# I am very confused by a video posted on Youtube to adjust a single jaw on a 4 jaw chuck.



## jbmauser (Feb 6, 2015)

I think this is wacky.  Am I not understanding? 

https://www.youtube.com/watch?v=V7Y3nErVCnc

I don't get it.  the error in a single jaw as stated was it was not parallel to the axis of the lathe, not a concentric problem.  The correction applied is the method of correcting a three jaw scroll chuck for one jaw being out of true or it is way out of center.  

Why would not a grinder run in parallel to the bed against the offending jaw not bring it back into line on a 4 jaw chuck.

This makes no sense to me and if it is correct and I am not I am in big trouble understanding the dynamics and geometry of my lathe.  It is possible..... please help a want to be machinist.

JB


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## Bishop (Feb 6, 2015)

Wood and bailing wire, not to mention painted pulleys.


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## JimDawson (Feb 6, 2015)

jbmauser said:


> I think this is wacky.  Am I not understanding?
> 
> https://www.youtube.com/watch?v=V7Y3nErVCnc
> 
> ...




It seems that the chuck jaws were bell mouthed, and apparently one more so than the others, it is also most likely the he did not have the jaws all the same distance from center when he started grinding.

You are correct, the grinder would grind true to the lathe axis, and the resulting grind on the jaws would have also been true to the axis.  Ideally, the jaws should have a very slight taper so that the front of the jaw hits the material first, and then springs a bit as it tightens down for full contact.


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## hermetic (Feb 6, 2015)

You are right, if that is an independant 4 jaw chuck, it is wacko, and even more wacko to mark the jaw numbers on the alternate gripping face of the jaws (which are reversible)
Don't understan it at all, although the machine looks immaculate!
Phil


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## hermetic (Feb 6, 2015)

Just watched it again, and now I am confused, I suppose if only one jaw was damaged or bellmouthed it might make sense.........................or not?


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## John Hasler (Feb 6, 2015)

hermetic said:


> Just watched it again, and now I am confused, I suppose if only one jaw was damaged or bellmouthed it might make sense.........................or not?



Well, it did let him do all four jaws in a single operation while minimizing the amount of material removed from any one jaw.

I'd want more loading on the jaws than what his bits of merchant wire could exert, though.

Might as well use wood to clamp a Dremel.  The case is kind of rubbery anyway.


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## ICanBreakIt (Feb 6, 2015)

Just as a complete novice... could you also accomplish this with a boring bar?  Is the grinder necessary?


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## JimDawson (Feb 6, 2015)

Not possible with a boring bar.  The jaws are hard.   The theory is correct, just not possible with the tool.


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## core-oil (Feb 6, 2015)

As far as I am concerned grinding in the lathe & grinding chuck jaws is always a no no, I would rather buy a new chuck, as I am of the opinion that grinding dust & my lathe slides are not compatible, however I have seen it done in an establishment I once worked in, this was to true up a badly bell mouthed three jaw chuck, Even after the guys had carried out their "precision tool repairing" the bother and end results far exceeded the cost of a replacement chuck

  The correct thing to do is to take a piece of bright round steel , true up & bore out the middle without altering the setting in other words make a steel ring,  place the ring on the outside of the chuck jaws & true it to run accurately on the outside face,   This stable ring holds your jaws tightly whilst grinding the inside holding face of the jaws.


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## caster (Feb 6, 2015)

Another fine example of internet misinformation.  He does sound knowledgeable and authoritative.  If you work with metal and have a 4 jaw why would you use wood, metal is not strong enough? Bailing wire is not my go to material when I want to solidly stiffen anything.  1/2 hour per pass and 7 passes to get the job done, did he hand feed the Dremel?

I can see some program producer thinking "I have seen a 3 Jaw being trued but never seen a 4 Jaw.  Eureka! I have an opportunity for original content"

Caster


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## higgite (Feb 6, 2015)

Aw, c'mon. Give him a break. I mean, after all, he DID use oak. :biggrin:


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## silence dogood (Feb 6, 2015)

This looks like an "independent" 4 jaw chuck.  Which means that he's wasting his time numbering the jaws.  If one jaw is not working properly, then it seems to me that the keyway or the screw adjusting the jaw is out of kilter. I'm not saying that the jaw is not worn. But I would eliminate everything else before grinding.   Something as simple as a piece of swarf or in this case a sliver of oak in the keyway could be the problem.  Mark


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## Andre (Feb 6, 2015)

Change of thought.


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## janvanruth (Feb 7, 2015)

So he got the jaws ground perfectly.( he thinks)
He has another video on the tube where he shows how he "restored" the lathe.
Ways were worn so he covered them all with rulon tape.
I bet he didnt grind/scrape the surfaces prior, so it will be crap and the lathe looks great but will work like a piece of .....


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## Andre (Feb 7, 2015)

janvanruth said:


> So he got the jaws ground perfectly.( he thinks)
> He has another video on the tube where he shows how he "restored" the lathe.
> Ways were worn so he covered them all with rulon tape.
> I bet he didnt grind/scrape the surfaces prior, so it will be crap and the lathe looks great but will work like a piece of .....



I knew the ways looked red, but I thought it was a reflection of maybe a red packing blanket hanging from the ceiling or something for noise dampening.

Hmm....


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## Metlmodr (Feb 7, 2015)

Well, as a "beginner", I thought that maybe the following shots grabbed from his video may point to where some of his problems emanate.


Looks like someone had big arms and small intellect to do this to the threads, or am I mistaken?


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## darkzero (Feb 7, 2015)

Since the key drive is so deep, looks to me like someone might have left the chuck key in there & turned on the spindle to cause that damage. If so, I wonder what the ways look like? And if so I bet they learned their lesson real quick!


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## JimDawson (Feb 7, 2015)

I would say he does really nice wood work. )


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## Micke S (Feb 7, 2015)

The red packing tape on the ways gives the great feeling of having a luxury item that has not been touched by anyone since it leaved the production line )


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## caster (Feb 7, 2015)

Having looked at the other videos in his channel I am getting a better understanding as to what is going on here.  The videos are very well made, the lighting is uniform with background shadows that enhance the image but do not detract.  The set is immaculately clean and organized with some items scattered to give the impression of use. You cant find a single chip or drop of oil on that work table. There are graphics to reinforce the narration and the narration is scripted, perfectly timed and overlayed. There are no images of the work being performed only of the finished results.  I think the time & effort put into making the video is at least as much if not more than the work performed on the lathe.

I think the lathe is meant to be industrial art, a nice conversation piece.  By his own admission he has not used the lathe, the "Franken-lathe" does not have a tool post.  It looks to me that this is meant to be pretty and not necessarily functional. Clean the grit and grease, remove rust, polish, paint, replace worn wires and broken parts, clean and clear coat the plaques, cover worn ways with tape.  I wonder if we are seeing product placement in the use of Rulon tape. 

I think this is meant to be entertainment like "Tool Time" and not a mrpete222 instructional video.

Caster


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## GA Gyro (Feb 7, 2015)

caster said:


> Having looked at the other videos in his channel I am getting a better understanding as to what is going on here.  The videos are very well made, the lighting is uniform with background shadows that enhance the image but do not detract.  The set is immaculately clean and organized with some items scattered to give the impression of use. You cant find a single chip or drop of oil on that work table. There are graphics to reinforce the narration and the narration is scripted, perfectly timed and overlayed. There are no images of the work being performed only of the finished results.  I think the time & effort put into making the video is at least as much if not more than the work performed on the lathe.
> 
> I think the lathe is meant to be industrial art, a nice conversation piece.  By his own admission he has not used the lathe, the "Franken-lathe" does not have a tool post.  It looks to me that this is meant to be pretty and not necessarily functional. Clean the grit and grease, remove rust, polish, paint, replace worn wires and broken parts, clean and clear coat the plaques, cover worn ways with tape.  I wonder if we are seeing product placement in the use of Rulon tape.
> 
> ...



Hmmmm...

The video does seem to be more 'studio' than 'shop'. :thinking:

I saw a few good points in the video... however I think I would watch a few more (which came from a shop that appeared to be worked in)... before I determined a procedure I was gonna follow.  :allgood:

That 'advise of many folks' thing...


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## fahrphrompuken (Mar 23, 2015)

Forget the lathe and chuck jaws, just use the Dremel rig for sharpening chainsaw blades.


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## atunguyd (Mar 24, 2015)

I am surprised no one pointed out the final part of the video. He shows an arbour that he just turned on his now perfect chuck and the video is zoomed in on a nice big bur or some sort of damage to the arbour. 

I am sure anyone serious enough about machining to put a video online on hire to perfect your chuck would never dream about showing a mistake like that on their video.


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## T Bredehoft (Mar 24, 2015)

My 4 jaw chuck, (new in box) came with numbered slots and jaws, also came with .007 taper in an inch. 
I'm in process of correction. I put a washer in the far back of the jaws, indicated each jaw in the center of its length and ground to clean up.  (Air powered die grinder in a boring bar holder) Next phase, after I figure out what happened is to straighten the jaws. when clamping on a round piece I can see daylight between the piece and the front of the jaws.  The jaws are a near perfect fit in the slots, no wiggle at all, so I haven't solved the problem yet.


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## bfd (Sep 18, 2016)

as he somewhat states in the video, the jaws were sprung , contacting work piece closer to the chuck and not touching near the tips so he was squaring the jaws to the chuck not fixing an alignment problem you state this in your post that truing up jaws is a 3 jaw operation. maybe I am misunderstanding . I am new to this sight so don tlaugh at my posts too much thanks bill


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## bfd (Sep 18, 2016)

also I am not a typist so errors will occur.


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## Tony Wells (Sep 18, 2016)

We all know Typonese pretty well by now, Bill. That's the last thing to worry about.


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## 12bolts (Sep 18, 2016)

As a few have pointed out already, but just to recap,
1) Red tape on ways, Painted Pulleys, Tie wire
2) @0:10 Bench vise "secured" in place by mini G clamps.
3) @1:38 Bolts pressing on (plastic) body of dremel tool to secure it in place
4) @1:55 A tool he has had for "probably 20 years" and it looks newer than the lathe that was made yesterday
5) @2:05 Wood T-nut with grain oriented to split
6) @3:15 Dial indicator measuring to thousandths of an inch but thats ok he can determine that with finger pressure
7) @3:28 screw holes that he drilled and tapped? I dont think so. Not in that conveniently placed piece of casting
8) @4:10 Flex in grinder stickout length. I mean how good is that bearing really? In his 20 yo cheap dremel tool
9) @4:19 Maybe more is being taken off that 1 jaw because the crappy piece of tie wire is not as tight as the other 3
10) @ 4:35 Precise arbor
11) @4:40 Setscrew mark
12) @5:00 Precision ground arbor that was previously secured in aforesaid "wonky" chuck.
13) Plus some others that I'm sure I missed........
All on a lathe that looks like good enough to have come off the production line yesterday. And a brand new chuck to boot. Those jaws arent bell mouthed from use, thats cheap and sloppy dovetails  in a cheap and sloppy chuck to locate the jaws.
There is so much wrong with this video...........


jbmauser said:


> I think this is wacky.  Am I not understanding?
> I don't get it.  the error in a single jaw as stated was it was not parallel to the axis of the lathe, not a concentric problem.  The correction applied is the method of correcting a three jaw scroll chuck for one jaw being out of true or it is way out of center.
> 
> Why would not a grinder run in parallel to the bed against the offending jaw not bring it back into line on a 4 jaw chuck.
> ...


No


jbmauser said:


> please help a want to be machinist.JB


I guarantee he is not one
This is an instance of where the BS filter needs to be applied. Heavily! I know I'm a mod and we need to be forgiving courteous and gracious, but sometimes we just need to get out the FBH.
Just because its on the internet doesnt make it true

Cheers Phil


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## 4GSR (Sep 18, 2016)

I have a chuck just like the one in the video but instead of a 6" chuck it is a 8" chuck.  Same lathe, a 9" South Bend Lathe.  Dad bought the chuck about the time I was born, late 1950's.  It was the chuck I learned on and used for many years in my youth.  When I was around 13 years old, I complained to dad about the bell mouth of the jaws and wanted to do something about it.  Well like everything else I learned and did from dad, I learned the "proper" way to fix the jaws by grinding them with a preload applied to the jaws, at the tip of the jaws, using a Dumore tool post grinder, which I still have.  The jaw fix lasted for a couple of years until the problem just worsen.  Finally retired the chuck and put a new 3-jaw in its place.  Now that I have larger lathes with nicer 4-jaw chucks, I really have no need to put a 4-jaw back on the 9" SBL.  I do have a older Cushman 6" 4-jaw in reserve to use on the 9" SBL if needed that is in good shape.  BTW: I've worn out a chuck key on that chuck over the years, never once applied a leverage on the chuck key to make it look like a pretzel!  Ken


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## TakeDeadAim (Sep 19, 2016)

Ive seen a couple of his videos on "restoring his lathe".  I cant imagine the welts I would have had as an apprentice had I called that a rebuild.

Just because someone claims to be a professional, there is no guarantee this is the case

The fact someone does something for a living, or in this case publishes on YouTube, is no indication of their ability


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## Tony Wells (Sep 19, 2016)

There is plenty of evidence on youtube that guarantees that there is no shortage of idiots for those villages who claim to have lost theirs.


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## Eddyde (Sep 19, 2016)

Most of the guys other videos are wood related and he's claims to a woodworker. IMO he's pretty irresponsible publishing videos on a subject he clearly knows very little.


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## Tony Wells (Sep 19, 2016)

I sometimes wish it could be user edited like Wiki. Kind of self-policing.


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## strantor (Sep 20, 2016)

jbmauser said:


> Why would not a grinder run in parallel to the bed against the offending jaw not bring it back into line on a 4 jaw chuck.


only reason I can figure (if there's any credit at all to be given to this video) to fix a bell-mouth is that running the grinder in against one jaw without the chuck rotating, might give cause that jaw to take the radius of the dremel wheel, which would be a small radius. by rotating and doing it like the way of truing up a 3-jaw, the jaw would take the radius of wherever it's positioned.

</devil's_advocate>


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