disassemble a three jaw chuck?

S

Strange_Days

AzB Silver Member
Silver Member
Hi all,

I'm in the process of setting up my first lathe. I've done a lot of it but now that I have it cleaned up real well and lubed up I checked out the runout and it was really off (like 20 thou). The lathe is new so wear is not an issue, next I removed the chuck and indicated the backing plate and it was less than a thou out everywhere. So it must be the chuck, and here's where I might have screwed up but I took the jaws out, checked they are numbered and then tried to clean out the scroll using acetone and tough paper towel as it appeared really dirty. I don't know if some of the paper towel is now stuck but the scroll turns fine without the jaws installed but now once I install the jaws I can barely turn the scroll at all. So I think I need to take the chuck totally apart and clean everything out properly but how to get it apart is a mystery?? I removed all the bolts but how do you get the thing apart?

thanks,

Matt LeClerc
 
I just took the jaws out of mine and separated the two jaw pieces to clean things myself. Though I don't have a problem with turning the scroll with the jaws back in, I am also interested myself in any responses.

At the risk of sounding stupid because I am no machinist...are you sure that you engaged them in the scroll properly? Number 2 and 3 were free and not engaged and once you started number as the lead scroll came around you had number 2 ready to engage, and ditto from 2 to 3?

This is how I viewed it when I put it back together, so I hope my question makes sense. Maybe someone can help you out and let me know if the way I am looking at it is correct.

Kelly
 
people make fun of me but I try to use past experiences (mistakes) to solve future problems... took my three jaw chuck apart, but I took three different colored markers and marked the jaws and the chuck to get the jaws back in the proper slots,,,worked for me.... j
 
Strange_Days said:
Hi all,

I'm in the process of setting up my first lathe. I've done a lot of it but now that I have it cleaned up real well and lubed up I checked out the runout and it was really off (like 20 thou). The lathe is new so wear is not an issue, next I removed the chuck and indicated the backing plate and it was less than a thou out everywhere. So it must be the chuck, and here's where I might have screwed up but I took the jaws out, checked they are numbered and then tried to clean out the scroll using acetone and tough paper towel as it appeared really dirty. I don't know if some of the paper towel is now stuck but the scroll turns fine without the jaws installed but now once I install the jaws I can barely turn the scroll at all. So I think I need to take the chuck totally apart and clean everything out properly but how to get it apart is a mystery?? I removed all the bolts but how do you get the thing apart?

thanks,

Matt LeClerc
Click to expand...

Matt, to check the scroll area you must completely disassemble the entire chuck. The face of the chuck must be attached to a back stop. This face is normally attached with large Allen head bolts.

My chuck is a Buffalo three jaw chuck, with the chuck removed from the back stop there is easy access to all the internal workings and gears that turn them.

Please take a front and back photo of your chuck and post or send it to me, I will try and help.

By the way, before you remove the front of the chuck from the back stop mark it, this will save some time when you re-install it.

Craig
 
All of the chucks I use are Buck brand. They split close to the center where the chuck key goes in them. You have to look close as the two halves should be machined to very tight tolerances. I dismount the whole chuck assembly off the lathe, sit it on the floor on a rubber mat, and use a rubber mallet to split it. Usually do this two or three times a year for a good cleaning. I do not use any lub on the scroll and the jaws when reassembling because it just gums up when you start making dust again.
Good luck........
 
Here are a couple pics of my chuck assembled. In trying to take it apart I removed all the bolts on the front and back and took off the jaws. The jaws are numbered and have a mating number stamped into the slots for them so I did not mark them. There appears to be a machined joining line about .35" from the back of the chuck but it won't budge and I don't want to damage it in any way. There was some small silver bits on the back mating surface which may account for a lot of the runout (I hope) :) Thanks for the replies so far all help is appreciated,

Matt Leclerc





 
I had a similar problem with a new lathe a few years ago. It turned out the nose of the spindle was not mating correctly with the chuck. Between the "flat" on the spindle and the "flat" on the chuck, you could insert a .015" feeler gage in one side. The runout didn't come anywhere near matching the test record that came with the machine.

I called Jet, they sent out a field tech and he found the same thing. He ended up using a tool post grinder to re-grind the nose of the spindle. While he was here he trimmed the jaws also. Everything has been fine since.
 
disassemble chuck

Looking at the photo, I think I see the problem. Made in China. Can't tell for sure, but that's what it looks like on the label. I have a 5c collet chuck that was made there. POS, It scrolls ok on one of the lugs, but hard on the others. Also, are you sure you had the D1-4 lugs totally engaged. As previously stated in this thread, it's probably not concentric with the back plate. LOL
 
cutter said:
Looking at the photo, I think I see the problem. Made in China. Can't tell for sure, but that's what it looks like on the label.
Click to expand...

Get a good chuck..............Bison....Buck.....something of this nature.
China tooling is trash.
 
Yeah you got it made in china, I'm sure I've added about 40 extra hours of work setting up my lathe because of that so far but now apart from this chuck everything appears to be working really well. The only problem is my wife is gonna cut off my you know what's if I keep spending money on this lathe lol ;) I'll work as much as I can with this chuck unless it turns out to be useless and in the meantime save up to get a 6 jaw set tru or something when I have the cash for it (unless anyones selling one for a good price :D ). So any ideas on how to crack this thing apart, should I try the rubber mallot on the floor like BarenbruggeCues suggests?

Thanks,

Matt
 
Strange_Days said:
Yeah you got it made in china, I'm sure I've added about 40 extra hours of work setting up my lathe because of that so far but now apart from this chuck everything appears to be working really well. The only problem is my wife is gonna cut off my you know what's if I keep spending money on this lathe lol ;) I'll work as much as I can with this chuck unless it turns out to be useless and in the meantime save up to get a 6 jaw set tru or something when I have the cash for it (unless anyones selling one for a good price :D ). So any ideas on how to crack this thing apart, should I try the rubber mallot on the floor like BarenbruggeCues suggests?

Thanks,

Matt
Click to expand...

Women.............always wanting to throw a wrench into our play time!

After looking at the pictures..............my guess is everything comes out from the back of the chuck. Just doesn't show any signs of spliting in half where the chuck key inserts.
That small ring in the center with the six little divots may be the key to opening it up. Use a magnifier and give it a close inspection....it may thread out. If not......I would remove all bolts that are in the chuck and try to tap the front of the scroll with a piece of wood and a hammer just to see if it will break loose some where.
These are just some of my thoughts and may not have anything to do with helping you achieve chuck splitting!

After further review of the pictures.............it looks as if the six bolts on the front may coincide with the six little divots on the back in that ring. I believe that may be the key to letting the guts outs of the chuck.
The fact that there are six bolts around the outside on the back have me puzzled though........the only reason I can see for them being there is to hold the two outside halves in place.........just don't see any signs of where it would split at.

Good luck...........
 
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Strange_Days said:
There appears to be a machined joining line about .35" from the back of the chuck but it won't budge and I don't want to damage it in any way.

Click to expand...
That is where it separates. Everything else on those chucks are solid. I took a look at my old original chuck, and it's identical to yours. I also zoomed in on your photo and can see where the two pieces join.

It appears to me that removing the six allen head bolts on the rear would make it possible to split the chuck. Just how to get them to move though, I don't have a clue.

I'm betting your problem is not in the chuck itself though. I believe the problem is with the nose of the spindle not being ground correctly.
 
TellsItLikeItIs said:
I'm betting your problem is not in the chuck itself though. I believe the problem is with the nose of the spindle not being ground correctly.
Click to expand...


Would I check this by installing the chuck and checking around the joint with a feeler gauge or is there something else I should be doing to make sure the two pieces mate correctly?

Also, I finally got a chance to have a go at it and I found my problem with the jaws... The six bolts on the front tighten the jaw slots and once I loosened them I can turn the scroll easy enough. I will try mounting the chuck and checking the runout again without disassembling the chuck for now. What kind of shop would I be able to get a precision ground dowel pin to check the runout? The best I can find is a piece of stainless steel rod from a local fastening store.

Thanks for all the help,

Matt
 
try any industrial tooling supply dealer

they sell ground dowel pins, or even drill rod may do OK.
Automotive machine shops may also have dowel pins, they use them sometimes. I am sure they can point you where you can get some.
 
Where the two pieces come together the allens that hold it all together. Loosen them up and reset the chuck indicate it from a piece of drill rod chucked up. And then tighten them back up. It will be a pain but cheaper than buying a new chuck. Also there should be a collar on the spindle that you can adjust. Depends on the lathe.
 
I did not understand this part from your first post:

"next I removed the chuck and indicated the backing plate and it was less than a thou out everywhere"

Do you mean you removed the chuck and indicated the spindle surfaces?
This chuck still has the backplate on it looks like to me (unless its one of the chucks without a backplate, and the lathe mounting built into the chuck). The 6 screws on the back of the chuck are what hold the backplate on. I see 2 holes on the backside (directly top and bottom in the picture). It has been years since i took mine apart, but I believe I put a punch in those holes and was able to tap on it to separate the backplate from the chuck body.

However, this will not reveal the inner workings of the chuck, when you separate the backplate. It will just reveal the back of the chuck. But there will probably be more clues as to how to get to the scroll once you remove the backplate.

But if you do take the backplate off, mount it to the lathe (without the chuck on it) and take a skim facing cut. This will give you the best chance of the chuck running true. Also, if there is not already a mark on the backplate and your spindle, add one so that anytime you remove the chuck from the lathe, you will remount it in the same position.
 
Strange_Days said:
Would I check this by installing the chuck and checking around the joint with a feeler gauge or is there something else I should be doing to make sure the two pieces mate correctly?

Matt
Click to expand...
That's the way I would do it. That's also how I found my problem on the original chuck. Using a flashlight on the opposite side of the chuck (shop lights turned out), I was able to see light between the mating surfaces.

How did you check the runout originally? Did you trim the jaws on the chuck?

Just curious, but if you were able to disassemble the chuck, what could, or would you do to correct a problem? I wouldn't think there are any adjustable parts inside.

Another thought, the machine being new, isn't it still under warranty? If so, why not look into the manufacturer correcting the problem?
 
Strange_Days said:
There appears to be a machined joining line about .35" from the back of the chuck but it won't budge and I don't want to damage it in any way.
Click to expand...

Matt..........I missed this part earlier.......now I can see the joint.
If you are going to use this chuck for cues, sooner or later you'll have to split it and clean it out. Take the 6 outer bolts from the back and use a rubber mallet to split it. Mark the two halves before splitting for reassembly.
Good luck.......
 
Strange_Days said:
Would I check this by installing the chuck and checking around the joint with a feeler gauge or is there something else I should be doing to make sure the two pieces mate correctly?
Matt
Click to expand...
I just thought of another way you might be able to tell if the "flat" on the chuck is mating correctly with the "flat" on the spindle nose.

Years ago (yeah, a LOT of years ago), I used to build Mercury flathead motors for drag racing. To check the clearance between the connecting rods/bearings and the crank shaft, we used a material called "PlastiGage". It's texture is similar to modeling clay but it's a plasticized material.

Put strips of it between two surfaces and tighten everything down & the stuff will spread out. You then measure the width of the material using a gage that comes with the packaging. The gage will tell you how much clearance you have. It's still available at some NAPA Auto Parts.

If you were to put a strip at each cam lug on the chuck then tighten the chuck to the spindle, it should tell you something. Might be worth a try.
 
iusedtoberich said:
I did not understand this part from your first post:

"next I removed the chuck and indicated the backing plate and it was less than a thou out everywhere"

Do you mean you removed the chuck and indicated the spindle surfaces?
This chuck still has the backplate on it looks like to me (unless its one of the chucks without a backplate, and the lathe mounting built into the chuck).
Click to expand...
Hi,

Yes, I was naming the parts incorrectly I think. The chuck attaches with a DI-4 camlock and I indicated the spindle where I would attach the chuck to the lathe. It's pretty much dead on.

TellsItLikeItIs said:
How did you check the runout originally? Did you trim the jaws on the chuck?
Click to expand...

I checked the runout by chucking up a piece of 3/4" stainless steel rod and setting my indicator on the crossslide and checking about 1-1/2" from the jaws. I believe now that either I didn't clean the mating surfaces properly or didn't seat them properly somehow. I've been stuck having to go to work extra the last couple days and have not been able to test it out. tomorrow :D I did not trim the jaws, wouldn't they be hardened and wouldn't I want to be running very true before doing that anyway?

TellsItLikeItIs said:
Another thought, the machine being new, isn't it still under warranty?
Click to expand...

Nah, bought it from a guy who bought three of these (was going to have a little shop at his house) but only set up one. Its been sitting in his garage unopened for two years. paid about half price :D

Thanks for all the replies, I'm gaining a much better understanding of my machine through these problems so its a mixed blessing I think to be forced to work it all out.


Matt LeClerc
 
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