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Does 4 jaw chuck quality matter

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Rainbows19/03/2018 19:50:20
632 forum posts
181 photos

Been browsing for a 4 jaw on the CJ18A.

I was wondering though is there any real difference in use between a high quality Burnerd or a no name Chinese chuck- or a well used one and a new one (discounting abuse rather than wear).

At the end any accuracy in the chuck is dialled in through a DTI so wear or slop gets adjusted out anyway. So my current hypothesis is that a chuck is a chuck is a chuck.

Am I wrong/right?

Nick Hulme19/03/2018 20:03:55
698 forum posts
37 photos

A 4 jaw chuck should still hold parallel sided work parallel to the spindle, just offset.

A worn one or a poor one may not.

John Haine19/03/2018 20:04:18
2591 forum posts
133 photos

Wait until you get one with a sloppy fit between the jaws and the slots, or where the steps in the jaw heights are different between the jaws, and reconsider your question. Guess how I know? When I bought my Super 7 I bought a good Bison chuck and have not regretted it, a big step up from what I had before.

Chris Evans 619/03/2018 20:22:59
1451 forum posts

As above, even 4 aw chucks suffer from bell mouthed jaws and sloppy fitting slots. You should see the length of tube some folk use on the chuck keys to tighten them !

Emgee19/03/2018 20:33:23
1157 forum posts
206 photos

Poorly made or worn chuck jaws will not grip throughout their length so not holding pre-machined work firmly or accurately.
Not such a problem if holding castings which do not offer parallel surfaces but care is needed to make sure the job doesn't move when being machined.

Emgee

MalcB19/03/2018 22:28:52
251 forum posts
29 photos
Posted by Chris Evans 6 on 19/03/2018 20:22:59:

As above, even 4 aw chucks suffer from bell mouthed jaws and sloppy fitting slots. You should see the length of tube some folk use on the chuck keys to tighten them !

You will also see a lot of independant 4 jaw chucks with significant cracks in the screws around the chuck key locations because of these " tube users ".

Pete Rimmer19/03/2018 22:46:30
400 forum posts
18 photos

Not only does quality matter but suitability does too. I have a couple of Burnerd lightweight 4-jaws and whilst you can't question the pedigree of the chuck you do have to be careful how much you tighten the jaws or it's easy to put a deflection in the chuck face. I guess that's why they made them with such small screws and chuck key.

Brian Wood20/03/2018 09:20:33
1942 forum posts
37 photos

A poor quality chuck is also quite likely to develop slop in the square mouth of the jaw screws caused by cracking from the inside of the squares, the better chucks will have screws made of better material and may even he hardened to resist that effect.

Brian

Mark Rand20/03/2018 09:49:46
743 forum posts

My Hardinge 4 jaw chuck has both a split jaw screw mouth and worn jaws. I haven't yet carefully measured the slots, but I expect that there is wear in them as well. OTOH, it's 66 years old.

My plan for it, and the corresponding three jaw chuck, is to skim the faces of the slots if needed, then make new jaws and screws to fit. That'll save me a small fortune compared with buying new chucks.

Russell Eberhardt20/03/2018 10:13:06
avatar
2476 forum posts
85 photos

You have to consider the cost. A new Pratt Burnerd chuck might cost half as much as the lathe if bought new. If bought second hand it might not be as accurate as a Chinese chuck. A new Chinese chuck from a reputable supplier will probably be as accurate as your little Chinese lathe.

Russell

old Al20/03/2018 10:21:51
139 forum posts

Somewhere along the line, i gained a brand new Indian made 4 jaw chuck. I was of the opinion that whatever the operator wanted, the 4 jaw would deliver. (I have always worked in engineering workshops with good old fashioned equipment.)

So, Im happy, i have something new and in it box, woopee.

Go to start work with said 4 jaw and find it holds on the back of the jaw. I have a 'new' doorstop.

Second hand good makes are a much better investment, especially as my 4 jaw is constantly fixed to my lathe

Neil Wyatt20/03/2018 11:42:33
avatar
Moderator
16446 forum posts
686 photos
74 articles

All has been said.

You may strike luck with a cheap imported chuck or not.

The better quality imported chucks from reputable suppliers are very good IMHO. I've had two 4" SC three-jaws that are both as good as figures quoted for a new Burnerd chuck. Only time will tell how well the hold their accuracy, of course, but owner-user tools tend to be treated well and I'm not hammering our work on them 24/7 in a production environment so I expect them to last.

Neil

Neil Lickfold20/03/2018 12:34:30
562 forum posts
102 photos

You will not regret buying a good quality 4jaw chuck. One that will hold the workpiece reasonably close to the lathes centre line. From my experience, the cheap chucks are just that. You spend more time setting up the job and with the time saved could buy the better chuck and not get frustrated by the poor quality one. You don't have to buy the Burnad chuck. There are plenty of good quality chucks out there. I would not buy any chuck sight unseen, but that is just me.

Neil

MW20/03/2018 13:20:50
avatar
2050 forum posts
51 photos

go with zither or HBM, both of which are perfectly good import brands.

Michael W

Rainbows20/03/2018 14:17:26
632 forum posts
181 photos

Probably going to buy one off chronos, they seem to be the cheapest seller that isn't a chinese ebay shop. Also the import chucks save me making a backplate. I considered zither but thats nearly 3 times the cost.

I suppose I could try grinding the jaws to all be level while in situ using a toolpost grinder? Not so much tool post grinder as a flexi shaft grinder zip tied to the tool post in my case. Dependent on if I get unlucky with the chuck I guess.

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