Machine Shop Maintenance: Truing up a 3-Jaw Chuck

Here is a fairly simple procedure you can use to true up excessive run-out in a worn 3-jaw chuck.
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[@pieterbotes8938]

Your method of creating tension is absolutely correct. Many people are doing it the wrong way. Note the following: A person can have the best setup, best grinder and correct way of tensioning the jaws, but if you have a spindle which is out of line with the bed, it's not going to help much. It will be best to first check if the spindle is parallel to the bed. My Opinion!

[@BoldUniverse]

Great vid! Also at the end there where you're measuring four thou out, remember you're measuring that off of cold rolled bar and that would likely be out as well. You did a fine job with the grinder and even gave me ideas by using that ring!

[@dalegriggs5392]

Kieth, You are correct, ordinary carbide inserts will not cut hardened chuck jaws. However, Blue Nano carbide inserts will. I had 11 thou run out on the three jaw on my smaller lathe. I am really hesitant to get grinding dust inside my machine so I didn’t want to use a tool post grinder so lived with the run out until I saw a video on Steve Jordan’s channel using the Blue Nano inserts on a boring bar to true up the small chuck on his mini lathe. I know, mini lathe chuck jaws may not reach the hardness of a bigger chuck but I didn’t have anything to lose but the cost of the inserts so I thought I would give it a try. To my surprise the Blue Nano inserts weren’t even faxed by the jaws on my chuck and I got it true within a half a thou using his method! Steve solves the problem of chuck tension by placing a piece of round stock on the very back portion of the jaws then tightens the scroll down normally. He shows how he accomplished this somewhat delicate operation. After the greater portion of the jaws have been trued up the billet, as he calls it, is removed and the small back teeth of the jaw are cut just a smidgen below the truer portion. I used a ring similar to the one you use only I just used the back grip on the jaws to provide the needed tension. You do loose the very back portion of grip on the jaws but there is still plenty of gripping force to hold the work. Pierre did a review on the Blue Nano inserts not too long ago if your interested. They worked for me and I’m comfortable that I gave my chuck and lathe bed a bit longer life by keeping it free of grinding dust. As you know the dust is impossible to control in a spinning lathe and grinding wheel and equally impossible to completely remove once it’s in there. Thanks for the video.

[@LarsBerntzon]

Its probably running more true if you test with a round stock with the same diameter as the jaws was open when you did the grind. I suspect the scrolls are worn in a irregular way so when you test the runout on a smaller stock you experience this irregularity.

[@marks6292]

I am just starting to learn about lathes and was looking for "how to true up your work piece in a lathe". I found all kinds of helpful videos that really didn't address that question, but answered other questions I didn't have. I didnt realize for example that you can have a 3 jaw chuck that has a 4 jaw adjustment to true it up. Now I found this video. I cannot tell you how much I appreciate you taking the time to spend teaching this method. I am sure a lot of others here really appreciate it too.

[@cubleycat]

Thankyou so much for posting this video. I have tried several times to true up my chuck on my hobby lathe and have not managed it until seeing this video, I had to drill the jaws and peg them to do it but now it is perfect thanks to you :-)

[@bobjimenez4464]

Buck chucks are worth every penny.

[@JackHoying]

Nice job with the video. You do a good job of staying with the subject at hand and not dragging the video out. I had a 3-jaw with in similar condition and made a tool post grinder from a variable speed router. It worked quite well, and brought the run-out down to under .004. I was disappointing with this at first, but soon realized from other peoples results that this is the best I can expect.

[@sinnovate3983]

I have exactly the same issue and I also have a toolpost grinder - so I'm going to make an arbor and do the same thing! Thanks for the video!

[@MR6.5]

I am getting ready to do the same job on my 16" South Bend. Thanks for sharing. Subscriber: Randy Wilson

[@george330ful]

I have seen it done the other way and thought as you did ,the pressure was wrong on the jaws but my jaws are not bolted on like yours now I know the way to apply the pressure .Thanks Kieth Like your videos !

[@jackcollins6070]

I suspect there is also wear in the centerline axis between the body and the Jaw mount. I would use an all-thread stud, washer, nut, washer, your ring, washer and another nut. This will secure the Jaw set just as if a piece were chucked up.

[@Buckrun11]

Your tool post grinder did a fine job. Enjoyed the video.

[@SpenCrowson]

That was great, gave me an idea so I'm off to check my lathe now.

[@klmartin1962]

I saw that video by Kieth Fenner, in my opinion this idea is brilliant in its simplicity. Good job..

[@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

[@ellieprice3396]

This is the correct way to true up the jaws. Thanks for the demo. You can probably improve that .004 runout by striking the high jaw with a soft mallet. Any improvement is a help so it doesn't hurt to try.

[@potlimit2002]

No it’s not correct. He preloaded the jaws in the wrong direction.

[@Maecky]

Keith a little tip. If you are dressing the Grinding wheel on the "backside" and grinding on the "frontside" you can run into problems when your tool post grinder is not perfectly parallel to your bedways. This means if you are off just a few thou you are doubeling the error and your grinding wheel will be conical, if you are dressing on the same side wich you will be machining later you dont have that problem. cheers Mäcky

[@EIBBOR2654]

Keith, How you did the rework of the jaws was okay and for your tolerances will work. Using the bolts in the outer jaws mounts like you did could cause another problem in some chunks and older chucks. I've seen the jaws tip or cantor with one cap bolt holding the jaws. Redressing or grinding the jaws when they do that will cause a very slight belling or taper to the jaws that will cause very bad accuracy and unwanted tapers in parts. A better way would be to make a steel bushing to go over the bolt shank and in to the cap bolt counter-bore so it will lock the back side of the jaw down too. Another way would be to make a wider ring with holes for the bolts to pass through so the bolt head will tie the back end of the jaws down. Another thing is to make sure that the chuck is kept properly lubricated with a good grease or dry lube. I know a lot of guys in this field that forget or do not like to do that. But it is absolutely necessary if you want that chuck to keep its accuracy for a long time.

[@Thunderstixx77]

Another great video Keith. 126K views, dude, you're famous !!! Great job.

[@VintageMachinery]

Thanks! Not sure about how famous I am though....

[@kappullen]

Someone touched on this after trueing a chuck up. A three jaw chuck will usually perform better accuracy wise using one of the three chuck wrench sockets. Mark the best socket and put it to use. Using random sockets will result in random chucking accuracy. This makes the chuck look worse than it is. On repeat work mark the stock and put the mark at the same jaw each time it is chucked. That way jobs can be machined in operations much quicker that resetting each tool for each part. My chuck on the P & W lathe was modified at some time with adjustment screws on the scroll plate to move things around a bit. I assume these are brass tipped set screws. Haven't taken it apart to look inside, if it ain't broke, I don't fix it. Kap

[@PeterWMeek]

Ditto for both finding the most accurate tightening gear, and for "indexing" the work to a particular jaw for repeatability. I have also found that tightening a 3 jaw progressively (snug on the first position, firm on the 2nd, tight on the 3rd; then tight on 1 and 2 again) may give the least runout on a new(ish) 3-jaw. It probably would also reduce the tendency for increasing runout as the chuck ages (if we should live so long as to notice).

[@BROCKWOOD64]

WOW. Comments are polarizing Keith. I like your videos & recognize that what you have to work with is generally 'old school'. I'm into old school myself. Trying to teach myself a new trade in tool making & find your results educational! My Chinese Lathe / Mill Combo will have a better run out once my tool post grinder arrives - but will need an extension to do it. My interest in your escapades is real.

[@VintageMachinery]

+BROCKWOOD64 Thanks for hanging out in the shop with me (virtually at least....)

[@michaelrodriguez-fb8fr]

thank you for the video i have been thinking about how i could resurface the jaws on my hendey lathe!

[@johnjennings8085]

Thanks Keith we have a tool post grinder i did not realize you could add a extension arbor to reach into the chuck.

[@custorio]

Hello Keith good day. I have a similar Lodge and Shipley lathe almost exact. My father obtained the lathe on a surplus buy. I an wondering what should i do to rehab the whole lathe? I've noticed an oil leak from the machine. The lathe does look a little bit beat up but i am wondering what advice you recommend i must do to have the bad boy running again. Any help would greatly be appreciated. thanks.

[@h0useisafeeling]

You can also have a little runout coming from the bolts; each round part of the bolt that is tighten the ring.

[@mahocnc]

Good set up! ..I do this with ring and 3 dowel pins installed which go inside the jaw hole in front, [need to be loose], my Forkardt chuck have holes in hard jaws, you could drill also], some people use the jaw screw holes for mounting ring which I see only a slight problem...the jaws might slightly be binding from each other and uneven forces are applied..but with care this can be minimal and for this purpose well suited. Your set up is better since the ring is free of binding while laying on bolt. About .003" taper to the back of hard jaws I grind or hard turn for spring back ..gives you greater clamping force in front where it's needed. When turning soft jaws very accurate, most often I use a ring with 3 - 90degree bolts installed on the side...threaded part goes inside the ring, the none threaded part goes inside front of counter bored screw holes, I can adjust easy to the size of parts turned by turning one or more screws in or out ...close to part size, [closer the better] very minimal of turning out soft jaws.

[@mtyquinn6]

Thank you Keith! Now that you have the center jaws "tuned" would you now go in and with drill rod chucked up - grind the other jaws?

[@bobcatt2294]

When testing for trueness should the test stock piece be rec-chucked several times then check with the indicator for each chucked position?

[@freebird1ification]

i also like to use centerless ground stock for this or if you have a piece of 1 inch by 6-10 inch round carbide laying around it is super for testing runout

[@freezerfreezer9097]

I read one time that you can just set your speed to the highest and the centrifugal force will throw out the jaws ... so i tried it .... .0005 runout .... worked great for me ... might be worth a try for you .just run it and zap a thou or 2 off and see . like you i didn't think it'd work too well either , but it did.

[@baccus61]

Just a small note. People often forget about the bearing surface the scroll has to ride on and that also wears out after a period of time. Your scroll may be in good condition but your scroll bearing surface may be worn and the only way to fix that is to build up the surface and machine/grind to a fine tolerance a new bearing surface. Otherwise the run out will be all over the place depending on which of the 3 points you use to tighten the jaws.

[@kennethhoward8950]

Can the inside of the scroll also be worn against the teeth of the jaws and how would you fix this

[@aintskairtolskol9520]

@@kennethhoward8950 scroll and jaws are same 14th so i would make a new worm gear if you have the machines to do so,you didnt show much on the grind,im curious if you let the stone spark completly out on last pass,every time i have ground jaws if you dont run that last pass a couple times at same zero you will have a small rocking that cause the jaws to still run out a smigin. with every thing original on the lathe,i would make a new gear,you notice how much the flats have got wider,if you go much more you want have the grip you want on scaled stock,just my tip hope it helps,before i retired i got were i like soft jaws and radius better than the adverage 3 jaw chuck

[@DonDegidio]

Anyone know which Keith Fenner video shows how he ground his lathe jaws?

[@nevinzimmerly4888]

That worked well. How I have done it before is to use 3-5" dia. Plate 1/4" thick with a 1 1/2" hole in it. Dril 3 holes in it for the bolts to come thru. If your Chuck has no bolts I have figured out a solution also with key stock.

[@samp1394]

To start with how do you know if the problem is the chuck or the rod?

[@dougguynn2622]

enjoyed watching ,& learning

[@howardtoob]

Can you tell me if the top hard jaws stand proud of the master jaws when new?

[@midgoog2]

Hi Keith Did you check the runout on the outer ends of the jaws and the intermediate steps for when the jaws are reversed or used for internal clamping too ?

[@Fabes002]

Would you be able to mark your piece and a jaw with a sharpie in order to reinstall the piece and match the original alignment?

[@shortribslongbow5312]

Wow that was interesting, I have an old Atlas I'm going to fix right now. Thank you :o)

[@prenticeemler7709]

Very nice great idea 😊

[@Rocky1234732]

Thanks for the video very nice.

[@thomsworkshop946]

Just watched this, such a great method. Who knew the song plays when you grind a chuck?

[@pieterbotes8938]

Its important to get pressure from the inside (like when clamping on a piece of metal) when grinding the jaws on the inside and not using a ring over the outside of the jaws which will cause pressure towards the inside instead of pressure towards the outside.

[@grumpyg9350]

Pieter Botes , I believe that's what he did

[@pieterbotes8938]

@@grumpyg9350 I didn't question what this brother did. I merely "sort of stressed" the importance of doing it the right way.

[@grumpyg9350]

Pieter Botes it's important to make clear comments as to whether they are reinforcing or critical. Most of us, at least on KZbin, have difficulty with our "mind reading" not always working correctly. I know I've been guilty of this, and have been called for it before. Maybe adding a simple little phrase like " I agree" or "I concur" is all it takes. ✌️👍

[@pieterbotes8938]

@@grumpyg9350 Will do

[@fastst1]

Thanks for the ideas, I have an older craftsman where the chuck could use some truing and I did recently find a tool post grinder.

[@guubagaaba8391]

in which video did keith do this process ? i think i've seen them all.

[@chuckwin100]

Interesting video and useful for machinists. Although I am not a machinist its still interesting for me.

[@steveallen8987]

When you tighten the Chuck do you just use one of the three adjustment screws? I had a runout problem on a small three jaw but changing my practice to always tighten all three adjustment screws the runout is down to just under 1/1000. Big result. I must be a bit ocd as I always tighten in order.

[@mikewebb111]

Great Video thank you Keith. At 2:30 did you run the lathe backwards or is that just a illusion?

[@cramersclassics]

Very nice presentation Keith! Your narration and image quality is first class. I have an old Cincinnati 12.5 x 42 lathe that is new to me. I can adjust the 3 jaw Buck Chuck on it to about 2 thou runout with its 4 adjusting screws. What do you think is acceptable runout?

[@kellyallen903]

Another suggestion for the grinding . Use your hand wheel to feed the grinding wheel back and forth fairly quickly . Literally feed it , feed it out . This works like honing a hole , the faster the feed the more rapidly the cutting action and more parallel the hole or jaws . The rapid feed breaks down the grits to expose new sharper grits and keeps the wheel from cloging up . Another suggestion is to dress the wheel on the same side as contact with the job . Another mistake most people make is using too fine of grinding wheel and also too wide a wheel . Narrow wheel has less pressure and more accurate . One last thing , cleaning out the inside of the chuck before doing this job may help . Cheers

[@stevenacarter77]

well done Keith

[@VintageMachinery]

Thanks!

[@MrZenerTech]

Ive never used a lathe and am bit lost on a few of the terms. It sure would be nice to see a video demonstrating physically why you cant reach zero runout on the chuck.

[@glenndavis2762]

Test it with a hardened pin instead of that 1018. I checked my 12" Bison and got .003" - I was thinking of grinding, but .003 seems to be the norm. Thanks for the video! Glenn in Spokane

[@StamD65]

Dear Sir, No,it is not a norm,Your chuck shoudl be repaired,unless ou do not make precise things. I have a 2 year old 250 mm Bison and the runout is 0,01 mm - and this is fair o.k Please look at the videos of Viktor Leontiev,and You will start to think differently.

[@glenndavis2762]

I agree Keith - How the heck could you get 3 tenths run-out on a three jaw????? I just check mine with a ground carbide rod and it showed .002" TIR - I think I can live with that.

[@baccus61]

***** Keith, The extra run out would be the spigot that the scroll runs on. To get it to have less run out you would have to build up the spigot and re-machine it true with the circumference of the chuck. 0.002 - 0.003 is pretty good in my eyes. I have a cheap Taiwan chuck that came with my lathe and the total run out on that is 0.0015 which I think is fantastic. Great vids matey and keep em coming.

[@davidfrancis8761]

The problem with doing it the way shown here on smaller chucks with narrow jaws is that it leaves the jaws concave. If stock of larger diameter than the jaws were set to when grinding is clamped then there is a tendency for the jaws to mark the workpiece because the edges of the concave bite into it. It also leads to runout due to the workpiece not being gripped evenly. The better way to grind narrow jaws is to not rotate the chuck but to fix it with the jaw to be ground at bottom dead centre then move the grind wheel back and forth across the jaw, slowly moving inward. Repeat the process with the other jaws each at bottom dead centre. The result will be flat faced jaws which can clamp any diameter without damage and without premature gripping.

[@eugene4154]

Thanks for the video, I have some questions A, did you check the lathe chuck mounting plate for run out B, did you then refit the chuck after a very good clean and polish and check the chuck body run out C, did you remove the bolt on jaws and check runout of check slides themselves D, did you confirm all jaws are in correct positions then check run out Those old machines are generally very very well made with good durable steel and unless previously someone used a tent Pole as a chuck spanner there should not be as much runout as you HAD I have setup a few lathes and always start with bearings, then step for step work my way outwards till I finally fit the jaws them selves and find very marginal tuning needed before the jaws are done, each thou adds up I would also use a true ground hard shaft as my clamped reference, never trust a standard machined bright steel rod The last point is check the runout at the jaw face then move dial gauge out 100mm from face and recheck runout, then when all done to within 1 thou recentre the tail stock to the jaw to make sure you don't introduce errors of the length of the bed All the best to you in your shop fella, Generally 1 to 2 thou can be overcome with a slight tap with soft block to the offending jaw before final lock down, but we would all like the jaws to be 100%true wouldn't we

[@dwightcarlson7136]

I imagine when you are grinding, the actual diameter which ends up being ground matches the diameter of the opening of the jaws during the operation. It appears that the jaw gripping surface has a radius smaller than the operation set up. Therfore the grinder won't contact the bottom of the jaw. The run out will greatly improve for larger diameter work pieces but maybe not for smaller diameter stock.????

[@sparkiekosten5902]

I'm sorry but I had to look twice to see it was Rucker written on that motor! Keep up the good work!

[@johnnelson2936]

Semi Newbie question...atlas 618,,,,test bar in spindle mt2 taper....0005 at 2 inches...turn new 3 jaw chuck on test bar backwards and check runout and adjust where it mates to faceplate in normal configuration. Would this be a decent way to help true chuck...

[@chrisstephens6673]

Nice job, isn't it nice when you can mount work in the chuck and can be reasonably accurate, got mine to about a thou run out at 1" dia. and removed all of the bell mouth which made parting off way more pleasant. One question, did you tighten on the ring using the master key hole? ATB chris

[@blanchae]

That would be true only for the diameter that you used. Once you change the jaw position (open or close), you would have to factor in the play caused by the out of round that the scroll has.

[@philffd]

Hey Keith, could some of the run out be from wear in the scroll teeth? I wonder if you ground the chuck at a diameter closer to your intended work if you wouldn't get better results

[@robertweak4226]

You have a good idea but, the load should be the other way around. Put like a two inch piece of stock way back in the jaws and tighten . Then bore. That way, the load will be right .

[@Machinist-wf1iw]

It helped a lot ..but you can cut the jaws with a good insert boring bar especially with them being serrated..but carbide doesn't like Interrupted cut I would have tried the bar first ..not gonna be any closer than 4 but where you ground the chuck jaws at that diameter it should be with in 1 in theory

[@phuzzz1]

Nice job Keith, just one question, I understand you have the chuck turning at you and the wheel turning away from you, but I don't know which way you turned the cross slide, was it inward as though you were turning, or outward as though you were boring??

[@phlodel]

A machinist where I worked used a ring in the inside jaws, tensioning the chuck outward. He used a cutter in a boring bar. Ruined the chuck. It resolted in more than .035 runout.

[@punishr36]

Decent video! Unfortunately a very small radius in the jaw from the grinding. Also you would want to check the jaws for squareness by noting the run-out in 2 marked spots along a true shaft not just indicating one spot and saying it's out .004. I would also suggest using the same key hole that was used when tightening the ring for the re-grind. I've done this operation a few times over the years and I surface grind the jaws contact face tangent to the regrind or relieve the back portion of the fixed jaw and open up the clamping diameter prior to the grind. Cheers!

[@skipgoryews1356]

Have you heard of anyone having problems on runout on a six jaw chuck ? thank you for all your vids . Skip Victoria Texas

[@brianfoley4519]

if the run out is at one jaw i ran a lathe in production shop, one jaw was .007 out while the others were really close, so i marked that jaw and used a .006 shim under the one jaw that was out.... made a world of difference...

[@Colin56ish]

I agree Brian. I have tried several different trueing methods, but find some shim is quickest for me.

[@Wolfesmetalfab]

A simple cheap and easy toolpost grinder for this or other purposes can be an air powered pencil die grinder mounted in a boring bar holder, or a regular size air die grinder along with a normal toolpost with a long toolbit or piece of square stock clamped in the toolholder, and a couple hose clamps, one on each end holding the die grinder to the square stock on both ends. Ensure that the clamps are tight and the die grinder is secure. Then you can just use a mounted stone in either one. no expensive toolpost grinder or fancy adapter arbor needed.

[@joandar1]

Totally agreed Wolfesmetalfab, I have used this method on several occasions with great success. On one occasion this was used to repair a tapered roller bearing surface that was suffering from Brinelling (indentations on the track, evenly spaced). The surface was integral with the gear shaft so the alternative was a replacement. Job was a success, the gearbox ran quietly when reassembled. Cheers from John.

[@DeanSegovis]

That's a great technique but it's only as good as where your grinder is mounted relative to the true center of the head stock spindle. I say .004" is pretty good!!! Well done!! I have an old South Bend 9A with a chuck that has about .011" run out measured at the chuck body, more on the work piece.

[@9neil]

Dean Segovis not true Dean. The grinding wheel can be anywhere inside the chuck, and as long as it cuts, it will work. The centre height and angles of the stone sre essentially imaterial.

[@TheEightdigits]

Love the videos, keep them coming!

[@TheDefeatest]

So if the ring is not perfectly round and the bolts are slightly different , wont that affect your new center line of the lathe after grinding the jaws?

[@DrewLSsix]

TheDefeatest no. the ring is just to tension the assembly, the position is still determined by the screws.

[@jonka1]

No any old ring will self-centre on the bolts and produce a true even tension on the jaws.

[@superdansilverman]

I had the same question about variance in bolt diameter.

[@aparfeno]

I believe you ARE correct. Just imagine that this ring would be oval. Sure, the jaws would grip it and there would be tension on each jaw. However, the jaws would not be equidistant from the center.

[@leoaslanian9666]

The video was a good demonstration of how to true up the jaws on the chuck. Yes it would be better if the ring was ground for accuracy and tension. The bolts are a good idea but to achieve a better seating on the ring. Hardened dowel pins would be a better option.

[@charlieroper3987]

Beings you didn't grind across the full radius of each jaw, how can the chuck be true for different OD's of stock?

[@jonka1]

What Keith did was the best for that badly worn chuck. It reveals itself to have an unevenly worn scroll so can never be true for all diameters-hence the run-out on the rod.

[@ScottandTera]

just curious but what about the outside of the jaws where the grip id

[@VintageMachinery]

+Scott Tyndall You could grind them as well with the tool post grinder on the lathe. I rarely use the outside of the jaws, but if I see a need to do it, it would be fairly easy to do. You would just want to chuck something up on the inside first to pre-load the jaws.

[@andrewkoetz3933]

Keith; I acquired a 10x42 Atlas lathe that came with a 4 jaw and a 3 jaw chuck. The three jaw came with two sets of jaws. Someone told me that you need to watch the jaws to see if they are set up for internal or external grabbing of stock. Is this true? This is my first lathe.

[@johnjennings8085]

This method makes more sense. This is the way the chuck will be under load.

[@ScottandTera]

thanks keith

[@VintageMachinery]

+Scott Tyndall Thank you for watching!

[@DumitruUrsu]

Do each of the 3 gears have a specific place in the chuck? I saw that the jaws are numbered, and matched them with the slots - but after cleaning the chuck, it has one point in a full turn where it binds 😟

[@opie7afe]

Yes the chuck should be numbered along with the jaws,remove jaws, find jaw #1 and turn scroll untill you see the entrance to the scroll(like a thread) then repeat for the other 2

[@shilohjim]

I need to true the jaws on a small bench lathe with one piece jaws. Any suggestions?

[@lt1376]

thread on yourself

[@axolpolly3366]

hello keith' 3 jaw chuck how much run out acceptable? my 3 jaw chuck there is about 2 thou' of an inch'' is this is bad? i had this one almost 3 years i used of and on only. thanks Keith,cheers

[@axolpolly3366]

thanks keith'' i like your shows,thanks again cheers. looking forward of your video's to watch.

[@ALSomthin]

I really like this method with a large ring rather than putting a plug in the chuck and tightening it leaving a bit at the end you can never get to.

[@pnwviking757]

I would have tore down the chuck to inspect and clean the wormgear and individual jaw mating surfaces. One jaw looked like it had more material removed and I suspect it might have a burr or some deflect between the contacting surfaces. That would cause the run out after resurfacing.

[@F5Tornado44]

Someone may have already asked this, but wouldn't the grinding wheel being worn down, as it is fed into the chuck, have a slight effect on the accuracy of the grind? It seems to me that it might have more accuracy if you advanced the cross slide feeding in AND out of the chuck. Or maybe that would just lead to a slight crown in the jaws.

[@Bigwingrider1800]

I think the piece used is to thin it flexed a bit you really want it closer then .004 unless the machine is hit..

[@Mercmad]

You are bit game running that tool post grinder without a face mask. I have had a wheel explode on a T/P grinder,which sent bits of wheel everywhere,Including one piece through the roof 60 feet above the lathe...and just like exploding dynamite, it happens quicker than you thought possible. :-)

[@CompEdgeX2013]

I would like to see it re-checked using the ground shank of an endmill. Thats how I checked mine...still got .003" though.

[@robertharker]

About the run-out and repeatability. If you marked the jaw and the piece it would allow you to put the piece back in the chuck in the same orientation. Wouldn't the original un-turned run-out be about the same so the turned part should have minimal run-out? Not perfect but better than slapping the piece back in willie-nillie.

[@littlerick3]

On some of your projects you have chucked bar stock which uses the jaws you ground and bored the inside of the part. Then to finish the outside chucked to the bore and finished the outside. Why don't you also grind the jaws on the outside? Is it because there is not a concentricity spec between the inside and outside of these parts?

[@Kalkaekie]

Interesting !

[@mikewasowski1411]

I watched a video once where the guys lathe stock was misaligned and he unbolted it and tapped it into alignment. Whilst that won’t fix run out, I asked if grinding the jaws would have fixed the his headstock skew as well as any run out all in one? He said no, but I’m still not convinced.

[@Travisfromoregon]

Just a note. I had a small 3 jaw chuck that was always off and couldn't figure it out when I first started playing with the lathe. Turn out the jaws are marked 1,2,3 if you don't put them back in the same order it won't work right. Check out mrpete's video about chucks for more info.

[@cpu64]

Yeah. more like 1/8" runout.

[@texasgonzo67]

not only are they ordered, mine has a specific numbered slot for each jaw.

[@bryantmaximilionalpha2840]

I've worked in machining for years and have found a very simple solution to jaw adjustment on such machines...Each jaw goes in a specific slot and when you don't do it like that, you'll have severe run-out. That's why you mark each jaw as well as the slot they're in, so that next time you know which slot each jaw goes into.

[@VintageMachinery]

Bryant MaximilionAlpha Yes, you are correct that each jaw is numbered to fit into a specific slot and failure to do so will result in the threads not lining up on the scroll right. However, that was not the case here - the runout is from excessive wear of the chuck. Had they jaws been in the wrong slot the runout would have been more than you could grind out!

[@mikecunningham3423]

+Keith Rucker - Won't the circumference of the grinder get smaller as you use it causing the jaws of your chuck to become wedge shaped ?

[@darrylwbraun]

+Mike Cunningham That's exactly what I was thinking. I wonder if there's a particular type of grinding wheel that works best for this sort of work or if the difference can be averaged out by sliding the crossfeed till contact is made at the front on one pass and repeating but making contact at the back on the next pass, and then a 3rd pass making contact in the center first.

[@TroubledTimes2024]

Yeah, I know old video, that said anyone just new to this video needs to finish the job, not mentioned is to disassemble that chuck first and clean, check for issues in mounting and jaws then after grinding disassemble again, clean, remove all that diamond dust and lightly lubricate.

[@ClownWhisper]

Is aluminum stiff enough for this? I just spent hours cutting a ring on a 1-inch hardened steel I thought it was cold rolled steel until I started smoking the room up LOL

[@DrewLSsix]

Clown Whisper the ring just tensions the assembly, it doesnt play any role in the jaws positions besides that.

[@ClownWhisper]

DrewLSsix I wasn't sure how much pressure you have to put on that if it's just to take the stuff out or if you have to put considerable tension on it

[@andrewking2590]

Interesting and impressive procedure. couldn't the .004 run out just be a result of the tolerance of the round stock?

[@VintageMachinery]

+Andrew King Possibly.

[@userwl2850]

should have put the clock closer to the jaws.

[@falcrum19]

Hey Keith, do you think a Logan Model 210 is good for Hobbyengineering? Got Hands on one in really good condition.

[@VintageMachinery]

+falcrum19 I used to have a Logan 210. It is a fine machine for hobby work. The only drawback to this lathe is that it does not have a quick change gear box for changing feeds and thread pitches - you have to manually change out the gears to get the right ratio. It is doable but a pain in that it takes 20-30 minuets every time you need to change the gears. Also, be sure that if you get this machine that it has a a complete set of change gears with it as you will find that you will be spending a lot of money to get the ones you need if you don't. While Logan is no longer in business, one of the family members of the company still has lots of parts and is very helpful if you have any questions on the machines. If you go to my web site at vintagemachinery.org, search for Logan and there are several publication reprints with more info on the lathe. Besides the quick change gear box shortcoming, it is a nice machine capable of doing fine work.

[@falcrum19]

Hey Keith, thank you for answering so quickly, I was able to win this auction, an the lathe costs me 491€ (~530$). The machine comes with several gears also for metric system, a 3 and a 4 point chuck, quickchanger for the lathe tools, several spindles, a table and many many other stuff. I think it was really cheap even for an 69 year old lathe that was redone. Sorry for may bad english, and greetings from germany ;)

[@jimsanker989]

Is it me or did you reverse the direction of the chuck? For an older lathe 4 tho would work for me, If ya got enough money we could always do better

[@andrewking2590]

+jim sanker i think during the fast forward section, the video makes the chuck look like it's running reverse, either a happy coincidence or he really did reverse it. :)

[@physicsguybrian]

Hey Keith is that a precision ground rod? The surface looks bad enough to make me wonder if the runout might be coming from the rod being out of round.

[@BlueRidgeMarine]

Keith, I realize this is an older video of yours but my question is. Would you not first remove the chuck and check the chuck nose for T.I.R? Do a complete head stock alignment first before grinding the jaw's? I have done this in the past, only after setting the complete machine alignment first. x and z axis (with gib job) then setting the tail stock on center before grinding. Your thoughts? Thank you for the great videos.

[@hendersonrosales5056]

All your good points are left out so that the beginner at home will screw up their lathe,it is unfortunate but many on internet leave out the crucial points or steps not always on accident. What about the wear of the grinding wheel if to hard a cut it will be more than a few thousands by time you get to back of jaw.

[@dawnconti2964]

I agree Blue Ridge, If you noticed . ONLY one jaw took most of the grind. do every spec inside first,. NOW, it is still not true and if the REAL problem is corrected, the jaws will need to be ground again. The way this was approached, the symptom is being treated, but NOT the problem. Yeah, i am a woman and machinist of more than 35 yrs. I am a mom of 3 married 25 yrs.

[@texasgonzo67]

+Dawn Conti hey, women make great machinists. It goes hand in hand with their ability to never let shit go. ;-)

[@BedsitBob]

Two questions. 1. Are you sure the 4 thousandth run-out, after grinding, isn't down to the piece of stock not being straight? 2. Why didn't you turn the jaws round, and the grind the other surfaces as well?

[@jonka1]

No it's due to an unevenly worn scroll. There is nothing that can be done about that.

[@fourwheeldrivenut]

hi Keith did you know alot of your older youtube's auto is on left side only?

[@VintageMachinery]

Yes, I had a problem with my wireless mic when I first started doing videos and did not catch it for a while. It has been fixed a long time ago but the old ones are the way they are....

[@fourwheeldrivenut]

thanks for the reply. Im working my way from your older videos to new one after i found you channel.