Lathe Chuck Questions

[Max MedhurstParticipant @maxmedhurst87650]

Hi,

I have just bought a Colchester Bantam 1600 Mk2 lathe and am very pleased with it. The issue is that it only came with a 5" chuck with internal jaws so it can't hold very large material (I need to be able to hold up to 4&quot. The existing chuck is a Pratt Burnerd and has cat no. 1217-24305 (but it is hard to make out so some of the numbers may not be correct) and stamped on the chuck is F8062.

So I'd like to get either some external jaws to fit the existing chuck or a new chuck altogether as that seems virtually as cheap as just the jaws.

What I'm struggling with is finding a chuck that will fit the lathe, I don't want to buy one then find it doesn't fit. I'm also struggling to find any exernal jaws to fit the chuck, I'm not sure exactly which chuck I have as I can't find that cat. No. anywhere.

Any help would be much appreciated

[Max MedhurstParticipant @maxmedhurst87650]

[EmgeeParticipant @emgee]

Hi Max, is it a D1-3 fitting chuck ?

Best measure and post all dimensions of the jaws, someone may have some spares.

Emgee

[Nick_GParticipant @nick_g]

Posted by Max Medhurst on 27/09/2015 09:10:32:

I'm also struggling to find any exernal jaws to fit the chuck, I'm not sure exactly which chuck I have as I can't find that cat. No. anywhere.

Any help would be much appreciated

.

Try giving Rotagrip a call.

Regards, Nick

[Max MedhurstParticipant @maxmedhurst87650]

There are 3 jaws, each is stamped with the letter W and the number 150 (and also obviously the numbers 1-3)

Each one is: 0.625" wide, 47mm long, slot width is 7.8mm, the depth of the teeth on the back is 4.2mm and the pitch looks to be about 6.5mm.

If you need any more dimensions just let me know!

[Ian S CParticipant @iansc]

What type of mounting does the chuck have.

Ian S C

[Nick_GParticipant @nick_g]

Posted by Ian S C on 27/09/2015 11:12:35:

What type of mounting does the chuck have.

Ian S C

.

It should be a D1-3 Ian.

Nick

[Max MedhurstParticipant @maxmedhurst87650]

It has got a Camlock, 3 pins each 14mm diameter with a centre to centre distance of 61mm, does that sound like d1-3?

[Max MedhurstParticipant @maxmedhurst87650]

Just checked all the dimensions on this website:

http://www.tools-n-gizmos.com/specs/Lathe_Spindle_Mount.html

And they all agree that it is a D1-3 chuck

[Mark CParticipant @markc]

I would be inclined to buy some soft jaws and machine them in situ. This will allow maximum size and best accuracy all in one go and they will be a lot cheaper than hard jaws or a new chuck. When you have machined them too many times, you can face them off and add a detachable top jaw and start again!

Mark

[Max MedhurstParticipant @maxmedhurst87650]

Ah yes I came across soft jaws but have never used them before, I was led to believe that you had to machine them to fit whatever workpiece you were using so say you would machine them to fit a peice of 3" round bar then they would need re-machining to fit 4" bar, so I would machine them all away pretty quickly.

Can you machine them so they will fit a variety of workpieces? (I don't have a milling machine)

[MuzzerParticipant @muzzer]

I notice that RDG do a variety of D1-3 chucks, faceplates and backplates. You might also find them here or on ebay etc. Building up a decent range of accessories for a lathe takes many years and you have to acquire what you need from a variety of sources.

[Mark CParticipant @markc]

I use them all the time, Machine to specific size for repetitive accurate jobs with special requirements, or machine to a larger diameter (as external or smaller diameter for internal) and use them just like hard jaws. You use them by mounting them in the chuck, gripping something with them (a small diameter bar or large ID ring) to take up any play in the direction you will use them and then machine a step to suit your requirements with a boring bar or external turning tool at a speed to suit the interrupted cut you will take on the jaws.

Harder to explain than do!

Mark

[Max MedhurstParticipant @maxmedhurst87650]

Ok, thanks for the link.

If I go for the soft jaws, does anyone know which size ones I need for my chuck?

[AjohnwParticipant @ajohnw51620]

Rotagrip may be able to get the original jaws for it but they are very pricey. They also stock a range of soft jaws. Pretty sure you will find dimensions on their web site. I've found that they sometimes need a bit of fitting to get them in the chuck. Easy to do providing that some care is taken to see which areas need a few thou removing. I find it's best to use a 10in flat file with a safe edge and rub the jaw against the file – lot easier to keep the surfaces flat and get a perfect fit.

You don't say what you want to machine. If it's heavy work 4in in a 5in 3 jaw is pushing it and an independent 4 jaw would be better. They grip work very tightly and in real terms for moderately accurate running don't take long to set up. They are usually bigger than the 3 jaw for any given lathe as well. Often they can be usefully bigger than the standard size that normally comes with a lathe. Just be sure saddle etc clears if needed and allow for a bit of jaw projection.

John

–

[Max MedhurstParticipant @maxmedhurst87650]

The 4" material would be HDPE billets (around 150mm long max.) and the 3" material would be titanium or aluminium billets (max 100mm long)

I have got an independent 4 jaw but didn't know you could grip round material with them, the way I was taught to use them was to centre dot your material and line up with a centre in the tail stock them tighten jaws, not sure how I'd mark the centre of a round peice of material.

[Mark CParticipant @markc]

With a center finder! Search for the term and you will see them – it is a type of set square based on a "v" block sort of thing….

Mark

[KWILParticipant @kwil]

And you think you will be able to machine Titanium, that comes along down the line after you have to learn to set up a lathe and get some practice.

[JasonBModerator @jasonb]

You don't even need to mark round stock, just rest a DTI against the side and keep adjusting until the needle stays still. Also use the DTI if clocking a punch mark as its far more accurate than using the tailstock ctr

[Max MedhurstParticipant @maxmedhurst87650]

Ah I hadn't thought of a DTI, I've used them for clocking up work on a mill but never thought of using one on a lathe.

I'll order a DTI and keep a lookout for a good D1-3 chuck.

And KWIL: I've got quite a lot of experience turning at school, in fact we had the exact same lathe (one of the reasons I chose it). I just have never had to go about ordering chucks or jaws as they already had everything we needed. That said I've never turned titanium so it will be an interesting experience.

Thanks for all your help!

[EmgeeParticipant @emgee]

Max, check your Inbox for a message.

Emgee

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