# New chuck question



## RichardG (18 Oct 2021)

I have a Simat 101 lathe which is "just" about good enough to do the small amount of metal turning I do with a 4 jaw independent chuck which has a fair bit of play. If I ever take something out of the chuck its impossible to get it back on the same centre line and I end up having to faff around to get it recentred. So I thought I'd buy a new 3 jaw self centering chuck. The lathe nose is M14x1.5 so I'm going to buy a tap and then make my own backplate which isn't a problem.

I'm not a great fan of buying unknown items off eBay so narrowed it down to one from RDG Tools and one from Warco. The RDG uses through bolts to mount on the backplate and the Warco has a threaded body. Is the through bolted design of the RDG worth having as I can't really see any advantage or am I missing something?


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## Gordon Tarling (18 Oct 2021)

The threaded body type will give less overhang than one using a backplate and thus be that little bit more rigid.

G.


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## Phill05 (18 Oct 2021)

I would go for the one with a back plate then if you change your lathe in the future you can change the back plate and keep the chuck.


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## RichardG (18 Oct 2021)

Phill05 said:


> I would go for the one with a back plate then if you change your lathe in the future you can change the back plate and keep the chuck.


Neither chuck comes with a backplate so I need to make one. The back plate on the RDG uses bolts through the chuck to mount onto backplate, you could use nuts or cut threaded holes in the backplate, whereas the Warco has a threaded body so the bolts go through the backplate and the fix into the chuck body.


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## RichardG (18 Oct 2021)

Gordon Tarling said:


> The threaded body type will give less overhang than one using a backplate and thus be that little bit more rigid.
> 
> G.


Sorry, my post was obviously not very clear....the Warco has 3 threaded holes for me to mount the home made backplate the RDG has through holes to mount the backplate. I guess you could use bolts and nuts on the RDG.


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## Phil Pascoe (18 Oct 2021)

Maybe ask a mod. to put your thread in metalworking? You might get some more replies.


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## RichardG (18 Oct 2021)

Phil Pascoe said:


> Maybe ask a mod. to put your thread in metalworking? You might get some more replies.


Doh, failed at the first step, will do....


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## sploo (18 Oct 2021)

If you use a lot of standard size rods then a collet chuck might be better, as they're much more suited to removing and remounting stock (without introducing runout).

Even a decent 3 jaw will give (some) problems when you remove and remount stock.


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## Gordon Tarling (18 Oct 2021)

RichardG said:


> Sorry, my post was obviously not very clear....the Warco has 3 threaded holes for me to mount the home made backplate the RDG has through holes to mount the backplate. I guess you could use bolts and nuts on the RDG.



Ah, OK. Most chucks with threaded holes are fitted to the backplate using studs in the threaded holes and suitable nuts/washers where they protrude through the backplate.

G.


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## kenledger (18 Oct 2021)

Going back to you betting a piece of work to run true after taking it out of the Jaws. You do not say how you are remounting it.
We used DTI's or clocks, you could get the work piece true that way. When it gets to 2, 3 though you would just tighten the side where it was running low, never release the jaw on the high side at all.
You may do this, if so apologies.


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## RichardG (18 Oct 2021)

kenledger said:


> Going back to you betting a piece of work to run true after taking it out of the Jaws. You do not say how you are remounting it.
> We used DTI's or clocks, you could get the work piece true that way. When it gets to 2, 3 though you would just tighten the side where it was running low, never release the jaw on the high side at all.
> You may do this, if so apologies.



The process I try to follow is, draw a line from a jaw onto the piece so I can put it back in the same place, undo 2 adjacent jaws, remove item, put the item back aligning to the mark and then re-tighten the 2 jaws I loosened. However this can still result in a movement of 0.1mm or more.


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## Sandyn (18 Oct 2021)

I have a 100mm 4 jaw, self centre HBM. I got it from RDG. It has a backplate. I have a Myford ML7 and it is huge compared to my 80mm 3 jaw Pratt. Twice as heavy.
The HBM is pretty good quality and accurate enough for what I do. I'm really happy with it. I just quickly checked. Run-out is about 1 thou, measured on the perimeter of the chuck. It had the backplate fitted by RDG. I would have preferred a direct mount threaded chuck, to reduce hangover, but that wasn't an option.


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## Fergie 307 (19 Oct 2021)

RichardG said:


> The process I try to follow is, draw a line from a jaw onto the piece so I can put it back in the same place, undo 2 adjacent jaws, remove item, put the item back aligning to the mark and then re-tighten the 2 jaws I loosened. However this can still result in a movement of 0.1mm or more.


I use the same procedure but undo each screw by a set amount, usually half a turn. Then remount the work and do each up again by half a turn. However if you want sub 0.1mm accuracy then you will probably have to do some fine tuning. In reality you are never going to see anything like that accuracy from a self centreing chuck. You would be better off with a collet chuck. Does the machine have a MT spindle, im guessing not given its size. If you can get one to fit then an ER type collet chuck would be ok. They are designed for holding tools rather than work so dont have a pass through facility, but are good for relatively short pieces. Most are accurate to around 0.0001in, so probably more accurate than your machine. And a good deal cheaper than a chuck as well.


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## Fergie 307 (19 Oct 2021)

Sandyn said:


> I have a 100mm 4 jaw, self centre HBM. I got it from RDG. It has a backplate. I have a Myford ML7 and it is huge compared to my 80mm 3 jaw Pratt. Twice as heavy.
> The HBM is pretty good quality and accurate enough for what I do. I'm really happy with it. I just quickly checked. Run-out is about 1 thou, measured on the perimeter of the chuck. It had the backplate fitted by RDG. I would have preferred a direct mount threaded chuck, to reduce hangover, but that wasn't an option.


Not sure that the run out of the chuck body is necessarily a reflection of the accuracy with which it holds work in the jaws, and thats what matters. Normally you would machine the backplate with it in situ on the machine it is to be used on.


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## clogs (19 Oct 2021)

I had similar prob.....always had rush jobs turning up....
so in the end bought another lathe....
Most chucks are made in Asia....u just gotta get lucky to get a good one.....
I dont buy from RDG mostley what turned up was not very well made and almost always the packaging was destroyed.....
bought a big set of adjustable reamers from them...the special wooden case was just splinters...


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## Fergie 307 (19 Oct 2021)

clogs said:


> I had similar prob.....always had rush jobs turning up....
> so in the end bought another lathe....
> Most chucks are made in Asia....u just gotta get lucky to get a good one.....
> I dont buy from RDG mostley what turned up was not very well made and almost always the packaging was destroyed.....
> bought a big set of adjustable reamers from them...the special wooden case was just splinters...


When you can pick up something as good as an old Taylor chuck for between 50 and 80 quid why would you want to spend the same on a not very good Chinese one is beyond me. For the tiny machine the OP has maybe a little old burnerd would be ideal.


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## Fergie 307 (19 Oct 2021)

Looking on lathes.co.UK it appears it has a Morse 0 taper spindle and tailstock. Whether anyone does a collet chuck with that fitting I have no idea.


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## RichardG (19 Oct 2021)

Fergie 307 said:


> Looking on lathes.co.UK it appears it has a Morse 0 taper spindle and tailstock. Whether anyone does a collet chuck with that fitting I have no idea.



It's worse than that as its a half morse 0 taper, i.e. its the thin half of a standard length morse 0!! No one makes this now.


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## RichardG (19 Oct 2021)

Fergie 307 said:


> When you can pick up something as good as an old Taylor chuck for between 50 and 80 quid why would you want to spend the same on a not very good Chinese one is beyond me. For the tiny machine the OP has maybe a little old burnerd would be ideal.


I have been looking used but I'm unsure about buying something like this from pictures especially as I will need to turn a backplate before I can even try it and often there's no returns or spares if it turns out to be well worn.


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## sploo (19 Oct 2021)

Agreed about needing to turn a backplate, but unless a Pratt Burnerd chuck looks like trash they'll generally be pretty good (in my admittedly limited experience). This document (http://www.rotagriponline.com/datasheets/Pratt/PrattChuckSpares.pdf) is hugely useful for decoding "what" a PB chuck is based on the model number (and it also tells you the part numbers for spares).


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## Fergie 307 (20 Oct 2021)

If you consider how well made the little Burnerd chucks are, and how little load there can be on a 3 inch or so chuck, I think you are likely to be pretty safe, if it looks ok it probably will be.


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## RichardG (20 Oct 2021)

Thanks for the info. Having now seen some pictures of the the older Burnerd chucks with the lever arm/tommy bar? tightening they look to be a much better size and weight for my tiny lathe so I'll keep on managing with what I have whilst trying to find a used one. I'm also going to try using the rohm drill chuck which is fitted with a mt0 to fit the tailstock in the headstock and see how that works?

Interesting Cowells still make almost the same lathe, complete with morse 0, although with some useful improvement, a 0.007mm accuracy and a £2000+VAT price tag. http://www.cowells.com/docs/90e.pdf.


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## kenledger (20 Oct 2021)

kenledger said:


> Going back to you betting a piece of work to run true after taking it out of the Jaws. You do not say how you are remounting it.
> We used DTI's or clocks, you could get the work piece true that way. When it gets to 2, 3 though you would just tighten the side where it was running low, never release the jaw on the high side at all.
> You may do this, if so apologies.


Going by eye is not very accurate, it' ok as a starting point, you would still need a clock to get the work piece really true. 0.1 mm is 4 thou to me (yes i am old) you should get it to 1 thou or zero with a clock.


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## Fergie 307 (20 Oct 2021)

RichardG said:


> Thanks for the info. Having now seen some pictures of the the older Burnerd chucks with the lever arm/tommy bar? tightening they look to be a much better size and weight for my tiny lathe so I'll keep on managing with what I have whilst trying to find a used one. I'm also going to try using the rohm drill chuck which is fitted with a mt0 to fit the tailstock in the headstock and see how that works?
> 
> Interesting Cowells still make almost the same lathe, complete with morse 0, although with some useful improvement, a 0.007mm accuracy and a £2000+VAT price tag. http://www.cowells.com/docs/90e.pdf.


It's a nice little machine, but the size does rather limit you options. I use a 5c collet chuck, but it probably weighs more than your machine! I had a look on line and saw the Rohm one. If it's accurate enough then hopefully it may well do the trick for you. You might find someone who does a chuck to take watchmaking collets, but then the collets themselves are ridiculously expensive. Alternatively some of the ER ones come with a straight shank, or in the larger MT sizes. So maybe an ER11 with a suitable sized plain or MT1 could be ground down to fit your taper by a local engineering firm? Shouldn't cost that much.


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## Fergie 307 (20 Oct 2021)

Just looked at the Cowells link. It reminds me so much of a miniature version of my old Myford 4.


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## RichardG (20 Oct 2021)

Fergie 307 said:


> Just looked at the Cowells link. It reminds me so much of a miniature version of my old Myford 4.


Yes, I've seen a Myford ml2 and my Simat is obviously a cheapo miniature copy. I'd love to upgrade it but it always just does what I need, although very slowly....


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## Sandyn (20 Oct 2021)

Fergie 307 said:


> Not sure that the run out of the chuck body is necessarily a reflection of the accuracy with which it holds work in the jaws, and thats what matters.


You are correct. My post wasn't very clear. What I was meaning to show is that RDG had made an 'OK' job of mounting the chuck to the backplate. There was about 1 thou run-out. The chuck is a DIN 6350, which will have a specification for max Axial run-out. I'm not sure what the max is.


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## Fergie 307 (20 Oct 2021)

RichardG said:


> Yes, I've seen a Myford ml2 and my Simat is obviously a cheapo miniature copy. I'd love to upgrade it but it always just does what I need, although very slowly....


I still use the Myford regularly, it's a nice old machine. And from memory the Simat was at least as well made. I used to have a Unimat, which is a nice machine but not as solid. I think you actually learn more using a little machine, you have to think about how you approach things a bit more carefully. I made some quite big pieces in the past using the Myford, as you say definitely a case of slowly does it. I dont think I would want to part with it, but it's semi retired now and just used for small stuff in plastic mostly. My Harrison takes on all the bigger jobs. That too is a great machine, but if anything it's too good so you don't have to make allowances for it. Not as much fun somehow charging through something on powerfeed rather than having to coax it along.


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