6 Jaw vs 4 chuck any users

[Jinx-)]

I'm big fan of 4 jaw chuck and rather stay away from 3 since anytime time I true anything on it I'm getting runout, but some people say 6 jaw is the perfection of all... Whatever..,,, I can index anything I need on 4 jaw and run true... So am I wrong?

 

[lazylabs]

Here is my take although I am a semi-machinist not a paid pro. The six will give you a little more even grip pressure on anything thin walled. If you use them on an adjust tru backplane then you get the dial in capability of the 4 jaw with the improved gripping power. If your using them as an improved 3 jaw on round stock they tend to be a little more accurate as far as just chuck and go. I would think that if you took a 3 or 6 QUALITY chuck on a fixed back plate on a solid piece of round stock they would be the same. If you took the six jaw on a piece of thin tubing with an adjust tru back plate you would exemplify the differences....... sorry to ramble just my simple way of seeing it.

 

[shortgrass]

I'm big fan of 4 jaw chuck and rather stay away from 3 since anytime time I true anything on it I'm getting runout, but some people say 6 jaw is the perfection of all... Whatever..,,, I can index anything I need on 4 jaw and run true... So am I wrong?

You're comparing "apples to oranges". The 3 jaw is a scroll chuck, all jaws move when you turn the key. Unless your 4 jaw is a "scroll chuck", it is an "independent" jaw chuck, meaning only one jaw moves at a time when you turn the key allowing a piece to be centered using an indicator . Many 3 jaw scroll chucks are not built on center as close as they should be. I have seen (and used) 3 jaw "independent" chucks. They're a pain!. I've used 4 jaw "scroll" chucks. They allow a square to be held as well as round pieces. The "True Set" mentioned in a previous post is available in 3 or 6 jaw. The 6 jaw, as mentioned holds thin sectioned pieces better (without crushing them or 'egging' them). The "true set" feature is nice for short 'production runs' of pieces the same size. I feel the best 3 jaw scroll chuck is one mounted on a back plate where the back plate has been trued to the machine. In the case of a D1 series mount I like to 'witness mark' it, so the same stud goes in the same hole if I remove it. A chuck mounted on a back plate can be centered up to run better than most 3 jaws scrolls built with an intgral mount. If I had only one chuck, it would have to be a 4 jaw indepndent. Would work for anything.

 

[J E Custom]

They all have there advantages.

3 jaw= fast and convenient but not as versatile as other chucks.
4 jaw= slower to set up because of the individual adjustments on each jaw but
very precise and they are able to hold something other than a round accuratly
centered.
6 jaw=better grip, most 6 jaw chucks are fully adjustable and can be trued for fast
accurate use. they are also the most expensive.

Like shortgrass, If I could have only one chuck it would be a 4 jaw.

J E CUSTOM

 

[ken snyder]

6 jaw for thin stuff that you do not want to distort. 4 jaw independent for TIR ( one of the adjustable set true ) 3 jaw for everything else. The amount of Taper just by differences of locking down a tail stock will generally surpass the chuck concern by a land slide. Once a part gets out far enough to need a center the chuck is of less importance than the lathes setup and the machinists attention to detail in making his set up.

 

[Trickymissfit]

I'm big fan of 4 jaw chuck and rather stay away from 3 since anytime time I true anything on it I'm getting runout, but some people say 6 jaw is the perfection of all... Whatever..,,, I can index anything I need on 4 jaw and run true... So am I wrong?

they make three jaw chucks that can be adjusted to zero run out. Look for a Buck Chuck (by the way the best chucks made). I like four jaw chucks, but they wont do everything just like a three jaw wont as well.
gary

 

[Trickymissfit]

Here is my take although I am a semi-machinist not a paid pro. The six will give you a little more even grip pressure on anything thin walled. If you use them on an adjust tru backplane then you get the dial in capability of the 4 jaw with the improved gripping power. If your using them as an improved 3 jaw on round stock they tend to be a little more accurate as far as just chuck and go. I would think that if you took a 3 or 6 QUALITY chuck on a fixed back plate on a solid piece of round stock they would be the same. If you took the six jaw on a piece of thin tubing with an adjust tru back plate you would exemplify the differences....... sorry to ramble just my simple way of seeing it.

I think we are all talking apples to oranges here. The better chucks are scroll chucks, and as I said a Buck is by far the best you can buy. All chucks will collapse the piece your turning if you use enough pressure on the jaws. Most guys that use their chucks daily keep several sets of jaws laying around for different aps. The way to get the best grip on the stock with the least pressure is to cut the jaws in to fit the O.D. of the part. Still when your looking at something that has a .06" wall you really need to go in another direction. A collet will work better here, but you can also make up a device to hold the thin walled stuff, and still cuck it up. The problem will a six jaw and the others is that the actual pressure exerted is in a small area, where a collet is over a much broader surface area.
gary

 

[ken snyder]

Apples and oranges is correct. Only speaking for myself here but when I have the need for a very high degree of minimal taper and run out it is usually a pre manufactured part that is being corrected. and in the case of most often it is generally a part with protrusions on it that require the use of a spider set up in which case any ole chuck that the spider will fit in and not slip is just as good as anything

 

[shortgrass]

I just priced a new Buck 6" independent, flat back, 4 jaw,,,,,,,,,, $765.

 

[Jinx-)]

thank you all for this information, it will take some time for me to digest it all, but for now I still like my 4 jaw independent chuck, yeah its slow, heavy and can't run at high rpm because of vibration

 

[Trickymissfit]

I just priced a new Buck 6" independent, flat back, 4 jaw,,,,,,,,,, $765.

well they have not gone up any in the last ten years. I paid $110 an inch over ten years ago for two three jaw scroll chucks with back plates, but you get what you paid for. Now if you want to really see just how good a Buck is compaired to the competetion, then compair it to some of the high dollar Japanese chucks (about the same price). You won't see much difference on day one, but after six months of hard usage you'll see a lot of difference. The Jap chucks have to be rebuilt twice as often. The other Asian chucks end up costing even more money after a few rebuilds. And this dosn't take into fact the wonder art of rebuilding these chucks after a hard wreck. Much of the time the cheaper chucks end up in the trash (I often just recycled them into mill fixtures)

Right now Buck is known in the industry as the best money can buy for a manual chuck on a hand lathe. In a power chuck there are many good ones out there, but these companys more often than not have left the manual chuck field. I think that had SP and a couple others stayed in the manual chuck business we might see a little less cash involved. I personally miss the good old Logans that were built like a tank.
gary

 

[shortgrass]

well they have not gone up any in the last ten years. I paid $110 an inch over ten years ago for two three jaw scroll chucks with back plates, but you get what you paid for. Now if you want to really see just how good a Buck is compaired to the competetion, then compair it to some of the high dollar Japanese chucks (about the same price). You won't see much difference on day one, but after six months of hard usage you'll see alot of difference. The Jap chucks have to be rebuilt twice as often. The other Asian chucks end up costing even more money after a few rebuilds. And this dosn't take into fact the wonder art of rebuilding these chucks after a hard wreck. Much of the time the cheaper chucks end up in the trash (I often just recycled them into mill fixtures)

Right now Buck is known in the industry as the best money can buy for a manual chuck on a hand lathe. In a power chuck there are many good ones out there, but these companys more often than not have left the manual chuck field. I think that had SP and a couple others stayed in the manual chuck business we might see a little less cash involved. I personally miss the good old Logans that were built like a tank.
gary

But, this IS a LRH (Long Range Hunting) forum and gunsmiths or hobbiests (who do barrel work) don't "run hard" like one does in production. I know of no one who is taking .040-.050" at .0075-.008" per rev. on a barrel. Yes, it's nice to have/use "top of the line" tools, but not really necessary, "middle of the road" works just fine. Yes, you need accurate tools, junk just makes junk, and isn't usually 'user friendly'. Just owning/using the "best" brand name tools doesn't necessarily mean the "best" work. No business buys more than it needs to be profitable. Hobbiests are the last to spend and many just "make do with what they have" until it becomes unrepairable or just plain falls apart!

 

[ken snyder]

I can see all the points mentioned in the previous replies. I am also reminded of the person in front of the lathe. There was a guy outside of Roseburg Oregon that helped me out a few times. His equipment was the single least impressive brought home from work for free stuff I have ever seen. But in his hands it was an outstanding tool. Not by equipment but by skill. Some of you may have known him he was a cast bullet guy, I don't know how many national records he had but I do know that at one point he held 7 at the same time!

 

[Trickymissfit]

But, this IS a LRH (Long Range Hunting) forum and gunsmiths or hobbiests (who do barrel work) don't "run hard" like one does in production. I know of no one who is taking .040-.050" at .0075-.008" per rev. on a barrel. Yes, it's nice to have/use "top of the line" tools, but not really necessary, "middle of the road" works just fine. Yes, you need accurate tools, junk just makes junk, and isn't usually 'user friendly'. Just owning/using the "best" brand name tools doesn't necessarily mean the "best" work. No business buys more than it needs to be profitable. Hobbiests are the last to spend and many just "make do with what they have" until it becomes unrepairable or just plain falls apart!

I'm a buy it once, and cry once kinda person. I've probably rebuilt three hundred (if not more) chucks in my lifetime, and they all are not the samething. You can get buy with a cheap chuck for sure, and if you only seriously use it four or five times a year your OK. But if you plan on seriously using it, you better look at a good one.

I kept a minimum of two spare chucks for each model of CNC lathe in the building, and in some case over a half dozen spares. In the tool room I had a three jaw scroll chuck and a four jaw chuck setting in the rack for each machine. When they got to acting funny the guys would come and get me, and I would rebuild it for them while they used a spare chuck (scrolls have a habit of getting chips in them). The average person would be better suited with nothing but a simple four jaw chuck in 98% of his useage. But a good collet setup is plenty good enough for 90% of the work.
gary