Lathe backplate chuck help

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

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

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

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

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.

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????

is it threaded spindle nose?

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

mine is latter .

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

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

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....

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

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....

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

Michael W

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

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........

No, it's close but not interchangeable.

Roger

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.

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

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

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

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