4 Jaw Chuck input for PM1228, PM's High Precision 8" vs.

[rwdenney]

I'm confused. I though the whole point of a 4-jaw chuck was so that TIR could be dialed out to ensure indicated concentricity. I didn't think there was a way to do otherwise, given that the jaws are independent.

Maybe it's the ability of the jaws to ensure the workpiece is parallel to the spindle, but I thought that was the job of bumping the workpiece in and indicating close to and far away from the jaws.

But I'm a beginner. What am I missing?

Rick "where would one measure TIR on a 4-jaw?" Denney

 

[maticulus]

But I'm a beginner. What am I missing?

I'm a hobbyist at this point with a lot of ideas and bend toward precise tooling, understanding the dependency on skill with the 4 jaw,

I intended that remark to indicate I'm aware of dialing in TIR of the work piece on a 4 jaw. My interest is in assessing quality and versatility and for that I need reference points for comparison and guidance.

 

[mksj]

The difference in the chuck speed ratings is a function of the material used (semi-steel/iron vs. forged steel) and the diameter, and to some degree weight. Forged steel chucks are stronger and can withstand high centrifugal force, they also cost more. The Gator chucks get mixed reviews, they are made in mainland China and are typically direct copies of the Bison chucks. My understanding of Gator was that it was started by several employees from Bison. Bison chucks are made in Poland as well as TMX, they tend to be better built chucks in my opinion. Since it is unlikely to be using an 8" 4J above 1800 RPM, either the Gator or PM/QMT chuck would be fine, as previously outlined the Gator jaws are more course so may be not be suitable for smaller stock. The main advantage of a 2 piece jaw would be if you were to use soft jaws. I have the QMT/PM 8" 4J independent chuck, I find it to work very well and smooth to 2000 RPM. Lighter lathes will be more sensitive to any chuck/work piece imbalance, in particular the smaller lathes with a high CG so a lighter balanced chuck would probably be better. Chucks can be a bit stiff when new, as they have very tight tolerances. The fit and finish on the QMT/PM chuck I would rate as very good and leaps and bounds better than most mainland Chinese chucks that often come with the smaller lathes.

QMT/PM 8" 4J independent chuck was very concentric and well balanced, it even had balance weights on the inside. At it's current price, it is a very well made chuck.

 

[maticulus]

The difference in the chuck speed ratings is a function of the material used (semi-steel/iron vs. forged steel) and the diameter, and to some degree weight. Forged steel chucks are stronger and can withstand high centrifugal force, they also cost more. The Gator chucks get mixed reviews, they are made in mainland China and are typically direct copies of the Bison chucks. My understanding of Gator was that it was started by several employees from Bison. Bison chucks are made in Poland as well as TMX, they tend to be better built chucks in my opinion. Since it is unlikely to be using an 8" 4J above 1800 RPM, either the Gator or PM/QMT chuck would be fine, as previously outlined the Gator jaws are more course so may be not be suitable for smaller stock. The main advantage of a 2 piece jaw would be if you were to use soft jaws. I have the QMT/PM 8" 4J independent chuck, I find it to work very well and smooth to 2000 RPM. Lighter lathes will be more sensitive to any chuck/work piece imbalance, in particular the smaller lathes with a high CG so a lighter balanced chuck would probably be better. Chucks can be a bit stiff when new, as they have very tight tolerances. The fit and finish on the QMT/PM chuck I would rate as very good and leaps and bounds better than most mainland Chinese chucks that often come with the smaller lathes.

QMT/PM 8" 4J independent chuck was very concentric and well balanced, it even had balance weights on the inside. At it's current price, it is a very well made chuck.

Thanks, that additional clarity on the PM chuck makes it the best choice for me.

 

[rwdenney]

I intended that remark to indicate I'm aware of dialing in TIR of the work piece on a 4 jaw. My interest is in assessing quality and versatility and for that I need reference points for comparison and guidance.

Okay--I think I'd judge the chuck based on how hard the lead screws and rack are on the jaws, and on how well they fit, if I really wanted to distinguish between various price points.

Rick "thinking screw or pinion teeth seem to be where the cheap chucks show the most wear based on tear-downs I've seen" Denney

 

[Larry42]

where the cheap chucks show the most wear

I wonder how much wear a hobbyist's 4 jaw chuck is going to get over the life of the lathe.

 

[Ischgl99]

I have the PM 8” 4 jaw and it is a good quality chuck. It is balanced at the factory, so that could partially explain the higher speed ratings over the Gator. I have no issues running mine up to 1,800 rpm on a 12x36 lathe. The jaws were a bit stiff when I first got it, making dialing in a challenge at times, but after using it a bit, it is smoother. I think it is a very good value for the price.

 

[sr71xjet]

The difference in the chuck speed ratings is a function of the material used (semi-steel/iron vs. forged steel) and the diameter, and to some degree weight. Forged steel chucks are stronger and can withstand high centrifugal force, they also cost more. The Gator chucks get mixed reviews, they are made in mainland China and are typically direct copies of the Bison chucks. My understanding of Gator was that it was started by several employees from Bison. Bison chucks are made in Poland as well as TMX, they tend to be better built chucks in my opinion. Since it is unlikely to be using an 8" 4J above 1800 RPM, either the Gator or PM/QMT chuck would be fine, as previously outlined the Gator jaws are more course so may be not be suitable for smaller stock. The main advantage of a 2 piece jaw would be if you were to use soft jaws. I have the QMT/PM 8" 4J independent chuck, I find it to work very well and smooth to 2000 RPM. Lighter lathes will be more sensitive to any chuck/work piece imbalance, in particular the smaller lathes with a high CG so a lighter balanced chuck would probably be better. Chucks can be a bit stiff when new, as they have very tight tolerances. The fit and finish on the QMT/PM chuck I would rate as very good and leaps and bounds better than most mainland Chinese chucks that often come with the smaller lathes.

QMT/PM 8" 4J independent chuck was very concentric and well balanced, it even had balance weights on the inside. At it's current price, it is a very well made chuck.
View attachment 418177

So you are happy with your PM/QMT 4 jaw chuck. Anything you can think of as a negative on it. Im looking at the PM 10" 4 jaw. I would assume same manufacture coming from Taiwan

 

[mksj]

So you are happy with your PM/QMT 4 jaw chuck. Anything you can think of as a negative on it. Im looking at the PM 10" 4 jaw. I would assume same manufacture coming from Taiwan

At it's current price point I would choose the PM/QMT Taiwanese 4J independent over the Gator unless I needed two piece jaws for soft jaws. If I needed two piece jaws I would probably get the Bison/TMX which run about 25% more. I have seen these chucks in the forged steel versions and they are impressive, but at the end of the day I do not see the added value unless you find one heavily discounted. All these chucks have gone up significantly in price and if one was to consider a Bison, TMX, PBA or similar chuck you would be 30-40% more. Long ago I purchased a Bison 8" combination chuck which is much easier to use for getting stock in/out and quickly dialing down the TIR. It is about twice the cost of the PM/QMT 8" 4J and also about twice the weight. I use my independent for rough stock, messy turning like cast iron or for odd shape stock, it has worked very well. It is a good value and works well enough. I previously had a Chinese 4J independent, it was crude, the jaws were rough/sloppy, the casting was so bad and lumpy that I couldn't get it past ~400 RPM.

There is a price performance ratio, but it diminishes the more expensive the chuck. A lot depends on the work you plan on doing and what other chucks you plan on getting. I am an advocate of getting a good set-true style 3J scroll, a slightly larger 4J independent for bigger/rougher/odd shaped stock, and a quality collet type chuck for smaller round stock. QMT/PM carries these chucks in mid-priced range versions, and I feel they offer very good performance to price ratio. If one has a bigger budget, then one can consider Bison/TMX/PBA/etc. chucks, but they all work well for their intended purposes. I would also be aware that many of the big chuck manufactures these days are offering lower price versions of their chucks or they buy lessor brand chucks and rebrand them with their name and up-charge for the brand name.

 

[sr71xjet]

At it's current price point I would choose the PM/QMT Taiwanese 4J independent over the Gator unless I needed two piece jaws for soft jaws. If I needed two piece jaws I would probably get the Bison/TMX which run about 25% more. I have seen these chucks in the forged steel versions and they are impressive, but at the end of the day I do not see the added value unless you find one heavily discounted. All these chucks have gone up significantly in price and if one was to consider a Bison, TMX, PBA or similar chuck you would be 30-40% more. Long ago I purchased a Bison 8" combination chuck which is much easier to use for getting stock in/out and quickly dialing down the TIR. It is about twice the cost of the PM/QMT 8" 4J and also about twice the weight. I use my independent for rough stock, messy turning like cast iron or for odd shape stock, it has worked very well. It is a good value and works well enough. I previously had a Chinese 4J independent, it was crude, the jaws were rough/sloppy, the casting was so bad and lumpy that I couldn't get it past ~400 RPM.

There is a price performance ratio, but it diminishes the more expensive the chuck. A lot depends on the work you plan on doing and what other chucks you plan on getting. I am an advocate of getting a good set-true style 3J scroll, a slightly larger 4J independent for bigger/rougher/odd shaped stock, and a quality collet type chuck for smaller round stock. QMT/PM carries these chucks in mid-priced range versions, and I feel they offer very good performance to price ratio. If one has a bigger budget, then one can consider Bison/TMX/PBA/etc. chucks, but they all work well for their intended purposes. I would also be aware that many of the big chuck manufactures these days are offering lower price versions of their chucks or they buy lessor brand chucks and rebrand them with their name and up-charge for the brand name.

Hey thanks for the info. We are just starting out, well i am, and my son went to school for it, so i think the PM will be a good way to start off with a 4 jaw.