# Taking Chinese 3 Jaw Metal Lathe chuck apart for cleaning



## JimDobson (May 29, 2019)

Taking the Chinese 3 Jaw Metal Lathe chuck apart for cleaning. Really happy I did this. The chuck hadn't been as smooth as it had been and there was a lot of crap inside it. Back to its usual smoothness and a pleasure to use again. Never done it before and it proved fairly easy. If yours isn't smooth, don't hesitate to take it apart and clean it.


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## goldstar31 (May 29, 2019)

Jim

Possibly the 'gunge' was nothing more than heavy preservative grease.  My 3 jaw came with the lathe which was second hand but all the bits that I bought, including the fixed steady and the faceplate as well as the 4 jaw self centering chuck and the independent were covered in thick red grease. In my 'cleanup' I even found the gears and the gear banjo were solid with the stuff. For what it is worth, I used brake disc cleaner for  everything and then oiled it all with 'some engine oil' as my car doesn't burn oil- yet.
Last year- or was it two years ago, I bought a 4 jaw self centering Myford chuck which hailed from India( ?) and apart from the colour it was also solid with grease.

Pretty. logical all this because containers are piled high on transport for thousands of miles.

The laugh came at the Doncaster Show when I bought a lightly corroded 3" rotary table for the miserly sum of £20- from the back of - literally of the Myford stand.

Funny thing though- all my other chucks for my Myfords have oilers!

Meantime, thanks for your useful and interesting video.

Norm


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## JimDobson (May 29, 2019)

Thanks Norm, I was happy that I got it apart and even happier when I had it back together working.  I was worried that those banjo gears (thanks for naming them I didn't know what they were called) might needed to have been matched to the same holes that they came out of.

Its nice to have the chuck operating smooth again that's for sure.


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## goldstar31 (May 29, 2019)

Thanks Jim!

Actually my Sieg lathe is a 2007 model and to free the banjo, I had to separate the bits with a 1/2lb hammer.  

I thought that - it was just me involved- and that the grease had gone really hard- over the years. Wrong again!

Keep posting Jim- I thought that it was just me

Norman


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## JimDobson (May 29, 2019)

Thanks Norman


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## ShopShoe (May 29, 2019)

I found out early-on that these Chinese chucks are prone to getting clogged with lube and also get full of swarf and etc. as you use them. So, periodic cleaning keeps them in good shape and lowers your frustration level.

Now, the OT part (skip if you want.):

I am still considering finding a really good chuck for my 7x Minilathe. I posted a question about this last year and since I have not done it yet I am still considering it.

Bison ($350.00)?   Phase 2 ($200.00)?    Potluck and just get another one from LMS and hope it's better ($100.00)? 

--ShopShoe


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## JimDobson (May 29, 2019)

What are you hoping for Shopshoe more accuracy from the new chuck?


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## goldstar31 (May 29, 2019)

ShopShoe said:


> I am still considering finding a really good chuck for my 7x Minilathe. I posted a question about this last year and since I have not done it yet I am still considering it.
> 
> 
> 
> --ShopShoe



Err, How good is "Good"?  All Self Centering Lathes are not accurate. The Good Book- well Tubal Cains' suggests a little more accuracy is by using the best results from ONE particular key hole.  The only true 3 jaw is  a Tru Grip which contains adjustments so that it becomes an independent 3 jaw chuck.

Probably, the cheaper alternative is to add and use soft jaws. 

OK, I have a set or three sets of collets which give reasonable accuracy( for me) but the rest of stuff from a dealer's box should quote the 'inaccuracy or accuracy' and the price should be indicative of what you will get.

Settle for a couple of sets of soft jaws and a good independent 4 jaw. If your pocket book can stand it it, get a set of collets and - ahem- a couple of different diameter faceplates and a tenths of a thous  clock gauge and a set of Johansson blocks.

I DID say a pocket book- make ita BIG one

Really, this IS the way to go

Cheers

Norm


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## JimDobson (May 29, 2019)

I did whip it back off today and lightly greased inside.


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## bazmak (May 30, 2019)

The Chinese chucks are well worth the money but its worth the effort to strip down and clean
I also take off the sharp edges even the gear teeth.As has been said a light coat of grease
once tried oil and learned by my mistake it tends to get thrown everywhere


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## ShopShoe (May 30, 2019)

Thank You Jim, Norm, and Bazmak,

I have 3 and 4 inch independent 4-jaws and a collet adapter and ER25 collets and you are right they are really the best approach. I have been gradually improving the lathe over time: It has become a project of mine, as is the case with the Chinese 7x lathes which we see as a kit to be finished. The original 3-inch, 3-jaw scroll chuck has too much run-out and is showing its "experience." As part of my campaign to improve the lathe I decided I wanted a new 3-inch chuck and asked this question before.

As my "shop life" includes a wide variety of different projects and tasks of all types, not just modeling and engine building, I like the idea of having the 3-jaw as the stock setup for quickly making bushings or modifying bolts, or whatever. If I can get to the place and the space (and the money) where I can get another lathe, that is my goal: Meanwhile I just keep tweaking this lathe and continuing with life as it is.

I don't want to create the ultimate "silk purse" from this pig's ear, but I think I can make it better with a little time and some money and I can see keeping it even if I do get another lathe. 

I would like soft jaws on a chuck, but to my knowledge a two-piece jaw system is not available on a chuck I can buy for my lathe. I am aware of the various ways of making soft jaws and "collets" and shims, and a lot of those approaches and have done them, but I'm after creating a "utility" setup which is convenient to use for a lot of the things I end up doing as part of some repair job or other. (I was able, as an experiment, to add such to my tired old chuck to cut a two-step end onto a flexible plastic ball-point pen ink filler once, but it took such a lot of playing around... Second try was with the ER collet, etc.) Part of the issue is also the 3-nut chuck attachment to the spindle with its limited room for working which makes chuck-changing on these lathes such a PITA, especially when arthritis is starting in my thumbs.

By the way the lathe  behaves with the 4-inch, 4-jaw independent chuck, I have decided I want to stay with a chuck close to the original size of 3 inches, so that also limits my options.

So, until a new lathe comes my way, I will tinker with this one and let you all know what occurs. I do plan on a summary of all I have done when finished. I am not posting this as an ongoing thread because life is getting in the way of shop time and it's often months between actual work sessions in the shop.

Thanks again to all who contribute here,

--ShopShoe


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## goldstar31 (May 30, 2019)

I am sure that we all would like to see your lathe performing 'as best as it can' and perhaps  an old dodge of having a chuck with a backplate 'may' be worthy of repeating here. Apologies for the long rambling but unusual account which the author of Screwcutting in the Lathe adopted on his Myford lathe.

He bought half a new Myford ML7 and ran it with 2 motors and overhead shafting and could only afford an independent 4 jaw chuck. When he became a little more affluent, he bought a 3 jaw SC and a backplate rather than the normal screw on standard Myford one.

Like you, he found the new chuck insufficiently accurate and slotted the fixing holes in the backplate so that he could knock the chuck to read 'tenthousands of an inch'
Similarly, Hemingwaykits in the UK made a adaptation to do much the same and offer it as a kit. Perhaps you might find it or the simpler one from the pen of Martin Cleeve.

For the record, Cleeve was made redundant and used his lathe as his only source of income  by making specialist screws for sale. 

I hope this might go someway to help solve your present issue.

Norm


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## JimDobson (May 30, 2019)

Thanks Norm, appreciated.


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## giel (Jun 1, 2019)

I am a cnc machinist, we have about every 2mm diameter from 4 till 600mm a set of soft jaws to have good accuracy and clamping force as high as possible,mainly on thin walled workpieces having a perfect fit around gives you more clamping surface and stability without distortion of the workpiece, if you don't have the options to obtaibobtai a big inventory on machinery (a set of 3 costs about 150euro) try making the face that clamps smaller about 10mm in widith this gives more clamping force only throwback on this is that you can hurt the finish faster,as greasing or oiling chucks.. only very light coat of grease is used here and we take chucks apart only once a month on 24/7 running machines


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## bazmak (Jun 1, 2019)

Hi shopshoe,the first 7x14 lathe I bought had a spindle to suit the 80mm chucks
However further down the line the second one I bought had a 100mm chuck
This I understand is now std/more common and much more suited to the size of the lathe
I fitted the the 80mm chuck to my homemade rotary table.I found the sansou 4" chuck 
to be more accurate than the the 3"


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## accelo (Jun 2, 2019)

Bison recommends grease for their chucks.
I even purchased a small can from them (A life time supply)
I have noticed the small oilers on the Myford chucks but never used them.
I just occasionally clean them out and use a small dab of the grease. 

For what it's worth;  
I just read about a guy that reground the jaws on his chuck.
The repeatability wasn't there like he expected after the regrind.
He lubed the chuck and had much better repeatability after that.
And yes he preloaded the jaws.


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## John Antliff (Jun 2, 2019)

One trick I use to improve the concentricity of a part which needs to be better than the normal 3 jaw or 4 jaw scroll chuck run out, is to tighten up the part using every chuck key position and then with a DTI or clock gauge find the low spot and tap the opposite jaw(s) with a copper mallet.  This often jolts the jaws into a better position which will hold true for the duration of the cutting process.  You can often move the part upto 2 thou or more depending on how worn the chuck is.


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## Wizard69 (Jun 3, 2019)

Honestly I wouldn't bother with a new scroll chuck unless you can find one with two piece jaws.  You can probably find such in a 5” class chuck but commercial chucks are heavy for that size of lathe.  

In a nut shell scroll chucks are not that accurate and the cheap ones wear rather fast.  Your time might be better spent making a collet chuck of some sort.  



ShopShoe said:


> Thank You Jim, Norm, and Bazmak,
> 
> I have 3 and 4 inch independent 4-jaws and a collet adapter and ER25 collets and you are right they are really the best approach. I have been gradually improving the lathe over time: It has become a project of mine, as is the case with the Chinese 7x lathes which we see as a kit to be finished. The original 3-inch, 3-jaw scroll chuck has too much run-out and is showing its "experience." As part of my campaign to improve the lathe I decided I wanted a new 3-inch chuck and asked this question before.
> 
> ...


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## harborfreight8x12 (Jun 4, 2019)

Hello all.  I'm resigned to periodic chuck disassembly for cleaning.  Any lube will cause swarf to cling to the gearing, and Mert Baker quoted as saying "Whomever oils their chuck has spots on their shirt".  That said, one way to true up a piece on a 3-jaw chuck is with a bearing mounted on a piece of square stock.  This has always worked splendidly for me.
Kind regards, Al


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## Jim Woodworth (Jun 4, 2019)

Al, 
Coffee not working yet, mind in slow motion....can you elaborate on your system for a newbie? I've just used my tailstock to pinpoint..
Jim


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## goldstar31 (Jun 4, 2019)

Jim Woodworth said:


> Al,
> Coffee not working yet, mind in slow motion....can you elaborate on your system for a newbie? I've just used my tailstock to pinpoint..
> Jim



In GadgetBuilder.com's site it is called a Bump Center

Norm


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## Jim Woodworth (Jun 4, 2019)

goldstar31 said:


> In GadgetBuilder.com's site it is called a Bump Center
> 
> Norm


This is going to require some "fun" in the shop to test. I'm very intrigued. Thanks for enlightening me.


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## JimDobson (Jun 5, 2019)

I made one a few years ago -


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## KarlH (Jun 5, 2019)

The square stock is mounted in the tool holder with the bearing vertical. The square stock is either perpendicular to or inline with the axis of the spindle, depending on which face you want to align.
With your work piece snug in the chuck, you slowly advance the bearing in toward the workpiece. Contact will be made at the "high" spot on the work piece, and the bearing will push the work piece a bit "lower." Eventually the bearing will be making light contact with the entire piece, and the piece is aligned. You can then finish tightening the chuck.


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## Tim1974 (Jun 6, 2019)

Or it flys out and hits you in the head ! Bit dodgy in my opinion


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## Jim Woodworth (Jun 6, 2019)

KarlH said:


> The square stock is mounted in the tool holder with the bearing vertical. The square stock is either perpendicular to or inline with the axis of the spindle, depending on which face you want to align.
> With your work piece snug in the chuck, you slowly advance the bearing in toward the workpiece. Contact will be made at the "high" spot on the work piece, and the bearing will push the work piece a bit "lower." Eventually the bearing will be making light contact with the entire piece, and the piece is aligned. You can then finish tightening the chuck.





JimDobson said:


> I made one a few years ago -



Thanks for the visual.


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## Jim Woodworth (Jun 6, 2019)

KarlH said:


> The square stock is mounted in the tool holder with the bearing vertical. The square stock is either perpendicular to or inline with the axis of the spindle, depending on which face you want to align.
> With your work piece snug in the chuck, you slowly advance the bearing in toward the workpiece. Contact will be made at the "high" spot on the work piece, and the bearing will push the work piece a bit "lower." Eventually the bearing will be making light contact with the entire piece, and the piece is aligned. You can then finish tightening the chuck.


Worded very well, added to the visual above I think I'm buying in to the process. Thanks, Jim


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## Jim Woodworth (Jun 6, 2019)

Tim1974 notes my one concern,  Would spinning the chuck by hand suffice?  
I can remember way back in school the instructors being very strict with students about not tightening work in the chucks thoroughly before powering up.


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## Jim Woodworth (Jun 6, 2019)

Thanks Jim Dobson for the original chuck cleaning post,
Because of your post I got brave enough to take down and clean up at least enough to function a 3-jaw that I had never used. it was stuck solid.


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## mcostello (Jun 7, 2019)

Hand speed will work also.


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## goldstar31 (Jun 7, 2019)

Of course. it is a wonderful way to 'bell mouth' a chuck.

A piece of exact diameter metal to the work to be machined and  placed inside the chuck  would avoid this. 
Ah well?

Norm


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## NickP (Jun 7, 2019)

bazmak said:


> The Chinese chucks are well worth the money but its worth the effort to strip down and clean
> I also take off the sharp edges even the gear teeth.As has been said a light coat of grease
> once tried oil and learned by my mistake it tends to get thrown everywhere



If you wanted to use oil you could try steam oil - it’s much thicker and more ‘gloopy’ so doesn’t tend to get thrown off things so quickly. Personally, although I’m no where near an expert I use grease in mine as it tends to stay put for the most part. 

Nick


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## harborfreight8x12 (Jun 8, 2019)

Hello all.  In answer to Tim1974, safety is my primary concern and I always wear a full face shield that meets Z87.1+ standard.  That said, first I try re-chucking the piece to see if it centers on its own, if not, then I use the 'bump' center but only turning the chuck by hand.  At this point, the chuck is only lightly snugged so as not to damage or 'bell mouth' the jaws.  Others have said that they use a bar of nylon pressed against the piece, but I love to make gadgets and skateboard bearings are reliable and inexpensive.
Kind regards, Al


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