3 Jaw Chuck run-out

Checking the run-out of a 3 Jaw chuck and trying the jaws in different slots.

[@AddictedtoProjects]

Hi Paul, many thanks for taking the time to make this video. I would be quite happy with 0.03mm runout on my chuck. :) I have a colchester student lathe mk1.5 (with gap to allow turning up to 18"). I bought an L0 backplate and a new Chinese chuck and fitted those. Because I only had vernier calipers to work with, I ended up with a runout of 0.20mm at the jaws. So you can see that your 0.03mm runout suddenly doesn't look all that bad. Its all relative! :) Cheers, Mich

[@dariobalice9138]

Guy you'r veeeeery lucky in having this chuck behavior. Trust me, in the 99% of the cases there is no way

[@stufields5125]

Thank you. I recently purchased a PM14x40BV lathe that came with a 3 jaw chuck. I just performed a runout ck and got 0.030". I'm thinking about using it to shake martinis.

[@oxtoolco]

Hi Paul, Good demonstration of why its a good idea to check your workholding and pay attention to the numbering. I have noticed that chucks also vary by the clamping diameter. In particular on old chucks they see a lot of wear in the 1/2 inch (13mm) to 1 inch (25mm) range. A cheap investment are a handful of gage pins in some common diameters to use for setups and interrogations like this. Individually they are quite reasonable. All the best, Tom

[@EVguru]

Hi Tom, My requirement for a 3 jaw chuck is mainly that the jaws aren't bell mouthed and/or loose in the chuck body. Run-out doesn't bother me that much. I had it drummed into me at school to machine all concentric features in one setup. I've used chucks where the runout was excessive because the jaw set wasn't the one supplied with the chuck, so I wanted to show that contrary to what some people believe, you can put the jaws in the 'wrong' slot. I don't think I made that clear enough. I plan to do an 'Anatomy of a Scroll Chuck' at some point.

[@pauljones3866]

Paul, I think most of us would be satisfied with a repeatable 0.0015" run-out on an older 3-jaw chuck. I found consistently tightening first with the master pinon (sometimes marked with a stamped zero or found through experimenting) produces the least run-out (less than 0.001" improvement but still better than none). I also found experimenting with chuck mounting lug positions on my D1-4 spindle and using the locking lug positions that produces the smallest TIR is worthwhile doing. Thanks for showing this video, Paul

[@carolanne8284]

Paul Jones

[@joeycaddell9103]

took mine from near .02 out to .0015 by using receipt paper between the backing plate and the Chuck. put a pipe in the Chuck for leverage and only one screw needs to be loosened to get paper in a position

[@AmateurRedneckWorkshop]

Interesting experiment. Your chuck is much more true than my Atlas 3 jaw. Thanks for sharing.

[@RustyInventions-wz6ir]

Just found your channel and subscribed. nice work.

[@EVguru]

Thank you. Hopefully I'll regain a little workshop space from other people's projects soon and make some progress on my own.

[@ChrisB257]

Interesting experiment Paul - may well mess with this on my rather ancient 3 jaw - just for the heck of it! Better still, win the lottery and buy a nice new 6 jaw! :)

[@chrishill6276]

ChrisB257 whats the go with a six jaw Chris. Are they dead accurate

[@dickmick5517]

I would have enjoyed seeing the run-out on the chuck body also. Frankly I am amazed the run-out is so little. I recently purchased a China metal square, it was out .020 per inch. I have plastic squares that were much more accurate than that. Of course I returned it and purchased a name brand. I am not saying that all China is junk, just the quality control is lacking on some stuff.

[@alberttorres4917]

The correct way to correct concentric runout is to check it like you did, then find the highest point the opposing jaw or jaw's is too high towards the center, now grind on a surface grinder the amount needed or a jig with a 1.5" diameter diamond wheel, grind it square perpendicular to the scroll teeth perfectly you should fall within .ooo5 like i did. You're adjusting the jaw to the scroll not the casing although it needs to be centered too. I hope this helps.

[@dvig3261]

That certainly will work for the exact diameter you grand the jaws at. But then as soon as you chuck a different diameter piece of stock, it will run out again. The trouble is in the scroll, not the jaws.

[@danielzunigagutierrez6300]

Jaws are numbered in position for one reason. End of the story.

[@dvig3261]

Why has noone pointed out that unsequencing the jaws will guarantee the runout to be on the order of the scroll pitch? The scroll is the source of the runout. Adjusting the jaws will limit the utility of the chuck to only that diameter. If you want the stock to run true, then use a chuck that can be adjusted...like a four jaw chuck.

[@EVguru]

The whole point of the video was to show that the sequence the jaws are inserted into the scroll is the most important thing for concentricity. Having them in the wrong numbered slots , but in the right sequence will throw off the concentricity only by the errors in the scroll machining. Only jaws that were ground in the same chuck are guaranteed to be most accurate in their numbered slots. Aftermarket jaws may er more conentric in different slots.

[@millomweb]

A 'left-hand' thread in a scroll - something I've never seen before !

[@wanabear5716]

Maybe blow some chips out the inside and before you clamp it down fully twist the stock just before your final tighten,Keith fenner does this all the time to make sure correct alignment..I did notice you done that on the last one,But you have a fair bit of stock hanging out the back side of the chuck aswell..Is it possible the test piece could be off a little.

[@abelferquiza1627]

There are videos how to correct without grinding the jaws getting even .01mm or less just tapping no hardly on the jaw of max deviation.

[@joshmeyer5280]

Thanks for the video Paul. I unscrewed the jaws to far on my leblond regal 13 and i was clueless on how to reinstall the jaws, i will also try switching them around and see if i can get the runout minimized. Thanks

[@robmacfarlane5864]

Position your indicator close to the jaws. Not out away as your are doing in the video.

[@Δημήτρης-η4ρ]

Would be a good practice to mark on jaw to aling with the bar?As two dot's so you could clamp the stock to the same spot?Also to put a mark where you took the first mesurment?

[@millomweb]

How many points do we deduct because you didn't measure the chuck run-out first ? Can't expect the jaws to be true if the chuck body isn't ! Step 1: dial-gauge on the spindle nose taper - then work along each bit you add: back plate, chuck and finally jaws.

[@HermanOtto-wr2nn]

Witam Kolegę z Polski przed sprawdzeniem bicia uchwytu należy go wykręcić rozebrać na detale wyczyścić z opiłków i wtedy można ze spokojem sprawdzić faktyczne bicie pozdrawiam miłego dnia

[@mahocnc]

Pretty good run out for a Chinese chuck....before any reading is done, clean out the scroll and jaw teeth.

[@felgate11]

Strangely?? when the jaws are in the correct sequence, the last chuck key hole just happens to be the one with the spot face in the chuck face - is that a clue for the best key hole?? 0.03 mm concentricity is Good enough all day long for hard jaws!! PS - can tap (fine tune) true with the wooden heel of a hammer/mallet on the jaws if that picky!!

[@iancraig1951]

1.5 thou runout---give it a tick----if that is repeatable that would satisfy me

[@robmacfarlane5864]

If you want your chuck to repeat accurately, put the chuck key in the same socket every time. Put some dykem around the socket.

[@dvig3261]

If you want consistent routines miti grrr ation, use a four jaw chuck.

[@ARC928]

How can you be sure that the rod is straight?

[@MrGGPRI]

Use ground rod..

[@howto6535]

Da, I am new to a lathe, and even I know they number them for a reason. #1 goes in #1 and so on.

[@jorgescordamaglia1654]

Hi Paul: I love your Harrison; is that a Late 12" L6? maybe one day you could give us a run of its features. Concerning Oriental offerings one the areas where is easy to cheat in marketing is the fact that lathe chucks they all look alike and the "proof is in the pudding" after you bought it and try it, you don't know. Therefore, it comes down to price because many of the "Premium" brands are also made there despite popular belief to the contrary and they are very good. . Regards Jorge

[@EVguru]

The lathe is a 1963 L5 and I do keep thinking that I could have done with an L5A or L6, but it was a nice machine at the right price. I thought I had done a piece on the lathe, but perhaps it never made it through the edit. I'll think about doing a feature soon.

[@OzyOzySM]

I will grind the jaws by insert a grinder wheel hold by the slide and run the spindle while the grinder spin till you grind all 3 true to almost true... then check it out! Oz

[@fransvermeulen3287]

This is one of the most stupid experiences I've ever seen !There is a very good reason why the jaws are numbered, and it's better to stick to that.How straight is the axis you're using ?

[@chrisstephens6673]

Hi Paul, If it is not marked, convention says the master keyhole is the one by the label or in your case the recess where the label would be. If your were using silver steel as your test piece did you check it for tri-lobe shape with a vee block or a vee anvil micrometer? A friend popped round this PM and showed me a photo he took, at AP, of us chatting, aren't you short.:>) LL&P chris

[@EVguru]

Yep, just 5'11" and I still often think the floor is inconveniently too far down!

[@TheWireEDM]

I would not "trust" any markings on the chuck, even if it says "master" next to a key slot by the manufacturer. The best position you find by trying to tighten the workpiece and watching your indicator. I have had the best experience when the DI is on top of the workpiece and I tighten from the keyslot that is closest to the position that my clock says "low". Just by doing 2 revolutions I can usually geta workpiece within just 0.03 mm on any given 3-jaw chuck.

[@ryanb1874]

3,2,1 or 1,2,3 when coming out? Why do the slots even matter. It's just not made super accurate...?

[@adoreslaurel]

Why use the key in 3 places? surely this should have no effect as you are just rotating the scroll anyway.

[@EVguru]

john brown The scroll has clearance in the chuck, so it doesn't just rotate, it moves sideways a little and binds. I cover this in my 'Anatomy of a 3 jaw chuck' video; kzbin.info/www/bejne/qabQppewg9eDns0

[@adoreslaurel]

Paul Compton Great, thank you, I will take note of that,

[@canidsong]

john brown It is also worth mentioning that the teeth on each pinion and the scroll in positions for frequently held stock diameters will wear more evenly if you tighten the pinions progressively, as this minimizes the chances of accidentally favoring one of them. I doubt it would matter for a reasonably long life of a chuck, but I was taught it as good practice anyway.

[@adoreslaurel]

canid song Thanks for that, I have just turned up and threaded a mount plate for an old 3 jaw chuck which was out to blazes, the wear on the jaws suggested a lot of "skidding" of work done by someone over many years however they provided me with rarely used reverse jaws which are in great shape.Finally got round to turning up a piece that had been in the too hard basket for 35 years to put this chuck to use. My old lathe is flat belt drive and I get belt slip when taking a cut of just about any reasonable depth [not tiny work, larger stuff], failing putting great strain on the flat belt I don't know how to overcome this problem, strange as the gap bed allows up to 20 inches {USA reading, 10 inch English]} swing, can never imagine how anyone could have achieved anything remotely like this size.

[@khemchand8231]

Jab chuck peechhe ko hota h.fir kaya kare.

[@secretsix6]

just moved the jawsround on mine no numbers on mine there are now what a difference

[@EVguru]

I'm glad someone gets what I was trying to show!

[@Deano_77]

Hi Paul. with regards to jaw 1 starting in position 1.. if a new set of jaws were fitted to a older chuck how relevant would it be for jaw one to start in the position starting 1?

[@EVguru]

Jaws supplied with a chuck are ground in position (tightened with the master key) . Replacement jaws are not of course and may centre better in the 'wrong' position. As long as a chuck grips parallel, that's the main thing. In my opinion far too much emphasis is made of how accurately a chuck centres.

[@Deano_77]

Paul Compton Thanks!

[@riflesmith1]

Hello Paul.......I have a Harrison L6. Nice lathes. Looks like you have a VFD on yours. Nice vid. I will sub.

[@cox315]

was that a snotrocket @ 5:20???

[@TheDarvec1]

I never use hard jaws, chamfered soft jaws are much less hassle. Just need to make a set of "spiders" and 1/4" pins that can slip into holes machined into the jaw faces. Then just re skim them when necessary. i.imgur.com/bkCJiM0.jpg

[@florentleider222]

when you fix the rod on the Chuck, you must secure the 3 screws Driving the jaws, not solely one !!!

[@EVguru]

You've obviously never encountered chucks that only have one key position! Chucks have ONE master key position, which is the one used for tightening and then grinding the jaws. Using this jaw then gives the best concentricity. Using all three positions allows you to get the chuck tighter for the same effort on the chuck key, but shifts the scroll position and changes the runout. Track down Abom's video where he mounts a new precision chuck and is surprised by how much runout there is compared to the chuck body. Adam always uses all three keys (except of course when he's showing off his 4 jaw skills!).

[@florentleider222]

@@EVguru it seems your Chuck has 3 key positions, clearly visible. 2 are only fake keys, . However at 10:40 you use the 3key positions????

[@bijoybasumatary4651]

Name of the T -shaped unscrewing and screwing tool please

[@EVguru]

Do you mean the chuck key?

[@bijoybasumatary4651]

Yes yes thank you

[@bijoybasumatary4651]

BTW what is the name of another T -shaped tool used for screwing and unscrewing the bolts in tool post?

[@mahocnc]

Don't know why all this... the first ting one learns is to install jaws correctly by matching numbers..but clean out chips first.

[@TheClascaster]

I'm trying this at work, my lathe is messed up.

[@abdulkhalegalghamdi6635]

👌👍

[@janj0n]

Swarf in the scroll, PULEEZE. Chinese chuck, come on. Yes, it was horrendous...

[@EVguru]

Is it possible that you heard the word 'Chinese' and shut your brain down? Most people would be delighted with just 1.5 thou of runout on a 3 jaw chuck.

[@AmateurRedneckWorkshop]

Paul Compton I know that I certainly would be satisfied with that.

[@MrGGPRI]

This is actually a SCROLL CHUCK and by design NON-ADJUSTABLE. Jaw for this chuck are numbered and then ground true at the factory- why would you expect to do better by rotating them ?? The real key to a good 3-J scroll chuck is the precision of the scroll and if not close to perfect, it could be 0.000 with one piece and way out with another of a different diameter. Fiddling with jaws is a waste of time-- the chuck was either made correctly or not...

[@mick9074]

Wasted time polishing a turd