# Am i Expecting too much out of a Chinese 4 JaW?



## Dman1114 (Oct 6, 2014)

Hi all....


I've been having issues with a 4 jaw chuck...   i can't seem to get anything to come close to dialed in.   Grizzly replaced the chuck for me and admitted that it was defective.   well i got the new one in and Im getting the same results.


The Jaws are not parallel to each other.  so it only tightens down on the from teeth.  I try to dial in a piece 2" round aluminum right in front of the jaws then   go out 3 or 4 inches and its way off.  
Here is a photo of the jaws.  there is no gap at the front, the back has a .012 gap.   this doesn't seem right.    Am i expecting too much out of the chuck i would think that they should clamp down even.  I think that it may work using a steady rest but the work I'm doing is too short.   

Would a bison chuck look like this?   I like my machine just a few bugs i gotta get worked out.

kinda hard to tell from the pic... but there is clear daylight on the back side.


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## chuckorlando (Oct 6, 2014)

Seems to be common. Alot of folks end up grinding them. You will need to indicate a part in at the chuck and further out if it's longer. You cant compare a bison to a cheap chuck I dont believe.


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## JimDawson (Oct 6, 2014)

Dman1114, I'm going to post my Chinese 4-jaw adventure in a little bit.  I's a pretty comprehensive write up on how I fixed mine.  Stay tuned.


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## MikeWi (Oct 6, 2014)

Mine was the same way .  I re-ground the jaws and that fixed it right up.


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## JimDawson (Oct 6, 2014)

See this post http://www.hobby-machinist.com/show...uck-Adventures?p=234042&viewfull=1#post234042


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## Dman1114 (Oct 7, 2014)

MikeWi said:


> Mine was the same way .  I re-ground the jaws and that fixed it right up.




I think that would take car of this too...

I just don't have the ability, tooling or know how to do it.


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## MikeWi (Oct 7, 2014)

Reading the other post about fixing a 4 jaw reminded my that I had more to do as well.  I had to re-face the backplate to get the jaw to fit square for example, and it needs more work to get it in balance although the balance is "good enough" for now, I know it's not where it could be.  The faceplate that came with the lathe needs work too, it won't even mount on the lathe.


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## chuckorlando (Oct 7, 2014)

Every man and women on this site has the ability. Pick up a die grinder or dremel tool. All it takes is a little "will" to get new skills. And some money


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## JimDawson (Oct 7, 2014)

Dman1114 said:


> I think that would take car of this too...
> 
> I just don't have the ability, tooling or know how to do it.



I reground my first chuck on my Atlas lathe about 45 years ago, and I didn't know how to do it either.  But I had a Dremel, and some stones for it.  I knew that I had to hold on to the Dremel some way, and feed the stone into the chuck jaws, at that point that's about all I knew.  I built a mount for the Dremel to go in the tool post.  I checked the clearances and started grinding.  It took me a while to figure out the feed and speed that worked, but I got the job done.  I recently reground a 5C collet chuck, that one was the second one in 45 years.  I used a HF air die grinder, and built a mount for it to go in the tool post.  This one went a little easier, having had a few years of machining experience, I actually knew what I was doing this time.  The way to get the experience is to just do it, but be safe.


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## Dman1114 (Oct 7, 2014)

Well I guess what's the worst that can happen....  

I might learn something!!!!  
As far as I'm concerned the chuck  is useless. ....

I've got a couple of good did grinders from when I used to bang rivets on airplanes....  

I also got me a dremmel too.      

Just gotta find me the right stones and I think I will be golden 


I think all I'm lacking is the confidence. But I may be getting over that so looks like I'll be giving them jaws A new makeover.  

Never really did a precision grinding.  

can someone point me in the right direction as far as what type of stone I might need???


Thanks guys


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## JimDawson (Oct 7, 2014)

If you have to buy some stones, I would go with a medium hard, 80-120 grit, and the most important...rated for your grinder speed.  I would also buy a diamond dressing tool, just to make life easy.    Take a look here to see how I did it.  http://www.hobby-machinist.com/show...-D1-4-Cam-Lock?p=211905&viewfull=1#post211905

I would load the jaws something like this  http://www.hobby-machinist.com/show...chuck-grinding?p=208594&viewfull=1#post208594  With a 4-jaw it is not critical to have the jaws exactly in a perfect ''circle'' like you would with a 3-jaw scroll chuck.  You could grind only one at a time, because all you want to do is get them parallel with the lathe centerline.  I would check the jaw track alignment like I did.  You could do this right on the lathe, it is not necessary to to it on a mill like I did.  Just mount up a dial indicator on the cross slide or tool holder.

Good luck.


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## chuckorlando (Oct 8, 2014)

Confidence stops more projects and ideas then skill will ever produce. On the buggy forums we get alot of guys who see the custom fab work others are doing.  They tend to all say the same things.... If I knew how, if I had the skill, I wish I could, etc, etc.... I always tell them the same thing " only diffrance between you and them is they were not scared to cut it up". It's metal and we deal in metal. 

The best thing is grinding takes very little so it's hard to ruin a jaw long as your awake.

Oh and I get intemidated all the time. Sometimes I even drag my feet so as to prolong that uncomfortable place where I have no clue. But it all ends the same, it has to get done. And no one I could pay to do it, is any smarter then me





Dman1114 said:


> Well I guess what's the worst that can happen....
> 
> 
> I might learn something!!!!
> ...


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## GK1918 (Oct 8, 2014)

Whats the worse that can happen?   well, we are talking about a independent 4 jaw (I hope).   I am one that doesnt refuse free junk, however I was given a four jaw bell mouthed,
fork mouthed but there is hope.  With a true test piece even my eyes see daylight, mainly the rear like .010. I feeler gauged it.   Took that jaw out and wisked it on the side with
a standard bench grinder #80 grit. Put jaw back in tighten it & grind until perfectly flat.  And one by one,  ground until I got a perfect contact.  Probably my jaw flats were ok, it was
(call it) dovetails are worn,  not too much you can do about that.  Whats happening is applying pressure cocks the jaw so now even contact is lost, bell-mouthed  so called.  You may
loose a little of the ring sights, I dont care about those, just getting a little more mileage..   If I get questioned?   all I can say It works for me.  3 jaw scroll is a hole different deal. 
Oh I talking about inside jaws not outside.  Outside don't care.  

sam


I'm probably going ta get the dunce-cap award for this one  Old school getter done


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## Bill Gruby (Oct 8, 2014)

chuckorlando said:


> Every man and women on this site has the ability. Pick up a die grinder or dremel tool. All it takes is a little "will" to get new skills. And some money




 It takes a little more than that Chuck. First, the jaws need to be preloaded from the OD of the jaws. This puts them all in the same position and the won't move during grinding. It's the only way to get the grind straight. The grinder itself must be held somehow, not hand held. The whole length of the jaw needs grinding so you might need a long shaft diegrinder. It depends on how far they are opened when preloading. Preloading is done with a ring chucked on its ID. That's it in a nutshell. It takes time and patience to get it right.

 Now, as to the OPs problem. Unless you can't wait, send it back again. This time tell them to check it there. Obviously they didn't.

 "Billy G"


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## chuckorlando (Oct 8, 2014)

I never said everyone knows how to do it. I said they have the ability to do it. And they do


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## Dman1114 (Oct 8, 2014)

They are taking this chuck back for the 2nd time.... They told me they were gonna make sure the next one is right.   If i get it back again and it is AFU Im going to fab me up a mount for my long nose die grinder and I'm gonna fix it myself.


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## visenfile (Oct 12, 2014)

The tone and experience in this thread should be enough to move it to the beginners section as a motivator.  Seems like these fixes are related to way scraping. I have used blue dye marker and hand tools for many successful efforts accross the years when I simply did not have proper machine tools.  Kudos!


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## Falcon67 (Oct 14, 2014)

chuckorlando said:


> I never said everyone knows how to do it. I said they have the ability to do it. And they do



Agree.  I get a little hesitant sometimes but I try to remind myself that if I really hose it up then 1) it was broke in the first place so what 2) can buy another one or 3) if its that important, pay someone to fix it.


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## Dman1114 (Oct 14, 2014)

I just got in another chinese 4 jaw From Grizzly.  This is the third chuck from them and its no different.  The jaws are not parallel.   Not sure what is going on here.   But when i put a piece in the chuck i would think that the jaws should make contact from to back.     Only the Front of the jaws makes contact. ...  Gonna call them tomorrow and see WTF is going on.  They told me they would check it out and make sure i got a good one....

kinda messed up how a company thinks... they would rather pay shipping on a chuck (probably not cheep) back and fourth 2 times now than just credit me the price of it toward a  bison.

If this don't pan out i will be fixing it myself.


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## JimDawson (Oct 14, 2014)

Some bias toward the front of the jaw is not a bad thing.  As you tighten the jaws, there is some spring in the system they will tend to contact more and more surface the tighter they get.  Bell-mouth on the other hand would be a bad thing.

EDIT:

It is important that the centerline of the jaws point directly at the tailstock center.  That's where mine was way off.


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## chuckorlando (Oct 15, 2014)

I dont suspect you will get anything better no matter how many they send. Everyone they have came off the same run, fixture, grinder, what have you. You get what you pay for in this case. Which is not bad compared to high end chucks. But I suspect if your not paying top dollar you run the risk of having to tweak the product your self. I have a 4 jaw that wont hold a 4x4 with out turning 2 jaws sideways. No matter how I set the jaws, it simply will not work in this range.

Your best bet is to just pre load and grind the jaws I suspect


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## Dman1114 (Oct 23, 2014)

well called grizzly again....     i asked them if the guy who inspected this one was blind.  any how they said they were gonna look into it and get back to me.

they called me back today to let me know that a supervisor personally inspected the one they are gonna send and i should have it soon....   

this will be #4 ....    

hopefully i get a good one this time:talktogod:


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