|646 forum posts|
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 Hulme||19/03/2018 20:03:55|
|748 forum posts|
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 Haine||19/03/2018 20:04:18|
|4086 forum posts|
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 6||19/03/2018 20:22:59|
1948 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 !
|2146 forum posts|
Poorly made or worn chuck jaws will not grip throughout their length so not holding pre-machined work firmly or accurately.
|257 forum posts|
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 Rimmer||19/03/2018 22:46:30|
|1042 forum posts|
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 Wood||20/03/2018 09:20:33|
|2435 forum posts|
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.
|Mark Rand||20/03/2018 09:49:46|
|1050 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 Eberhardt||20/03/2018 10:13:06|
2689 forum posts
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.
|old Al||20/03/2018 10:21:51|
|184 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 Wyatt||20/03/2018 11:42:33|
18721 forum posts
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 Lickfold||20/03/2018 12:34:30|
|717 forum posts|
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.
2051 forum posts
go with zither or HBM, both of which are perfectly good import brands.
|646 forum posts|
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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