# Suggestions For A 4 Jaw Chuck



## BriancCc (Nov 14, 2016)

I picked up a Clausing 100 and it lacks a 4 jaw chuck. It is a 1 1/2" 8tpi. What size should I get 6" or 8"? How do you guys suggest I go about getting one? Used off Ebay? New off Ebay? Grizzly? 

If I get an 8" do I need to get an 8" backing plate or can it be just larger that the bolt circle?


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## Paul in OKC (Nov 14, 2016)

Depending on what you want to spend.........You should be able to get a chuck with that thread on it. Determine the size needed wither by through hole, or by how large a piece you will need to hold with the jaws reversed. I would probably go with the 8", myself.  Here is a 6"   http://www.shars.com/products/toolh..._category=4+Jaw+Lathe+Chucks&mounting=1-1/2-8.  There are others, in a price range from $115-ish, but a backing plate will run another $50-60.


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## intjonmiller (Nov 14, 2016)

I have been very impressed with Shars tools. My Logan came with a very good condition 4-jaw and a beat up 3-jaw. I got a 4-jaw scroll chuck from Shars for about $180 or so, including shipping, and including a 1 1/2 - 8 tpi threaded back plate. They had a number of options for that spindle configuration.


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## BriancCc (Nov 14, 2016)

Thanks Jon and Paul. The through hole is like 7/8" and I don't have specific work pieces that plan on needing to hold.


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## intjonmiller (Nov 14, 2016)

That is a typical spindle bore for 1 1/2 - 8 tpi. I think mine is "25/32". Enough to handle 3/4" stock.


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## Wreck™Wreck (Nov 16, 2016)

This is a Bison 8" that I changed to on a 15" X 48" Romi lathe today, excellent chucks and this one is less then a year old. My employer makes me do all of the 4 jaw work so I will be Spongebob Squareparts for the next several days.
Chuck size is entirely dependent on the size of work that you intend to do and what your machine is capable of, an 8" chuck on a 1 1/2" threaded spindle nose seems a bit much but what do I know?

This particular lathe is 2"+ through the spindle with an A taper nose. The only thing that I do not like about this chuck is that it has VERY coarse threads on the jaw screws, 6TPI so knocking out that last .001" is annoying.

These aluminum parts are 2 1/2" X 1 1/2" X 8" long with a 7/8" through hole off center and .985-.986" X 1.063" deep bearing bores on each end, concentricity and parallesim between the bores is .003", this is 5 hours of setup and 1 hour of machining, very very tedious. I put nylon pads under the jaws because the parts will be clear anodized after machining


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## BriancCc (Nov 17, 2016)

Wreck, 

Thanks for the info.

That job looks serious!  Do you chuck it, do the through hole and bearing on one end then flip it around? How many of these are you going to have to do in this batch?


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## 4GSR (Nov 17, 2016)

Wreck brought a good point when using four jaw chucks.  

Four jaw chucks are made for work holding with a tight grip without your work piece moving on you.  The jaws will mark up the surface of what ever it is that you chuck on.  For most work, this is not a problem.  To prevent this or reduce the chance of marking the surface, you usually put some kind of "soft" material between the work piece and the jaws.  Aluminum and thick brass shim stock is what I use.  Wreck mentioned using nylon pads under the jaws for aluminum.

Ken


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## Wreck™Wreck (Nov 17, 2016)

BriancCc said:


> Wreck,
> 
> Thanks for the info.
> 
> That job looks serious!  Do you chuck it, do the through hole and bearing on one end then flip it around? How many of these are you going to have to do in this batch?


Drill and ream 7/8" half way through then bore, flip and repeat, this sort of thing must be carefully indicated. If you do alot of square and rectangular lathe work buy a 2" travel indicator, I hold one in a tool block on a qctp,

Each end takes 15-20 min. to set up and 20 min. to machine, the pic is 1 of 2 parts, there are 6 others with a different bore size.


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## Christian Poulsen (Nov 17, 2016)

Just model preference here but I always have liked Buck Chucks...I know the subject is 4 jaws  but for smaller rounds (Let's say around 3" and under and depending on the lathe and stock (specs of a steel work pc.)...and down to small odd sizes (non collet sizes), I have become hooked on bucking 3 jaws...
...you can slap the rough stock in it and do your thing on that side of the part, then turn the part around, indicate, and loosen/tighten the 4 adjusting set screws ("buck") dead on easily to what you have turned on that 1st side...
But yes, as for holding power and still adjusting; A 4 jaw should be 1st for a metal lathe...
....and  as said by others in this thread: Go as big as the swing of your lathe allows and also what the motor will handle.

http://www.buckchuckusa.com/products/manual-chucks-atsc-3-jaw.html

Ha, I see many manufacturers have those spring loaded chuck wrenches to make sure we don't leave the wrench in the chuck (I know it's probably not good to say but I always took those out as I found pushing on a spring irritating while I tightened (Disclaimer (lol): But don't do as I say)


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## Uglydog (Nov 17, 2016)

I've been using aluminum roofing flashing. 
Seems to work well, is inexpensive, and recyclable.

Daryl
MN


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## Christian Poulsen (Nov 17, 2016)

....also for "soft" between the hard jaws of a chuck and the work pc when wanted/needed., I sometimes snag a groove in  aluminum or brass shims and use rubber bands to hold them on ifn' i don't want to fumble with them...
...also over the years I have a box of various sizes of aluminum "rings" I have cut off of aluminum "tubes", some I have bored the ID when needed,...anyway, then saw a split and just slip them over your work pc.


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## BriancCc (Nov 17, 2016)

Christian,
Thanks, I had heard the term buck chuck and didn't know what it meant. 

So it means this style of three jaw chuck with type of centering adjustment? (and the brand?)


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## Christian Poulsen (Nov 17, 2016)

BriancCc said:


> Christian,
> Thanks, I had heard the term buck chuck and didn't know what it meant.
> 
> So it means this style of three jaw chuck with type of centering adjustment? (and the brand?)


Yes, Buck is a brand but also "bucking" means/allows 3 jaws and 6 jaws to indicate your part by way of tightening/loosening 4 adjusting set screws (usually brass tipped set screws or "pushers'')  that are 90 degrees apart that are on (through) the major OD of the chucks (But maximum adjustment/movement is usually only around +/- .03o)

Note: The SHCS's that hold the chuck together on these are to be kept more than snug but not absolutley tight to allow the chuck to adjust

Note: A 6 jaw, like a collet, although good for "off" OD sizes (unlike a collet), is only good for finished round or skimmed round OD's (or you will ruin a 6 jaw (or collet)


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## talvare (Nov 17, 2016)

I believe what Christian is referring to is called a Set-True chuck. Buck does make Set-True chucks as well as other manufacturers. I have a 6", 6 jaw Gator chuck with the Set-True feature. Which brings me to the point of your original question about what chuck to buy and where. I have purchased two used Rohm  4-jaw chucks on eBay and both were good chucks at good prices, but you are taking your chances buying used chucks sight-unseen. You can buy chucks manufactured specifically for your particular mounting system (1 1/2-8 in your case) or you can buy a universal chuck and put a back plate to adapt it to your mounting system. The advantage to the first is that it will have less protrusion from the spindle because there is no back plate and there is less possibility for run-out error (which really isn't that important with a 4-jaw chuck). As far as brand, it depends a lot on your budget. Buck, Pratt-Bernerd, Rohm, Bison, are all good chucks but are pretty pricey. My Fuereda/Gator chuck I find to be middle of the road for quality and price. I don't have experience with the less expensive chucks from some of the suppliers like Shars, CDCO, Grizzley, etc. so can't speak to their quality.

Ted


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## kd4gij (Nov 17, 2016)

That is a 12" lathe I would go with 8" look on eBay for atlas craftsman lathes. 4 Jaw 1 1/2-8 chucks show up often at fair prices.


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## Wreck™Wreck (Nov 18, 2016)

The other parts are extrusions (much like 8020 extrusions) with an existing bore that is turned larger on each end so are more easily located in the chuck however they must still be indicated in 2 axes, I use 2 indicators for this purpose.


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## 4GSR (Nov 18, 2016)

Wreck,

Your web posting for pictures was kicked back by my virus scan software as being malicious and a threat to my computer.  You may want to repost your pictures from another source.  Ken


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## wa5cab (Nov 18, 2016)

The preferred method for displaying photos is to upload them to this site.  That way if something happens to your host site, the photo is still available.  To upload, just click the UPLOAD A FILE button next to the POST REPLY button below where you type in your message.


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## Wreck™Wreck (Nov 18, 2016)

wa5cab said:


> The preferred method for displaying photos is to upload them to this site.  That way if something happens to your host site, the photo is still available.  To upload, just click the UPLOAD A FILE button next to the POST REPLY button below where you type in your message.


Yes I understand this, I normally  have pictures hosted by such services as Photobucket or Smugmug however I'm in the process of switching providers so used the first free service that turned up in a Google search in the interim. I would rather use the nearly unlimited resources of a large provider then the meager resources of the Hobby Machinist servers, free comes with adds as you well know.
Is this better?


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## BriancCc (Nov 18, 2016)

Thanks for the advice everyone. I bought a Grizzly chuck and back plate. I think this would be below your quality standards.


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## wa5cab (Nov 18, 2016)

Wreck,

Yes.  Thanks.

But out of curiosity, why is the photo foggy.


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## talvare (Nov 19, 2016)

BriancCc said:


> I think this would be below your quality standards.



I don't think that's necessarily true. But glad you got your chuck. Of course, you do realize that we don't believe you until we see pictures, right ? 

Ted


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## Wreck™Wreck (Nov 19, 2016)

wa5cab said:


> Wreck,
> 
> Yes.  Thanks.
> 
> But out of curiosity, why is the photo foggy.


Old worn out phone camera with a dirty lens, or the machine is on fire.


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## wa5cab (Nov 19, 2016)

OK.  I didn't think of the second one.  But CoolMist did come to mind.


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## Wreck™Wreck (Nov 19, 2016)

wa5cab said:


> OK.  I didn't think of the second one.  But CoolMist did come to mind.


I work in a machine shop, 5 lathes and 7 mills none of which use mist coolant, it is either flood or nothing, however a mixture of dishwashing soap and water in a spray bottle works well on aluminum jig plate when finish milling.


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## BriancCc (Nov 19, 2016)

Model K72 4 jaw chuck, grizzly part G9866 and a 8" back plate T10100.


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## 4GSR (Nov 20, 2016)

Brain,

There is nothing wrong with using that chuck for the home shop machinist use.  Just don't tighten the crap out of the jaws and it'll give you years of good service.

Like any other Chinese made chuck, first thing I would do is take it apart and clean out all of the grit and crud.  Next, lightly grease, and I mean lightly grease, with some moly-disulfate based grease.  If you over grease, you will wear the excess for years to come every time you turn on the lathe.  Don't ask me how I know this.  They do make special grease for chucks, it is very expensive and not worth it in my opinion our use.  Industrial, yes.  

Ken

EDIT:  Just thought of something, the last chuck I serviced, I used a little Never-Seize on the jaw screws.  Again, a little dab goes a long way.  Ken


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## Christian Poulsen (Nov 21, 2016)

Yes, when I take apart, rework, clean (yada) a chuck, I use Lubriplate (An old quart can I "inherited" about 20 yrs ago that is still 3/4 full!)

Add:...tightening and "bucking" chucks is kinda' a science in itself but tighter is better! (But not cyborg tight!?)..."medium" tight and indicate (tap, tap, tappy with your "knocker" for "straight"(and pull your indicator tip away when doing so!)....then tighten' (and indicate and tap tap tappy again if needed)

"Loose chucks sink ships"


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## wa5cab (Nov 23, 2016)

One other comment on choosing a chuck to buy is that it's worth it in the long haul to try to find one that fits your spindle nose without having to have a separate back plate..  All other things being equal, the chuck with separate back plate will be heavier and longer.  My 6" Pratt-Bernerd buck chuck with two-piece jaws is over a pound lighter than a more or less equivalent from Shars.


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