# D1-4 Spindle & Chuck Measurement and Setup



## Ray C

Hi Folks,

By popular demand, I'll post some information about D1-4 spindle and chuck dimensions which I hope to include various techniques to measure things. We'll need to do all kinds of measuring, use granite plates etc. This will take a few days to get through but by the end, it will show a technique I've been using to true-up chucks so they mount perfectly and repeatably. This is only loosely structured as I'm really low on time these days. -Have 2 paying jobs in the shop and the 9-5 day job is getting in the way too... Hang in there. I promise this will pertain to Metrology using a live example.

Note: I'm not a professional machinist -just a lifelong shop rat that loves this stuff. If along the line, I use incorrect terminology or improvements/suggestions are in order, shout it out. 

Regards

Ray


Part 1:

When I recently mounted my old collet chuck on a new D1-4 back, I discovered the back was pretty crude. It would not mount repeatably and closing the locking lugs was next to impossible. Please see the first picture that shows the problem in exaggerated form. There should be no light coming between backplate and spindle face. BTW: I'm demonstrating on a back that's already been properly fitted so, this will show a "sunny-day" scenario of what's going on.

Also, take a look at the PDF. If you have Adobe Reader, you can click the image and rotate it with the mouse. Please note, the faces of the back and spindle nose must contact at the same time the tapered part of the spindle nose contacts the inner race taper of the back. This is a tough geometry to get right -but if you do, your chucks will mount perfectly -every time.

Part 2 coming in the next thread...


View attachment 95507


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## jgedde

*Re: D1-5 Spindle & Chuck Measurement and Setup*

Looking forward to it!  Not to hijack your OP, but by interest is piqued.

I've made some D1 type attachments for my lathe (a collet closer head and a dog driving plate)...  Here's a 3d model of the collet head and a photo of the assy:




I have a drawing for the camlock pin that I made for anyone's reference.  They're much easier to make than one might expect...  The threads aren't shown in the dwg...



John


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## Ray C

*Re: D1-5 Spindle & Chuck Measurement and Setup*

John,

Very cool... And I like the way you inserted the PDF as a JPG.  I'll do that from now on.  Should have thought of that earlier.



Ray


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## Ray C

*Re: D1-5 Spindle & Chuck Measurement and Setup*

Part 2

Word of caution: When you're doing this, make sure your gears are in a neutral/disengaged state and all the safety locks are activated. Nothing here is done under power but you don't want your lathe turning on accidentally while your fingers, hand, head etc are deep inside the cutting area.

As mentioned I'm intermixing a real problem with Metrology. In this case, the problem is easy to see. -The back is crude and doesn't fit. In real life, the space between the faces was about 2-3 thou meaning, the nose taper was bumping into the back taper first and the overall assembly could not sit flush.

In general when diagnosing a chuck problem, all relevant geometry should be analyzed. First thing I wanted to do is check for gross errors in the spindle. Use a well trusted square, place it on the ways and verify the spindle face is perpendicular to the ways. Rotate the spindle and check in several spots. Square should meet-up flush with the spindle. If something is way off, it needs to be corrected.



Use a good parallel flat bar and make sure the spindle face is even. No (or extremely little) light should shine through. When I got my lathe, I immediately noticed raised areas around the holes that receive the studs. This was an artifact from the drilling process no-doubt. I used hand tools and very carefully removed the burrs and bumps.



While you're at it, you might as well check to see if your crossfeed is square. Check the DI as you hold the parallel in place and run the x-feed back & forth. If there's a problem, it could either be head-misalignment or crossfeed misalignment. Fortunately, this lathe is dead-on!




Now, it's a good idea to measure the angle of the nose taper. First, set the angle of the toolpost to match the angle of the nose taper. I used a small square. Metrology Issue: Getting the DI to meet the taper perpendicularly is important. The ball tip of the DI is parabolic -not round. If the shaft of the DI is not perpendicular to the angle, your measurement could be off a thou or two and in this next measurement, we can't afford that. Please see the next 2 pictures to see what's going on. -And I acknowledge, there are other ways to skin this cat but, this is how I happen to approach this and the steps I personally took. Again, other ideas are more than welcome.





OK, moving right along... Now we need a way to measure horizontal travel of the carriage. We're going to measure "Rise over Run" to calculate angle. Put another DI to measure the carriage travel. If you have DRO, more power to you! Here's how I set it up. -Pretty intuitive...




Ready for our first Metrology measurement now... Position the Toolpost DI at the tall edge of the nose taper and then move your carriage DI to contact the carriage. Zero the faces. Helps to thump the machine a few times to make the DI's settle-out. Next, move the carriage to the right until the toolpost DI reaches the other edge (low side) of the taper. Measure both DI's. You probably want to do this 4-5 times to make sure your setup is rigid and repeatable. Adjust your mag bases and fixtures for rigidity until you get several readings of consistent numbers.

In my case, the spindle DI gave me 0.025" the carriage moved 0.200". Arctan (0.025/0.200) = 7.125*. Guess what, the D1-4 spec says it's supposed to be 7*, 7", 30s -and that equals 7.125*. So far, the spindle is looking good. 

OK, Sasha is extremely bored with this and has decided to rest her head on a pile of laundry to demonstrate (in only a way a dog can do) that it's time to do something else. Not only that, 5:30AM is coming up soon and I gotta sleep fast.

More tomorrow....


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## tripletap3

*Re: D1-5 Spindle & Chuck Measurement and Setup*

Ok I am now subscribed. So I can ask lots of questions. Some may be dumb. :nuts: First one. I see you are using your PM1236 which is a D1-4 for demo purposes. Are your taper measurements only for a D1-5 or do they work for both?


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## Ray C

*Re: D1-5 Spindle & Chuck Measurement and Setup*

Oops.  LOL...  Another lathe I used was D1-5 and I got the title wrong.  Hopefully I can change the title.  :thinking:

EDIT:  BTW, the nose angles for D-4 & 5 (and all the D-types) are the same.  Diameters are different though but everything here custom-mates all the pieces so, getting the diameters right happens by virtue of the process.




tripletap3 said:


> Ok I am now subscribed. So I can ask lots of questions. Some may be dumb. :nuts: First one. I see you are using your PM1236 which is a D1-4 for demo purposes. Are your taper measurements only for a D1-5 or do they work for both?


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## Ray C

All,

I'm going to go back and revise history and change all occurrances of D1-5 to D1-4 to go along with the example. Some might be wondering if the reason my chuck didn't fit is because I had the wrong back. -No, that's not the case. A #5 wouldn't even come close to fitting a #4 spindle and all of the factory supplied backs were maladjusted in the same way. Truth be known, just recently, I mounted several #5 chucks for the prototype shop at work and the two numbers are bouncing around in my head...

I apoligize for the confusion.


BTW:  A quick search of D1 Spindle Dimensions will bring you to a chart like this -which is worth having a look at.  http://www.tools-n-gizmos.com/specs/Lathe_Spindle_Mount.html

Ray


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## GaryK

Great stuff Ray!

Here's a jpg of something close to the link you provided.


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## Ray C

Part 3:

For this example, I'll be citing the dimensions read off this machine, specific to this example.  You'll need to make your own measurements -don't use mine verbatim for obvious reasons.  As you're doing this, take careful measurements.  -Triple check yourself.  Also, note that some of these pictures are staged -taken tonight even though I did the work a while back.  ...Decided to pull a chuck apart to show you guys this because if done right, the results are very rewarding.  Since I put witness marks on the chucks, they'll go back together in a jiffy and it only takes a few minutes to center them.

The tapered nose on the spindle is build-up on a shoulder that has a recess.  See the gap my finger is pointing at in the picture below:




To measure this we'll take low readings from the face of the spindle then, we'll use a shim that butts-up to the very edge of the wide part of the taper.  Admittedly, this is a little dicey but, I couldn't think of any other way to do it.   I got lucky and found a piece of scrap that to the best of my eye, came right up to the edge as needed.  If anyone can suggest a better way of making this measurement, I'd be glad to hear about it.  To make the measurement, you could use a depth gauge or, you could use a DI mounted on the spindle provided the DI has enough throw to gap the distance.   Turns-out, the differences indicated a gap space of 0.100".  See the setup below:





We also need the diameter of the wide part of the taper.  That's easy enough.  It turned out to be 2.475".  See below:




Next, we need to setup for the cutting operation and must adjust the compound to the exact angle of the taper.  I used the back end of a carbide holder mounted in the toolpost and adjusted the compound, carriage and x-feed until it matched exactly.  Back the compound (not crossfeed) in/out until it's an exact match.  Even though we know the angle is 7.125*, you can't trust the markings on the compound as shown.  My compound showed about 6.9* as far as my eyeballs can read the fuzzy lines yet, using very precise   measurements, we found it to be exactly 7.125*.   When you set the correct angle, lock down the compound. See the setup below:







OK, almost ready to have some fun....  In the next part (coming tonight) we need to flatten the back then cut the taper.  See you in a while...


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## 4GSR

I made a chuck adapter several years ago that had to have the taper nose on it for an A-20 mount.  It was 26" in diameter with a 12-1/2" ID hole in it.  The register diameter was 16.250" diameter.  All I had to measure it with was a veriner caliper.  It must have worked, the customer never blinked an eye over it.


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## Ray C

All,

I've deleted the text from this post and split it into 2 parts and re-posted it.  Some kind of weird error occurred with the attachments...  The written text did not change.


Ray


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## Ray C

OK, it seems the attachments in the last post went south for some reason.  Don't know why; nothing different was done than before.  I'll see what can be done and possibly re-post if needed...


Ray


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## Ray C

Since something went wrong with the last post, I'll cut/paste and break it into two posts denoted: Part 4 1, 2.  Hopefully that fixes the problem.

Part 4-1:

When I first checked the plate, it looked pretty crude overall -spun  fast and dirty. Using a parallel, it was easy to see it was everything  but flat. You could cut the back on the lathe but, I love using the  surface grinder and happen to know that few things are prettier than  surface ground cast iron. Turns-out, it was not flat by a good 7-8 thou  as that's how much I recall taking off to to get even cuts across it.  See the pics on how to check for flattness and the finished work (ain't  that purdy?).





OK, now for the real work. It's tedious and you'll probably need to  mount/unmount your chuck several times. The name of the game is to go  light and not take off much. We're going to use the dimensions we  calculated before as a starting point that we back off from.

First, you need to mount the back (taper side out to make the cut) very,  very precisely. It must be flat and centered. Of course, I used a 4J  and had to thump it into position to achieve flattness. It's done in  several steps. First, get it very close to center by reading off the  inside of the taper, then read off the flattend surface to make it flat.  Go back and forth until it's a perfect as you can get it. -Took me a  good 5 minutes or more for each attempt and I had to re-do this 3 times  to get it nailed. Note that since this is a staged stot, you'll see the  TDI reading off the recess cut that was done earlier. The recess cut is  actually coming up next.

Here's how I indicated. See Pics.






.... Continued ...


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## Ray C

Part 4-2:

Now, remember that 0.100" shoulder recess we measured before, we'll cut  that in now. Actually, I cut it a few thou less than 0.100 and the  radial depth doesn't matter because, the nose taper doesn't contact that  part of the back. The little edge that we're making will be the  starting point of the back's taper and we'll turn that taper to about  the diameter we read directly from the base of the nose spindle.  Remember, don't use my numbers. Calculate your own off your equipment.

To make this cut, I moved the whole carriage to the left just a few thou  shy of 0.100. Depth is controlled by pulling in the crossfeed. Go slow,  take your time, measure carefully, work smart and keep your mind on  your work. Here's the edge cut:






Now cut the taper. Go at it real light and keep making measurements at  the very edge to just a few thou less than the diameter of the base of  the spindle. In my case, that was 2.475 and I think I stopped cutting at  2.472 or so.

Here's the cut and a pic of where I read the diameter off of. It helps  to slather a little layout fluid when you're ready for a test fit. The  goal, it to adjust the diameter of the plate taper such that it's snug  on the nose taper yet allows the flat backs to come into contact. Go  cautiously and keep your head on your shoulders. You may have to break  apart, do a test fit and re-center to take more off. See the pics:









Once you get a perfect fit, install the lugs, mount your back, trim the  shoulder flat to accept the the chuck, trim the side and break the  edges. I like the side to be just a bit higher than the chuck body. Your  call. (Edit:  Don't strike witness marks now).  Edit:  It's a good idea to trim the side to the diameter you prefer now.  Coming-up, we'll check the pieces for static balance so, excess material should be removed before balance checking or adjustments.  See the pics:






OK, that's it for tonight... We still have much to do. You can mount the  chuck now for grins but we still have more work to do like verify  flattness, check for static balance and centering... I center different  types of chucks differently... We'll get there. -And yes, I actually use  those cheap HF carbides on CI because I hate ruining my $4.00 tips.  They actually work OK.


Ray...


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## Ray C

Part 4-2 (continued)...

Also, while trimming the side and flattening the shoulder, the center should be re-bored...





Please note that in the previous post, two pictures are repeated at the bottom.  I have no idea why.  They are not shown in the editing panel.

Ray


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## Ray C

OK Guys... The silence is deafening and I'm wondering if this is coming across and well received or if this procedure is being dismissed as lunacy...

In any event, I'll continue later this evening on how to verify the chuck and do basic static balancing checks and adjustments.  The balancing part requires a reasonable balancing apparatus (easy enough to make) and carefully testing on the lathe at different RPMs.  


Ray


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## 4GSR

Thanks for showing a super job of "tuning up" the spindle nose and back plates for yor lathe.  It's a shame that you have to chase problems and fix "junk" that is new, that should have been correct to begin with, from the factory of the far west.


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## Ray C

Wheew.... OK, at least you guys can see this.  I was wondering because of all the weird problems posting the pictures if the posts weren't even reaching anyone...

As far as the quality issue...  Wow, what to say...   The whole world is in a fast-paced mode and people seem to accept quantity over quality.  Everyone (US, China, etc) is in a hurry to finish the product with as few hours of labor as possible -and so the burden of fine detail is left onto the consumer.  In this case, at least the problems can be corrected.  Heck, some things we buy these days can't be fixed so if it doesn't work, you're out $$$.  ... If all you have are lemons, make lemonaide.  In this case, I'll choose to look at it as an opportunity to learn and do new things.  These days, I've had to try to find the sunny side of things -because if I don't, I'll have too much to be sad about ).

Ray

PS:  Writing up the last segment for tonight.  Will post in an hour or so.  -The dog is bored again and we both need a walk.




4gsr said:


> Thanks for showing a super job of "tuning up" the spindle nose and back plates for yor lathe.  It's a shame that you have to chase problems and fix "junk" that is new, that should have been correct to begin with, from the factory of the far west.


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## Ray C

Part 5:

Put your chuck together.  No matter how you mount it, the rim of the back plate should center pretty well -provided you didn't cut the taper too big.  If you did, you haven't damaged the structural integrity but, you'll need to use a DI to center the plate while tapping with a mallot while the D1 lugs are just firm but not tight.  Also note that the D1 lugs should not be screwed-in too deep.  Often times, the threaded holes are not straight and they stick out crooked.  That can influence how the faces mate-up.  All the ones I've seen have a line cut in them.  That line should be 1 turn above flush with the backplate.

Once again, safety...  disengage gears, apply safeties etc...

So far we've been working our way from the left to the right (spindle face, back/spindle interface, chuck shoulder...) etc...  We continue...

OK, wipe all swarf off all mating surfaces and reassemble the chuck and mount on lathe. Remove the jaws and put a TDI at the outter edge of the chuck face.  Spin the chuck by hand and verify that each segment (in this case 3) is perfect.  Over the years, of my 5 chucks, only one was dead on.  All others were out a half thou or more -and that don't cut it for me.  Now if your chuck face is all banged up, you need to set your expectations of how good a reading you can get...   If you're happy with the readings, you can skip a little ahead.  See the pic:




If you're not happy with the readings, most likely, the issue is with burrs, swarf somewhere, or either the backplate or, the width of the chuck body is cock-eyed around the diameter as shown:




How to check who's the culprit...  You really need a granite table for this.  A piece of glass or something else that you think is flat -probably is not.  I should be using a proper height gauge but I don't have one so I get by with a tenth's TDI and a standard mag fixture.  Wipe all your surfaces very clean and first check for small burrs or swarf.   Slide the "height gauge" around on both the body and back as shown and find-out who's the culprit.  If the body is showing a problem, flip it over and check the rim side.  Areas with drill holes are notorious for having a raised ridge.  Take corrective actions.  In one case, I had a body where the backside needed to go in the surface grinder.  Most of the time, it's a burr or hole ridge.  See pics:





You need to work on correcting the problem but before taking any drastic action, go back and check the basics like the spindle face, bearings etc...  Proceed with caution and with your wits about you.

Once things are corrected we can go on to basic balance checking.  Next part, coming up.


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## Ray C

Part 6:  Balance checking and improving the odds...

You need a simple balancing apparatus but it doesn't need to be ultra precision but, should be half-decent.  Here's one I made and it gets used a lot.  Nice feature is that the legs are adjustable for height when dealing with a shaft with different end-diameters.  Also has a 3-point base for quick leveling.  This one has nice roller bearings at the ends of those studs and it can detect as little as 1 gram on a 40lb chuck.  I don't bother to balance to that level though because the jaws at different diameters always throw things off.  That too could be corrected but it's never been enough of a problem for me to lose sleep over...  Pic shown:





Now, get a half-decent shaft (doesn't need to be too special) like a good, unbent boring bar and make a plug with a centered hole that fits in your backplate.  Check the backplate and mark the heavy end.  Put the bar in the chuck by using the jaws (w/o backplate) and find/mark it's heavy side.  After doing about a dozen of these things, I've never encountered either a chuck or backplate that balanced right off the bat.  See pics:






Clean all the surfaces again and put the the two pieces together with heavy sides opposite.  This increases your odds of ending-up with a balanced unit.  Of course, your holes may already be drilled and there's only so much you can do to get the heavy sides opposite.  Try it a few different ways if needed and it's your call if you decide to re-drill holes in a different spot.   See Pic:




Once reassembled, remount the overall assembly on the bar using the jaws and check for overall balance.  How'd it turn out?  

We haven't finished centering things but, you can run it on the lathe and play around.  Make sure your bolts are tight and jaws either removed or safely installed.  Work your speeds up slow to fast even if your chuck is pretty balanced because dynamic balance could still be off.  I have corrected those kinds of things based on my own theories.  So far it's worked but I don't claim them to be bullet-proof.  Also, the type of correction that's made depend if it's a universal, collett or independent chuck as well as how out-of-balance it is.  -Not sure if that aspect is related to Metrology but, I will mention and show the kinds of corrections I have made with the understanding that this is a difficult area to deal with and your mileage may vary...

Going forward, all things related to balancing are your call if you decide to do it or not.  I can't guarantee results and I'm only showing you what I personally did to my chucks, by buddie's chucks and the chucks at the prototype shop at work.  I don't want to cause anyone grief or upset.

That's it for today.

Ray

PS:
... How are things going for everyone?


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## Ray C

Some obligatory statements of common sense and safety...

If you're taking your chucks apart, make sure you're tightening the bolts adequately when testing them on the lathe and work your speeds up slowly -even (especially) if you have new chucks.  

Don't run your chucks with the jaws wide open.  Make sure you have plenty of engagement with their acme screws or scrolls.

If you're not ready to make precision cuts on your backplates etc, wait until you've practiced enough to proceed.  Maybe take some drops and do some trial runs and make a backplate first before chopping-up your originals.

EDIT:  And if you're happy with your chuck the way it is, leave well-enough alone.  You know what they say...  if it ain't broke, don't fix it -or risk fixing it until it is.

-And don't mess with your spindle unless you're willing to suffer the consequences.


etc, etc, etc...  

Sorry to be such a nit about this and I suspect you know where I'm coming from...

Ray


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## GaryK

That's some great stuff Ray!

Now, if I could only get you down here to do all of my chucks!

I would really enjoy seeing you do your thing. )


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## Ray C

Thanks for the kind words, Gary...

You'd have more fun doing your own chucks rather than watching someone else do it.  I admit that taking some of those measurements and making the cuts aren't easy.  -And getting that disk flat and centered for the taper cut is critical.  Very difficult geometries to work with because 2 things need to come together perfectly.  Undercut is the way to go -hard to stick metal back on once it's been shaved off.  Do this when your comfortable and ready for it.  And I must admit, I screwed-up one of my plates doing this.  How?  Instead of cranking in the compound to make the taper cut, I cranked-in the carriage.  -Happens!  No biggie, I just made another one.  Making them ground-up is easier than modifying one.  Finding a piece of stock thick enough is the hard part :angry:.




GaryK said:


> That's some great stuff Ray!
> 
> Now, if I could only get you down here to do all of my chucks!
> 
> I would really enjoy seeing you do your thing. )


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## Ray C

Guys,

Sorry for not finishing the post yesterday about centering/balancing the 3 jaw.  I was having an "off-day" and aside from that, needed the chuck to finish a job.  I took pics of re-centering it and will post later today -probably early evening.

Later on, I think a thread on importance, detection and symptoms of out of balance chucks is in-order.  I'll post my collective observations but don't have answers for some of my own questions...  Anyhow, I don't want this thread about D1-x measurement to get "contaminated" with chuck centering and balancing.

Also, I will start-up a thread about how to inspect, calibrate and do calculations using the compound angle markings...

How's that sound?


Ray


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## tripletap3

Ray C said:


> OK Guys... The silence is deafening and I'm wondering if this is coming across and well received or if this procedure is being dismissed as lunacy...
> 
> Ray



I have been following along and have been taking measurements. Looks like my spindle is dead on and I am not going to touch that. The backing plates on the other hand are machined horrible. Easy fix when I get my stuff from QMT! 
Oh well someday.


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## Ray C

Ok guys, I'm going to make this quick and talk about an easy-case balancing and a few thoughts about body/shaft centering.  Will start a thread later on specifically for balancing and centering issues.

Safety Issues:  When working on your chucks, make sure the jaws are safe, snug-up the bolts well during tests,  work speeds up slowly -And don't leave keys or allen wrenches in the chuck.  Remember, if they're not in your hand, they're on the table -but not in the chuck.

Also, this involves modifying your stuff...  Don't do it if you're not comfortable or willing to take the risks.

Part 7:

By this time, your backplate fits well and centers about dead-on.  You've checked the static balance of the backplate and chuck body and the opposite heavy sides have been put back together.  When testing chucks on the machine, I leave the balance rod locked in the jaws of the chuck.  Note that jaw position impacts the balance.  Obviously, the further they are open, the more it impacts balance.  I have weighed-out jaws on balance scales and they're far from uniform.  It causes noticeable differences in balance but only with an empty chuck.  If you're cutting big diameter stock, chuck balance will be impacted anyhow in ways you cannot predict.  I have had situations whereby rotating the workpiece a little made a vibration go away.  This is not idel and woudn't fly for high-end production/CNC machines but, we can get-away with it on manual homeshop stuff.

With the opposite heavy sides put back together, with any luck, the chuck has a more neutral balance than it did before.  If you haven't already, tighten the bolts and test it on the lathe working the speeds from slow to fast.  If you have little to no vibration at all speeds, quit while you're ahead and take the afternoon off.  In the absence of a dynamic balance machine there's not much more you should do.  If the chuck is really out of whack, it can shake the machine pretty good.  -That's what the emergency stop switches are for!

If you have vibrations which you know will show-up on the workpiece, a small amount of correction can be made in one of two ways.  If there's a gentle settling toward the heavy side, you can either drill divots in the backplate on the heavy side or, if you have a chuck that has internal cavities, you can internally add weight to the light side.  I've done both methods with good success. I won't be discussing in this thread how I added internal weight.

When finding how much the chuck is off, I've found it helpful to tape coins to the light side.  This will give you a ballpark idea of how much drilling to do. You need to wrap tape all the way around because of the oily chucks...

 One thing to note:  A chuck that is perfectly statically balanced could shake like hell when spun at-speed.  -Dynamic imbalance rears it's ugly head -and sometimes at one speed but not at others.   The point is this:  Don't keep drilling divots until the static balance is perfect.  No, instead, drill a little divot that helps the static balance a little then, go back and test at all speeds on the machine.   If you have a very heavy chuck -too bad!  Do the tests anyhow.  Proceed and make adjustments conservatively.  If you get to the point that the chuck is statically balanced but still shakes, read the next paragraph.

It's entirely possible you have a no-good chuck no matter what you do.  -It's never happened to me or anyone I know but, from a mathematical and physical point of view, it's entirely possible.  Of course, someone with the abilty to do dynamic balancing could identify the problem area(s) [note the plural].  I have a technique to approximate this but, it's not tried & true.

That's about it for balancing (as far as this thread goes).  Here's a picture of divots in one of my back plates.  Note that I spread them out a little.  A Word of Caution About Divots:  -Not that you should not be putting your hand on the chuck when it's spinning at any time -But, if you happen to get your pinky in that divot hole, you're going to have one finger shorter than the other.  Drill the divots shallow.  BTW: the same injury could occur due to the bolt-hole recesses. -Get it?  -Don't put your hand on the chuck.  I did it once and ended-up with 7 stitches (fortunately, I know how to suture myself but my wife had to tie the knots).

Anyhow, this chuck now balances very well at most speeds when not loaded with a workpiece.  BTW: One of the reasons, I'm switching my machines to 3 phase is so I can tweak-out vibrations with frequency control.




Part 8 coming up -a quick thought about body vs shaft centering when mounting a chuck to a backplate.


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## Ray C

OK, here's the last of it...

Part 8:

The back now centers well and now the body needs centering.  These are my own practices and I'm not claiming them to be the best or only way.  And mind you, this is geared toward homeshop manual lathes and "average" chucks.  The situation probably changes with high-end equipment and high-dollar chucks...

For a 3J chuck, I don't center the body perfectly with the backplate but rather, center the body based off a known shaft in it's jaws.  Why?  First, all jawed chucks have their issues.  Swarf can throw them off and with 3J's the scroll and ring gear may not be perfect.  Every one I've used may center well at some diameters but not others...  With 4J chucks, I center the body reading with a DI on a smooth part of the body.

Standard Safety Issues Here:  Watch the keys, allen wrenches, power switches etc...

Once the chuck is on the lathe, mount a good rod and if it's dead on, tighten the bolts and go buy a lottery ticket because it's your very lucky day.  After that, loosen it's holding bolts just enough so a tap with a mallet can make an adjustment.  Of course use a block of wood etc as a buffer.  For 3J, hand spin the chuck and make body adjustments until it's centered while reading a TDI indicating off a test rod.  Simple as that.  If the shoulder on the backplate is cut very tight, you may have to tweak it to make body adjustments.  Don't bang real hard on the body -the spindle bearings don't like that.

Again, for 4J, DI off the body, make adjustments with the mallet then tighten the bolts.  After that, you can center a shaft and admire your work.  Of course, it's possible that taking a reading 6" down from the shaft that everything is off again.  Since we know everything else (spindle, backplate etc) is flat, the problem is due to jaws not holding square.  -That's another issue to talk about later.  One thing I will say, if you want a shaft perfect, most chucks won't get you there.  You stand a chance with a good collet chuck and can only clinch it by turning between centers (if possible).  Life isn't perfect...

Here's some obligatory pictures.  I'm showing a collet chuck because the 4J is on the mill at the moment.  -and keep in mind that I broke the allen-wrench rule because nobody was around to take the picture -and I only have 2 arms.  BTW:  My collet chuck is so dead-on, I can center off the body or off the shaft and get pretty-much the same readings.  Differences are due to the collets themselves.  When I "body center" a collet chuck, I read off the taper the collet sits in -not the body.  This $175 chuck was well made!

...  That's pretty much it.  This was intended to pass on some of my observations and techniques (for better or worse) and maybe to help set expectations for folks that are new to lathes.  -And again, I am NOT a professional and all the above is worth what you paid me for it.

Ray


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## outsider347

Outstanding info here Ray. I even understand most of what you are doing

Anyway, my lathe is a basic screw on  Atlas spindle & I know it has dimensional issues, chuck related.

Now I think I can better locate  the problem areas & have confidence to fix it. Every little bit helps

Keep up the good work & basic verbiage for us rookies


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## Ray C

Glad it's helpful.  If you encounter issues as you address your own problem, don't be afraid to post questions.




outsider347 said:


> Outstanding info here Ray. I even understand most of what you are doing
> 
> Anyway, my lathe is a basic screw on Atlas spindle & I know it has dimensional issues, chuck related.
> 
> Now I think I can better locate the problem areas & have confidence to fix it. Every little bit helps
> 
> Keep up the good work & basic verbiage for us rookies


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## MikeWi

I've greatly enjoyed reading this thread Ray, and as I'm receiving a new lathe at the end of the month, it helps me to check up on things before it gets used.  I'll need some practice before being brave enough to do any adjustments, but hopefully it won't be too far off out of the box. 

I'm learning an amazing amount on this site.  This is better than any book, although I always collect all sorts of books on my hobbies.


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## Ray C

Thanks for the kind words...

It surprises me how far off some of the back plates are and it's really annoying when they don't fit well (or if they fit at all).

Just remember, proceed cautiously as once you take metal off, it's real hard getting it back on.  And if you make a boo-boo, you'll probably still end-up with a better fitting chuck than what you started with.  At least it will go on and sit flush then, you can tap it into center before cranking the lugs tight.  In the worst case, you'll need to buy a new back plate.  It's all part and parcel of learning this stuff.

Good luck with your new equipment!

Ray

EDIT:  You might want to look at the recent tread about fitting a chuck to a backplate.  There's a few more details to ponder.
http://www.hobby-machinist.com/showthread.php/13332-Fitting-new-chuck-to-backplate-for-beginners



MikeWi said:


> I've greatly enjoyed reading this thread Ray, and as I'm receiving a new lathe at the end of the month, it helps me to check up on things before it gets used.  I'll need some practice before being brave enough to do any adjustments, but hopefully it won't be too far off out of the box.
> 
> I'm learning an amazing amount on this site.  This is better than any book, although I always collect all sorts of books on my hobbies.


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## xalky

This is an excellent write up. Our lathes are very similar except mines older. I'm going to be making a faceplate for it sometime in the near future This tutorial will help me to make it just right.


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## Ray C

One thing to mention...  You don't absolutely need a surface grinder to flatten the side of the backplate that contacts the spindle.  If you don't have a SG, just make a witness mark (with ink at first) on the side of the spindle and backplate and always attach it in that orientation.  Next, mount the plate and surface the side that contacts the chuck.  -Then follow the rest of the procedure.  Doing it this way will mask any potential mis-alignment between the spindle and backplate.

Ray




xalky said:


> This is an excellent write up. Our lathes are very similar except mines older. I'm going to be making a faceplate for it sometime in the near future This tutorial will help me to make it just right.


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## xalky

No SG here. I can get the faceplate  roughed in on the mill and then finish cut it on the lathe.  When I did my Chinese chuck and faceplate on the Southbend 9 a was able do get it dialed in by changing the chuck orientation to the backplate, i had 3 positions by rotating it 120 degrees. I was able to get real close that way. and then just snugging up the backplate to chuck bolts a little and tapping the chuck with a soft face hammer, i was able to get it within .001 in all directions, checked with a piece of drill rod chucked up in the jaws, and indicating to the drill rod. I was pretty proud of myself. )


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## Ray C

Just want to mention that there's no mysteries to be solved here.  Fitting a chuck is a basic and simple operation.  Here's my general philosophy and procedure.



The interface between the spindle and backplate must be flat and repeatable. 
The chuck should be fairly well balanced.  The backplate should be fairly well balanced.  The overall combination of the two should be fairly well balanced.  It's hard to achieve perfect dynamic balance at all speeds thus, static balance is usually the best you can do. 
The interface between the backplate and chuck should be trued-up such that the face of the chuck shows no runout.  If there is runout in the face, you start by facing the backplate. After adjusting that, if the face of the chuck will not read with zero runout then, you need to adjust the back of the chuck. 
I am not a big fan of making a shoulder on the backplate that tightly fits the chuck.  The chuck should be centered on the backplate such that a rod placed in a collet chuck or 3 jaw scroll chuck shows little/no runout when reading about 1" protruding from the jaws or collet.  A 4 jaw chuck should be centered on the backplate by reading off the side body of the chuck.  If you make a tightly fitting shoulder, you won't be able to make these adjustments and you're at the mercy of how well centered the chuck cavity is when it was machined. 
The jaws of any chuck should be adjusted such that there is minimal runout  (up to 4 thou) when reading with a DI off a rod about 6" from the face of the jaws.   This is adjusted by filing/grinding the gripping teeth of the jaws.  If you have a chuck with sloppy fitting jaws within their journals that will not repeat and hold within 4 thou, it's likely time for a new chuck. 

This is how I adjust all my chucks and if I need to spin with higher levels of precision, I use a dog and spin between centers.

Ray


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## miannini

This post is great. I´ll try to fix my lousy D1-4 chucks (the 3J is off by 4 thou and the 4j is off by 15-20 thou!). And they are not repeatable at all.

It may be a lot off topic, but I´ve readed in "Home Workshop Hints and Tips" about using a accurately machined between centers piece of round stock, mount it between centers, tighten the chuck´s own jaws in it´s middle and then turn (face) the chuck back plate. Has someone tried it? It seemed pretty ingenious to me. This topic of the book was called "curing the incurable chuck".


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## Bruce Bellows

This may be a little more information then what members might be looking for but I happen to have the manufacturing dimensions and tolerances for lathe chucks and spindle noses that I purchased from ASME (American Society of Mechanical Engineers). Its a copyrighted doc. # USAS B5.9 - 1967  (45 pages) . It covers spindle nose Types A, B, D, and L . I will share info from it with those who need it.


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## extropic

Hello Bruce,
I bumped into this old thread because of your recent reply.
The OP wrote (#1) "There should be no light coming between backplate and spindle face."
I'm interpreting that sentence to mean that both the planar faces and the conical surface are supposed (designed, intended) to be in intimate contact simultaneously.
I've read that opinion before but never seen it in a controlling specification.
I'm wondering if B5.9 makes any statements that would support the OP's statement?
Can you shed any light?


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## Bruce Bellows

Hi extropic

It will be a few days before I have the time to dig through the specs but I will get back to you with what I find out.


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