What type of chuck should I get??

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CMS

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I've a SB heavy 10 that's in need of a new chuck, I think. I've not had this lathe but a month, so I'm still in the process of getting to know it. But I had noticed that it's a bit touchy to get items of 1" or less to turn with less than .005" runout, but I could spin and jiggle the work around while tightening the chuck and come out close enough, at least I thought.
I started making a spider like one in another post from this sight by black85vette, I think, but using 5" round. I reversed the jaws and no matter what I do the runout will get no better than .020". It has two piece jaws, they're numbered, but I tried moving them around, no good. The chuck is a Skinner and the outside of it runs true along with the hub the chuck mounts too.
I even asked one of my helpers what I should consider as a fix to my problem. Well as you can see, his answer will always be correct.


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tel

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Given a choice of one?? Get a decent 4 Jaw - you can do most things with that once you master centering workpieces in it
 

rcplanebuilder

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I would suggest setting up the machine correctly before you buy anything. Getting taper out, and all that good stuff.

Then make a ring, and turn the jaws true. (someone here can outline that procedure, or I will later, if need be.) If it's a repeatability issue, that will show up once you true the jaws.

More later when I can.

T
 

Blogwitch

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The first thing you need to do before checking anything is to get the chuck mounting area cleaned up.

The whole D mount should be spotless, including the recess and faces on the back of the chuck. Any flattened on swarf on any of the faces needs to be very gently and carefully scraped off. Even a small amount of swarf in or on there will kick the chuck way out of line. That area is the most important on your lathe, anywhere else can usually be tweaked or adjusted for.

You should also find the position of least runout on both the chuck and mount, and mark both, so you can always remount the chuck back in the same 'best' position.

With regards to the chuck itself, I would forget about truing up the jaws, that only puts them right in one exact position at exactly that time you do it. It sounds like the scrolls in your chuck are either worn out or bent, and in that situation, no amount of playing about or quick fixes is going to change anything.

The machine looks to be fairly old, and the chuck as well. It has most probably had hundreds of thousands or even millions of tighten ups and undoings, many of them will be gross overtightens, and you are still expecting it to have no wear and run true.

Methinks it might be time for chuck retirement.


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Tin Falcon

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Is this lathe new to you ? make sure it is properly leveled.
As far as the chuck clean and gently stone all the mating surfaces I see a lot of chips there and if chips were in the mating surfaces that can cause craters. Craters have high edges,if you stone just take the edges down . remove only high spots. you may also want to disassemble the chuck and clean and inspect the scroll . If the scroll is trashed then you better look for a new chuck. but you will likely find the chuck full of swarf. Removing the chips may be all you need.
so clean inspect and then make a determination. As Tel said if you have one chuck a 4 jaw is the way to go.
Tin
 

rake60

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I don't have an opinion on the chuck, but if that apprentice foreman
needs further training there is a Grandpa here who would be willing to
take him into his shop. Afternoon break comes with popsicles, soda
and chocolate bars. Please be on time to pick him up at quitting time! ;)

Rick
 

CMS

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Thanks for the input, I took the chuck apart, cleaned it up and suprise!! Did cut the runout about half, will have to look a bit futher into the procedure of truing the jaws as I've never heard of such.
Hey Rick, that sounds like a very welcome invite.
 

Tin Falcon

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CMS do not expect a 3 jaw or any scoll chuck to be perfect and as it may have been mentioned runout can change with the size of the stock. For precision and second operation work you need to use a set true chuck a four jaw or collets. also mill finish stock is never perfect anyway so you throw in a piece a little bigger than finished size and machine it true.
As for the budding apprentice forman here is a poject
http://www.homemodelenginemachinist.com/index.php?topic=384.0
I have gotten some amazed looks when people see this one run
Tin
 

CMS

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Seeing how a four jaw chuck was included with the lathe when purchased, might as well get to know it too. As far as buying a new three jaw, are there any recomendations? Don't think I'll be able to afford a USA made unit, would like to stay under $300 and use the old D mount.

Tin, looks like a great Big Buddy, Little Buddy project. But fellas, I can't leave out my Little Buddy #1, he went with me when I bought my lathe and other things. I also think his enginerring skills may be in a different field.

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dieselpilot

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I got a cheap but decent Enco three jaw with my lathe. This summer it started to get out of true. I indicated the body and it was within .0002. I took the jaws out and cleaned the jaws and scroll. This brought the chuck back to .001-.002. That's all it took.
 

rcplanebuilder

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As everyone is saying here, you have to start with the set up of the machine. There are many things to do for a properly set up machine. Many times the manufacture will actually supply an outline for doing this in the owners manual, or online in their owners manuals.

Leveling the machine, and bolting it down is a very important first step for a lathe. On a big machine it can take days of leveling and even using J-bolts to pull things down in some areas. A very very small adjustment can make huge differences in the performance of the machine, especially when dealing with 2 heads (more than you are asking, but it still holds true) . Often you need to go back to leveling when things won't line up. (Back to square one).

I do a lot of moving of a lot of really big machines for a living now, and set them up, and put them back into working order after they get piled up.

Set up is key. Starting with leveling. Then comes test cuts, spindle adjustments, turret adjustments, etc... , and after all that, you can start looking at the performance of the chuck. Precision levels are needed, accurate to .0002" or better.

I've seen a lot of parts changed without the desired results netted, because that wasn't the problem. If the chuck is worn out, it's worn out. But as stated here, if repeatability is important, then other chucking methods are preferred, such as collets. Or, turning single purpose jaws off of a master jaws, then they will repeat.

But if indicating in previously turned material is important, a 4 jaw is designed to do that, a 3 jaw isn't. Normally, a 3 jaw doesn't have to be true, it;s just holding stock, and it gets trued during normal turning.

Also, make sure you are using something like a gauge pin for checking the jaws. I got called over to a machine last week, because the part wouldn't transfer to the sub spindle collet. And after setting up co-axial indicators and such, I determined the machine was right where I had set it the last time it got crashed. I loaded the bar stock, (Partially made part) and checked it at the spindle and it was pretty close, then I moved it out about 12" inches and it was .028" off. The bar stock was bent. ::)

Grease your chucks regularly. Take them apart, and clean, and lube them if you are able. Lube is good, chips are bad. Once they get worn, you can't bring them back by yourself. But you can touch them up a bit and get them closer. But it's usually the last step of many. Truing rings are designed to load the chuck so they can be cut under clamping pressure. There are a ton of designs (I just looked) out there on the Internet available to copy for this purpose. Here is one that looks odd, but looks like a good simple design. http://www.loganact.com/tips/chuck-jaw.htm

And this is from 1940... http://books.google.com/books?id=2CYDAAAAMBAJ&pg=PA199&lpg=PA199&dq=truing+lathe+jaws&source=bl&ots=YujHATg45l&sig=0mnCnjWjna7cyLpCrOnIEfCEgOU&hl=en&ei=tsD_SpXxLpX7nAfm5JGfCw&sa=X&oi=book_result&ct=result&resnum=9&ved=0CCMQ6AEwCA#v=onepage&q=&f=false
 

CMS

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I ended up buying a chuck from Tools4cheep. I mounted it Friday and have .001" runout, think that I can live with that and at $140, well I guess I can live with that too.
 

bazmak

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Good decision.The old chuck will still work well enough for when the job is turned without reversing the job.Use it for older heavy duty work.
 

DJP

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My experience in truing up jaws of a worn out 3 jaw chuck is that it works but only for the diameter set during the process. The chuck is still useless at other diameters and a new chuck is the only way to end the frustration.

My theory is that the scroll was worn on my old chuck and for that there is no quick fix.
 

Cogsy

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Just an FYI guys but this thread is over 5 years old and the OP hasn't been active on the forum for 2 years so there probably won't be a response from him.
 

vascon2196

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Your question was "What type of chuck should I get?"

Not sure if anyone answered that yet?

I would suggest a Bison, both a 3 jaw and 4 jaw.

They make a damn good chuck...pricy but well made and will probably outlast all of us.
 

MachineTom

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Start with The spindle bearing, Its really a split bushing. Using a DI check the clearance and adjust accordingly. NOTE: the bearing cap does not just come off, your first remove the 2 plugs on top then remove the screws inside there, then remove the bolts the hold the cap on. Look carefully at the shim packs, they will be different front and rear, some shims may be stuck together, very thin .0005 are in there as well. Go online for more details.

If you want a new chuck I have purchased 2 New chucks from Bison. But they will not be $300 closer to double that and more. Good fit and finish, although I stone the edges of the jaws because they don't. Good repeatability, there is nothing like new. That spindle is a D1-4 a fair number of machines use that size, but not cheap when purchased new.
 

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