Tailstock alignment.

There are two usual methods to align a lathe tailstock.
1. Put a bar between centres and take a cut along its length, measure each end, adjust tailstock and repeat procedure until it is within acceptable limits. This is time consuming and you reduce your bar to swarf.

2. Get a standard ground alignment bar made for the purpose. Mount it and traverse its length with an indicator. Adjust tailstock to suit. This can be much quicker than method 1. but you need to have an alignment bar.

Having been born with a hefty dose of the lazy gene I wanted something with less work and this is how I do it.

Attachment 15554
Just rotate the chuck and watch the clock. Adjust as required.

This works as to the centers, when adjacent. Alignment bars determine this too, along with an indicator, that detect alignment and parallelism regarding both planes to the ways. Taper when machining originates in one or all.
C-Bag just tested his, and regulated from .004 something to a couple tenths. In a part of any length that's a reduction of 20x.

Thanks Tony, I like the method you use when machining shorter parts. I use several different methods for tailstock alignment for longer parts and have come the conclusion that no matter how well it is initially aligned, there are too many other production factors that can still cause a slight tailstock misalignment when machining a batch of the same parts to be within +/- 0.0005" of spec.

I also recommend learning to use a good lathe file and emery cloth, and taking periodic micrometer measurements along the length of the part to finish the part to a tight spec. I found that even after waiting for the part to cool down after machining, the hot halogen work light can throw your part off spec and may need to be turned before taking the final measurements.

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Originally Posted by Paul Jones

Thanks Tony, I like the method you use when machining shorter parts. I use several different methods for tailstock alignment for longer parts and have come the conclusion that no matter how well it is initially aligned, there are too many other production factors that can still cause a slight tailstock misalignment when machining a batch of the same parts to be within +/- 0.0005" of spec.

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Of course you are right, that method only checks alignment when up close, but on the other hand an alignment bar only checks it when not up close. However, if the two differ then there is more than tailstock alignment to consider. Either worn ways, badly aligned bed or head misalignment, which need fixing anyway. I can't recall ever needing to machine a long taper by offsetting the tailstock, neither do I often need to make long parts between centres so my main concern is relatively good alignment for drilling and reaming etc.
I didn't have an alignment bar and that left me with the No.1 method in my post, that is OK for checking the adjustable lateral alignment but not so much the non-adjustable vertical. I was suspicious of the vertical alignment on my lathe and that was really the motivation for checking that with the dial gauge method. I was right, the tailstock seems to have been let out of the factory lower than the headstock. Shimming was the only way to fix it, not ideal but needs must, unless I machine the base of the head stock and that wouldn't be too easy. I wish that the tailstock had been high, I could have fixed that easily.

Quote:

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Originally Posted by Paul Jones

I found that even ......, the hot halogen work light can throw your part off spec and may need to be turned before taking the final measurements.

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Ha ha, there is an easy cure for that. I use LED lights for the up close machinery illumination.

I had a guy come in and scrape the ways on one my old lathes. Ideally we should have removed the head stock then trued the entire bed but time and money really didn't allow this extensive of a repair to be done. Jack specialized in truing up machines for a living and although I knew the process and had done 1 or 2 bed scrapes on smaller lathes like Atlas and Craftsmen, but for my Victor 16/22x 60 I felt that a professional could do a better job a whole lot faster than I could have done at the time.
He rolled in a couple of wooden boxes and his tool chest then we started in. First he opened 1 8ft long box with a hollow 1.70" diameter truing bar in it and a polished thin wall tube about 18" long the thin tube went in the spindle bore to protect the truing bar as it was slid through the spindle My lathe had a back thread on the outside of the spindle where I kept a small 4 jaw chuck mounted for when I machined long cylinder rods so this was a help in checking the head alignment to the bed He put on a pair of nitril gloves than a pair of soft cotton gloves before he handled his truing bar after checking the bed in dozens of places he determined that about .003" would be the minimum that needed removed but that would still leave a slight dip of about .002" in one small 12" long area We opted to remove the full .005" Then he trued the cross slide but did not remove the carriage top from the apron which he felt really needed attention I just couldn't afford that extensive of a repair If I could have we would have removed the head stock to set everything perfect. After the work on the bed and cross slide was completed we removed the tail stock from its base and shimmed it back to the proper height it took nearly .015" apparently it had been low for along time or someone had scraped the bed long before I got the lathe.
I don't have a problem with a shimmed tail stock just like I didn't have a problem with paying the $1,500.00 for the work he did because it would have cost me twice that to have tried to do the job by myself even if I could have rented the necessary equipment that I didn't own for the task

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Originally Posted by Frank S

I had a guy come in and scrape the ways on one my old lathes. ...equipment that I didn't own for the task

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My lathe had hardened ways with little use so previous scraping wasn't the culprit for my low tailstock. It had to have come out of the factory like it or someone had changed the tailstock at some stage but it gives every sign of being original. I wouldn't have been too happy with the idea of shimming if I was in the habit of having to offset it, but once aligned it stays where it is. Although I check it again before anything critical.

I can understand where you are coming from. I've never offset any of my tail stocks I did at one time have an adjustable live center which could be offset that I found quite handy a few times.

Hi Tony
Thanks for your excellent postings I shall be following them with great interest, lovely bike buy the way, I cant recall the Italians ever making a bad one. Re tailstock alignment every production lathe I have used has had a dropped tailstock due to wear of the base casting having a smaller footprint than the saddle, and probably sliding along the bed a lot more in use. One of my earlier posts was reboring the tailstock in sit u and making a new barrel, been great ever since.
Given your obvious expertise in machining morse tapers etc I am sure you could do this if you wished.
Regards
Olderdan

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Originally Posted by olderdan

Hi Tony
lovely bike buy the way, I cant recall the Italians ever making a bad one.

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The Italians didn't make that, I did. That's what I use my tools for.

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Originally Posted by olderdan

One of my earlier posts was reboring the tailstock in sit u and making a new barrel, been great ever since.
Given your obvious expertise in machining morse tapers etc I am sure you could do this if you wished.

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Thanks, I'll look out your post. Actually it would be great idea for me because I'd like to go up a step with the morse taper. It is only MT2. I still have a lot of MT3 stuff from a past life.
Just an idea but I could permanently dowel and bolt the two halves of the tail stock together to essentially turn it into a single piece.

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Originally Posted by olderdan

Hi Tony
lovely bike buy the way, I cant recall the Italians ever making a bad one.

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Oops, did I get that wrong? Maybe I'm thinking of the wrong bike. The pics that I posted in another thread were made by me except for the engines. Maybe you were thinking of the Aermacchi engine photo, The cases of that engine were Italian but the innards and the chassis were mine again. I didn't post a pic. of that in a chassis so here are a couple.
Attachment 15562 Attachment 15563

And some putting it to use.
Attachment 15564 Attachment 15565

Thanks Tony for the pics, I could see that your bike is very special but to me still still has the lines of a classic machine, quite an achievement. I love those 4LS brakes and Ceriani type forks.
I'm stuck in a time warp with old British iron and don't ride any more but still enjoy restoring them, I envy the fun you are having.

Dan,

Sorry to read that you don't ride anymore but you are right I am having a bunch of fun.
I built it for classic races, it is basically a replica of the bike that I built in the early 70s, they weren't considered classics then. I used disc brakes back then, but under most classic racing organization's rules now I have had to go back to drums. I much prefer discs.
I have two main ambitions, I raced at Daytona in 2006 and I want to do that again when I'm 80. The other is that I'd like one more crack at the IoM, I rode there several times in the early 70s. I would like to ride in the classic TT.
I cut my teeth on Brit iron but never liked them much except for Vincents which I never owned. Most did three things that I hated.
1. Leaked oil.
2. Vibrated.
3. Broke down, often due to the Prince of Darkness.

Here is a pic of my first race (1960) on the race bike that I built up. A Maton (Matchless engine, Norton frame).

Attachment 15583 Attachment 15584

This is at Ballaugh during my first visit to the island and my first race at Daytona some 46 years after my first ever.

Attachment 15585 Attachment 15586

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Thanks tonyfoale! We've added your Tailstock Alignment Method to our Measuring and Marking category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-tailstock-alignment-method-2"> <img src="/uploads/162681/homemade-tailstock-alignment-method-2.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-tailstock-alignment-method-2">Tailstock Alignment Method</a> <span> by <a href="http://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/alignment'>alignment</a>, <a href='http://www.homemadetools.net/tag/measurement'>measurement</a>, <a href='http://www.homemadetools.net/tag/tailstock'>tailstock</a> </div> </div> </div> </div>
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tonyfoale,
Very clever idea. I like and will use that method. Keep in mind that vertical shimming up the dropped tailstock (a few thousandths) matters little as long as the work is machined at 9 o'clock position. Again, clever idea!
---Joe

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Originally Posted by j.bickley

tonyfoale,
Very clever idea. I like and will use that method. Keep in mind that vertical shimming up the dropped tailstock (a few thousandths) matters little as long as the work is machined at 9 o'clock position. Again, clever idea!
---Joe

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Joe,
I hate misalignment in any direction. A dropped tail stock will make a drill wobble and drill oversize just as much as the same lateral misalignment.

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Originally Posted by tonyfoale

Joe,
I hate misalignment in any direction. A dropped tail stock will make a drill wobble and drill oversize just as much as the same lateral misalignment.

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Tony, you are very right about that. Maybe a chucked up small diameter end mill drill might alleviate some that problem by "boring" action rather than drilling. One of the flutes's cutting edges will have to be at top dead center and hopefully the deep hole is not a requirement! :p
Happy New Year!

---Joe

I'm with Tony when it comes to misalignment of the tail stock. Just getting it true centered with the spindle fully retracted is not enough It needs to be true centered when fully extended as well.
I often power tap holes from 3/8" through 1 1/2" For larger taps it is not much of a problem but the smaller taps can snap right off. Not to mention how a deep hole can become a tapered hole or even out of round from the flexing of the drill bit.

Hi Tony,
I don't forget to make pictures from my milling machine. ;-)
What you describe here was made in a similar idea as a specialised tool called "Centricator", it was very expensive but usable on a lot of situations, the most important thing when we measure that centering is to make it on two or more positions of the bar, not only at one point, I've seen some repaired CM2 which were 0,5mm. out of center on 50mm.
The Centricator documentation : http://www.lecollectionneur.ch/archi...ator-c-iii.pdf

I have just put up a video showing how I use this method as well as the more conventional methods.
Also here is a post showing a modification to my tailstock to help maintain the alignment
http://www.homemadetools.net/forum/i...255#post130774

https://www.youtube.com/watch?v=hfr2PXMkr74

Tony, doesn't your described method only align the tailstock on the assumption that the chuck you're using is itself 100% accurately centred? In saying this it appears from the photo the dial indicator is effectively mounted in the chuck.

May I suggest that mounting the DI onto a faceplate would be more accurate.

I take that back if you've attached the DI onto a freshly machined surface which hasn't yet been removed from the chuck. In which case this procedure would be necessary for each alignment check.

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Originally Posted by Bony

Tony, doesn't your described method only align the tailstock on the assumption that the chuck you're using is itself 100% accurately centred? In saying this it appears from the photo the dial indicator is effectively mounted in the chuck.

May I suggest that mounting the DI onto a faceplate would be more accurate.

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No it does not depend on the accuracy of the chuck or whatever mounting arrangement you use. The working end of the dial gauge rotates about the spin axis of the headstock, regardless of the structure between the lathe spindle and the dial gauge.
On the other hand, the method of using a precision bar to clock up on relies on how concentric the headstock centre is with the spin axis.

I'm sorry Tony, but despite the translation with Reverso i can't understand why if it's an un-centered chuck it can function, later I go to the workshop to try myself because without a good translation it's difficult for me.
When you describe the most common methods, we learn a good one when I was an apprentice which I use on a lathe when it's not at home, using a bar with a design like a bobbin mounted between centers and taking a light part of metal at each end it need just a measure with the caliper and a fast calculation for an horizontal alignment.
Out of subject commentary. ;-)
On some Schaublin system it's a good vertical and horizontal dead end which I'm now modify to put on another lathe and make some pictures for the forum if it's some interest in that adaptation.

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Originally Posted by Okapi

I'm sorry Tony, but despite the translation with Reverso i can't understand why if it's an un-centered chuck it can function, later I go to the workshop to try myself because without a good translation it's difficult for me.

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I shall try to explain in a clearer fashion. If that does not work then maybe another forum member with better powers of explanation can jump in and take over. Maybe Rick or Marv could make it clearer.

1st try.
The dial gauge is fixed to a support bracket, the connection point between the bracket and gauge is offset from the spindle axis. The connection point will travel on a true circle centred on the spindle axis. So if the support bracket is fitted to a chuck with some runout it does not matter. The bracket shape and dimensions are purely arbitrary and only have to hold the gauge plunger against the tailstock centre. The ball on the end of the gauge plunger does not even have to be dead centre because its travel will still be on a circle centred on the headstock spin axis.

If you mount an indicator on the tool post to check the concentricity of a bar, the point of the indicator does not have to be dead centred. There may be an error in the amount of runout that is indicated but it will still tell you if there is runout or not. The same thing applies to the tailstock centering method that I described. Unless the offset of an indicator is large the error in the runout magnitude will minimal anyway, but it will still indicate if you are aligned or not.

2nd try.
Image that you have a chuck or face plate on a lathe that has been fitted such that it has a lot of offset. Run the lathe and it will be obvious that the outside is NOT concentric with the spin axis. Now image that you paint a small dot on the outside of the chuck or face plate. Now run the lathe. You will see that the dot describes a circle centred on the spindle axis regardless of the fact that the chuck as a whole is eccentric.
Apply that reasoning to my gadget. Any given point on the chuck-bracket-gauge assembly will be rotating true to the spin axis, and that is all that is required.

That is it, I have no other ammunition with which to convince you. I understand that technical explanations can be difficult in a language other than one's mother tongue.

Tony, surely your video on the laser centre finder depicts the same principals, anything rigidly mounted can only rotate about the true axis of the lathe or mill mandrel.

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Originally Posted by olderdan

Tony, surely your video on the laser centre finder depicts the same principals, anything rigidly mounted can only rotate about the true axis of the lathe or mill mandrel.

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Alan,

Yes exactly.

Thanks Tony, then I understand what you mean, it's clear than in every manner you fix the dial gauge on the nose of the lathe it will make a perfect center from this point, looking your video more concentrated was the best way, at the first time when not perfectly in the subject I suppose you have a rotating piece on an arbor and not rotate the chuck because i've not take the time to heard your commentary…:embarrassed:
Sometime swhen you're translating, you go totally in the wrong way and it was what I've made.

It's very clear now, thanks. I too mistakenly thought the DI rotated about the chucked workpiece, whereas it's actually fixed onto the workpiece and rotates about the spindle axis. Should have looked at the excellent video. I'm annoyed with myself.

Tony has a very rigid & compact assembly to hold the indicator. But just a word of caution if you were thinking to replicate the rotating indicator action with a typical mag stand. All bets are off as gravity can act on the extended arms & joints. The dial will read differently upright than inverted & depending on the extended arm, even laterally side to side. I've attached a RK video link below.

I crudely mimicked this with my equipment & got the following on a mini mag holder vs typical mag holder. Your mileage may vary.
Noga 6"? Mini + Mitutoyo 0.0001" DTI: Level reference = 0.0000", 90-deg = 0.0005 - 0.0008", 180-deg (inverted) = .0011
Noga 12"? + Mitutoyo 0.001" DTI: Level reference= 0.000", 90-deg = .0042", 180-deg = .0055" (suspect a smidge more because it didn't return to zero & there might be some flex in my bar).

https://youtu.be/u08SfxVgxNgAttachment 29612Attachment 29613Attachment 29614

Yes, this is clear that the gravity can interfere with a measurement, with Tony's methodology, the use of the more rigid and more lighter the system is and better it is, with low quality arms especially you can have some variations between the different positions, the system you show is not a good idea for measurements on a rotation axis, for having made some tests on the horizontal milling machine those articulated arms can vary from % on a 180° horizontal position due to the construction with heavy parts.

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Originally Posted by petertha

Tony has a very rigid & compact assembly to hold the indicator. But just a word of caution if you were thinking to replicate the rotating indicator action with a typical mag stand. All bets are off as gravity can act on the extended arms & joints. The dial will read differently upright than inverted & depending on the extended arm, even laterally side to side.

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Peter,

Thanks for pointing that out. I should have done that in my original post. I have always hated the typical methods for mounting gauges, it is rare to see any that come anywhere near being rigid enough. I have not watched the video yet but I need no convincing that those mounts are woefully inadequate despite their widespread use.

Attachment 29615 Attachment 29616 Click images for full size.

In the desire for rigidity I have even replaced the original clamping method with a welded on tab, as the pix show.

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Thanks tonyfoale! We've added your Dial Indicator Mount to our Measuring and Marking category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-dial-indicator-mount-4"> <img src="/uploads/223353/homemade-dial-indicator-mount-4.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-dial-indicator-mount-4">Dial Indicator Mount</a> <span> by <a href="http://www.homemadetools.net/builder/tonyfoale">tonyfoale</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/dial-indicator'>dial indicator</a>, <a href='http://www.homemadetools.net/tag/mount'>mount</a> </div> </div> </div> </div>
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