Self centering 4 jaw chucks

[prepman]

I can see the benefits and downside to these....does anyone have first hand experience and opinions? Much appreciated before I spend my newspaper round money.

 

[Kram]

Better to have a decent independant 4 jaw chuck, keep an eye on ebay for a Bison.

 

[My Old Landy]

I have both, to be honest, I have not used the self centering one for a while. If you can get only one, as Kram says, go for a decent independant.

 

[pressbrake1]

I have one, a chinesium one from vevor.
I only got it for a production job machining a round onto some square. Also use it for milling square bar on end
Other than that can’t see a use

 

[prepman]

I have both, to be honest, I have not used the self centering one for a while. If you can get only one, as Kram says, go for a decent independant.

Can you explain how the SC 4 jaw operates?

 

[prepman]

I have one, a chinesium one from vevor.
I only got it for a production job machining a round onto some square. Also use it for milling square bar on end
Other than that can’t see a use

What about rectangular stock?

 

[Seadog]

It's a scroll chuck, same as a 3-jaw.

 

[Kram]

Same as a 3 jaw, it has a scroll that pulls the jaws on, rather than independant worm screws.
A scroll gives less jaw contact so you get a smaller safe gripping range for the same size chuck, and you need a second set of jaws.

I suggest an er40, small 4 jaw independant and big 4 jaw independant, all you need with a lathe.

 

[prepman]

It's a scroll chuck, same as a 3-jaw.

I appreciate that....but how does it cope with non square section. With 3 jaw it's straight forward, the work piece is pushed towards centre. Can even clamp rectangular section for facing. But all 4 jaws coming together at the same rate leaves me a bit baffled. I already have independent 4 jaws Pratt Burnerd. If I got Sanou sc 4 jaw I'd have to make another L0 backing plate.

 

[Seadog]

Why? They come together in the same way.

 

[My Old Landy]

I will go and take a pic but as others say, it just comes together on a scroll as a three jaw.

 

[pressbrake1]

What about rectangular stock?

It’s self centring. That’s the clue as to how it’s going to handle rectangular stock!

 

[prepman]

Why? They come together in the same way.

For that very reason. If opposing jaws clamp and the other pair are not because the piece isn't uniform. e.g. rectangular....what happens? The other jaws continue? If so then it isn't the same as 3 jaw which works off a simple scroll. There has to be some kind of differential involved?

 

[Hood]

Waste of time in my opinion and experience. Unless the square is pretty good then you won't get even clamping as two opposing jaws will have a better grip than the other two. Rectangles it is impossible to grip, well it will grip but only on two opposing jaws that are on the largest side. Even round, if the round is not bright then chances are it will not grip securely.
Much better with a 4 Jaw independent or a 3 jaw for round, especially if you have soft jaws for the 3 jaw.

 

[prepman]

Waste of time in my opinion and experience. Unless the square is pretty good then you won't get even clamping as two opposing jaws will have a better grip than the other two. Rectangles it is impossible to grip, well it will grip but only on two opposing jaws that are on the largest side. Even round, if the round is not bright then chances are it will not grip securely.
Much better with a 4 Jaw independent or a 3 jaw for round, especially if you have soft jaws for the 3 jaw.

That's what I wasa thinking.

 

[My Old Landy]

The smaller one is self centering and you can see it is the same as a 3 jaw with the key in-between the jaws. The independent has a key per jaw. I used to use it for square stock but it is not that useful to be fair.

 

[prepman]

The smaller one is self centering and you can see it is the same as a 3 jaw with the key in-between the jaws. The independent has a key per jaw. I used to use it for square stock but it is not that useful to be fair.
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So it's no go on rectangular stock? The SC 4 jaw?

 

[My Old Landy]

So it's no go on rectangular stock? The SC 4 jaw?

Sadly they are fairly useless as I found out after purchasing this one!

 

[prepman]

Sadly they are fairly useless as I found out after purchasing this one!

Hmm...was afraid of that. It's like pub tables used to have 3 legs for stability. Also very heavy so they couldn't be launched on Saturday nights.

 

[pressbrake1]

So it's no go on rectangular stock? The SC 4 jaw?

I hope you’re trolling now!