Which Chuck?

[RMO]

I have a 1340 Acra Chinese lathe, but it is missing a chuck. It is a D1-5 mount. If I can only afford one chuck in the immediate future, what would you recommend? Not sure what I will be turning yet, just want to get the lathe operational and go from there. I am considering a 4-jaw or a collet chuck. Any suggestions for a beginner? Probably won't see much use as I don't have much time to spend on hobbies right now, but eventually...

The lathe is also missing a tool post of any kind. Thinking about that as well.

 

[bearcar1]

Well RM, perhaps it would be prudent to save your hard earned cash for other things that are needed in life right now as it sounds like any lathe work will be few and far between for you. Personally, if I were faced with the choice of chucks, it would be a 4jaw. Given the circumstances, it would be next to impossible to center an odd shaped piece in a three jaw but other than the time spent, any round can be made to run true in a 4jaw. That and the fact that you do not have a tool post either. Like I said, maybe later when your schedule presents itself the time for hobbies, why spend the money if it is to just go unused for who knows how long, and if it never comes around then the money will have been wasted. Just my $.02 on the subject. Best of luck.

Cheers

BC1
Jim

 

[portlandron]

Go with the four jaw chuck it will give you the ability to hold round stock, square stock any most any other shape.

 

[Mike N]

I have a 1340 Acra Chinese lathe, but it is missing a chuck. It is a D1-5 mount. If I can only afford one chuck in the immediate future, what would you recommend? Not sure what I will be turning yet, just want to get the lathe operational and go from there. I am considering a 4-jaw or a collet chuck. Any suggestions for a beginner? Probably won't see much use as I don't have much time to spend on hobbies right now, but eventually...

The lathe is also missing a tool post of any kind. Thinking about that as well.

I think your lathe uses a D1-4 mount for the chuck.
Check Ebay for a 3 or 4 jaw chuck with the proper mount.
Your spindle has a MT5 internal taper.

 

[RMO]

According to the manual and what measurements I have taken it is a D1-5, and a MT5 spindle.

I am leaning towards the 4-jaw.

The thought about just saving up until cash and time becomes available is also a very valid idea. I will keep my eys open and see what I can find. I have found that if I wait long enough something eventually turns up even cash.

 

[Mike N]

According to the manual and what measurements I have taken it is a D1-5, and a MT5 spindle.

I am leaning towards the 4-jaw.

The thought about just saving up until cash and time becomes available is also a very valid idea. I will keep my eys open and see what I can find. I have found that if I wait long enough something eventually turns up even cash.

I could be wrong! but this link has the specs for your lathe.
http://www.acramachinery.com/Manual_Machines/SPECS/PRECISION_ENGINE_LATHES/1340GSMspecs.htm
Good luck!

I have a Jet 1440 lathe with a D1-4.
Almost all 1340 China lathes have a D1-4

 

[tel]

The standard advice is 'If you have to choose - get the 4-jaw first.' I did that when I first got my Myford and it was probably another 3 or 4 years before I added a 3-jaw.

 

[steamer]

+1 for the 4 jaw

You need to find the skill and patience to center the work, but after a few hours of use, you master that pretty quick. Then it really shines as it is very versitle.

Dave

 

[Ken I]

My vote also for the 4 jaw.

Anything you can do in a three can be done in a 4

4's normally have reversible jaws and can hold larger stock disks or bar ends than a 3.

Sure its a little bit of work to clock up - no biggie.

I have both and seldom use the 3 jaw.

My 2c

Ken

 

[Swede]

I guess I'm the odd ball... if you can find an "adjust-tru" style of 3 or 6 jaw, I'd go for that. You get the benefits of extremely rapid standard 3 jaw chuck use, AND you can tweak it for zero runout faster than you can dead center in a 4-jaw. About the only thing it can't do is square stock, and there are ways around that.

 

[ShedBoy]

Get the 4 and get, find, make, liberate a second key for it, makes for much quicker set up. If you are new to 4 jaws practice for a while and if you are like me be prepared to walk away, cool down and relax. I have come so close to throwing the DTI (Devil Turned Instrument) across the shed many times.

Brock

 

[Ken I]

As regards clocking a 4 jaw - if all you are doing is mounting stock where the OD is going to be turned anyway - then the MkI Eyball is good enough. (Move a tool in and clock the gap.)

If you need more accuracy then the 3 jaw isn't good enough anyway.

2c - Ken

 

[Maryak]

A four jaw chuck can do everything a 3 or 6 jaw can and everything the 3 or 6 jaw can't. It can also be used as a face plate with a little ingenuity.

Best Regards
Bob

 

[Ken I]

Maryak, I have a small faceplate on a stub-shaft which I mount in my 4 jaw - its a lot easier to get a part dead true with the 4 jaw than tapping the part on the faceplate with a knockometer.

Ken

 

[90LX_Notch]

Ken has that right. I have a couple of rectangular blocks that I use as "universal" fixtures. I can mount them in the four jaw, machine table or vice. In the four jaw they are just like a faceplate, except that you can adjust the chuck jaws to zero an odd shaped part out very quickly.

 

[peatoluser]

Like everybody else my vote is for the 4 jaw. Don't even own a 3 jaw. The only job I can think of that a 3 jaw is better is holding hex material, so I built a filing rest and file the hex onto round bar.
here's a video of why Brock recommends a second key
[ame]http://www.youtube.com/watch?v=2KMhx4DbyDg[/ame]

but in defence of the 3 jaw, I believe it's possible to drill the offcentre hole in eccentric sheaves for models using the formulae

T= 1.5E ( 1- 0.5E/D - 0.375(E/D)cubed)

T= DESIRED ECCENTRICITY
D= O.D. OF SHEAVE
T= THICKNESS OF PACKING TO BE PLACED UNDER ONE JAW.

for obvious reasons (see first line of post) I've never tried it. I believe it gives a theoretical accuracy better than a 3 jaw's runout.
has anybody tried it? and how good is it?
got the formulae from Tubal Cain's 'model engineer's handbook' and his books are generally first rate

 

[mklotz]

That formula is only an approximation because it ignores the thickness of the chuck jaws. For a more precise computation, see my ECCENT archive. Also contained in that archive is a better technique for doing eccentrics in a 3-jaw.