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SIEG C0 Chuck Options

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Adam Wilson20/06/2021 14:26:49
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A little while back I acquired a SIEG/Axminster C0 at a reasonable price. I am well aware of the size limitations, and the massively improved capability of larger machines. At the time I had one job to do, and the lathe+tooling was less than the cost of sending it out, so effectively the lathe has paid for itself and is now a freebie to enjoy. I have plans to get a significantly more capable lathe when I have the floorspace for it, but for now please work with the concept of making the C0 more usable, rather than getting something more capable.

The supplied chuck is somewhat 'meh', the jaws are poorly toleranced in the casting, so whilst they grip reasonably in the middle of the range, at the extremes they like to come loose, or grab at a wonky angle. To the extent that there's a gap between the upper end of the inner jaw setting and the bottom end of the outer jaw setting that just can't reliably hold work. Not to mention to requirement of a 3rd hand to operate the tommy bar design.

I'm looking for recommendations for a replacement chuck(s), at a minimum I want a 3 or 4 jaw self centering chuck to replace the supplied one, and possibly a 4 jaw independent chuck for eccentric work. Almost all of the recommendations I am reading are to suppliers that either don't exist anymore, or no longer carry stock of the recommended part (arc euro trade springs to mind). Could anybody recommend anything still in stock, or a used part that can be reliably sourced in a usable condition.

One other option I am considering is to use the 80mm chucks recommended for the mini lathes with a custom backplate, but I have been warned that this is too large for the C0 so I am hesitant to pull the trigger until I have more opinions. Does anyone have experience of a set up like this?

JasonB20/06/2021 14:41:31
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Arc have not sold the C0 for a number of years so no longer keep the very small chucks to fit it.

Probably the best option is to look at the Sherline chucks as they are well made and several are available with M14 x 1 mount but check spindle register.

Edited By JasonB on 21/06/2021 07:39:35

br20/06/2021 15:09:28
697 forum posts
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As Jasom, Sherline are brilliant, but Unimat 3 chucks are same thread. Usually on ebay.

bill

Edited By br on 20/06/2021 15:09:58

Howard Lewis20/06/2021 15:18:43
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Ideally, you will need both a 3 Jaw self centering chuck, and a 4 jaw independent chuck.

Self centering chucks very rarely hold work absolutely concentric.

A good 3 Jaw should hold work withing 0.005" (0.127 mm ) But the eccentricity may vary according to the diameter being held, because it depends on the accuracy of the scroll in the chuck, and the teeth on each chuck jaw..

A 3 jaw chuck will allow you to hold, round, hexagonal or triangular work.

A 4 jaw independent chuck will allow you to hold, square, rectangular, octagonal or irregular work.

It will allow round work, or bores to be centred accurately. With a finger clock and practice, it should be possible to centre work within 0.0005" (0.012 mm )

It will allow work to be machined off centre deliberately. Not too long ago, I used a 4 jaw independent chuck to ream a hole 2.5 " (63.5 mm ) off centre.

Ideal for turning eccentrics for engine valve gear!

If chucks cannot be obtained which fit directly, it will be necessary to machine a backplate for each chuck. If suitable backplates are not available, you may need to machine both sides, (Register for the flange on the Mandrel, and then the register and face for the chuck )

Not impossible jobs, by any means.

Measure the flange on your lathe and then look at the Arc Euro catalogue to see what prefinished backplates may be available. You will still need to machine the register and face to suit the particular chuck that you have

Howard

Howard Lewis20/06/2021 15:31:47
5298 forum posts
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P S.

Fit studs into the chucks, and use nuts to secure to the flange.

A worn stud can be replaced easily. A worn thread in the chuck can be more of a problem!

Danny M2Z made up a wonderfully simple Widget to hold the nuts when fitting or removing. Article in MEW some time ago.

Saves a lot frustration and lost time hunting for dropped nuts. (Somewhere under my mini lathe there is a M6 nut, from before making his Widget!)

Howard

Howard Lewis20/06/2021 16:18:12
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Have just looked at the Arc Euro Trade website, and backplates for C0 are in stock.

They are 62 mm diameter so can be turned down to suit chucks with 55 mm register For a C0, 80 mm would probably large enough without overlading the front bearing.

There are three, one for 3 jaw, one for 4 jaw, or plain.

HTH

Howard

Adam Wilson20/06/2021 17:43:37
4 forum posts

Thank you for the very swift replies.

I should probably have pointed out that I am familiar with lathe operation, having had access to several larger machines and pretty much every chuck and tool I could need, unfortunately no longer have the same access.

@JasonB thank you for the Sherline recommendation. Honestly, they're a bit more than I was hoping to spend, but if it's going to end up costing a pretty penny anyways then they'll be the way I go.

When it comes to Unimat 3 chucks, are compatible ones worth considering, or just go straight to original ones, and any particular problems they're prone to that I should look out for when handling one prior to buying. I'm hesitant to buy one without trying it or having the option of returning it if it isn't up to scratch.

When it comes to machining backplates I'm not too concerned, just need to find a suitable chuck first, though the tip on fitting studs will come in useful for chucks with through holes, though I suspect each backplate will be permanent to the chuck it's fitted to.

John Haine20/06/2021 18:45:37
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Good original U3 chuck are like hens teeth

JasonB20/06/2021 19:44:23
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One problem with going down the backplate and 80mm chuck route apart from the added load on bearings and motor when it starts up is the total length is a lot more than the slim pin tightening chucks like the original, Sherline and Emco so think if you can afford the loss in distance to the tailstock.

JasonB20/06/2021 19:54:31
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Posted by Howard Lewis on 20/06/2021 15:31:47:

P S.

Fit studs into the chucks, and use nuts to secure to the flange.

They are 62 mm diameter so can be turned down to suit chucks with 55 mm register For a C0, 80 mm would probably large enough without overlading the front bearing.

It's not a flanged spindle like the larger Sieg etc lathes, it's threaded

Stock C0 backplates won't take 80mm chucks as fixing PCD is larger than the backplate diameter.

br20/06/2021 20:09:31
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Posted by John Haine on 20/06/2021 18:45:37:

Good original U3 chuck are like hens teeth

Three genuine Emco on ebay at present - stated to be in good condition .

bill

Mick B120/06/2021 20:40:36
2018 forum posts
116 photos

When I bought my C0 in 2015, Ketan (I think!) told me there's some compatability issue with Unimat 3 chucks because there's a plain diameter location register on one but not the other. I'm not sure which way it works, or whether it's resolvable - but maybe it's worth looking into.

Howard Lewis20/06/2021 20:53:18
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Quite right Jason.

Page 14 of the Arc Euro Catalogue 11 is where I found the details of the backplates.,

In the section devoted to backplates suitable for the C0., with M14 x 1 thread, and 15 mm register, and the same 62 mm OD as the smaller chucks..

Page 13 lists 60 mm (62 mm OD actually ) chucks which will be suitable with 45 mm PCD for the 4 jaw independent, and 51.5 mm PCD for the 3 jaw self centering fixings, so a 62 mm backplate can be turned down to make the 43 and 55 mm registers.

The chucks can be fixed to the backplates with either M5 studs and nuts, or setscrews.

So food for thought for the OP

Howard.

JasonB21/06/2021 07:02:17
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I think you need the latest catalogue Howard, ARC only have 4-jaw independent chucks at 62mm which I expect are remaining stock and won't be restocked once sold.

I don't know the quality or compatability but Chronos do 70mm chucks with M14 x 1 threaded body so they may be a good compromise between the large 80mm and standard 63mm and hopefully no need for a separate backplate, the design means there will be little if any additional overhang and you don't need two pins to tighten.

 

Edited By JasonB on 21/06/2021 07:58:52

JasonB21/06/2021 07:41:24
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Posted by Mick B1 on 20/06/2021 20:40:36:

When I bought my C0 in 2015, Ketan (I think!) told me there's some compatability issue with Unimat 3 chucks................

C0 has a 15mm spindle register, U3 has a 14mm register. Would also want to check what any other backplates or threaded body chucks use to make sure they will fit the C0

I even have a feeling now that the Sherline ones have the smaller 14mm registersad

 

Edited By JasonB on 21/06/2021 08:00:34

br21/06/2021 08:14:26
697 forum posts
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Adam

Recently passed on my U3 lathes, but just come across a new boxed Emco 4 jaw which was overlooked

Ref compatability, I can photograph the back of it and send a dimensioned drawing if it will help you in deciding.

Just send your e-mail address via PM.

bill

Howard Lewis21/06/2021 16:48:46
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Jason,

Are saying that Arc Euro have now produced Catalogue 12? (11 is my latest )

Howard

JasonB21/06/2021 17:18:47
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Your page numbers are not the same as my No 11 so assumed you had an older one.

Page 14 has the 3 chucks but two of these are no longer listed on website as ARC no longer use Zither as a supplier. backplates are on page 15

Howard Lewis22/06/2021 14:00:53
5298 forum posts
13 photos

Hi Jason,

Fat Finger syndrome on my part!

Howard

Adam Wilson22/06/2021 20:04:52
4 forum posts

So having a look through the replies it seems I have a few options, and several things to look out for.

Fit an oversize chuck and backplate and accept that I'm losing a portion of the working space.

Try and source a smaller chuck intended for a backplate, options for which in the UK seem slim, and the usual issues ordering direct from China/India are present.

Buy a chuck intended for an EMCO with the possibility that it has the 14mm register and then either modify the chuck or spindle to match.

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