# Sherline Tailstock Misaligment



## tomw (Jun 15, 2015)

Dear All,

I have a Sherline 4400 Lathe, purchased new back in February. In doing some work between centers on a very thin piece, I discovered that my tailstock appears to be misaligned. The misalignment is enough to taper a 2" piece 6 thou. I did some tests, and this 6 thou taper over 2" occurs when using 3/8" stock as well. The tapering is uneven, and there is a ton of chatter when cutting near the tailstock, diminishing as you move towards the spindle.

My spindle is aligned perpendicular with the lathe axis. A 4" long brass 1/2" diameter rod will have .0005 TIR when machined using only a chuck (not between centers). 

I took a photo of the tailstock with a live center against the spindle with a dead center.




The misalignment also helps explain why I keep getting slightly off-center holes when I drill on the lathe. I thought it was my technique.

My question is how much misalignment should I expect. Is this pretty standard for Sherline? If so, I am surprised, because all of their other features seem very precise for a machine of this price.

Sherline offers adjustable tailstock holders. Given this degree of misalignment, I am going to have to buy all of them. This will make the lathe much less fun to operate, as I will have to do the alignment each time I switch between centers and drills. 

Thank you for your help.

Cheers,

Tom


----------



## brino (Jun 15, 2015)

Hi Tom,

Is that picture looking down on the alignment of the two centres? That is, you need to adjust your tailstock in the same direction as the cross feed.

or.....

Is that picture looking from the front of the lathe towards the back (along the same direction as the cross feed). That is your tailstock centre is higher than your headstock centre, and you would need to shim the headstock up?

other things:
-are you certain that there are no chips in the headstock or tailstock tapers?
-have you ever re-turned the point on your headstock live centre to match exactly your spindle centre?

-brino


----------



## tomw (Jun 15, 2015)

Brino,

That is looking down. The tailstock center is very lightly used, and gives me the same look as an unused (except for this project) dead center. 

I took the tailstock apart and cleaned everything, readjusted the gib, etc. I made sure the tapers were clean on the centers and the tailstock and spindle bores. No change in the alignment. It is still off by 12 or so thou.

Thank you for your help.

Tom


----------



## brino (Jun 15, 2015)

Hi Tom,

Looking at the page here:
http://www.sherline.com/setupins.htm

It looks like the tailstock is not adjustable, which is why you mentioned the "adjustable tailstock tool holder".

Did you go thru the headstock alignment procedure?

The only other ideas are chips between the headstock/tailstock and bed ways.

Hopefully another sherline owner will jump in with some knowledge.

-brino


----------



## mikey (Jun 15, 2015)

My Sherline 4400 is over 20 years old and I've used the live center thousands of times and have nowhere near this amount of run out, either with the old style tailstock or the newer one so this is unusual. I think you need to isolate exactly what the problem is, Tom.

It can be the brass tailstock gib. Try removing the gib altogether and push the dovetail against the way to see if this improves things. 

It can be the machining of the dovetail of the tailstock. The above will help sort that.
Since the offset is the same with the dead and live center it is not likely to be a bent morse taper on the live center but it might be a burr or debris in the morse taper socket. 

The tailstock body itself may be warped for some reason.
The ram may be distorted or the morse taper is inaccurately cut for some reason. 
The morse taper of the tailstock may be off for some reason. You can put a test bar between centers and index the live center in various positions to see if it is off. My tailstock definitely has a position where the live center runout is reduced so I marked the center and the ram.
My Sherline live center was okay but had a TIR of 0.0008. I bought the adjustable live center and while it can be made to run more accurately it is a bear to align. Every time you remove it and replace it you have to realign the thing, which is a royal pain. My solution was to make my own live center with replaceable tips. It has near zero run out with the 60 degree point and only about 0.0002" TIR with an extended tip. I cannot post pics for some reason; PM me if you need them.

In any case, you have an issue but I'm not sure what it is. Maybe check the list above and we can go from there.


----------



## RJSakowski (Jun 15, 2015)

If you are holding a 1/2 thousandth TIR over 4", your headstock should be aligned.  The .006" taper would result from a .003" offset which Sherline may deem acceptable.  The unevenness of the taper could arise because of mounting the piece in a chuck.  Normally in cutting tapers using an offset, the work is mounted on a headstock center and driven with a lathe dog.  By using a chuck and an offset taper, you would be introducing a bend in the part which will change as you turn the part.  It would also explain the chatter you are experiencing.

Tailstock misalignment can come from two factors: there can be an offset parallel to the ways or the tailstock could be rotated.  The latter would be indicated by a change in the amount of offset as the tailstock ram is advanced or by having different offsets for different lengths of drills. 

About ten years ago I was doing some lathe work with very small features (drilling .009" holes in stainless, e.g.).  I designed and made an adjustable chuck for the tailstock based on the "Set Tru" lathe chuck design principle and using a 1/4" Albrecht chuck.  I had four adjustment screws which allowed me to dial in the runout on the chuck.  I also had four adjustment screws from the back which allowed me to zero out any angular misalignment.  I then made my own mini live center with a 1/4 straight shank.  

It may be that Sherline's adjustable tailstock tools are similar in design.


----------



## kvt (Jun 15, 2015)

Is this the 4400 or the 4000,   I have both.   You said It is new in the last year,   I would take the picture and send it to them,   I hate to say it,  They have been good to me and tried to fix and make up for things I have had problems with on my new one.   But it almost seems their QA has fallen into a bad state at times.   They say they put each one together and check it but if that was the case why are there so many problems.   Another person had problems with his new MIll as well.  I had problems with several things when I got my new 4400 in Dec.   often I do not use the Tail stock so I have not check it.  I guess I should.   The adjustable tail stock that I have seen, it is actually for use on a mill, and attaches to the T slots.  I have seen several on the web actually make an adjustable tail stock to replace the original by cutting the top off, then using a heavy piece of alum angle.  They machine it where they can hold it to the old base, and adjust left and right,   And if need by they can also adjust up and down.   The one thing you have to worry about is keeping it level to the bed as well.   That way when you do drill with it you drill straight and level.  
From the look of the picture I it is not the brass gib on the tail stock, but rather the Alum on the back side of the tail stock,  Ensure there is not any chips etc in the edge of the dovetail.   It can happen,  Check to see that it seets properly.   Even a glob of bad grease can cause some alignment on the back.   Also, make sure that the GiB on the front is putting enough pressure on it to keep it moved over properly.  Note at least it is better than the old tail stocks which used a pinch method which was often out of alignment.  
One of the other things to check is to see if the head stock is correct.  I do this by attaching a gauge to the cross slide then checking down the side of a precision drill rod  to see if there is any change from the head out.  If there is then the head is a little out of alignment. Some times there is a little bit of play in the alignment bar on the head stock so you may be able to adjust that out.

Good luck and let us know what happens


----------



## tomw (Jun 15, 2015)

Thank you all for your replies. I am quite certain the problem is not in the tapers for either the spindle or ram or the centers. I cleaned and checked them all. I will do some additional checking tomorrow and also contact Sherline.


----------



## Steve Austin (Jun 15, 2015)

I had that same problem with my 4400. I had to use a wooden mallet on the headstock to tweek it with the alignment bar in it and tightened down. Also I found that using the thumb screw that locks the ram pushed it off center as well. I drilled and tapped the opposite side and made a thumb screw to be able to center it up. If you do that, make sure you deburr the hole on the inside of the tailstock so you don't scar the ram. Also, don't forget to loosen the screw before moving the ram. I need to replace mine but worry about the quality of a new one. Good luck


----------



## tomw (Jun 16, 2015)

Steve,

Thanks for the information. I already aligned the headstock. The alignment screw on the rear is a good idea.


----------



## tomw (Jun 18, 2015)

I spoke with Fred at Sherline. He thinks, given that the lathe is only 5 months old, that something is amiss. I have sent my lathe bed, headstock and tailstock back to Sherline. I will report on what they find.


----------



## kvt (Jun 18, 2015)

I told you And wait a min,  Is your also a 4400, because mine was ether Dec or Jan,   And I had some problems with QC on it as well.  Like they did not get the plastic finished properly and sharp edged on the chuck to the point I got cut by it.   But like I said they are trying to work when things are found.   As soon as I get the piece off of mine i'm working on,   I will recheck it.   As like I said I very rarely use the tail stock,   Most of mine has been small short stuff  or stuff that did not matter if tapered or something.   But now I am starting to do some things that matter more so I better get it checked.


----------



## mikey (Jun 18, 2015)

Too bad we lost Joe Martin. I hope Sherline can pull it together because they introduce a lot of folks to machining. The older machines didn't seem to have these QC issues. In fact, the lathes had much tighter tolerances than Sherline published.


----------



## GraySmith (Feb 8, 2018)

I too had a slight alignment issue.  I first read all the documents regarding initial setup and alignment, but disregarded the suggestion of using a mallet on the headstock to "bump it over". 

 The reason I chose to disregard the mallet method was because the gib in the headstock fit very tightly and  no amount of  "bumping it over" would succeed.    Since there was no physical way to move the headstock and reduce the angle of the headstock with the gib in place, I decided to make some room for this allowance.    On only 1/2 the length of the  gib, I  gently used my 1" belt sander and removed microns of material from one of the horizontal sides of the gib.   Note the 1/2 length mentioned earlier, next I reinserted the gib only 1/2 the way into its  slot and then tightened down the headstock assembly.  The taper on the lathe went from a positive  taper (.002) over 2 inches to a negative taper (-.002) over 2 inches.  Therefore I proved I moved the headstock and a negative angle was achieved.   I was able to further adjust the headstock (without using  a mallet)  and achieved a  respectable .0003 - .0005 taper over 2 inches.  When such perfection is not required, I can  just slide the gib back fully into its slot and the get the predictable .002 taper.   BYW, most larger lathes have compound tapered gibs.


----------



## blu73 (May 30, 2018)

I have a 4400 lathe that I bought in 2008 and it had the same misalignment problem as shown in the image in the first post.  Being as I was used to working to tolerances as close as +/- .0002 as a tool and die maker, this was totally unacceptable.  I thought about modifying the tail stock by using the method shown on YouTube by a guy from Brazil named Luiz Ally.  He has a five part series on how to deal with the tail stock problem.  I ended up with a tail stock that can be dialed in with a lot of fussing around, but the effort was worth it.  Basically, I had my tail stock split in two on a wire EDM machine so I was able to use a combination of clamping screws and shims to get it right.  What I did is probably not the best answer to this problem, but it worked for me.  Here are some images that I hope will make this a little clearer.  The first one shows a pattern of six holes drilled through the tail stock.  They are #21 all the way through at this point to allow for tapping 10-32 and clearance drilling as needed.  Disregard the two odd holes, as they were not needed when this was all sorted out.  These six holes were drilled through at this time to ensure alignment when the two halves of the tail stock were mated up again.


This next image shows the results of the wire EDM process.  Finish the clearance drilling and tapping of the 10-32 holes at this point.  I had to have the clamp screws enter from opposite sides, as I didn't allow enough room between the top and bottom rows for the screw heads to clear each other.  So much for all that tool and die work.  Missed something very basic.


When the two halves are ready to be mated again, an alignment rod must be prepared.  Start with a 3-1/2" length of 5/8" or 3/4" diameter aluminum rod and make a skin cut 2-1/2" long.  Check for any taper in the cut and adjust the head stock as needed.  This method is recommended by Sherline to align the head stock.  If using 5/8" diameter rod, be sure to take very light cuts, as the final diameter needed is .6188 to match the diameter of the tail stock ram.  When the rod is the correct diameter with no taper, the two halves of the tail stock can be set up for the mating and aligning to begin.


Next, you can see the two halves mated up and the clamping screws installed.  Now for the fun part.  Working with feeler gauges, you need to determine how much shim stock to insert into the gap left from the EDM process and adjust the relative positions of the two halves so the assembly will easily slide on and off the alignment rod.  Be sure to have the tail stock gib snug, but not tight on the bed ways.  You need to be able move the tail stock along the bed ways, but you also want to minimize any twisting motion.  When mine was all done, I ended up with .002 more shim at the dial end of the tail stock than the chuck end.  That doesn't seem like much, but when you think about how far out a drill chuck extends and an inch or two more for the drill, that taper over two inches becomes quite a bit more at the point of a drill when you need a hole centered on a work piece.


If you choose to watch the YouTube videos by Luiz Ally, you can see that his method is easier to accomplish than this one when the final alignment is being done.  But, I've always done things the more difficult way.  A real problem of mine.
Here is a copy of the web address of the video.  



Sorry, but I don't know how to make the address clickable.  You will need to copy and paste to get to the first of five and go from there.
Well all right then.  A moderator or someone who knows how to install a hot link to the video has taken care this.  Thanks.


----------



## tomw (Jun 2, 2018)

Very nice write up. Thanks!


----------



## Karl A (Jun 18, 2020)

I purchased a Sherline 4400 lathe in January 2020. I found that the tailstock was misaligned more than the specification, which is <3 thousandths of an inch. I estimated that the misalignment was 7 thousandths, from the photo. I emailed Sherline about the problem; they told me to send the lathe back -- which I did.
I received an email message from Karl Rohlin, the shop foreman. He wrote that they replaced the tailstock; the misalignment with the new tailstock was 2 thousands. He wrote that they use a lathe mandrel and check between dead centers, with the measurements taken four inches apart. He included two photos showing the measurements.
Karl Rohlin did not state what was wrong with the original tailstock. When I received the lathe back, I saw that the new tailstock included two screws for making the gib friction even at both ends. The original tailstock did not have the two screws; it had unthreaded holes. Ironically, the lack of adjustment screws made repositioning the original tailstock over the other side of the cross slide, to photograph the misalignment, easier to do. 
Karl


----------



## Karl A (Jun 18, 2020)

Here are the two photos that Karl Rohlin from Sherline included in an email message to me, showing that the misalignment between the headstock and new tailstock was 2 thousandths inch: zero at the headstock, and 0.002" at the tailstock 4.0" away. I appreciate the documentation.


----------



## mikey (Jun 18, 2020)

So what do you get when you put the live center in place? Most of us will almost never use a dead center, nor will we use a center up close to the spindle. What you really need to do is make a test bar and test the tailstock alignment with the tailstock about a foot away from the spindle where it sees the most use.

To make a test bar, find a piece of 3/8" drill rod about a foot long. Use your 4 jaw chuck and zero the rod up near one end. Face the end and drill an accuate 60 degree hole in it with a new sharp #1 center drill. Flip the rod over and repeat on the other end. Now mount this rod between dead centers and use your lathe dog to drive it. Machine a short section, maybe 1/2" long on the end closest to the chuck. I suggest you use a sharp HSS lathe tool and take a 0.010" deep roughing cut, then a 0.003" deep sizing cut, then a 0.001-0.002" finish cut and strive for a clean finish. Once you do this, you have a test bar that will serve you for many years so take care of it.

To use it, remove the lathe dog and mount the test bar between dead centers. Be sure the tailstock is lightly locked down and also lightly lock down the tailstock ram; this is how the tailstock will be configured in use so test it this way. Mount a dial indicator in your tool post and get the tip on center. Now bring the indicator tip into contact with the turned section of your test bar and preload the indicator about 0.015" and zero the dial. Then loosen the tailstock locking screw and flip the test bar so the turned end is now on the tailstock end. Do not touch the dial indicator or the cross slide hand wheel. Use the X-axis handwheel to crank the saddle toward the tailstock until you can position the dial indicator on that turned section. You will need to lift the tip of the indicator away from the rod as you traverse all the way down to the end, then gently bring it back into contact with the test bar. The reading you see on the tailstock end is the amount of offset that exists in your tailstock. Repeat this with the live center in place and that will tell you how much offset there is with the live center in place, which is the information you really need to know.

Essentially, Karl used the same procedure except they used an unturned rod, which is not nearly as accurate as making one as outlined above. You can also test for vertical offset, although there isn't much you can do about it if it is there.

You will find that your readings will vary with how tight you lock down the tailstock to the ways and how tight you lock down the ram. Try to be consistent in how much torque you apply; it doesn't take a lot.

You will also find that the two gib adjusting screws can be a little finicky to adjust but it is well worth the time it takes to get them right. You want to adjust them so the tailstock slides with little effort but there is zero play when you lift the front or rear of the tailstock by hand. The screw in the center, between these gib adjusters, is only meant to lock the tailstock in position. The better you adjust the gib screws, the less force it takes to lock the tailstock to the ways.

Oh, and just so you know, 0.002" is a LOT of offset. I know this is within Sherlines standards but on long work pieces, this much offset will result in unavoidable tapers. This is why I made a live center myself; to get around this issue. That brings me to my point. You may be able to index the OEM live center so that it minimizes or hopefully eliminates the offset. This is where the true value of that test bar comes in. If you can rotate the live center and find a position where the live center has minimal run out, make index/witness marks on the live center and the tailstock ram so you can align it that way every time you use the live center. This will minimize any tapers that occur and it is my sincere hope that you can find such a position.

Hope this helps.


----------



## Karl A (Jun 18, 2020)

Mikey,
You post definitely helps.  I have wondered how to make and use a test bar. I have wondered to what goal to adjust the gib adjustment screws.
I have two questions in regard to your instructions for making a test bar:
#1: "Face the end and drill an accurate 60 degree hole in it with a new sharp #1 center drill." When I ordered my lathe, I ordered a #2 cobalt-steel center drill from McMaster-Carr. I didn't know which size to order, and I have not seen any guidelines on which size center drill to use when one is going to turn between centers. Is #1 generally the best size for turning between centers?
#2: "Now mount this rod between dead centers and use your lathe dog to drive it. Machine a short section, maybe 1/2" long on the end closest to the chuck." Do you mean close to the lathe dog?  The lathe dog would seem to be in the way of machining at the end.
Karl


----------



## mikey (Jun 18, 2020)

Yes, thanks for catching that, Karl. You need to cut your test bar on the tailstock end, not the chuck end. My mistake, period.

There is no hard and fast rules for which size center drill to use. I use the smallest I can that will support the work piece I have. For most things on a Sherline lathe, that's a #1 center drill. On my larger lathe, #2 is the smallest I use. Either is accurate but the deeper and bigger you go, the more weight you can sustain. There is no point to going bigger than absolutely necessary.

The tailstock locking screw is a pain; I hate having to grab a tool to lock something down. Make a rod and put a screw on one end to go into the tailstock and the other end with a handle or knob of some kind. Makes it tolerable to use. 

Try not to overtighten stuff on Sherline tools. Much of our equipment is made from aluminum and it can strip. Most things will lock down when you feel contact + 1/8 turn. My tools are over 30 years old and nothing is stripped or damaged so this works.

I meant to tell you to verify headstock alignment before making and using your test bar. To do that, chuck a piece of 1/2" - 3/4" 12L14 or 6061 aluminum so that about 4-5" of the rod is sticking out of your chuck. You can use your 3 jaw for this and you do not use a live center for this procedure. Now take a skim cut of about 0.010" deep all the way down the bar, followed by a 0.003" deep cut, then a 0.001 deep cut and strive for a good finish. Now measure the OD on the far end, the chuck end and in the middle. All readings should be the same. If it is not then the headstock is out of alignment. 

There is a set screw in front of the headstock that holds the headstock to a large post in the bed. There is also a key under the headstock that provides rough alignment but it is not accurate. Anyway, loosen that screw and move the headstock in the appropriate direction and do another 0.003", then another 0.001" deep cut and re-measure. Repeat this until you get zero difference anywhere along that rod. THEN your headstock is aligned. I meant to mention that Sherline probably did not bother to do this and if this is so then their measurement procedure is meaningless, as is their statement of accuracy. It is always best to test and verify yourself. 

The Sherline lathe is an incredibly accurate, precision tool. It is accurate because of their leadscrew and surprisingly, their gibs! Who would have thought that reinforced plastic could be an effective gib material but it is and they will last a lifetime when adjusted correctly. Spend some time adjusting them. To do so, back off the gib adjuster screw so the gib can move. Now tap the gib out a little so it is definitely loose. When I do this, I take the gib out and lube it, then reinstall for adjustment. Shake the thing you're adjusting with hand pressure and you should feel movement. Gently and slowly tap the gib back in, twisting and moving the thing you're working on with hand pressure until all movement and slop is eliminated. Go slowly and in tiny increments until you eliminate all slop, then lock the gib down. Take your time because it is likely that the gib will not need adjustment for a decade or more so get it right. Do this for all the gibs on your machines. 

The other thing that allows the Sherline lathe to be so accurate is your turning tools. I highly recommend you stick with HSS on this lathe. HSS will easily outperform brazed carbide, inserted carbide and inserted HSS tools on this lathe. Most users use 1/4" bits but I prefer 3/8". If you're interested, join us on the model tools thread.

Anyway, welcome to HM. If we can help, sing out.

Mike


----------



## mikey (Jun 18, 2020)

Deleted duplicate.


----------



## Karl A (Jun 19, 2020)

Mike,
Thank you for the clarification, and additional instructions and information. I like high accuracy and precision; I am glad to read that the Sherline lathe can be adjusted to achieve them.
I am a beginner in machining. For example, when I see a collet, I amuse myself by asking, "What do you call it?"
For the tailstock, I have the Sherline adjustable live center, an adjustable chuck holder, adjustable bullnose live center, and adjustable custom tool holder. For setting these, I have the idea to add to your test-bar usage instructions a dial test indicator for checking and achieving vertical alignment. (Dial indicator for horizontal alignment, and dial test indicator for vertical alignment.)
I want to learn to grind my own HSS tools. How cutting tools work is generally a mystery to me. It would be good for me to understand them for my iob, house repair and improvements, and hobbies.
Last month, I took advantage of Sherline's 20% off sale on milling machines to buy a model 5400 with extended column and DRO. I am following your recommendations in other threads in selecting accessories for it.
Karl


----------



## mikey (Jun 19, 2020)

I really like my 5400 mill. Once upon a time, it was my only mill and I used it for everything. It is far more capable than you might think and is just as precise as the lathe. 

You are starting with a Sherline lathe and mill but they are real machine tools. Everything you learn will transfer to larger machines if you choose to step up in size some time. My Sherline tools taught me almost everything I know about hobby machining and I am so grateful that I chose to listen. 

If you have questions, ask.


----------



## Karl A (Jun 19, 2020)

ps: Aloris had a 20%-off sale in May. I ordered an MA-SET: MA-series quick-change tool post & three holders.


----------



## mikey (Jun 19, 2020)

Big bucks!


----------



## Karl A (Jun 21, 2020)

mikey said:


> Big bucks!


Yes, the set costs a significant amount of money. 
I was motivated to buy by this statement, "Had I known I would still be using my Sherine 20+ years later, and had the Aloris MA been available, I would have bought it without a second thought. The tool bit is the interface between the work and your intention; it must be held solidly. For my money, today, that would be the Aloris post." -- from "New Sherline Lathe Cutting Tool Recommedations Needed" begun on Nov 30, 2015.


----------



## mikey (Jun 21, 2020)

I remember saying that. I currently use an aluminum tool post by TS Engineering, a now defunct company. It is like all aluminum tool posts on these lathes - okay, but you know that a good solid steel post will do better. I believe that if you can learn to grind a good HSS tool, your lathe will outperform mine with that Aloris post. I don't just mean it should rough deeper; I mean it should finish more precisely as well and that, Sir, is saying a lot. 

You are going to find that your lathe, with a good tool, will pretty much cut what you dial in. If you can interpolate consistently, your lathe can take a tenth or two accurately. Not many lathes can do that. I believe that a good tool post has a lot to do with what the lathe is capable of so despite the rather large cash outlay, I suspect it will be money well spent. 

Next we need to get you grinding some good HSS tools. Please believe me; it makes a difference.


----------



## Karl A (Jun 21, 2020)

Mike,

I accept/believe that shape of a cutting tool is an important factor in achieving good results in an efficient manner.

Toward the goal of grinding my own HSS tools, yesterday I read parts of "Models for Grinding HSS Lathe Tools". I came across another statement by you that is akin to statement regarding the Aloris MA tool post: "I think that if I was looking for a belt sander today, I would opt to buy or build a 2x72." 

I think that I am going to end up with both an Aloris MA and a 2×72, because of you. 

Karl


----------



## mikey (Jun 21, 2020)

A good belt sander is one of the most useful tools in any shop and the best of the breed for metal workers is the 2 X 72. Go for it!


----------



## Buffalo21 (Jun 21, 2020)

I have a 2” x 48” high speed Jancy RadiusMaster, one of the most used tools in the shop


----------



## Forty Niner (Jun 21, 2020)

I, like previous posters on the subject of tailstock alignment, have had my frustrations with my first Sherline lathe bought in 2012.  The headstock on that lathe is out of alignment with the tailstock.   When the headstock is in very good alignment with the ways, the tailstock is out by 0.005".   That's 0.010" TIR!     Back then Sherline even exchanged my headstock when I complained.  The replacement was no better. I thought of ways to correct the alignment, but gave up.  I had thoughts of making an offset key that would move the headstock over 0.005" but Mikey talked me out of it.  I then realized that the hold down arrangement did not have enough slack in it to allow such an offset in the headstock anyway.   I lived with it.
 I had to choose whether to align the headstock to the bed ways or to align it to the tailstock, depending on the job..  Never both.  
I bought the adapter for the tailstock with the small chuck that can be used to compensate for the misalignment, but don't really like it.  And the thought of having to use that and an offset center....well...not so good.
Then....
I came across a lightly used Sherline lathe on Craigslist last year at a good price and bought it.  My intention in buying the Craigslist lathe was to set it up just for threading.   It was made around 2017.  To my joyful surprise it does not have such tailstock alignment problems.   Because it turned out to be the better lathe all around, I set up my older lathe for threading instead.  Most threads I cut are very fine and pretty short.   

My point in this rambling discussion is that not all Sherlines are created equal.  I think Mikey must have gotten a good one to start with.  I got one with lousy alignment and one that aligns pretty well.

Now I am happy with my setup.  Of course the good thing about the Sherline headstock is being able to take the key out and turn the headstock to cut tapers.  I have used it to cut odd tapers like the ones on on watchmaker lathes.  Very easy to dial in.

However, I WISH that the Sherline tailstock was designed so that the misalignment could easily be corrected.  If some entrepreneur offered up a good modification to the tailstock that would  allow the user to align it both vertically and horizontally, I am sure I would be their happy customer.


----------



## mikey (Jun 21, 2020)

It can be done. I don't think there is enough meat in a Sherline tailstock to be strong enough so you would need to make a custom tailstock but that wouldn't be all that hard to do, either. I thought about it once and decided I rather just make a more accurate live center and that worked out okay for me.


----------



## Karl A (Jun 24, 2020)

Buffalo21 said:


> I have a 2” x 48” high speed Jancy RadiusMaster, one of the most used tools in the shop


I didn't know about it. I found a 2"x48" RadiusMaster Series II belt grinding machine at www.trick-tools.com. From the description and photos, I'd say that is quite a tool. I see that it's made in Australia.


----------



## Buffalo21 (Jun 25, 2020)

Karl A said:


> I didn't know about it. I found a 2"x48" RadiusMaster Series II belt grinding machine at www.trick-tools.com. From the description and photos, I'd say that is quite a tool. I see that it's made in Australia.





Yep, a combination vertical and horizontal belt grinding machine, with the radius wheel cartridge, that has 3 different rollers, that can be changed almost effortlessly. I have no idea where it’s actually made, but it is an Australian design. I found it’s incredibly versatile.







						RM48, Radius Master Series II Belt Grinder, 2x48 belt sander
					

The Radius Master grinder offers greater versatility than any other belt grinder. 7 grinding surfaces include 5 radius wheels with no tools required.




					www.trick-tools.com
				





Damn!! That’s gotten expensive, when I got mine I paid about $1600, and I felt somewhat violated, but after using it, as long as I live, it will not be leaving the shop. I also have a 2” x 72” Burr-King, the RadiusMaster is my go to machine.


----------



## Karl A (Jun 26, 2020)

Does your Radius Master machine have variable speed control? If so, is it an important feature to you, or could you easily get by without it?


----------



## Buffalo21 (Jun 26, 2020)

No, the speed is constant, at roughly 3800 fpm, the Burr-King is variable speed, I guess some people find it to be an asset. I just turn it on and use it. I’ve never felt the need for more speed, even at 3800 fpm and a 50 grit ceramic belt, I can remove some serious metal, but still have enough control to do light touch ups. Would variable speed be a bonus, maybe, but so far I have not needed it.


----------



## Karl A (Sep 29, 2020)

Mike,

I checked headstock alignment, following your instructions in your 2020-June-18 post. Doing this took three tries. Here is what I did the third time:
I cut a 3/4" OD 6061 aluminum rod 5" long on a bandsaw. With the rod held in the three-jaw chuck, I turned down four-inch-length-of-it with 0.010", 0.003", and 0.001" cuts. I achieved a decently smooth finish using a HSS tool bit that was custom-ground for aluminum by Jeff. I cut with 500 rpm at the spindle, 25 rpm at the z-axis handwheel, which works out to 0.0025" feed/spindle revolution). Using a micrometer, I measured the OD of the rod at 3.5" and 7" to the right of the pivot point of the headstock (where the locking screw is located). These locations on the rod corresponded to roughly 3.75" and 0.25" to the left of the right end. The OD at 7" to the pivot point of the headstock measured  0.0075" greater than the OD at 3.5" from the pivot point. The headstock was definitely misaligned (not square with the ways).

To align the headstock, I preloaded a dial indicator against the rod at 7" from the pivot point of the headstock. I loosened the locking screw, and tapped the headstock until the dial indicator showed that the rod had moved 0.0075" toward the front. I tightened the locking screw. To check the new alignment, I covered the 4" turned length of the rod with black permanent-marker ink. Removing the ink from the entire 4" turned length required two 0.003" cuts. After the second 0.003" cut, the point at 7.5" from the headstock pivot point was 0.0010" greater in diameter than the point at 3.5" from the headstock pivot point. I made a final 0.001" cut, and the difference in diameter went to zero (not measureable).

Comment: When I measured the misalignment, I wondered whether there was enough play between the headstock and the alignment key to move the rod 0.0075" and achieve alignment. Based on my observations during tapping and watching the dial indicator, approximately 0.009" was  the maximum amount that the rod moved.

Karl


----------



## mikey (Sep 29, 2020)

Very good, Karl. If you can cut all the way down a 4" rod and have zero difference in the diameters at any point on that rod then the headstock has to be aligned with the ways. Get used to this procedure because if you ever have to cut a Morse taper, or any taper, then the way you do it is to offset the headstock. Then you have to put it back. Now you know exactly how to do it!


----------



## Karl A (Sep 29, 2020)

Mike,

Aligning the headstock was the prelude to making a test bar and measuring the tailstock misalignment. I followed your instructions in your June 17 and June 18 posts, except that I made the test bar six inches long instead of twelve inches long. I didn't expect to succeed with the first one, and my projects so far have been on pieces less than six inches long.

I  cut my 6" piece of drill rod from a 3'-long 3/8"-diameter tight-tolerance W1 tool steel rod (McMaster-Carr #8890K247). I made the machined section 1" long instead of your "maybe 1/2" long". I initially made the section 1/2" long, but that length required large tailstock ram extension to be able measure the diameter with my dial test indicator mounted in a Sherline insert holder tool post (#7600). For facing the ends and machining the section, I used a Sherline 55° RH carbide insert 3/8" tool holder (#2256) with carbide insert (#7605), as I don't yet have an adjustable tool post for mounting the custom "square" HSS tool bit that Jeff ground. (Cutting conditions for the section: 340 rpm spindle, 12.5 rpm z-axis leadscrew handwheel (0.0018" feed per spindle revolution); 0.010", 0.003", and 0.001" depth of cuts; and Boelube 70104-L machining lubricant.) The section came out adequately smooth.

I measured horizontal and vertical misalignment values across 4.4" of the 6"-long test bar. The values were 0.0032" and 0.0006", respectively. Here is a photo of my measuring set up, using a dial indicator mounted in the Sherline insert holder tool post (#7600) for horizontal, and dial-test indicator mounted in Sherline riser rocker tool post (#1288) for vertical.


Question: Are the horizontal and vertical misalignment values of the tailstock closer to 6"/4.4" times greater than what I measured? (multiplied by the ratio of the test bar length and the length that I measured across)

In doing this exercise, I came to realize that a dead center from Sherline can have significant runout. I measured 0.0008" TIR at the dead center in the headstock. The TIR varied between 0.0006" and 0.0010" as I loosened, turned, and reinstalled the dead center through 360° relative to the headstock spindle. (On July 16, I measured 0.0002" TIR at ID of the headstock Morse taper, near the mouth.) The misalignment values I reported above were measured with the spindle turned midway between the high and low points on the dial indicator (when the machined section of the test bar was at the headstock).

I didn't measure the runout of the tailstock dead center. I measured 0.0010" TIR on my Sherline adjustable live center (#1201), and 0.0002"-0.0003" TIR on my Sherline adjustable bullnose live center (#1205).

Karl


----------



## Karl A (Sep 30, 2020)

mikey said:


> Very good, Karl. If you can cut all the way down a 4" rod and have zero difference in the diameters at any point on that rod then the headstock has to be aligned with the ways. Get used to this procedure because if you ever have to cut a Morse taper, or any taper, then the way you do it is to offset the headstock. Then you have to put it back. Now you know exactly how to do it!


If I buy and use Sherline's compound slide, does that eliminate the need to offset the headstock?

Sherline in its _Miniature Lathe and Milling Machine: Assembly and Instruction Guide_, eighth edition, states, "... Then stand the lathe on end with the alignment key pointing upward and put a few drops of LocTite(R) on the joint between key and headstock. Capillary action with draw the sealant in, and when it hardens, the key will be locked in place. We prefer this method to 'pinning' the head with 1/8" dowel pins, because it offers you the option to change your mind. The headstock can be removed by prying with a screwdriver blade in the slot between the bottom of the headstock and the lathe bed to break the LocTite(R) loose should you wish to be able to rotate the headstock again." p. 13.


----------



## mikey (Sep 30, 2020)

Karl A said:


> If I buy and use Sherline's compound slide, does that eliminate the need to offset the headstock?



The compound works for short tapers but not so well for longer ones. You will also find that it is more accurate to mount a sample taper in an accurate chuck and turn the headstock to the angle of the taper, then remove the sample and insert your work piece. Doing it this way allows you to indicate the sample taper in very accurately and where Morse tapers are concerned, this matters. In addition, turning the headstock is vastly more rigid than using the compound.

I've been turning that headstock for decades now and actually find Sherline's system to be an advantage because you can accurately dial in a taper and then re-align the headstock to dead zero quickly. No other lathe I know of allows such precise headstock alignment with so little fuss.


----------



## Karl A (Oct 1, 2020)

To confirm the horizontal misalignment that I measured using a test bar, I used the method described in Sherline's article "Lathe Alignment and Micro-Drilling". It involves mounting a dial test indicator [DTI] in the headstock (I used a collet), placing the tip inside the Morse #0 taper inside the tailstock spindle, and turning the headstock spindle while reading the total indicated runout [TIR]. I was unable to turn the headstock spindle through 360° because there was insufficient space above the table for the dial to pass. I was, though, able to measure the horizontal TIR by turning through 180° from rear to front.


Starting with the dial facing the rear and the needle set a zero, the needle turned one full revolution + 1.1, or 9.1 whole units. The angle of the lever on the DTI was 15°. Adjusting for cosine error, the TIR from back to front was 9.1 x Cosine 15° x 0.001"/1 = 0.0088". Dividing the TIR by two yields the horizontal misalignment: 0.0044".

I measured 0.0032" misalignment using the test bar, but that was across 4.4" of the 6" length. Extrapolating for the 6" length, 0.0032 x 6"/4.2", yields 0.0044".

Thus, the test bar method and the dial test indicator method both gave 0.0044" horizontal misalignment. Both showed that the tailstock is misaligned toward the rear.


----------



## Forty Niner (Oct 2, 2020)

Karl,
I have had very similar results as you when assessing the tailstock alignment on my Sherline lathe.  I found that mine was also misaligned to the rear, like yours.  I have modified my tailstock with the addition of a brass locking screw on the backside of the tailstock.  It somewhat compensates for the misalignment by forcing the slack of the tailstock towards the front, instead of the back as the OEM locking screw does.  I've posted a picture of it in another thread I think.


----------



## Karl A (Oct 2, 2020)

Forty Niner,

I saw your post. It's in the thread "Offset key for Sherline Lathe Headstock - need one made". It's a creative idea. You wrote, "I started the test before the modifications and had 0.0035" taper over 4.5" on a piece of 5/8" round.  Using the two locking screws in concert I reduced the taper to 0.0002."

By "0.0035" taper", do you mean that the diameter of the rod was 0.0035" greater at the right end? If yes, then I think that would be within Sherline's tolerance, assuming you don't have much vertical misalignment. Sherline states, "If your headstock is aligned and the total indicator movement is less than 0.005", your tailstock is within tolerance."

I got 0.0088" total indicator movement, which is out of tolerance.

I sent my lathe back to Sherline in March (six months ago) for two issues:  0.0011" TIR at the headstock spindle, and the tailstock misaligned 0.007" to the rear.  It came back with a new headstock and tailstock. Karl Rohlin wrote to me, describing what he did. In regard to tailstock alignment, he wrote that headstock alignment was close to perfect. He measured tailstock misalignment using a test bar between centers. In photos, he showed that the tailstock was misaligned only 0.002" to the rear.

I don't know why my measurement value and Sherline's measurement value are so different, but: On June 17, Mikey pointed out that Sherline "used an unturned rod, which is not nearly as accurate as making one as outlined above." On June 18, Mikey in his instructions for verifying  headstock alignment wrote, " I meant to mention that Sherline probably did not bother to do this and if this is so then their measurement procedure is meaningless, as is their statement of accuracy. It is always best to test and verify yourself."

Karl


----------



## fcs (Feb 7, 2021)

I thought I would describe my experience with tweaking the alignment of my Sherline lathe; maybe it will be helpful to someone.

*Background:* I am new to machining and this is my first and only lathe.  Lots of things I am learning for the first time are common sense to most of you, I suspect. My main hobby is building bamboo fly rods.  I got the Sherline this summer to try my hand at making my own metal ferrules.  Typical metals are nickel silver, various bronzes and sometimes aluminum.  The outside dimensions are not super critical; a thou plus or minus is not important.  What is more critical is the inside.  The female internal is from 0.125 to 0.300 diameter and 0.75 to 1.5 inches deep; it is drilled, reamed and then honed.  This hole must be straight, round and uniform.  The outside of the male slide is also finished by honing, but that doesn't concern us here.

*Headstock:* I started at the same point as the original poster. Dead centers in the head and tailstock did not quite meet, though my deviation looked a little less than his.  I followed the procedure in the Sherline manual.  I machined a few inches of 0.75 aluminum with tiny passes and checked the diameter along its length.  Had a taper.  The manual said to tap the front left of the headstock with a small hammer.  Re-machined; no improvement.  Hit it harder; managed to hit the pulley.  No improvement.  Put away the hammer. I set up a dial indicator on the end of the stock. loosened the headstock setscrew, and applied a clockwise torque to the headstock with my left hand while watching the indicator move; tightened the setscrew with my right. Improvement.  After a little tweaking I got rid of the taper to 4 digits.  I did a happy dance.

*Tailstock/ram/jacobs chuck: *My main concern is drilling & reaming straight round holes.  Making a ferrule the first step is drilling. I start with a spotting drill, then a 0.125 drill, then larger by steps until the reamer comes out.  *The problem* I have is that every drill seems to hit the previous hole not square, but to the front. You can see it move to the rear just a little bit each time it enters. As you peck the hole you can hear a different sound as the drill exits the hole. This happens with every drill size and the reamer too. I don't know if this problem originates in the tailstock, ram or chuck; and I don't know if its really affecting the final bore, but I don't like it and want to get rid of it.

I chucked up a piece of drill rod and measured the runout as I advanced the ram.  Over its 1.5 inch length of travel the indicator showed 0.006 travel inward (toward me) as the ram moved. I tried rotating the drill rod in the chuck; same result.  I tried removing and rotating the chuck in the ram; again same result.



So where does the problem lie?  I thought about this until my head hurt with no conclusions. (I was never much good at billiards either.) I looked for ways I could shim things to help me diagnose the problem. I tried the solution of adding a brass tipped setscrew to the backside of the tailstock;  I let the ram locking screw drag along the ram. Not good approaches for all the drilling, and didn't make a difference.  Finally I tried adding a shim between the chuck and the Morse taper adapter.  It seems that a shim of 0.002 solves my problem:



With this shim; the runout drops to 0.001 and drills now hit the center of the previous hole (at least to the naked eye.) I still don't know WHY the problem is there and WHY this shimming seems to solve it.  And WHY the shim is on the backside of the chuck when it seems it should be on the front.  

Thanks for your time in reading all this.

Frank

P.S. after reading all this, maybe the Morse taper in the ram is just a little off?


----------



## mikey (Feb 7, 2021)

I have a few comments:

Headstock: you should always loosen the locking screw in front of the headstock before trying to align it. That set screw bears on a groove in the post that locates the headstock. If you fail to loosen it first and go banging away at the headstock with a hammer you will mar that post; this will make future alignment attempts very difficult because the screw will be trying to move around on upset metal. When aligning the headstock, you only need to loosen the screw so it is touching a tiny bit, then align the headstock, then snug the screw back down. You should be able to align the headstock to zero taper on a 3-4" long rod this way, thereby assuring the heastock is aligned with the ways.
Your tailstock is probably off. I say this because alignment relies on machining that is not all that precise. Sherline is pretty good and most tailstocks are off by a few thou but I haven't ever heard of one that is dead on accurate. For drilling and rough work, this is not that big a deal but for precise alignment with a live or dead center, it is a big deal. To see if yours is off and by how much, you need to make a test bar and use a dial indicator to see how off it is. Unfortunately, knowing this information is not useful because you cannot make any adjustments to it anyway - frustrating!
Reaming: Reamers, specifically chucking reamers, need to and will bend to follow the hole. This is true even if the hole is not accurately located, resulting in an accurate sized hole that is not concentric with the OD and that is the issue. When you need an accurately located hole that is truly concentric with the OD, bore the hole, then ream it if you must. OR learn to bore accurately and forget using reamers.
It is clear that the chuck is not mounting square on the arbor. The rear of the chuck is registering on the front of the arbor and the face on the arbor where the chuck is making contact is likely not square. If I were you, I would face that registration face on the arbor so it is square. 

Once the drill chuck is threaded on the arbor it still may not sit dead on accurate in the tailstock taper. One way to assess this is to chuck up an accurate rod that you know is straight and round, then use a DI to find a position where the rod is held straight. You need to mount the DI to the cross slide so you can move the DI along the rod. It will likely show a taper on the first run or two. Remove the chuck from the tailstock and rotate it a few degrees, then reinstall it and check for taper with the DI. Keep doing this until you find a position that shows zero or at least minimal taper and make witness marks on the tailstock ram and chuck so you can install it in this position every time. If you mounted the drill chuck accurately on the arbor and you aligned that arbor as accurately as possible in the tailstock then that is the best you can hope for with that chuck. You might want to consider switching to a better chuck, like an Albrecht or Rohm keyless chuck.

If you must have accurately reamed holes, consider learning to bore accurately. A bored pre-reamer hole will, by definition, be concentric with the lathe spindle and the reamed hole will therefore also be concentric. Personally, I rarely ream holes. Instead, I taught myself to bore accurately and most of my expensive reamers sit in a box.


----------



## Karl A (Aug 8, 2021)

mikey said:


> Your tailstock is probably off. I say this because alignment relies on machining that is not all that precise. Sherline is pretty good and most tailstocks are off by a few thou but I haven't ever heard of one that is dead on accurate. For drilling and rough work, this is not that big a deal but for precise alignment with a live or dead center, it is a big deal. To see if yours is off and by how much, you need to make a test bar and use a dial indicator to see how off it is. Unfortunately, knowing this information is not useful because you cannot make any adjustments to it anyway - frustrating!


This weekend, I turned a dead center for my Sherline adjustable tailstock custom tool holder (#1203).


This combination is a workaround for the tailstock on my lathe being off.
I have a Sherline adjustable live center, but it has significant runout.
I hope to eventually get my tailstock into better alignment; I have an idea to try.
I hope to eventually follow Mikey's article on making a high-quality live center.

Here is a positive design aspect of my adjustable tailstock custom tool holder: The ID is 0.6256 inch. I made the OD of the dead center 0.6250 inch ± 0.001 inch, and it fits nicely. Any tool or split bushing that I make in the future can simply be made to have a 0.6250 inch OD. 
Karl


----------



## Forty Niner (Aug 8, 2021)

Karl A said:


> This weekend, I turned a dead center for my Sherline adjustable tailstock custom tool holder (#1203).
> View attachment 374660
> 
> This combination is a workaround for the tailstock on my lathe being off.
> ...



I look forward to seeing how your idea to improve tailstock alignment pans out.   Like other owners, I have developed workarounds to improve accuracy when using my tailstock.


----------



## blu73 (Aug 10, 2021)

I know I may be stepping into a really big pile of manure here, but I think I've figured out a way to enjoy an adjustable tailstock that could be the answer to all the problems and various attempts to resolve tailstock misalignment.  I have committed a major alteration to my tailstock, and I've documented my efforts in posting #15.

After I got the lathe up and running again, I decided to look at the possibility of going about dealing with the issue in a more user friendly manner.  The reality is that not everyone has access to wire EDM equipment.  When I figured out a less involved solution, I sent my idea to Sherline to see if they would be willing to look into what I had come up with.

Okay, so the upside of the idea is that the tailstock could be adjusted in almost any direction needed for that final bit of fine tuning that a user may to fight for.  Not only straight in and out in relation to the operator side of the machine, but also allow for the tailstock to be twisted to a limited degree.

The downside.  It would cost Sherline whatever is needed to have new extrusion dies made that would allow my suggestion to be implemented.

Recently, I have been in contact with Karl Rohlin at Sherline.  I believe he is in charge of the production area and seems to have the power to say yes or no to a proposal.  Karl gave me some specs on how industry standards are applied to production equipment and he felt the Sherline products fell within those tolerance ranges.  He ended his reply with what looks like a final decision, and it is that Sherline will not be getting involved in any changes to a component that already falls within accepted industry standards.

I feel it is not quite a fair comparison to use a machine weighing hundreds or thousands of pounds, where the size is measured in feet, and the cost ranges to nearly a million dollars against what we use at the hobby level.  Our machines can be carried around the shop, are only inches in any dimension, and have prices starting below a thousand dollars.  To me, it's all a matter of scale.  If the accepted industry tolerances of two or three thousandths of an inch for production equipment is shrunk down to the size of a Sherline lathe, it would easily fall within one thousandth of an inch.

The somewhat crude image I've included here shows the change I've proposed to the base of the Sherline tailstock.  As one can see, by adding shims to the top or side of the added gib, the base of the tailstock is allowed to move in relation to the bed of the lathe.  The shims effectively change the distance between the operator side and the far side of the base.  When properly shimmed and secured, the base of the tailstock is forced into alignment when the standard front gib is tightened.

I am biased, of course, but I feel I have solved a nagging problem with tailstock misalignment.

Please examine the image and pick it apart at will.  Challenge me in what I have come up with.  I think I can explain any questions one may have as to how it all works.


----------



## Forty Niner (Aug 10, 2021)

You show the second GIB to be secured with 10-32 screws.  Am I right to assume that these will be cap screws of some sort and that there will be two vertical and two horizontal?  And that when tightened, they will securely assure that the GIB will be, so to speak, an immovable part of the tailstock casting?  If so, then the design looks like it could work.  I looked at my tailstock and unfortunately  see that there is not enough meat to incorporate your design to my existing tailstock, and like you said, would require a modified casting.

If it requires a modified casting design to incorporate your design change, then it might also be just as easy to make a tailstock the same way that they have been made for larger machines.  They can be adjusted horizontally with screws and vertically with shims.  A simple design that has worked well on other lathes for a century.

I think for my tailstock I would only need to have about 0.003" shaved/machined from the angled surface on the opposite side from the existing gib in order to obtain really good alignment.  Mine only needs to come towards the operator a smidgen.  I don't have the cutter or a good enough milling machine to make that cut though.   I keep thinking, but have not come up with a better solution.

I go crazy thinking about the tailstock alignment


----------



## Karl A (Aug 10, 2021)

blu73 said:


> I am biased, of course, but I feel I have solved a nagging problem with tailstock misalignment.
> 
> Please examine the image and pick it apart at will.  Challenge me in what I have come up with.  I think I can explain any questions one may have as to how it all works.


I think that you have solved the  problem conceptually. I think that your idea is ingenious. Unfortunately, it requires participation by Sherline -- which does not seem to be forthcoming.

I wonder whether a simpler version of your idea can be implemented by hobbyists on existing tailstocks, using a Sherline milling machine. I am thinking of a thinner gib installed without a top shim and without the top screws. In this simpler version, the tailstock would be milled to require a side shim. In other words, after the modification the tailstock would be misaligned forward, and a side shim would be added to move the tailstock back toward better alignment.

I looked up the Sherline tailstock gib: sku 40112, $ 15.86. Perhaps a Sherline tailstock gib can be milled thinner for this simpler version of your idea.


----------



## Karl A (Aug 10, 2021)

I have been pursing a different approach to achieving better tailstock alignment. It is to make a spindle that contains a Morse taper with the opposite misalignment of the tailstock. The idea is to cancel the existing tailstock misalignment with an intentional spindle misalignment.

Today, I received a blank tailstock spindle that I ordered from Sherline. On my order, I specified "not ground to OD, not stamped with rule, no slot". It arrived that way.

Unfortunately, the diameter of the blank tailstock spindle is only 0.625". I not sure that I will be able to turn it down to both fit the ID of my tailstock and include the 4 to 5 thousandths horizontal offset on the Morse taper to counteract the tailstock misalignment. The ID of my tailstock is 0.6192".


----------



## blu73 (Aug 11, 2021)

Forty Niner,
You are correct in that there would be two cap screws in both the vertical and horizontal directions.  When properly shimmed and secured, the second gib becomes an immovable part of the tailstock base.  Your observation on the lack of enough stock to incorporate this modification on a stock Sherline tailstock is in line with mine.

Karl A,
Yes, it does require involvement and expense on the part of Sherline, and yes again, Sherline doesn't seem to be interested.  I have not had any replies from Sherline other than the one from Karl Rohlin, so I don't know if this has been discussed with anyone else at Sherline, or if Karl is actually the final word.

As far as the thinner gib that could only be shimmed at the rear, that is an alternative I hadn't thought of.  If the gib was properly sized, the tailstock would be too close to the operator side.  In my thinking, that would be the more desirable condition to start with.  Adding shims to the far side of the gib would then force the tailstock away from the operator.  By staggering the shims, it should be possible to "twist" it also and achieve that last bit of alignment.  I think my only concern with a thinner gib would be the amount of material that would be available to add the tapped holes to secure the gib and shims well enough to ensure no movement of the gib and shims in relation to the base of the tailstock.  Going to have to give that one more thought.

You stated in your next posting (#53) that you were able to acquire a tailstock ram from Sherline in an unfinished condition.  I wonder if it is also possible to buy a gib from them with no holes added.  If the idea of a thinner gib works, it would relieve someone trying this modification from having to drill holes in locations that had to match any that were in a stock gib.

Well then.  At the moment it looks like there may be an alternative that doesn't require involvement by Sherline.  This is precisely what I was hoping for.  A different point of view that brings to light something I had overlooked.  This is starting to get interesting.


----------



## Karl A (Aug 11, 2021)

blu73,
I wonder how many lathes Sherline sells per year, and what percentage of buyers care about the tailstock misalignment and/or are not satisfied with the adjustable tailstock tool holders. Perhaps if I was in Karl Rohlin's position, I would make the same decision: to not implement your idea. As a hobbyist, I am like Forty Niner: "I go crazy thinking about the tailstock alignment"

I have not measured amount of twist at the bore of the tailstock casing on my lathe. I plan to do so. Up until now, any twist hasn't seemed to matter, being that the tailstock ram (called "spindle" by Sherline) is wobbly inside the tailstock casing. I measured 1.2 thousandths clearance between the ID of the tailstock casing and the OD of the tailstock ram. I intend to make my new tailstock ram fit tighter.

In regard to buying a gib without holes, I doubt that Sherline is willing to sell one. On the webpage for ordering a tailstock spindle (sku 40270, $23.66), Sherline states, "The tailstock spindle is ground to fit each individual tailstock case. Please measure your tailstock spindle OD and enter the dimensions in the box below.
_If no dimensions are entered the spindle you receive will be between .618-.619"_
Instead of entering an dimension, I entered "not ground to OD, not stamped with rule, no slot". I imagined that Sherline has tailstock spindles in inventory that are not ground, and consequently such spindles are not stamped with a rule and do not have a slot. In contrast, I expect that all the tailstock gibs that Sherline has in inventory have holes.

I don't think that the holes in the gib matter for implementing your idea. The holes are vertical, and I expect that they would be milled off to make the gib thin enough to use on the tailstock at rear side of the lathe.

I am glad that you are pursing an idea for improving tailstock alignment that others, without access to a wire EDM, can implement.

BTW, a new tailstock casing (sku 40111) costs $46.03.


----------



## Karl A (Aug 11, 2021)

This photo shows a mock up of how I plan to turn my new, unfinished tailstock spindle [ram] from Sherline.


The set up has a 4-jaw independent chuck, the Morse-taper half of an adjustable toolstock tool holder to hold the ram on the left side, a dead center in an adjustable tailstock custom tool holder to hold the ram on the right side, and a 1/4-inch turning tool. (I will be able to position the holder for the turning tool closer to the ram.)

The set up allows the ram to be mounted with an intentional amount of runout, to achieve the desired amount of misalignment of the Morse taper in the ram (to counteract the existing misalignment of the tailstock) when the ram OD is turned down to fit the ID of the tailstock casing.

I don't expect the existing threads of the ram to work after turning it down with the intentional runout. After turning the ram, I plan to drill the existing threads out of the ram, press fit a plug, and make new threads in the plug that are concentric with the OD of the ram.

The final step will be to mill a slot down the side of the ram, in the correct location on the circumference to cancel the existing misalignment of the tailstock casing on the  lathe.

I think that I need a better 1/4-inch turning tool -- one with optimum angles for steel, and a small nose radius for removing 0.001 to 0.004" from the ram OD. I am still working on modifying a belt sander for grinding my own tools.


----------



## Forty Niner (Aug 11, 2021)

Sorry to say this, but I don't think that setup will accomplish what you want.  It will only allow you to offset the headstock end, not the end you show running on the dead center in the tailstock.  If you back off the dead center, the setup could be made to offset the entire length of the spindle, but it probably would not be stiff enough to cut on.  You would need something like a 4 jaw chuck mounted on a live center on the tailstock to get that end held and offset.

Or make a plate with a threaded nub that would go into that end.  The carefully put a center in the place where it is needed.  Maybe you could drill the center of that plate with the setup you have, having set the offset up using the 4 jaw and insuring that the entire length is all wobbling the same way the same amount at the same time.


----------



## Karl A (Aug 11, 2021)

Forty Niner said:


> Sorry to say this, but I don't think that setup will accomplish what you want.  It will only allow you to offset the headstock end, not the end you show running on the dead center in the tailstock.  If you back off the dead center, the setup could be made to offset the entire length of the spindle, but it probably would not be stiff enough to cut on.  You would need something like a 4 jaw chuck mounted on a live center on the tailstock to get that end held and offset.
> 
> Or make a plate with a threaded nub that would go into that end.  The carefully put a center in the place where it is needed.  Maybe you could drill the center of that plate with the setup you have, having set the offset up using the 4 jaw and insuring that the entire length is all wobbling the same way the same amount at the same time.


You're right. Thanks.

I  have a second 4-jaw independent chuck.  

I like your suggestion of a plate with a threaded nub.


----------



## Forty Niner (Aug 11, 2021)

OR, just face the end of a threaded bolt so it is smooth, then screw it into the spindle, then drill a center into that to hold the tailstock end?


----------



## Karl A (Aug 11, 2021)

Forty Niner said:


> OR, just face the end of a threaded bolt so it is smooth, then screw it into the spindle, then drill a center into that to hold the tailstock end?


Yes. Faster and easier.

The bolt needs to have left-handed threads, though. The threads in the ram are 1/4-20 left-handed.


----------



## blu73 (Aug 26, 2021)

I've taken a few basic measurements on the near (operator) side and the far side of the tailstock base.  There is some stock to work with, but any modifications to the far side of the base would have to be carefully thought out.  I don't know much about the strength of materials, nor the forces that would be applied when dealing with clamping something where angular pressure would be seen.  It may be possible to predict those forces with finite element analysis software.  It's easy to see that a small radius (around .020) would be needed in the corner if one were to mill the base of the tailstock to accept a modified gib.  A sharp corner would create a stress riser in a location where the material would end up being the thinnest.  I'll try to come up with a sketch showing dimensions, and let others here on the forum comment on the value and practicality of what I've come up with.


----------



## Karl A (Aug 26, 2021)

blu73 said:


> ...  I don't know much about the strength of materials, nor the forces that would be applied when dealing with clamping something where angular pressure would be seen.  It may be possible to predict those forces with finite element analysis software.


I have an idea for an approach: Confirm through beam-deflection equations that a modified tailstock base deflects much less than the neck of the Morse taper to force applied along the x-axis to a tool installed in the tailstock .

I imagine that the neck of the Morse taper on a tool installed in the tailstock is the weakest point.

I have a book that contains equations on the defections of beams: _Mechanics of Materials_, 2nd edition, by Gere and Timoshenko (1984). It was the textbook in a civil engineering course that I took 30+ years ago.


----------



## blu73 (Aug 26, 2021)

Karl A,
I hadn't thought of measuring the deflection of the tailstock spindle.  My main concern was the strength of the thinnest part of the base if it is milled to accept a gib.  The quick measurements I took seem to show the amount of material left would be somewhat lacking in cross section.  The area that troubles me most would be at the inside corner left by a milling operation.  Even with a .020 radius in there, it could be the one place that would be most likely to fail.


----------



## Karl A (Sep 21, 2021)

I came across a blog post by Tom Carbone describing a modification to the Sherline lathe tailstock to make it adjustable:
Shereline Lathe - Adjustable Tailstock

The blog post also includes a photo of the adjustable tailstock that A2Z CNC sold. I had only read about it; I had not idea what it looked like. I read somewhere that A2Z incorporated Sherline's mill accessory the Adjustable Right Angle Tailstock.    

Here are photos from the blog post.





Karl


----------



## Karl A (Dec 8, 2021)

I came across an A2Z video on YouTube from 2013 that describes the A2Z Adjustable Right Angle Tailstock.

https://www.youtube.com/watch?v=OFsX0T

Other A2Z videos are available here:



			https://www.youtube.com/user/A2ZTim/videos
		


I like the Lathe Depth Stop.


----------

