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Lathe backplate chuck help

Finding the right chuck

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Christine Walker06/12/2016 09:33:21
37 forum posts

Hello

Can anyone help please.

I need to buy a 4 jaw independent chuck for my Chinese made lathe, and of course, for a beginner, it is the usual minefield!

The lathe has a spindle nose of 39x4mm.. a stupid question perhaps, but which chuck should I go for? I am guessing I'll probably have to buy an adaptor, but after speaking to a recognised UK model engineering supplier, they have never heard of that spindle nose! Why? it's a flipping standard lathe... I can't be the only person in the world with one of that size?

Thanks for any advice in advance.

Christine

MW06/12/2016 09:43:07
avatar
2050 forum posts
51 photos

Hi Christine,

Yes you are correct, there probably are people out there with the same size,if you want to machine your own backplate RDG tools sell some meaty iron castings to swivel away at. **LINK** (Just realized you'll need a 4 jaw in order to do that anyway so it wont help!, but useful to know anyway)

You will probably have more success if you can quote the overall diameter of the register on the lathe face, Is the spindle nose threaded? In which case you'll need to know the diameter, pitch and threadform of the nose in order to get any further. If this isn't the case then i'm sorry for rambling on.

Chucks when they are sold tend to have the overall diameter quoted rather than the register size. If you can tell me the exact name of the lathe I will be able to have a search for it, as no doubt others will too.

 

Michael W

 

 

Edited By Michael Walters on 06/12/2016 09:46:11

Roger Provins 206/12/2016 10:01:13
342 forum posts

I have same lathe and had the same problem.

Little Machine Shop in the US has what you need, both 4" and 6" versions **LINK**

They are happy to post to UK - not cheap though.

Roger

Iain Gordon06/12/2016 10:03:36
23 forum posts
14 photos

Hi Christine,

If your lathe is the generic 920 then you will need a backplate to fit the chuck. They are available in the States but I've not been able to locate one here, and I've been looking for years.

You can buy a blank backplate casting and machine it yourself but the lowest speed on the lathe is too fast and the short length of the thread makes this a hazardous operation.

I asked on here a while ago for help in machining a backplate but there was no-one within reasonable distance able to help.

I'm sorry I can't help further.

Regards,

Iain

Christine Walker06/12/2016 10:25:07
37 forum posts

Hi Michael, Roger and Iain and thanks for your replies. What a nightmare! You would think, wouldn't you, that an industry standard would prevail, obviously not!

I don't have the skills to machine my own and was hoping (obviously naively to buy one off the shelf... just can't understand how a 3 jaw can come with the machine, yet a 4 jaw be like trying to find hen's teeth.

I've just checked with Little Machine Shop and it would be $78 just for the backing plate to be bought and delivered to the UK. The job doesn't warrant that I am afraid.

Back to the drawing board.

mark smith 2006/12/2016 10:28:01
599 forum posts
302 photos

chester sell them at £50 quite expensive though i`m confused why they state they are for the 920 lathe but are listed at M40x 4mm????

mick7006/12/2016 10:29:03
524 forum posts
38 photos

is it threaded spindle nose?

or like some of the chinese lathes does backplate fit with 3 bolts?

mine is latter .

Roger Provins 206/12/2016 10:32:02
342 forum posts

Christine,

I'm surprised you didn't get a 4 jaw independent chuck with the lathe. One was originally supplied with mine.

I'm in Gloucester and you be welcome to borrow one of mine.

Roger

Roger Provins 206/12/2016 10:36:50
342 forum posts
Posted by mark smith 20 on 06/12/2016 10:28:01:

chester sell them at £50 quite expensive though i`m confused why they state they are for the 920 lathe but are listed at M40x 4mm????

They are $23.95 at LMS in US. Usual rip off Britain I'm afraid.

If those at Chester really are 40x4mm they won't fit.

Roger

Christine Walker06/12/2016 10:42:52
37 forum posts

Oh Roger, thank you, that is very kind of you. I am in Coventry so it's quite a way but not the other side of the world.

naughty boy (nice name) it is threaded yes... I have pictures of it but can't seem to post them on here! This is the link to photobucket.....

http://i304.photobucket.com/albums/nn184/christineanniewalker/IMG_3299_zpszwseih1c.jpg

Thanks Mark. I will look at Chester....

Jonathan Garside06/12/2016 10:47:33
40 forum posts
3 photos

Christine

Try Warco their 918 lathes have 39 x 4 mm spindle nose. I have bought already threaded chuck backplates from them in the past 2 years so they should still have them in stock. You will have to machine the backplate to suit your chuck but plenty of advice and how to do this on this site or you tube.

Jonathan

John Rudd06/12/2016 10:49:31
1366 forum posts
58 photos

I also have a Chester 9x20 and have had backplates from them too. Fitting was straightforward with no dramas..

Christine, give Tony a call he is very helpful......

Blank plates are available from RDG, although they need drilling and threading and require a degree of accuracy in machining the register. Hand tapping a 39 mm thread isnt an easy task....even though I do have a set of taps....

MW06/12/2016 11:04:12
avatar
2050 forum posts
51 photos
Posted by John Rudd on 06/12/2016 10:49:31:

Blank plates are available from RDG, although they need drilling and threading and require a degree of accuracy in machining the register. Hand tapping a 39 mm thread isnt an easy task....even though I do have a set of taps....

And trying to keep 0 runout on it is even harder! laugh

Michael W

Christine Walker06/12/2016 11:10:56
37 forum posts

Thanks for all your replies. Unfortunately, any machining is a little beyond my capabilities at this point, I am pretty new to all this (as you can probably tell by my questions!)

It has just been suggested to me that 39x4mm could possible be 1 1/2 x 6 TPI... thoughts? Or anyone know of a way I can check this please?

Thanks again

C

clogs06/12/2016 11:22:32
476 forum posts
12 photos

Hi Christine,

I'm sorry ur having such troubles.....but something say's to me you'd be better off getting rid of this lathe and getting something that has a better service and parts network......this will not be the only problem you will have.....

there's plenty of other makes out there and flebay would sell yours quite quickly........

Have yourself an early Xmas prezzy.......

good luck Clogs........

Roger Provins 206/12/2016 11:36:04
342 forum posts
Posted by Christine Walker on 06/12/2016 11:10:56:

Thanks for all your replies. Unfortunately, any machining is a little beyond my capabilities at this point, I am pretty new to all this (as you can probably tell by my questions!)

It has just been suggested to me that 39x4mm could possible be 1 1/2 x 6 TPI... thoughts? Or anyone know of a way I can check this please?

Thanks again

C

No, it's close but not interchangeable.

Roger

Christine Walker06/12/2016 12:00:05
37 forum posts

Thanks clogs but I can't really afford to change it at the moment. I was hoping when I bought it, the dealer I bought it off might be able to provide some kind of backup/service. Sadly, that doesn't appear to be the case. Said dealer didn't even know what thread it was.

For the amount of use I require, a more expensive lathe isn't financially viable, although it would be lovely. But hey.

Thanks Roger, I suspected it wouldn't be. Couldn't be that straight forward could it.

At this point, I guess my only option is to go with the original suggestion of loosening the bolts on the faceplate and lightly tapping it until I get a good centre.

Appreciate your time gentleman, thank you.

SillyOldDuffer06/12/2016 12:00:10
4711 forum posts
1010 photos

In the related thread KWIL provided a **LINK** to the manual. This reveals:

christine_specs.jpg

christine_3jaw.jpgchristine_flange.jpg

The manual doesn't say how the chuck is removed but it appears to me that the flange screws on to the spindle and that the chuck is bolted to the flange? I could be wrong. Also, that the nose thread is different depending on whether the lathe is Imperial (8 tpi) or Metric (4mm)? Again I'm guessing. No wonder Christine is confused!

Christine: are you able to take your chuck off and post some pictures and measurements please? Does it unscrew or unbolt? Is your lathe metric or imperial? I think we're danger of misleading you through lack of information.

If all else fails the other thread has some good advice about how to do the job without a 4-jaw. I

Cheers,

Dave

Roger Provins 206/12/2016 12:00:45
342 forum posts

Christine,

You've had rather a bad start to your lathe but that 39x4 spindle thread is really the only troublesome feature to overcome. Everything else you might need is easy to come by and fairly standard. The 9x20s from many sources are all the same machine under different paint jobs.Grizzly, Jet, Enco, Harbor Freight and many others - they are all basically the same lathe.

PDF manual here http://cdn0.grizzly.com/manuals/g4000_m.pdf

This is the Grizzly manual but it is identical to your lathe,

Roger

mgnbuk06/12/2016 12:05:27
512 forum posts
13 photos

The Warco 918 metric version will probably be M39 x 4 - backplate part number 5424 @ £36 each

**LINK**

Warco also did a version of the 918 with the Myford nose IIRC, which is probably the Imperial version they show.

Chester list their equivalent as 40 x 4, but while the "M39" is the thread, the parallel register is 40 diameter (according to a Roehm spindle nose drawing), so Chester may be refering to that in their description.

A call to either should confirm suitability. IIRC pretty well all the 918/920 machines were originally supplied with both 3 jaw SC & 4 jaw independant chucks and a faceplate, so probably not much call for plain backplates.

HTH

Nigel B

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