.9375 mm / rev of the chuck.

If you want an even finer feed, Neil Wyatt published a program to print 100T gears. Not having a 3D printer, I made mine, but it means that the gear cover has to be modified on the non - operator side to clear the gears, and the locking for the Banjo needs to be modified to clear a foul. with the !00T gear on the Leadscrew.

The 25:1 reduction that this provides, gives a feed rate of 0.06 mm / rev.

HTH

Howard

Andy_G25/02/2021 17:32:39
118 forum posts
Posted by Julian Newstead on 25/02/2021 14:17:22:

Hi I am new to machine work have bought a 7x12 lathe CD 210V and need help, I am trying to find out what the original gear set up is for the power feed . Got in a bit of a muddle with the gears.🤔

There are photos of a 'CD 210V' change gear setup on various ebay listings (whether it is the *same* CD-210V or not, I don't know:

Listing is here if the picture doesn't work:

https://www.ebay.co.uk/itm/UK-CD-210V-MINI-Lathe-Machine-Tool-Woodworking-Table-Metal-Gear-750W-Spindle-CE-/154105712191

Tim Stevens25/02/2021 17:42:33
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1411 forum posts

My calculator makes that 0.09375mm per rev, Julian. How much finer than that do you need?

Cheers, Tim

john halfpenny25/02/2021 18:02:31
142 forum posts
21 photos

Julian, being new to machine work, perhaps you don't realise that you can choose the relative speed of the power feed by selecting the appropriate pair of gears. Several combinations will work, and all are correct according to, for example, the material being machined and the depth of cut.

Howard Lewis25/02/2021 18:18:42
4678 forum posts
10 photos

Thank You Tim,

Proof reader failure, YET again!

Howard

Tom Sheppard25/02/2021 18:25:20
27 forum posts

Thought a 210 was an eight inch lathe. They often have different gear ratios but the principle is the same.

Bob Stevenson25/02/2021 18:33:47
489 forum posts
7 photos

The lathe in the photos looks to be very similar or facsimile to Warco WM180 (which is also "7x12"...although the '210' in name suggests a larger lathe......

 

WM180 has a printed table both in the users manual and on the front of the machine below the speed indicator window....the table gives both the change wheel tooth pitches and the layiout on the banjo.

 

In your second photo the banjo is the darker gears on the right of picture.....the banjo is released by means of an allen key at the bottom and then hinges forward for changing the change gears.

 

If you have a metric lathe the change wheel train is shown in layout and the table gives the gear pitches for wheel at 'A' 'B' 'C' 'D' 'E' & 'F'.......the finest feed or thread pitch is for 0.30mm

 

If you look at the YouTube channel of 'Ades Workshop' you will find an excellent video of fitting the change wheel train on WM180.....be sure to place a strip of paper between the gears when fitting them to the banjo to get best fit.

Edited By Bob Stevenson on 25/02/2021 18:39:16

Edited By Bob Stevenson on 25/02/2021 18:43:05

Martin Hamilton 125/02/2021 18:54:27
185 forum posts

The 210 lathes are 8" x 16", the 210 is reference to the lathes swing over the bed 210mm (4.13" center height) X 16" between centers. Check out the Amadeal AMABL 210 lathe, this is there offering of the 210 lathe made by Weiss.

Howard Lewis25/02/2021 18:58:10
4678 forum posts
10 photos

FWIW, when using the paper strip to ensure backlash between gears, setting the backlash starting at the Leadscrew end, will allow the banjo to swung into a position where the gear on the first stud to set the correct backlash against the driver gear.

Backlash needs to be about 0.075 mm, so run the paper into the mesh, and move the gear up to just grip the paper. Having done that, and clamped up, move onto the next mesh and insert the paper again. Continue until it is time to swing the banjo upto the Driver gear.

Basically, the greater the speed reduction between the Mandrel and the Leadscrew (slower rotating vs the Mandrel ) the finer the feed, and hopefully, the better the finish..

Whatever you are doing, make sure that the tool is sharp and on the centre height of the lathe.

If it needs to be said, the finishing cut should be much shallower than the roughing cuts.

But with a mini lathe, my C3 Operator Manual says that a roughing cut is 0.254 mm. As you gain experience, you may find that with certain materials, you can exceed that slightly without damaging the machine. But that is not a licence to take 6 mm a side cuts, for fear of doing big and costly damage.

I have seen a mini lathe where someone tried this, with a fast feed. The repair bill is going to be close to half the cost of a new machine!

Howard

Chris Crew25/02/2021 22:44:07
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43 forum posts

Dear me, I never knew about putting a strip of paper between change-wheels to set the backlash. After over forty years of cutting every thread, external and internal, that has been practically possible on a non-gearbox Myford the change-wheels are in as good a condition now as when I bought the lathe. It's just a piece of pedantic nonsense, IMO.

Edited By Chris Crew on 25/02/2021 22:49:14

not done it yet25/02/2021 22:58:52
5786 forum posts
20 photos
Posted by Chris Crew on 25/02/2021 22:44:07:

Dear me, I never knew about putting a strip of paper between change-wheels to set the backlash. After over forty years of cutting every thread, external and internal, that has been practically possible on a non-gearbox Myford the change-wheels are in as good a condition now as when I bought the lathe. It's just a piece of pedantic nonsense, IMO.

Edited By Chris Crew on 25/02/2021 22:49:14

Too much backlah a gears will be noiy. Noisy gears will wear. Binding gears is worse as the mechanical parts will also be over-loaded. For many new starters a reliable means of setting backlash is important. Therefore I disagree with your statement that using paper as a guide to setting backlash is a piece of pedantic nonsense. It is,IMO, a good guide for a new starter. Further, the lathe make/type may require just the one idler setting while others need the whole gear train adjusting in a methodical order.

Edited to add that some chinese gears may not be as concentric as one might hope for.

Edited By not done it yet on 25/02/2021 23:01:25

Chris Crew25/02/2021 23:23:14
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43 forum posts

Jeez! You are in a back-shed workshop, beginner or no, not setting up a super precision gear train in the tool-room at Rolls-Royce. You will not notice any difference in noise levels, loading or wear with any common-sense meshing of involute gears. That is the great advantage of involute gears and why they are so universally used. And as for Chinese gears not being concentric they will be as concentric or not as any other hobbed gear, in fact the hobbing process tends to correct any slight eccentricity in the blank. Can we start getting over this xenophobia about Chinese products, everything that I have bought that is made in China from the dash-cam, the computer I typing on to the industrial products I own have all worked first time, every time and worked well. I would suggest this is most people's experience the world over if they actually use the goods or materials in a manner that they were designed or specified for.

I know it hurts some people that Britain is no longer the workshop of the world, and I feel their pain, but I don't feel the need to pick non-existent fault with Chinese products because the fact it is the world, and amateur workshops, couldn't now function without them and haven't been able to for very many years now.

Sometimes I think good old common sense died with the rest of British-owned manufacturing!

Edited By Chris Crew on 25/02/2021 23:38:12

Pete.25/02/2021 23:39:07
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456 forum posts
60 photos

It's just the truth Chris, a lot of stuff made in China is crap.

Chris Crew25/02/2021 23:58:43
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43 forum posts

Peter, not my experience I can assure you, and I would hazard that is not most other people's experience either if they were being open and objective. Maybe I have just been very lucky but 80% of the electrical, electronic and mechanical products in my household are made in China, and those that are not will be bolted together using Chinese parts. I would suggest it may be the same for you and with your car whatever else the branding may suggest. So Chinese products, whatever they may be, are not 'just crap'. They are so good and reliable they are making China the biggest economy in the world. I can understand, and possibly agree with, the political fall-out from that, but it does not alter the fact that you have to be very unlucky indeed for a Chinese product not to work perfectly well for the purpose and level of performance it was intended to serve.

Edited By Chris Crew on 26/02/2021 00:00:24

Bob Stevenson26/02/2021 01:10:56
489 forum posts
7 photos

I love my little Chinese lathe,...and I loved it's forunner which was a Chinese 'mini-lathe' however, they are NOT precision machines and are nicely 'cheap' for what they are which is very basic and made 'down to a price'.....ie., a price I'm willing to pay without it breaking the bank.

I also have a (old) Colchester Master.........I have never placed paper between the gears of that machine or even thought about it as I always assumed it to be just something that 'amateurs' did! However, the change wheels and banjo of my little Chinese lathe, Warco WM180 are so badly made that the paper strip thing is essential for smooth operation!.....And, as I said; I love it to bits as it does everything that I have asked of it for not much money so what's not to like?

My wm180 is fairly poorly engineered in that the quality of the wheels is poor and the banjo is not acgtually square to the machine so the cogs alway run at a slight angle and are thus very noisy ....unless you carry out the paper strip thing....

What I would say to you Chris, is that if you have never come up against 'Chinese crap' then you have indeed been very lucky so far! The Chinese are a very pragmatic people who will go on making crap for as long as merchants in the west go on buying it,...which they will if people go on buying from said merchants. it's that simple really!

Chris Crew26/02/2021 01:19:20
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43 forum posts

"What I would say to you Chris, is that if you have never come up against 'Chinese crap' then you have indeed been very lucky so far! The Chinese are a very pragmatic people who will go on making crap for as long as merchants in the west go on buying it,...which they will if people go on buying from said merchants. it's that simple really!"

Bob, absolutely, I agree with that. If I could quote myself "but it does not alter the fact that you have to be very unlucky indeed for a Chinese product not to work perfectly well for the purpose and level of performance it was intended to serve."

Your words put it so much more succinctly. Thank you!

Gerard O'Toole26/02/2021 08:17:11
111 forum posts
9 photos
Posted by Julian Newstead on 25/02/2021 14:17:22:

Hi I am new to machine work have bought a 7x12 lathe CD 210V and need help, I am trying to find out what the original gear set up is for the power feed . Got in a bit of a muddle with the gears.🤔

I have a similar lathe , MV210, and the gears used as standard are A=80, B=33, C=20, D=72 , E=84 and F= spacer.

The diagram on the front of the gearbox cover shows which position is A , B etc.

As mentioned , other ratios are possible but these ratios  are  the gears that came with the lathe.. I have used 3D printed gears successfully

Edited By Gerard O'Toole on 26/02/2021 08:18:55

Howard Lewis26/02/2021 11:34:50
4678 forum posts
10 photos

Chris Crew,

I fear that you wish to mislead newcomers,to the hobby and non engineers.

You choose to differ with established engineering practice?

You know better than Sentinel, Rolls Royce, Perkins, to name just a few, not to mention loads of other trained and qualified Engineers?

Perhaps being pedantic is what made and keeps them leaders in their field?

Howard?

Edited By Howard Lewis on 26/02/2021 11:37:02

Chris Crew26/02/2021 12:07:48
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43 forum posts

No, Howard, I don't want to mislead anybody. You have actually made my point for me because we don't work for Rolls-Royce etc. in our back shed workshops, do we? So standard engineering practice doesn't apply. and I very much doubt if fiddling with bits of paper between the change-wheels of a 'toy' lathe is standard engineering practice anyway. It certainly wasn't when I was in the apprentice training school at BREL in Doncaster in the 1960's. The point I was trying to get across was that all you have to do is apply common sense to anything you are learning to do and applying the standards that you might think are applicable at Rolls-Royce in your back shed with necessarily limited equipment is just ridiculous and could put off a newcomer.

As I have said before, several times, there is no right way or wrong way of doing anything in the privacy of your own workshop, there is only your way! By all means use standard engineering practice, whatever that may mean to you, as a guide and starting point but if it fails, or you don't yet have the equipment to apply it, use your noddle and try something else. Nobody is going to send round Inspector Meticulous to sack you and you will eventually find ways of working that succeed for you and probably for you alone, because we all learn from our mistakes, don't we?

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