Mini Lathe Chuck Runout

hi it's Frank who's from mini-live calm a few days ago I posted a video on spindle run out on the mini lathe and I got to thinking about some of the issues there and decided I'd like to do a follow up which is this video having to do with run out associated with the three jaw Chuck the concepts I'm going to be talking about here are really directed towards new lathe workers new metal lathe workers so if you've been using a metal lathe for a year or more there's a good chance you're pretty familiar with the topics I'm going to cover here so you may not want to spend your time on this one but I hope there's some good material and if you're real new to working with metal layers you might find a few tips here that explain some mysteries that you've either encountered or probably will encounter if you haven't already so I hope you can find some good material here thanks for our first run-out test with the Chuck I'm gonna just take this shank from a broken end mill and chuck it in here it's a little less than five thousandths of a run out and that's what we call total indicated run out or TIR you may have seen that term but it's just a full swing of the indicator so let's check the concentricity of this over on the measuring mention just to make sure that piece really is round I have the end mill shank set up here in a V block there's a precision V block and I've got two heavy one two three blocks holding it in place just so I don't you know vertically move it while I'm trying to rotate it and I have the indicator set up let me see if I can move in a little closer here so you can see what's happening with the indicator now what I'm going to try to do is rotate this carefully let's first put some preload on the indicator so you can see that we are indeed touching now I'm going to use my finger if you look carefully you may be able to see there's some writing on the shank there and you'll see that rotate around or maybe you will see if I couldn't assume out just a bit there okay and I'm now rotating it around if you look at the indicator needle see there's virtually no movement or maybe if there is it's probably well under a tenth of a thousandth so we know this piece is very round and that's what you'd expect since it's a end mill shank and it has to fit tightly into a collet or an end mill adapter just for comparison I've taken a piece of six-oh six-one aluminum stock here and I'm going to rotate it you can see then the needles jumping all over the place and that's mainly because the surface isn't really that rough but as I try to rotate it let's use two hands here no be less bumpy there you go so mostly what we're seeing here is some surface roughness but there's a probably well over a thousandth of run out as we go all the way around the diameter so that's pretty typical for you know rough stock if you're using something like drill rod it would be a lot less run out and a lot smoother another factor to be aware of is that with a three jaw Chuck the jaws are numbered and they should be installed in a specific sequence of one two three as you go clockwise around as you turn the Chuck clockwise around and I've marked on my chucks I typically put little punch marks here so I have one punch mark for job one two punch marks for jaw two and three punch marks for jaw three but if you remove the jaws and you look carefully inside on most chucks even low-cost ones the number one the hole for the number one jaw will have the serial number steamed down on the face of the Chuck say if you start from there you put your number one jaw in that location then you rotate it around and put your number two Chuck number two jaw in and then your number three jaw in now if you had two jaws out of sequence for example if you have one three - they wouldn't meet in the middle at all but it is possible for example to put them in sequence but in there not in the original starting hole so you might for example put JA one into slot 2 and then JA 2 into slot 3 and then JA 3 goes where the number 1 ja would normally go and there's a lot more information about this on my website on the trucks page if you're interested now we saw in the video from yesterday that the the important surface when it comes to using the chuck at least is this raised boss here on the front of the spindle because that's the surface against which the recess in the Chuck aligns and on this particular lathe you can see that there's a you know maybe three to four ten thousandths of run out there but anything under a thousandth that's pretty good under half a thousandth is what I'd like to see on a mini lathe but let's put the truck in place and see what we get when we mount the Chuck on the spindle this recess on the back of the truck is going to line up with that raised area on the front of the spindle and that helps to ensure that the chuck is very closely aligned with the centerline of the spindle so let me get the screws in place then we'll do a measurement out here beyond the chuck jaws I'm getting ready to put a shank from a broken end mill in here but first I want to make sure that there are no chips or other residue in here that might throw off the alignment so if you're trying to do precision work that's always a good ideas clean off your Chuck jaws before you insert your work but as most of you are well aware you can't really get precision concentricity using a 3d jaw chuck in general and that's what i'm about to explain is the in general part I didn't do anything special when I clamped down on this I just put the Chuck key and for told it was accessible and I didn't even notice whether I used more than one hole but often I'll tighten it down on all three holes because that I like to think that that helps to provide you know more and more even clamping force on their workpiece but as you can see just as I turn they check by hand here there's quite a lot of movement in fact I don't even have enough don't have the indicator down all the way there but easily 6/10 I guess are not six tenths but six thousandths but there's a lot of slop typically in the drawers themselves and the scroll behind the jaws the tightening mechanism and I have to be careful here with this flat so I'll try to place that between two of the jaws so it doesn't introduce any further variations there but let's try that again now having adjusted it and what you see is it didn't really help much so the bottom line here is that a chuck of this quality you know and it's not a bad quality Chuck this is just typical for inexpensive three-jaw chucks that's typically what you'll get is something like that now you may luck out you can get a particularly good one that is better than that or you may get one that's a little worse than that but that's just sort of the way it is with a three jaw Chuck and that's why when people want to do you know work that has to be precisely aligned they use a collet or a four jaw Chuck rather than a three jaw Chuck so I'll try one more attempt here I'll loosen this up one more time and twist it around a little bit let me put it a little bit farther back in the drawers there see if that makes a difference and this time we're going to tighten all three of the key positions there get our indicator back in place and it's still pretty bad so just to be sure it's not the workpiece itself let me take this one out and try something else try another pick the workpiece this piece of material is a part of a shaft that I removed from a laser printer some years ago and it looks like it's precision finished but let's test it with the dial test indicator and see how it checks out well as we did before I'll just rotate this slowly in the V block and as you can see there's really no discernible movement if I lift up on it you can see it really is making contact but as I rotate it there's almost no visible movement on the dial indicator so that tells us that this is a very accurately round piece of stock or at least it has very few surface imperfections okay I've got it in there and chucked in place and what you can see is that they're still you know about five thousands or so maybe six thousandths of run-out let's try to run my lathe and see what we get we'll take that same piece and put it on the bigger lathe okay this time we're looking at the precision Matthews PM 12:28 d4 camlock spindle and on that type of a spindle the registration of the chuck is on the outer surface of this boss here and let's bed and turn the lathe on and see what type of run-out we see there you can see zoom in on the dial indicator there and you can see it's pretty low it's well under 1/10 well I won't say it's under a tenth but it's not much more than a tenth he can see is a little bump there and those divisions again are half a thousandth or five ten thousands apart so it's pretty good and we'll check the the taper surface as well in this way that has a Morse taper number five or maybe it's a number six let's see the number five Morse taper on the boar and you can see I've shaved that a little bit you can see it better I think but it's a pretty low run out you know not more than a tenth I would say and that's not surprising since this is a this lathe costs you know more than four times as much as the mini lathe and of course if you had a ten or twenty thousand dollar leave you might see even better results but this is pretty good and certainly for home shop work it's uh it makes me happy so there we go all right well I went ahead and mounted the stock six inch diameter anomaly three jaw Chuck this is the standard Chuck that comes with this lathe and I've put our same test piece in here looks got some sort of bump on there but let's go ahead and turn it on zoom in on that a little bit and we're getting looks like about three thousandths maybe of total indicator to run out maybe two and a half let me see if I can lined it up with a zero mark there not that it really matters it's actually around mm looks like so what's the difference the difference is that this particular chuck is inherently a little better than the one that's on the mini lathe but it's a three jaw Chuck and as I said because of the scroll mechanism you know that that's about as good as you can expect if you find a three jaw Chuck but tightens consistently to under a thousandth of run-out you've got yourself a a good Chuck and there are Chuck's by the way you've probably heard about them or have one maybe that have adjustments that you can they once you've clamped your workpiece in here you can make an adjustment after that and align the Chuck or zero in the Chuck using a dial indicator we're back over at the mini lathes now and I've chucked that same work pieces here in the three jaw Chuck and let's take a readout on that and as before we're seeing you know six or seven thousandths of a run-out and if we go down here to this surface where it's been turned down previously maybe a year ago who knows just the piece I grabbed out of the scrap drawer see there's a lot of run out there but it's probably concentric now there's enough to run out and you can probably see it yourself if i zoom in on this work piece it's there's enough to run out that you can actually see it going up and down without even looking at the indicator so that's a fair amount of run-out when you can see it by eyeball the next thing I want to do is take a cut you know so I'm gonna advance the tool there a little bit and then I'll just take a light turning cut here you can hear it sort of pulsing and that's due to the off-center nature of that workpiece but if I make a second pass it should be a little better let me turn up the RPM some [Applause] all right so we made a third pass and got that surface pretty clean there and let's put the indicator on it with the indicator down on to the workpiece and lo and behold our run out now is way lower it's just maybe a tenth or two and it's probably very close to or the same as the run out that we measured on the spindle itself so that's the interesting thing that you have to keep in mind you can see if you look out here at this tip that I didn't turn it's still wobbling up and down but in the back part here is wobbling up and down but the surface that I turned is now concentric with the spindle itself so that's the the magic of turning work in a three jaw Chuck a lot of people don't realize this or a lot of newbies don't realize it is that once you take your first cut that surface will now be as concentric as the spindle itself or close to that and if you now make additional cuts I'll go ahead and turn the surface out here and turn another surface all of those surfaces also will be concentric so and if we'd then cut that piece off and we're done with it then we have a piece that's very concentric regardless of the fact that it was off-center when we started but there's a caveat and I'll get to that and you probably know what it is off camera I turned down to another section of this work piece right here and right now I have the dial test indicator indicating against the surface that was not yet turned and I'll take a look at that we've seen that before and there's our run-out that we had before but if we now move the indicator over here to the part that I just turned and touch the indicator up against there you can see this very little run out you know maybe just a few tents and so the lesson there is that once you take a turning cut on your workpiece regardless of how off-center it is in the Chuck the part do you turn will be concentric with the spindle and usually to within the accuracy of the spindle bearings so good thing to keep in mind now here's the caveat that's great as long as you are machining a series of surfaces that you can if you can cut all the surfaces in one pass or multiple passes one checking I should say of the workpiece and then you're done then everything will be great the problem comes about is if you need to turn the workpiece around to do work on another end when you reach chuck it to do the second end then it's that's and will not be concentric with the first end so in that case you can't use a three jaw Chuck to get concentricity you have to go to a call up or a four jaw so let's look at that I've checked up a piece of 3/4 inch diameter 6-0 6-1 aluminum bar and it's had some previous work done it has a very rough cut on here from some previous life but I've chucked it up and let's check the run out on the piece as it's in there right now and again it's around four to five thousands maybe a little better than we were getting before but that's probably just the luck of the draw so let's make a turning cut on that I've engaged the power feed which should give us a little bit smoother and more even cut than turning by hand we'll make one more pass here [Applause] well that's good enough for what we're doing here let's get the dial indicator on it I've just a note on terminology I called this a dial indicator technically it's a dial test indicator but it is a form of dial indicator and it's just a different configuration that is the advantage of a dial test indicator it has this fine tip that lets you reach down inside of a bore or other difficult to access surface all right so let's bring the indicator probe down onto the surface there and as you can see there's a little bit of jitter there but it's you know looks like it's during about a half thousand maybe maybe a little more maybe a little less but less than a thousandth in any case that's not too bad but let's suppose now that for whatever work piece whatever thing it is we're making we need to machine another feature on the other end so we're going to take this work piece out and I'll cut it off a little bit shorter and then we're going to flip it over and reach uh KITT on this end and then turn a feature of it on what will be the Sun down here okay I took the workpiece over here to the four by six bandsaw there we go you may wonder why I didn't cut that off in the lave using a cut-off tool and the answer is it's difficult to cut things off on the mini lathe as most of you probably know if you have one this is an ancient 1999 model Harbor Freight 4x6 bandsaw which has been modified quite a lot you may have seen it in some of my other videos but I've gotten to fine-tune I'm pretty happy with it I made this nice bench for with a big chip tray underneath but let's get the work back over to the lathe now I'm going to take our finished end and before I do that I want to clean off any chips on the Chuck jaws just because they could affect the registration or the you know the accuracy with which the workpiece seats in the jaws if you have a chips in there other residue it's going to affect the alignment and will tighten up on all three holes and then just to see where we are we'll do a test on this surface here okay I've got the dial indicator dial test indicator set up on there and let's turn it on and see we got Wow so we've got like what is it maybe nine thousands or something like that quite a lot of run out there yeah it looks like ten thousands so what does that tell us well when you take a workpiece out of the three jaw Chuck and flip it over when you clamp it back down all bets are off as far as concentricity with the machine side but let's now take a cut on this side and see what happens all right I made a couple of passes over it and face the end put a little chamfer on it here to get the sharp corners off let's put the indicator on and see what it looks like okay well turn the lathe on and bring the indicator down and as we saw when we machined the other side now that we've taken a couple of cleanup passes grounds pretty good you know it's only like a thousandth or less half a thousandth maybe pretty darn good so it's all perfect right well maybe maybe not the Aral issue is when we flip this over is the new surface now concentric with the old surface alright so now I'm clamped on the surface that was out and this is our original surface and you probably already know what's gonna happen but let's turn it on and see well back to our old run out again and therein lies the tragedy of the three jaw Chuck all right then so that sums up our work on the three jaw and I hope to do another episode soon where we'll compare that with a four jaw Chuck and some of the reasons why you use a four jaw rather than a three jaw but if you're new to all this I hope you learned a few things and if you're not new I hope I didn't bore you to death but in any case thanks for watching see you next time

Channel: Frank Hoose

Views: 92,046

Keywords: 3-jaw chuck, lathe runout, dial indicator, dial test indicator, mini lathe, mini-lathe.com

Id: KWuk8DpIyQs

Length: 24min 40sec (1480 seconds)

Published: Wed Nov 08 2017