# Do You Use a 3 Jaw or a 4 Jaw Chuck?



## Janderso (Apr 12, 2018)

I have a pretty accurate 3 jaw chuck (Chinese) that came with the lathe , SB 13 single. I bought a 4 jaw Cushman, that is also in great shape. The 3 jaw is so simple to use and I have never mounted the 4 jaw yet. 
Just wondering, should I mount the 4 jaw and learn how to use it or continue with the 3 until I have a rectangle or something that I can only use the 4 jaw?
Just wondering what you do.


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## British Steel (Apr 12, 2018)

I rarely use the 3-jaws i have, they only come out when I can make something in one chucking or don't need to worry about concentricity of different features - anything that needs to come out to turn around, for instance, goes in whatever's most suited: 4-jaw, collets or between centres (between centres is the easiest for e.g. shafts that need to be tried for a fit but needs centre drillings in both ends... 4-jaw's essential for eccentric features (cranks, cams etc.), collets for repetitive work small enough to go through the spindle and collet.
A big help when setting up and indicating in the part in a 4-jaw is a second chuck key so you can work on opposing jaws together, makes it a lot quicker! That also implies that you'll need a decent indicator and mount to measure eccentricity, useful (and a nice easy lathe project) is a telescopic "pump centre" when you want to pick up a punch dot on an interesting part to drill / bore / ream - it goes between the tailstock centre and the punch mark and the indicator rides on it, adjust the jaws to centre it, easy peasy!

Dave H. (the other one)


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## magicniner (Apr 12, 2018)

Yes, but mostly an ER40 Collet Chuck!


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## Chuck K (Apr 12, 2018)

Most of my 3 jaw chucks have too much runout to be useful for anything other than a one of part.  I have a small 5c 3 jaw chuck that runs just about dead nuts that I like to use for small odd size diameters.  90% of the time I use a 4 jaw.  If your 3 jaw has .003 or less of runout I wouldn't have a problem using it for a lot of things.  What you don't want to do is avoid using the 4 jaw becauce it's too much work.  If you don't take the time to play around with it,  it will always be something you avoid.  Once you get comfortable with it, it can easily become your go to chuck.  There's something to be said for having your material spinning dead true.


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## benmychree (Apr 12, 2018)

On my 19" lathe, I have a 10" 3 jaw buck chuck, can be fine tuned to run dead true, I use it most of the time, also have a 12" 4 jaw and an 8" 4 jaw for square / rectangular work; if work will be ground or removed for fitting, I have a driving plate and dead centers, and a large faceplate for work of that character, and Jacobs rubber flex collets; for the 9" lathe, a new 3 jaw, a nearly new 4 jaw, face and driving plates and collets, both rubber flex and solid type,   Bottom line is that perhaps 90% of the time, I use a 3 jaw chuck.


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## westsailpat (Apr 12, 2018)

Getting round stuff to run true in a 4 J is something good to get comfortable with and using your test indicator . For me though just doing general 
(round) work  I like my 3 J and collet . But say you have to turn a eccentric or you need to hold a block in your lathe or a bunch of other stuff the 4 J is your friend .


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## Ray C (Apr 12, 2018)

Sooner or later, you'll need to hold a square or rectangular piece and a 4 jaw chuck will be needed.  There are scroll-type 4 jaw chucks but, you won't be able to hold pieces at offset positions with them.

Which one do I use?...   6 Jaw, 3 Jaw, 4 Jaw and 5C Collet.  Whichever one is best suited for the task at hand.

Ray


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## mikey (Apr 13, 2018)

If I'm turning something from raw stock then it doesn't matter if I use a 3 jaw chuck; it will run concentric with the spindle centerline until I take it out of the chuck. It is only when you are doing a second operation on an already turned piece that you have to deal with concentricity issues. In that case, a 4 jaw chuck or a set-tru type chuck is your friend; they can be dialed in to be more accurate than a collet will run, albeit much more tedious to use.


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## Nogoingback (Apr 13, 2018)

I agree with Chuck K.  I have a 4 jaw that I use quite a bit and the more I use it, the better I get at setting it up.
I have a Jacobs spindle chuck for parts where runout won't matter.


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## cathead (Apr 13, 2018)

4J


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## Jake2465 (Apr 13, 2018)

I mostly just use my three jaw unless I am dealing with bearing surfaces or something like that. But, most of the time I only use my lathe to turn something round and shoot holes down the center for tapping work. Real simple stuff. Anything odd shaped, I just let my mill handle it. That's mainly because I really only make parts for my hobbies. So, I know what is good enough for me. I imagine working parts for paying customers would be a different situation altogether.


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## Buffalo21 (Apr 13, 2018)

Ray C said:


> Sooner or later, you'll need to hold a square or rectangular piece and a 4 jaw chuck will be needed.  There are scroll-type 4 jaw chucks but, you won't be able to hold pieces at offset positions with them.
> 
> Which one do I use?...   6 Jaw, 3 Jaw, 4 Jaw and 5C Collet.  Whichever one is best suited for the task at hand.
> 
> Ray


Ray 

I have a 8” Bison scroll-type 4 jaw chuck, it has the scroll that opens all the jaws, but also each of the jaws are adjustable, it will hold any odd shaped part, the open with the scroll, then close back down, to do multiple parts.


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## Janderso (Apr 13, 2018)

I was considering drilling and tapping this replacement band saw vise base with my 4 jaw chuck. I am thinking it is the best way to hold the work at a proper 90 degree angle. I am almost done with the milling.
I also have a drill press or the Bridgeport.
What do you think?
Should I drill the 3/4 hole first, then the two 1/2” holes?
(pic is before I started the job. I have completed the milling and need to decide which way to approach the drilling and tapping)


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## Asm109 (Apr 13, 2018)

Drill it in the Bridgeport. Use an edge finder  and dial in the location of the holes.  Mounting that part with the part way off center in the 4 jaw will lead to vibrations you won't believe. You might think your lathe will walk across the shop.


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## Janderso (Apr 13, 2018)

Good point. When I tap the large hole I will use a center to support alignment, I think I will chuck it up in the lathe and use the tail stock as my friend.
The 3/4 hole needs to have left hand 10 tpi threads. I had to buy that one, wasn't laying around the shop.


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## MrWhoopee (Apr 13, 2018)

Agreed, 4-jaw that one. Might even be able to power tap in the lathe, if you have the cojones.


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## Janderso (Apr 13, 2018)

No cojones in my pockets.


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## BGHansen (Apr 13, 2018)

I have a 10" 3-jaw set-tru chuck on my Grizzly G0709 14" x 40" and use is most of the time.  Have used the 4-jaw once, never turned between centers with a faceplate and dog.

Bruce


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## savarin (Apr 13, 2018)

My 9x20 three jaw is well out so I only use it if I do not have to replace the part back in it.
The four jaw gets a lot of use for that reason, and the face plate and between centres.
For most of my smaller stainless stuff I use the collet chuck I made but still have to grind the internal taper for final alignment. Its almost there.


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## Bobby Bailey (Apr 13, 2018)

We basically almost never use a three jaw. Not accurate enough, and we have set trues.  Go to chuck for quick and close is a Jacobs rubber Flex, 5C, or a four jaw.


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## JPMacG (Apr 13, 2018)

I use both, and would not want to be without either.  But if I had to get along with just one then it would be the 4-jaw.


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## Janderso (Apr 14, 2018)

British Steel said:


> I rarely use the 3-jaws i have, they only come out when I can make something in one chucking or don't need to worry about concentricity of different features - anything that needs to come out to turn around, for instance, goes in whatever's most suited: 4-jaw, collets or between centres (between centres is the easiest for e.g. shafts that need to be tried for a fit but needs centre drillings in both ends... 4-jaw's essential for eccentric features (cranks, cams etc.), collets for repetitive work small enough to go through the spindle and collet.
> A big help when setting up and indicating in the part in a 4-jaw is a second chuck key so you can work on opposing jaws together, makes it a lot quicker! That also implies that you'll need a decent indicator and mount to measure eccentricity, useful (and a nice easy lathe project) is a telescopic "pump centre" when you want to pick up a punch dot on an interesting part to drill / bore / ream - it goes between the tailstock centre and the punch mark and the indicator rides on it, adjust the jaws to centre it, easy peasy!
> 
> Dave H. (the other one)



I saw a video where Kieth Rucker made a cross feed nut. The rectangular piece of brass had to be drilled. He followed your lead Dave. He used a center with a tang between the tail shaft and the center drilled brass nut. Found eccentricity for drilling and tapping using a micrometer on the center.
Watching someone center a rectangle in a 4 jaw chuck in a few seconds seems like magic to me.
I will work on it, I have a project ready to be drilled and tapped. It’s a rectangle.


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## Ulma Doctor (Apr 14, 2018)

i use 3 jaw, 4 jaw, ER32, 5C, and turn between centers at will.
it really depends on the work to be produced, as to how i hold it 

the 3 jaw chucks get the most use.
if you are turning the od, the lathe will turn concentric parts even if your 3 jaw chuck is worn-
you just have to do all the operations in a single chucking to keep concentricity,
otherwise you'll introduce the error of the chuck to the new part


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## mksj (Apr 14, 2018)

Use my 5C about 50% of the time, I have an ER40 lathe chuck, but dealing with the wrenches is a PTA. Stiil the ER40 provides better holding power then the 5C and works well for odd size stock. I use a 1/32 ER40 collets set.  Otherwise like Ray, I use my 8" Bison 4J combination chuck about 40% of the time as it is very quick to use the scroll to insert stock and you can dial down the TIR to zip in under a minute. It repeats within 0.001" with the same stock piece in/out.  Works great and often I am working with dimensional stock that I need to use the full diameter, so I need to have minimal TIR error when holding the stock. I do have a 3J Set-True scroll that I use if I need to repeat multiple steps (in/out) on stock bigger than 1", i.e. that won't fit the 5C. If I was starting from scratch I would just get the combination 8" chuck and the 5C chuck.

Bison combination chuck holding 1.5" stock then flipping the piece to cut a 1.5-18 thread on the opposite end.




5C is great for small stock.


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## pacifica (Apr 14, 2018)

I use 5c collet chuck the most, doesn't damage work . For work 1.25 to 3 " diameter I  use a 4 jaw 5c collet chuck, not the best holding power but is fast and easy.


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## Janderso (Apr 15, 2018)

I got this piece centered in only 15 minutes. My first time using a 4 jaw.
Next time it won’t take long.


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## British Steel (Apr 15, 2018)

Janderso said:


> I got this piece centered in only 15 minutes. My first time using a 4 jaw.
> Next time it won’t take long.



Practice, practice and more practice, you'll get it below a minute 

Dave H. (the other one)


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## Chuck K (Apr 15, 2018)

Congrats.....you can always use the 3 jaw as a door stop.


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## Janderso (Apr 16, 2018)

I did notice when I spun this rectangle in the 4 jaw there was significant runout. I have not measured it but the first time I mount a round piece of stock I will look into this further.
I must say, using the chuck and tail stock made quick work of this 3/4 LH tap.


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## cascao (Apr 17, 2018)

4 Jaw is great when you need to:
  Turn square ou any weird form object
  Face any part if you don't have a milling machine
  Grip a round object acuratelly
  Precisally drill a hole you punched

Practice and this two little tools help a lot when we set a part to 4 jaw.


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## Glenn Brooks (Apr 17, 2018)

An old time machinist taught me how to make work perfectly concentric in a three jaw. Now I hardly ever use my four jaw.  Set up the work a little loose - not much - in a three jaw.  Then turn on the lathe at slow speed, say 100 Rpm.  As it wobbles around, tap the high spots with a light hammer, or length of steel. After 2 or 3 taps, you’ll get the piece perfectly concentric, usually well under 3 thou. Tighten the jaws and make your part.  

Works every time. I hardly ever use my four jaw anymore, except when I have some odd shaped work.  They all sit there collecting dust. This is the way machinists used to set up work before precision DTI’s were invented.

Glenn


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## MrWhoopee (Apr 17, 2018)

Glenn Brooks said:


> An old time machinist taught me how to make work perfectly concentric in a three jaw. Now I hardly ever use my four jaw.  Set up the work a little loose - not much - in a three jaw.  Then turn on the lathe at slow speed, say 100 Rpm.  As it wobbles around, tap the high spots with a light hammer, or length of steel. After 2 or 3 taps, you’ll get the piece perfectly concentric, usually well under 3 thou. Tighten the jaws and make your part.
> 
> Works every time. I hardly ever use my four jaw anymore, except when I have some odd shaped work.  They all sit there collecting dust. This is the way machinists used to set up work before precision DTI’s were invented.
> 
> Glenn



This is how I learned to do it, with the exception of rotating the chuck by hand and gradually tightening as it gets closer. We never used a 4-jaw for round parts unless you needed eccentricity. Much easier than changing a 12 in. chuck.


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## Bobby Bailey (Apr 19, 2018)

Perfectly concentric is in the eye of the beholder. LOL    Within .001 is almost10 times too big for us and is why we don't use a 3 jaw. And even if it was acceptable for our work, tapping the 3 jaw around is slower than just dialing in a 4 jaw to start with.  4 jaws are fast once you use them.


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## MrWhoopee (Apr 19, 2018)

Bobby Bailey said:


> Perfectly concentric is in the eye of the beholder. LOL    Within .001 is almost10 times too big for us and is why we don't use a 3 jaw. And even if it was acceptable for our work, tapping the 3 jaw around is slower than just dialing in a 4 jaw to start with.  4 jaws are fast once you use them.



Yes, if you need to hold tenths, particularly on multiple parts, a 3-jaw is not the best choice . But then again, this is a hobby site. Few of us need to hold tenths, nor do we have machines that will. Indicating a 4-jaw might be faster. I say might because tapping in a 3-jaw can be quite fast and only requires tightening one adjustment, not four. Just getting a 4-jaw within the initial runout of a 3-jaw will usually take longer than getting the 3-jaw within .001. If you have to put the 4-jaw on the lathe first, then it's no contest. A lot of times, whatever is on the lathe when you walk up to it determines what is fastest. And, of course, in a hobby shop situation, ease, not speed, is the primary consideration.

If I had neither, I would get a 4-jaw because it is more versatile. Having both, the 3-jaw gets much more use (and the collets more yet).


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## dtsh (Apr 19, 2018)

I have only the 3 jaw that came with my lathe and for now it supports all the work I do on it, which is admittedly not much. I plan to get a 4 jaw eventually because some of my future projects can utilize it and I look forward to having the added flexibility of what I can do with it, but until those projects get closer I can't justify getting one. If I could have only one chuck, it'd be a 4 jaw and a collet block.


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## chips&more (Apr 19, 2018)

I just read all of this thread. And I wonder how my folks have used a really nice 3 jaw chuck? I’m not selling them! But say, like a Buck set-tru. IMHO, I think your 4-jaw (except odd shapes) and collet stuff will collect dust after you have tried one…Dave


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## MrWhoopee (Apr 19, 2018)

chips&more said:


> I just read all of this thread. And I wonder how my folks have used a really nice 3 jaw chuck? I’m not selling them! But say, like a Buck set-tru. IMHO, I think your 4-jaw (except odd shapes) and collet stuff will collect dust after you have tried one…Dave



My 3-jaw is a Buck Ajust-Tru. It's a beautiful chuck and runs dead nuts without having to adjust it frequently. I still prefer collets if the stock size permits.


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## NEL957 (Apr 19, 2018)

I put a 8 inch 4 jaw on my 10K and after using it I'll never go back to 3 jaw. I also made up a ER 32 collet holder when I need the accuracy.
I read some where about the lathe walking, turn the damn speed down. Not everything runs 3000 rpm's
Nelson
As far as a Tru-chuck, you can not turn a square block.


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## Pro70z28 (Apr 19, 2018)

I use the 3 jaw unless the part doesn't start out round or needs an offset.


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## Bobby Bailey (Apr 20, 2018)

MrWhoopee said:


> Yes, if you need to hold tenths, particularly on multiple parts, a 3-jaw is not the best choice . But then again, this is a hobby site. Few of us need to hold tenths, nor do we have machines that will. Indicating a 4-jaw might be faster. I say might because tapping in a 3-jaw can be quite fast and only requires tightening one adjustment, not four. Just getting a 4-jaw within the initial runout of a 3-jaw will usually take longer than getting the 3-jaw within .001. If you have to put the 4-jaw on the lathe first, then it's no contest. A lot of times, whatever is on the lathe when you walk up to it determines what is fastest. And, of course, in a hobby shop situation, ease, not speed, is the primary consideration.
> 
> If I had neither, I would get a 4-jaw because it is more versatile. Having both, the 3-jaw gets much more use (and the collets more yet).



Hobby site or not, it is about imparting knowledge and I believe you would agree on that. There is no reason a hobbyist can't learn or improve from a non-hobbyist or the non-hobbyist from a hobbyist.
My comment is not that you should not use a 3 jaw if that is what one likes. It is rather about;  so many guys, especially new guys avoid a 4 jaw thinking the 4 jaw is hard to use, hard to learn, and too slow. When none of those things are true.
Using two chuck wrenches, 180 dregrees apart, one can dial in a 4 jaw with just a few revolutions to 0.0005, a couple more revolutions and its down to a couple of tenths. Its fast and easy. I just want new guys to see that the 4 jaw isn't really scary or slow or hard to use.
"And, of course, in a hobby shop situation", the 4 jaw can meet both  ease and speed, they are not mutually exclusive things.  Its about learning and trying new things to expand ones skills.

Having equipment to hold accuracy is not hard for a hobby shop.  We run two South Bend heavy 10's and a South Bend 10K. All three are considered by many to be hobby shop size and all three are accurate. Clock making, model engine building and gunsmithing all benefit from it, and I do know many hobbyist that do worry about holding tenths.

As far as putting the 3 jaw on the lathe, I'd have to dig in the back of the cabinet to get the 3 jaw and then clean it. LOL


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## MrWhoopee (Apr 20, 2018)

NEL957 said:


> I put a 8 inch 4 jaw on my 10K



I'm surprised to hear that an 8 inch chuck is practical on a 10 inch lathe. Have you encountered situations where the jaws and ways wanted to occupy the same space?


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## Janderso (Jun 3, 2018)

savarin said:


> My 9x20 three jaw is well out so I only use it if I do not have to replace the part back in it.
> The four jaw gets a lot of use for that reason, and the face plate and between centres.
> For most of my smaller stainless stuff I use the collet chuck I made but still have to grind the internal taper for final alignment. Its almost there.



Interesting, even if you have a loose 3 jaw, as long as you can finish the job without a re-chuck, no problem?
I should have kept the set of 5C South Bend collets that came with my Sb lathe. I had no idea what they were so I sold them on eBay.
Idiot!!
I’m learning every day.


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## Scruffy (Jun 3, 2018)

I was never a machinist or had any schooling besides you guys. I have always got away with my 3 jaw if I don’t have to remove the part from the chuck, i’ff you have enough material.
Thanks Ron from in ohio


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## rwm (Jun 3, 2018)

Being really lazy, I leave my Bison 3 jaw on most of the time. It is within 0.002" for most of the scroll. 
Robert


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## NEL957 (Jun 14, 2018)

MrWhoopee said:


> I'm surprised to hear that an 8 inch chuck is practical on a 10 inch lathe. Have you encountered situations where the jaws and ways wanted to occupy the same space?


I can honestly say no. When there is a problem I turn my jaws around and after turning it a few turns by hand. Plus that 8 inch circle can hold a lot of metal and more than likely bigger than I going to work on. I am in it as a hobby not a business.
Nelson


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## silence dogood (Jun 14, 2018)

I will use whatever  chuck that the project seems to call for.  There even has  been times that the face plate will work best.  It's also a good time to clean and check the spindle bore before the next chuck goes on.  Admittedly,  the lathe is a little  8x14, so it's not a big deal.


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## Silverbullet (Jun 16, 2018)

chips&more said:


> I just read all of this thread. And I wonder how my folks have used a really nice 3 jaw chuck? I’m not selling them! But say, like a Buck set-tru. IMHO, I think your 4-jaw (except odd shapes) and collet stuff will collect dust after you have tried one…Dave


Even those once set on one part is usually  good it comes down to how many times you open and close the jaws. For some reason ,,wear, they just loose the set. With four jaw it's set up every time to as close as possible. There is no perfect solution . Even cnc machines reprobe the set up cking often.


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## chips&more (Jun 16, 2018)

Silverbullet said:


> Even those once set on one part is usually  good it comes down to how many times you open and close the jaws. For some reason ,,wear, they just loose the set. With four jaw it's set up every time to as close as possible. There is no perfect solution . Even cnc machines reprobe the set up cking often.


I understand your concern. But personally, I do not have that problem AT ALL. I use Buck chucks daily and have been for many decades. They are just as good as the first day I bought them new. I take them apart clean and grease about every 6 months. I NEVER wrench down on stubby parts barely in the end of jaws, that will spring your jaws. I always clean the material before I chuck it. I can go on, but I think you get the idea. I try and take care of my chucks and that goes for everything in my toy house. I firmly believe the chucks I own will outlive me. Giving outstanding accuracy all along. I do own full sets of Hardinge 5C collets and lathe chucks to hold them. But because my Buck set-tru chucks are so nice and accurate the collects collect dust (very thick dust!). And I’m not affiliated with Buck & Company in any way…Dave...Happy Father's Day


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## 682bear (Jun 16, 2018)

3 jaw or 4 jaw?

Yes...

IOW, I have both, I use both... also a 5c collet chuck. I'd say none of them really gets used more than the others... each has its place.

-Bear


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## kd4gij (Jun 16, 2018)

"Do You Use a 3 Jaw or a 4 Jaw Chuck?"

yes.


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## kvt (Jun 17, 2018)

I use both and have both for both of my lathes,   10x24 lathes,  and have both 6 and 8 inch chucks in both 3 and 4 jaw.   Often depends of what I am doing and what will hold it best.   But I have had no formal training just what I learned in HS many years ago and what I learned here. So I do what I can and learn from my mistakes.


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## Silverbullet (Jun 17, 2018)

chips&more said:


> I understand your concern. But personally, I do not have that problem AT ALL. I use Buck chucks daily and have been for many decades. They are just as good as the first day I bought them new. I take them apart clean and grease about every 6 months. I NEVER wrench down on stubby parts barely in the end of jaws, that will spring your jaws. I always clean the material before I chuck it. I can go on, but I think you get the idea. I try and take care of my chucks and that goes for everything in my toy house. I firmly believe the chucks I own will outlive me. Giving outstanding accuracy all along. I do own full sets of Hardinge 5C collets and lathe chucks to hold them. But because my Buck set-tru chucks are so nice and accurate the collects collect dust (very thick dust!). And I’m not affiliated with Buck & Company in any way…Dave...Happy Father's Day


You have a different set up over normal hobby machinist, most can't afford buck chucks . And if they do find a used one we all know why there selling them. I'm not knocking buck quality or your using them . I'm trying to be objective in just saying the best reason for four jaw chucks. I personally use a six jaw I got used many years ago from cooks tool . He sold me the chuck but only the inside jaws , looking around his showroom I found the outside set which he tried to get more money for till I should him they were for my six jaw. I have 5C collets but need to mount the lever and adjust the tube to fit my logan . My three jaw is really old and shot for close tolerance work. My four jaw is old but in great condition.


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## tomw (Jun 17, 2018)

I personally like the 4 jaw chuck for reversing work and re-chucking. But I am also making tiny stuff with thou or less tolerance (hobby: tiny steam engines. Work: carburetor needles and the like). I just find the 4 jaw let's me make these tolerances quickly. From reading the thread, that seems to be the message. If you need tight tolerances, use a 4 jaw or a collet. If not, the 3 jaw is great. It all depends on what you need, want, and desire. 

And I desire to make close tolerances because it gives me a tingle up the leg...

Tom


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## Norppu (Jun 23, 2018)

I do have a 3-jaw but a  certain video making personality with a lot of torque has convinced me to use the 4-jaw.

Here is another reason why.




Edit: OMG .... just noticed that this is a SB part of the forum.... Hopefully You can tolerate this blasphemy as that is a cheeap import lather being as far from SB as can be.


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## Winegrower (Jun 23, 2018)

I don’t even have a 3 jaw.   Study the two chuck key method, then make an indicator holder for your QCTP, so it is always right on center and you don’t have to mess with a mag base.   It is less than a minute (as previously noted) to whatever accuracy you want.


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## derf (Jun 24, 2018)

I haven't used a 3 or 4 jaw in decades. My big lathes have 6 jaw adjust tru chucks, my small lathe has 5 C collets. I have on occasion removed jaws to accommodate odd work pieces, other than that, the chucks have never been removed from the spindle in 20 years. On projects that most guys would mount in a 4 jaw, I usually figure out how to do it on a mill.


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## Tozguy (Jun 24, 2018)

Janderso said:


> I have a pretty accurate 3 jaw chuck (Chinese) that came with the lathe , SB 13 single. I bought a 4 jaw Cushman, that is also in great shape. The 3 jaw is so simple to use and I have never mounted the 4 jaw yet.
> Just wondering, should I mount the 4 jaw and learn how to use it or continue with the 3 until I have a rectangle or something that I can only use the 4 jaw?
> Just wondering what you do.



Yes mount the 4 jaw and learn to use it. Get to the point where you don't hesitate to change the chuck so you can use the best one for the job at hand. 
In my case the 8'' 4 jaw is heavy and a chore to handle delicately enough for the D1-4 spindle. I dreaded having to install or remove it until I cobbled up a small overhead winch. The 4 jaw stays on the winch above and to the back of the lathe when not in use. The 6'' scroll chuck is light enough for me to lift on and off the lathe by hand.


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## Janderso (Jul 6, 2018)

I am embarrassed to say I have learned enough recently to discover my 3 jaw chuck is a set true type. It has the 4 adjusting screws.
I was able to adjust the run out in a chucked piece of 2" aluminum to less than .001". 
As I was adjusting the set screws I also discovered they work the opposite of a 4 jaw, meaning when I was moving in, I was actually moving out.
You know what I mean.
With the ease of set-up, the 3 jaw is my go to but I have become proficient with the 4 jaw.
Thank you all for the encouragement and wisdom, as always.
Jeff


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## MrWhoopee (Jul 9, 2018)

Janderso said:


> I am embarrassed to say I have learned enough recently to discover my 3 jaw chuck is a set true type. It has the 4 adjusting screws.
> Jeff



Congratulations! That's quite a discovery, the value of that chuck just tripled. 

The same thing happened to me. Although I knew what an Adjust-Tru chuck was, it took me a couple of weeks to realize I had one. Happy day.


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