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Richard Rogalewski18/01/2020 16:12:24
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Hi. This year I hope to purchase a lathe. If I do, I'll need a lathe with a chuck that can accept work of at least 45mm in diameter. So, I'm looking at products available. Now, obviously I'm concerned that the lathe can take bar up to at least 45mm in diameter. Here is the specification given for a popular lathe:

Motor – 300W/230V
Distance between centres – 300mm
Swing over bed – 180mm
Spindle Taper – MT3
Spindle Bore – 20mm
Tailstock Taper – MT2
Spindle Speeds (Variable) – 100-2500 rpm
Imperial Thread- 18pcs – 12-104tpi
Dimensions – 820 x 295 x 300mm
weight 45kg

There is a link which is supposed to give "info on this machine" If this worked maybe I would not be making this post.

Anyway, no mention of the size of work the lathe can handle with the supplied chuck.

Also, looking for a possibly larger chuck, I've spotted a 4 jaw chuck on a different site. Apart from the description "4 Jaw Independent Chuck" I'm given the weight as 5Kg. Although I can contact someone by way of messaging.Discovering the capacity of the chuck is not proving to be a matter of reading a specification. Seems odd that. Rich

JasonB18/01/2020 16:18:22
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Your spec looks to be for a typical mini-lathe which depending on who you buy it from will come with either an 80mm or 100mm diameter chuck, both of which will be capable of holding 45mm dia work with the use of the supplied external jaws.

You don't say how long your 45mm dia material is or whether you need to machine the end or sides as this will also be a factor in what can be machined for example if it is 200mm long then you will also be in need of a fixed steady but may run out of bed length if you then need to drill the end of the work

Neil Wyatt18/01/2020 17:46:15
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Typically chucks can hold work up to about the diameter of the chuck using the 'outside jaws'.

5kg would be a monster chuck for a mini lathe... that would be roughly a 125mm body.

Neil

mark smith 2018/01/2020 19:03:37
671 forum posts
331 photos

Or if your refering to passing it into or through the spindle then, your specs state 20mm spindle bore. You would need a much larger lathe for 45mm. My southbend 9A has a pitiful 3/4" spindle bore.

JasonB18/01/2020 19:11:13
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Seems like it is teh Clarke CL300M being sold by Chronos as their link does not work. Almost certain this comes with an 80mm 3-jaw

not done it yet18/01/2020 19:15:36
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Lathes are defined primarily by centre height (or, alternatively, swing over bed) and effective length (distance between centres).

No point in quoting that spec if the lathe cannot hold a workpiece of that radius (or diameter) or length. JB points out the need for centre drilling(s) being a bit more of a challenge for that maximum length....

JasonB18/01/2020 19:24:58
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Most will hold work to the max they can swing using a faceplate and if you are holding the inside of a ring with a chuck then again you can turn to the swing.

Richard Rogalewski18/01/2020 21:35:28
72 forum posts
14 photos

I think I'm getting it now. "Swing over bed" is that distance between the headstock spindle centre and lathe bed. It's 180mm for the lathe I quoted a description for. But, the description still fails to state what diameter of work the supplied chuck will hold. Perhaps the sellers feels it perfectly sufficient to simply state the diameter of bar that will go through the spindle, as being the effective maximum diameter of bar the chuck can hold.

Although, having said this, if I attempt to make a flange set, I could make this from a bar say 50mm in length. This might feasibly fit into a chuck without protruding into the spindle. And that is what I have in mind and so feel peeved nothing is said about the capacity of the supplied chuck.

I'm recalling the days of my father who was a watch & clock repairer. He had a watchmakers lathe which had chucks that could hold say a 40mm bar, but no-way would that go through the headstock spindle. All understood by the lathe designer.

Edited By Richard Rogalewski on 18/01/2020 21:45:14

David Davies 818/01/2020 21:42:21
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Note that for longer work the swing over the cross slide is more important than the swing over the bed.

Stuart Smith 518/01/2020 22:51:12
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Some info on the Warco website for the chucks they sell:

**LINK**

with dimensions.

Michael Gilligan18/01/2020 23:33:57
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Posted by JasonB on 18/01/2020 19:11:13:

Seems like it is teh Clarke CL300M being sold by Chronos as their link does not work. Almost certain this comes with an 80mm 3-jaw

.

Assuming that Jason is correct [usually a safe assumption] ... this might help: **LINK**

https://www.clarkeservice.co.uk/manuals/metal_lathes/cl300m.pdf

MichaelG.

JasonB19/01/2020 07:05:37
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I did look at the Manual via Machine Mart and nothing about the chuck there not even how to change jaws or change chucks.

Why not try a different supplier/lathe if you are not happy with the info supplied.

"I think I'm getting it now. "Swing over bed" is that distance between the headstock spindle centre and lathe bed."

NO. "Swing over bed" is the maximum diameter the lathe can turn. "Centre height" is distance between spindle ctr and bed.

Michael Gilligan19/01/2020 07:29:10
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Posted by JasonB on 19/01/2020 07:05:37:

I did look at the Manual via Machine Mart and nothing about the chuck there not even how to change jaws or change chucks.

[…]

.

Sorry for any confusion, Jason ... I offered the link for Richard’s benefit, not yours

[ and simply quoted you as a courtesy ]


MichaelG.

.

Edit: General information, rather than chuck-specific 

Edited By Michael Gilligan on 19/01/2020 07:32:21

Ron Laden19/01/2020 08:17:17
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Having had a mini lathe I think a couple of points worth considering is to go for one with a 100mm chuck, 400mm between centres and a 500 watt motor (ideally brushless direct drive)

If I was buying one now it is what I would aim for.

Michael Gilligan19/01/2020 08:32:14
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Too late to edit my previous post angry

The Clarke manual does state that external jaws are provided, and describes how to change them.

MichaelG.

Gerard O'Toole19/01/2020 10:36:12
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Posted by Richard Rogalewski on 18/01/2020 21:35:28:

I think I'm getting it now. "Swing over bed" is that distance between the headstock spindle centre and lathe bed. It's 180mm for the lathe I quoted a description for.

Edited By Richard Rogalewski on 18/01/2020 21:45:14

I think 'swing over bed' is the largest diameter of material it can turn. The distance from the ' headstock spindle centre and lathe bed' would be half this size, .e. 90mm

Richard Rogalewski19/01/2020 12:07:45
72 forum posts
14 photos

All understood. Off to YouTube to see how to do the things needed to turn a bar into this flange set I'm wanting to make. Also, as to a lathe, I'll be looking also at getting a second-hand one at some point in the year..

Bandersnatch19/01/2020 18:40:43
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Apart from the (slight) drift of topic, I thought the OP had a point. It's curious that (in my experience as well as his) the largest dia the chuck will accept in the jaws is rarely stated.

Michael Gilligan19/01/2020 20:04:37
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Posted by Bandersnatch on 19/01/2020 18:40:43:

Apart from the (slight) drift of topic, I thought the OP had a point. It's curious that (in my experience as well as his) the largest dia the chuck will accept in the jaws is rarely stated.

.

Probably because there is no reliable single answer to what is safe to hold:

First; there are two sets of jaws available

Second; the other features of the workpiece [length,weight, surface finish, etc] all need to be considered

Third; need to take into consideration the type of machining to be done.

In these litigious times, Suppliers may feel more comfortable simply avoiding the issue and letting the user make his/her own considered decision.

MichaelG.

Neil Wyatt19/01/2020 20:26:01
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Posted by Richard Rogalewski on 18/01/2020 21:35:28:

I think I'm getting it now. "Swing over bed" is that distance between the headstock spindle centre and lathe bed. It's 180mm for the lathe I quoted a description for.

No swing over bed TWICE the distance between the axis of the spindle and the bed which is the 'centre height'.

There's also the swing over the cross slide which is a practical limit on most turning of all but short work.

The largest diameter a chuck can hold is moot, as the answer is 'it depends' so it is rarely quoted and when it is the values are very conservative. This is because you can use outside jaws which might hold work larger in diameter than the chuck safely (or might not) or fit soft jaws to take oversize work.

In practice I have not come across a chuck that isn't capable of holding a bar of the same diameter as the chuck although it may need tailstock support to do so safely with any but short workpieces.

You can also hold really big work between centres, if the lathe can take the weight safely.

Remember just because you can turn a given diameter or a given length doesn't mean you can turn a bar of that size.

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