# Aligning a mini-lathe



## WobblyHand (Aug 30, 2020)

It seems to me that aligning a mini-lathe is a little different from bigger ones.  For one, the geometry of the lathe is different.  So the adjustments would be a little different.

I've found a copy of Rollie's Dad Method of Lathe Alignment.  I've just done the first horizontal measurements.  The test rod is ground and 20 mm in diameter.  20 mm just fits through the spindle bore.  The rod is sticking out 13.25" from the chuck.  The measurements for the horizontal are:
0.5" from the chuck:  min 0.0000", max 0.0018", average 0.0009"
9.75" from chuck    :  min 0.0008", max 0.0038", average 0.0015"
So the horizontal misalignment is 0.0006" if I've done this correctly.  However, I'm not sure of the arithmetic sign.  Is it negative in my case?
Next post I'll have the vertical measurement.

_From RDM:  9. The difference between the "near end average distance" and "far end average distance" is a
measure of the misalignment of the spindle axis with the ways._

RDM tells us to put a shim under the near-side foot at the head stock end of the lathe.  What do I need to do here?  If I look at my mini-lathe drawing, are we talking about under that head stock casting #10, or under the ways casting #32 on the left side, or under the rubber donut #127?


A little confused, help me get un-befuddled.  Thanks!


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## addertooth (Aug 30, 2020)

To get in the ballpark, I am cheating.  My spindle is an number 3 morris taper (3MT), my tailstock is a 2MT.  I bought a precision ground rod which has 3MT on one end, and a 2MT on the other.  A separate bar will be mounted up in the chuck, and lightly turned without tail-stock support and the OD will be checked over the (roughly) one foot of machined surface to examine taper.  The chuck will be removed, the 3MT end of a purchased reference bar will be slid into the headstock spindle, and then a dial indicator will be mounted to the compound.  I will measure the error over the full length of the ways (horizontally and vertically).  Then it will get popped out, and the 2MT end will be put in the tailstock.  The same vertical and horizontal error will be measured over the full length of the ways (measured by the indicator mounted to the compound). This will be used to give me the original "factory" error of the lathe prior to the full tear down.  The 3MT/2MT bar is supposed to be true to 0.0002 inch combined error to the tapers and O.D.  I can use it for checking headstock to tailstock alignment, by putting it in the spindle, putting an indicator on it (horizontally and vertically), and then sliding the tailstock end over the 2MT end, and look at how much, and in which direction it changed. Once all of these errors are known, then I can calculate and correct the error.


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## WobblyHand (Aug 30, 2020)

Measured the vertical displacement:
At 1.2" from chuck:  0.0016" max, 0.00045 min, 0.000575" avg
At 10.5" from chuck: 0.0019" max, -0.0001 min, 0.0009" avg.
Near - far = -0.000325" over 9.3"

For horizontal Near - far = -0.0006"  over 9.25"

Both measurements were taken with a dial indicator reading to 0.0001". 

Relatively speaking, measuring the error is easy.  You see, it's done.  Having a ground rod is helpful.  I measured the rod near both measurement points and the diameter was the same to a tenth.  (0.7868" for both measurements)

Don't know what to do next.  Honestly don't know where or how to shim this thing.  Can someone help me with the how to shim part?
Which of these circled areas is the right place?


Thanks!


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## WobblyHand (Aug 30, 2020)

The test rod was from Amazon.  It was $12 for a 15" custom cut piece of 20mm bearing rod for linear motion.


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## addertooth (Aug 30, 2020)

I would only reach of a shim if the error was huge,  Even a shim which is 1/1000 of an inch thick in one corner seriously moves the angle the chuck is pointing.


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## WobblyHand (Aug 30, 2020)

addertooth said:


> I would only reach of a shim if the error was huge,  Even a shim which is 1/1000 of an inch thick in one corner seriously moves the angle the chuck is pointing.


Is the correction 1:1, or something less, or more?  Thinnest shim stock that's commonly available seems to be 0.0005".  Half a thou would bring in the error on the horizontal to 0.0001".  That would suit me fine.  

Still don't know where to put the shim though...  No one has answered that question...


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## addertooth (Aug 30, 2020)

If the block which is the headstock is 6 inches long, and you shim one end with a 1/1000 shim, by the time you are 12 inches from the block, your shift will be 2 thousandths of an inch.  very small shims make a huge difference over the length of the bed.  Keep in mind that the jaws of the chuck is about 4 inches out from the headstock block.  Think of it like a lever, where your movement gets multiplied.


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## mikey (Aug 31, 2020)

The RDM method is supposed to be a check for headstock alignment. If your numbers suggest horizontal misalignment then *no shims* would be required. It means the headstock is not aligned with the ways and you need to shift it to correct the amount of "off" you are measuring. In other words, you need to shift the headstock itself toward or away from you and then remeasure to see what that does. If you are also going to try to correct vertical misalignment then you may need to use shims under the headstock. That is a whole other can of worms.

EDIT: I wasn't clear above. You will need to rotate the headstock in minute amounts, retighten the locking bolts and repeat the RDM measurements. Repeat as necessary until you eliminate any significant error.


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## NortonDommi (Aug 31, 2020)

Rollie Dad Method - Spindle alignment on my mini Lathe from Micromark 7x14 - YouTube


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## WobblyHand (Aug 31, 2020)

mikey said:


> The RDM method is supposed to be a check for headstock alignment. If your numbers suggest horizontal misalignment then *no shims* would be required. It means the headstock is not aligned with the ways and you need to shift it to correct the amount of "off" you are measuring. In other words, you need to shift the headstock itself toward or away from you and then remeasure to see what that does. If you are also going to try to correct vertical misalignment then you may need to use shims under the headstock. That is a whole other can of worms.
> 
> EDIT: I wasn't clear above. You will need to rotate the headstock in minute amounts, retighten the locking bolts and repeat the RDM measurements. Repeat as necessary until you eliminate any significant error.


So it would seem my headstock is off by 6 tenths in the horizontal and 3 tenths in the vertical over about 9-1/4".  What is confusing to me is the correction.  @mikey For a mini-lathe, the horizontal correction would be to partially loosen the 3 bolts #131 that fasten the headstock casting #10 to the bed way #132, and rotate the headstock relative to the bed way?  Please state yes or no, sometimes things are not obvious to me - that's why I am asking the question.

How does one move the headstock such a tiny, minute, amount in a controllable fashion?  Does one tap the casting with a hammer? Use a lever?  I could see myself battling with this for ages, some practical experience would be most helpful.


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## WobblyHand (Aug 31, 2020)

NortonDommi said:


> Rollie Dad Method - Spindle alignment on my mini Lathe from Micromark 7x14 - YouTube


I watched this.  It was the first video I found.  Unfortunately, the video sort of blunders its way through the measurement, but does not show how to actually make the corrections.  I measured the error.  Now I need to take some of the error out.


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## WobblyHand (Aug 31, 2020)

Now thinking about this...  RDM checks for headstock alignment to the ways.  The measurements were made at 2 points (actually 4 points, since the horizontal and vertical were done at different start points).  But lets say the horizontal and vertical corrections were made, what else needs to be done?  (Besides the tailstock, which is its own project - one of the adjuster screws is stuck...) Sometime I need to make a test cut, yes?  What else?


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## addertooth (Aug 31, 2020)

Other errors... Chuck mounting plate on spindle and chuck (wobble).  Head-stock Bearing play.  Mal-adjusted Gibs, which shift more under heavy load, than under light cuts.  Tool post flex/slop.  Tool flex.  Lathe not level in both planes also contributes to errors.


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## homebrewed (Aug 31, 2020)

Here's a description of one approach that was taken to align a mini lathe, which includes the shimming procedure:  Lathe Alignment.  Among other things, it answers your question of just where the shims are placed.

Examination of your RDM results suggests that you really don't need to worry about your mini's headstock alignment.  I bet it's better than mine, and I've been using mine happily for years.  There are other components that often are much further out of alignment (like the notoriously-bad tailstock).


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## Weldingrod1 (Aug 31, 2020)

Hershey bar foil was half thousandth...
The shims should go between the headstock and the bed: two steel parts.
If you have 0.006" in 15", then 0.0005" on 4" might actually be a useful correction.

I bet you find goo/junk under the headstock!

Sent from my SM-G892A using Tapatalk


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## Weldingrod1 (Aug 31, 2020)

You might want to loosen those bolts and see if you CAN rotate the headstock with respect to the ways. In a perfect world there would be perfect, solid contact between the headstock and the alignment features on the bed. In the real world, there might be slop. If there is, you want to shim it solid and move shims around to get solid alignment. You really dont want the headstock alignment depending on friction.

That said, aligned by friction is better than not aligned! You could always align it and then wick some bearing retaining compound or some "after-lock" in there to fix it!

And, yes, tapping is a time-tested machinist alignment technique capable of sub 0.001" work if you have the measuring tools and some practice.

Sent from my SM-G892A using Tapatalk


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## mikey (Aug 31, 2020)

WobblyHand said:


> So it would seem my headstock is off by 6 tenths in the horizontal and 3 tenths in the vertical over about 9-1/4".  What is confusing to me is the correction.  @mikey For a mini-lathe, the horizontal correction would be to partially loosen the 3 bolts #131 that fasten the headstock casting #10 to the bed way #132, and rotate the headstock relative to the bed way?  Please state yes or no, sometimes things are not obvious to me - that's why I am asking the question.
> 
> How does one move the headstock such a tiny, minute, amount in a controllable fashion?  Does one tap the casting with a hammer? Use a lever?  I could see myself battling with this for ages, some practical experience would be most helpful.



Typically, the headstock is located on the ways by the angled rail in front or a pin. In your case, it is the rail in front. You would loosen whatever bolts hold the headstock to the ways and see if there is enough play to shift it in the direction you want the headstock to go. If not, then you may need to very judiciously file the contact point under the headstock to allow for the correction. 

0.0006" is not a lot of misalignment and for most work you would not notice it. However, on long pieces it will show. How critical this is going to be is unclear at this point. For myself, I would correct it.

Actually, for myself, I would put a 1-1/2" OD aluminum or 12L14 rod in the 3 jaw and stick it out about 4". I would take a 0.010" cut to take off the skin, then take 0.003" to smooth it out and then a 0.001" deep cut all the way down the bar with a sharp, well ground HSS tool set dead on center height. Measure the tail end and the chuck end and see if there is a difference. If there is then move the headstock to correct it without disturbing the rod. After a correction is made, repeat the cuts until any error resolves. I don't use the RDM method or any other method; I use this one because it is self-proving.


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## WobblyHand (Aug 31, 2020)

homebrewed said:


> Here's a description of one approach that was taken to align a mini lathe, which includes the shimming procedure:  Lathe Alignment.  Among other things, it answers your question of just where the shims are placed.
> 
> Examination of your RDM results suggests that you really don't need to worry about your mini's headstock alignment.  I bet it's better than mine, and I've been using mine happily for years.  There are other components that often are much further out of alignment (like the notoriously-bad tailstock).


My RDM results are a lot better than I feared.  To be honest, I thought something was really wrong after I stuffed up my saw arbor. Now I realize I'm just a poor machinist.    Hope to get better with time and practice.

My tailstock is off by many thousandths, it's one of my (many) projects to tackle.


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## WobblyHand (Aug 31, 2020)

Weldingrod1 said:


> Hershey bar foil was half thousandth...
> The shims should go between the headstock and the bed: two steel parts.
> If you have 0.006" in 15", then 0.0005" on 4" might actually be a useful correction.
> 
> ...


My numbers are 0.0006", (not 0.006")  over 9.25".  Would need to be a mighty thin shim.  Maybe gold leaf?  That is about 0.1 microns, or 4 millionths of an inch.  That's really thin.  Silver leaf comes at 0.32 um or 0.0000126" thick per sheet.  $9.31/2 square feet.  (25 pieces of 3.75" x 3.75")  silver leaf  Gee, this doesn't sound impossible, but it doesn't sound easy either.  If all 25 sheets were stacked and the air was smoothed out the leaves would be 0.000315" thick.  Sure wouldn't want to sneeze!


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## WobblyHand (Aug 31, 2020)

mikey said:


> Typically, the headstock is located on the ways by the angled rail in front or a pin. In your case, it is the rail in front. You would loosen whatever bolts hold the headstock to the ways and see if there is enough play to shift it in the direction you want the headstock to go. If not, then you may need to very judiciously file the contact point under the headstock to allow for the correction.


The contact point might be a section on the angled rail, say on the front edge?  (or rear?)   Just enough for there to be a tiny movement in the horizontal plane?  Would using a diamond stone be better (slower) than a file?  How would one shim vertically with a pyramidal way?  _/\_        __  



mikey said:


> Actually, for myself, I would put a 1-1/2" OD aluminum or 12L14 rod in the 3 jaw and stick it out about 4". I would take a 0.010" cut to take off the skin, then take 0.003" to smooth it out and then a 0.001" deep cut all the way down the bar with a sharp, well ground HSS tool set dead on center height.


Have 2" OD 6061 11.5" long, 2.25" OD 6061 x 12" and lots of 1" OD 12L14, 303 and 6061.  Is it necessary to shorten the 2" 6061?  I have a 16" bed, so it should be able to turn the full length.


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## mikey (Aug 31, 2020)

The contact point for your headstock IS that front rail. Still, with the machining tolerances of import machines there may be enough play to shift the headstock enough to align it ... maybe. If not, then I would file enough material from the contact point of the headstock where it touches the rail so I can move it. As for vertically shimming the headstock, this is rarely necessary and I would not do it unless there is a major error. The reason for this is that once you do it then aligning the spindle centerline with the tailstock becomes problematic vertically, right? Since there is no provision for aligning the tailstock vertically, I would leave vertical alignment alone. 

The reason for suggesting a very short 4" stick out is to limit deflection. Using a long rod will defeat the purpose of this test. 4" is short enough that a sharp properly ground HSS tool will take a 0.001" deep cut with very minimal deflection, thereby giving you a very accurate test. My Emco lathe is aligned this way and a tenths indicator cannot detect any deviation. My Sherline lathe has been aligned like this maybe 50 times or more, probably more, and I can get the headstock aligned to zero deviation using this method. 

Over the years, I've tried just about every headstock alignment method I've ever heard of except for using a MT test bar; I don't trust the stacking tolerances part of that method but that is just my personal bias. This test cut method has been the most reliable, repeatable and accurate method for me so I use it. If a test cut made with a good tool using the ways/saddle/tool post of the lathe being tested produces a cut on a rod that shows no deviation over a 4" run, and that rod is heavy enough not to deflect from cutting forces, then the headstock pretty much has to be aligned with the ways, don't you think?

While I'm at all of this, my personal approach to set up is to align the headstock, then level the lathe, then align the tailstock - in that order. If the headstock is off axis then everything else you do will also be off. Think about it.


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## WobblyHand (Aug 31, 2020)

Wasn't serious about doing the vertical, as it's 3 tenths over 9 inches.  That's in the "leave that one alone" category.  Horizontal is 6 tenths, so might try to correct that.  First I'll see how hard it is to get access to those bolts.

Ok, will chop off a piece of the 2" aluminum.  I have a 1-2" micrometer to measure.  Just get it round first then take a fine 0.001 cut, using a nice sharp HSS tool?

@mikey When you say level the lathe, you mean check for twist, correct?  You actually mean check that the level of the ways near the headstock is the same as near the tailstock?  How good of a level is needed?  Could one get away with a $60 evilBay level?  On a limited budget, so want to minimize expenditures on _low usage_ tools.

As for the tailstock, mine's off in both dimensions by a few thousandths.  (What a surprise...)  Horizontal is _easy_ to fix.  (If I can free up the screw - it doesn't want to move)  Don't recall if the TS is high or low. Measured it once, but have forgotten what it was.  Fixing the vertical offset seems to be a bit of work.


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## mikey (Sep 1, 2020)

WobblyHand said:


> Ok, will chop off a piece of the 2" aluminum.  I have a 1-2" micrometer to measure.  Just get it round first then take a fine 0.001 cut, using a nice sharp HSS tool?



Yes, get it round and smooth, then take a very light cut to minimize deflection and measure the rod. If the headstock is aligned correctly it will read the same all the way down the rod. If it does not, move the heastock until you get a cut that does read the same all the way down the rod.



WobblyHand said:


> @mikey When you say level the lathe, you mean check for twist, correct?  You actually mean check that the level of the ways near the headstock is the same as near the tailstock?  How good of a level is needed?  Could one get away with a $60 evilBay level?  On a limited budget, so want to minimize expenditures on _low usage_ tools.



Yes, when I say to level the lathe I mean to remove all twist from the bed. As for how sensitive a level is required, a simple Starrett 98 will do it but a more sensitive level in the 0.0002"/foot range will be faster. Both will work and you will still have to do a 2-collar test after using either one. The difference is that it will take a lot fewer trial cuts with the more sensitive level to finalize your settings so in terms of time and frustration, the more sensitive level is worth its cost. As for "low usage", your lathe will move over time and require you to recheck level periodically. By that, I mean annually at least and bi-annually if possible. You also need to check it after turning heavy or off-balance work pieces because vibration can loosen settings. I pull my precision level out at least 3-4 times per year and considering how much time it has saved over the years it is certainly worth what I paid for it.


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## WobblyHand (Sep 1, 2020)

mikey said:


> Yes, get it round and smooth, then take a very light cut to minimize deflection and measure the rod. If the headstock is aligned correctly it will read the same all the way down the rod. If it does not, move the heastock until you get a cut that does read the same all the way down the rod.
> 
> Yes, when I say to level the lathe I mean to remove all twist from the bed. As for how sensitive a level is required, a simple Starrett 98 will do it but a more sensitive level in the 0.0002"/foot range will be faster. Both will work and you will still have to do a 2-collar test after using either one. The difference is that it will take a lot fewer trial cuts with the more sensitive level to finalize your settings so in terms of time and frustration, the more sensitive level is worth its cost. As for "low usage", your lathe will move over time and require you to recheck level periodically. By that, I mean annually at least and bi-annually if possible. You also need to check it after turning heavy or off-balance work pieces because vibration can loosen settings. I pull my precision level out at least 3-4 times per year and considering how much time it has saved over the years it is certainly worth what I paid for it.


Took 0.030 off the diameter of the 2" OD 6061 rod to get to bare metal.  Then a 0.001" deep pass.  My 1"-2" Micrometer seems to be 0.0003" off from the 1" and 2" standards.  At least it is consistent.  Since its not clear to me the standards really are any good, won't adjust anything just yet.  The average near headstock reading was 1.970233" (6 readings). The average near tailstock reading was 1.969250" (four tight readings).  So the tailstock reading is 0.000983" smaller than the headstock.  This taper is over 4".  I need to do better than this.

The above measurements match my recent boring experience.  There was a taper in the bore.  Hence this thread.

Thanks for clarifying the usage.  It wasn't clear to me that I'd have opportunity to use the level again.  If there's some re-use, I can justify getting one of these levels.  Are the $60 0.0002"/10" levels any good?  Or are they just heartbreak in a wooden box?

One last question, kind of off-topic.  When the 6061 was turned, the finish had little white discolorations on it on a bare metal background.  Is this because of the material itself, or due to there being a tiny defect on the lathe tool bit, or something else?  I used WD40 as a lubricant and tried Aluminum Tap Magic, both seemed to give the same finish.  Kind of speckles.


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## addertooth (Sep 1, 2020)

Little fine point "freckles" are less common when you use a tool with a large and generous radius.  I use one of those circular carbide elements when I am trying to get a very smooth surface.


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## mikey (Sep 1, 2020)

What kind of tool did you use for your cuts? Was it HSS? The finish suggests you used something sharpish but used the nose radius to cut. You will find that the nose radius deflects the most and a large radius will deflect much more than a small one so larger nose radii are less accurate than small ones. You will get a much finer finish by using the end cutting edge adjacent to and just behind the nose radius to make your passes. This will also deflect less, giving you better accuracy; since accuracy is the point here, you may wish to review your technique. This is NOT a criticism of you because you're relatively new and may not be aware of this stuff. I'm trying to tell you those things you need to know to work accurately so you can rely on your results.

If you used a carbide insert then I hope it was at least a CCGT-AK insert with a sharp ground edge. Here, too, you can use the end edge just behind the nose radius to improve accuracy and finish. Just keep in mind that when doing test cuts of any kind during lathe set up (headstock and tailstock alignment and leveling), you should avoid carbide inserts and use a sharp HSS tool that is capable of taking accurate micro-cuts. 

Your results suggest the tail end of the rod is closer to your cutting tool than is the chuck end so you would need to nudge the front end of the headstock away from you and re-tighten the bolts. Repeat your cutting tests and adjust again as necessary until you get zero deviation down the bar. Do not rely on a dial indicator run across the front of the rod to tell you if the rod is off; measure the diameters. 

If you care about your lathe and its accuracy, you will use that level often. I know we're just hobbyists and all but some of us work to rather tight tolerances and having the machine set up well is important. As to the quality of those import levels, I don't own one so I cannot comment. Others who do own them seem to think well of them for the most part but if I were you I would start a thread and ask. I own a Kinex level; that one is very good. 

As to the tiny flecks, I don't know if there are inclusions in the material or not. I don't see them when I turn aluminum.


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## WobblyHand (Sep 1, 2020)

mikey said:


> What kind of tool did you use for your cuts? Was it HSS? The finish suggests you used something sharpish but used the nose radius to cut. You will find that the nose radius deflects the most and a large radius will deflect much more than a small one so larger nose radii are less accurate than small ones. You will get a much finer finish by using the end cutting edge adjacent to and just behind the nose radius to make your passes. This will also deflect less, giving you better accuracy; since accuracy is the point here, you may wish to review your technique.


It was HSS.  A general purpose square tool, similar to post #21 of the models-for-grinding-hss-tools thread.  It is quite possible that I'm using it incorrectly.  I find the tips of my HSS tools are prone to breakage.  Sometimes the tips break below the point.  Can you show me a picture of the correct angle of the tool relative to the work piece?  This is how it was set up for all the cuts.  (Except it was actually cutting!)  You can see the chips of the last cut sitting on the tool holder.


I do have some TCTGT carbide inserts, which do leave a nice finish, especially when new.  If I recall correctly they have a 0.007" nose radius.  But, I was following your guidance to use HSS.

I don't see the flecks when cutting with new sharp carbide.  My guess is there is a defect on the cutting tip or edge of this HSS tool bit.  All the tools I've ground seem to develop this problem after a while.  They are sharp, and then an edge cracks or something. They never have dulled from use.  And no, I don't bang them around or into anything.


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## mikey (Sep 1, 2020)

Okay, try turning the tip of the tool a few more degrees to the left. You are going to use the end edge just behind the nose radius. Just touch the work and make a pass, then come back and feed in a thou and make another pass. Increase your speed and slow your feed. It should make a clean cut with no ridges. Try that and report back.


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## WobblyHand (Sep 1, 2020)

mikey said:


> Okay, try turning the tip of the tool a few more degrees to the left. You are going to use the end edge just behind the nose radius. Just touch the work and make a pass, then come back and feed in a thou and make another pass. Increase your speed and slow your feed. It should make a clean cut with no ridges. Try that and report back.


So the tip goes towards the headstock, and the tail goes towards the tailstock?  I'll loosen the tool post and rotate CCW a few more degrees.

As for changing the feed rate relative to the speed, alas, this lathe cannot independently control this.  The feed rate is proportional to the spindle RPM.  I could change gears and change the ratio.  The gears are set to 20/80/20/80 right now.  I think that is the slowest feed rate relative to spindle RPM, correct me if I am not understanding this correctly.


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## mikey (Sep 1, 2020)

Yes, turn CCW a bit and see what happens. As to feed, just do it manually. It will work better for you.


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## WobblyHand (Sep 1, 2020)

Ok, tried the experiment.  The back of the tool had about a 0.015" gap vs the nose touching the workpiece.  The finish is a little better, but not mirror smooth.  Still has speckles.  Since there was 0.5 beers in me, I had to take it slow.  Didn't want to post in the _don't do this section_.  The rough difference in diameters is about 0.001.  I didn't take a lot of measurements of each.  That will have to wait.


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## WobblyHand (Sep 1, 2020)

This was with autofeed.  I could just fit the edge of my Mitutoyo steel ruler under the back edge of the tool.


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## mikey (Sep 1, 2020)

Try maxing out the speed. The tool position looks good. Use some WD-40 and feed slow.


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## WobblyHand (Sep 1, 2020)

So max spindle RPM and manual feed slow?  I can do that, says the guy that just finished a beer...

Actually, he can't do that and get a good finish.  Starting and stopping manual feed on a mini-lathe, isn't a good way to get a nice finish.  The lathe just isn't rigid enough.  Had markings where ever I stopped feeding.  Not nice.  Ran it at a higher spindle speed. Max spindle speed had some noises, aka chatter.  Backed it off a little, and no chatter.  Finish is getting better, but still could be improved.


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## mikey (Sep 1, 2020)

Yup, try it.


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## WobblyHand (Sep 1, 2020)

Apologize for ninja edit.  Manual feed was not so good.  Lathe isn't tight enough.  Need to tighten up the gibs.  Had installed in an extended cross slide kit and things are close, but not quite as tight as I usually run it.  

High RPM (and autofeed) does improve the finish some.  It's a little better.

Waiting for another 6 mm hex key.  Need to grind the arm shorter so I can adjust the headstock.  Didn't want to mess up my regular key set.  Have to disassemble a bit to get to the headstock bolts - and have to reassemble a bunch to be able to turn on the lathe safely.


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## mikey (Sep 1, 2020)

Okay, keep us posted.


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## WobblyHand (Sep 2, 2020)

Received my $1.99 6 mm hex wrench and ground it on the belt sander until it was only $1.83.  The short part of the L interfered with the lead screw. Have to say they don't make it easy to access these points.  I can turn all the headstock bolts now.  One was OMG tight, the others were a lot less tight.  

Since the tailstock end of the turned workpiece was smaller than the headstock end, I want to rotate the headstock away from me (CCW) correct?  How do you suggest this is done?  The bolts are (as seen from over head) like: 


Have #1 sort of tight, and loosen #2 & #3 a bit and tap at #2 towards #3?  Or something entirely different?  At the moment all bolts are tight.


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## mikey (Sep 2, 2020)

I think I would leave the rearmost bolt snug, just loosen the two bolts on the right and bump the headstock over a tiny bit and lock it down. Then repeat the cut.


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## WobblyHand (Sep 2, 2020)

mikey said:


> I think I would leave the rearmost bolt snug, just loosen the two bolts on the right and bump the headstock over a tiny bit and lock it down. Then repeat the cut.


@mikey That's a little confusing to me.  Do you mean bolt #3 in my drawing, or #1?  Not sure what rearmost means in this context. That's why I numbered them in the sketch.


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## mikey (Sep 2, 2020)

I meant to leave #1 snug, not tight. Loosen #2&3 and lightly snug them Tap the headstock in the direction you need and tighten#1, then #2 & 3.


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## WobblyHand (Sep 2, 2020)

mikey said:


> I meant to leave #1 snug, not tight. Loosen #2&3 and lightly snug them Tap the headstock in the direction you need and tighten#1, then #2 & 3.


Thanks, that helps.  

Since the piece was smaller at the tailstock than at the chuck, I want to rotate the headstock away from me which is counter clock wise, correct?


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## mikey (Sep 2, 2020)

Yes, I think so. Try it and see.


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## WobblyHand (Sep 3, 2020)

Ok, after disassembling a lot, I made an attempt at correcting the horizontal error.  Had #1 snug but not full tight, loosened #2 & #3 a tad.  Tapped the headstock near #2 to rotate the HS CCW.  I tightened #1 first, then #2 then #3.  

Took another 0.001 pass.  Really didn't believe what I was seeing.  (0.7 tenths)  So I took another pass of 0.001, reasoning that making another cut shouldn't make any difference, but should remove effects of the headstock adjustment a little.  The second set of measurements was better.

If I believe my second set of measurements (avg of 7 measurements at TS, and 8 at the HS) the HS is 1.96044" and the TS is 1.96086".  This is a difference of 0.00042", with the TS being larger (still).  I've reduced the error by a factor of 2.  It took me a while (6 readings each) before I really settled down taking measurements.  (On the second set.)  Had to get a feel for the right sensation as I rotated the micrometer off the maximum.  If it didn't feel right, I looked at the measurement, but rejected it.  After a dozen measurements or so the feel seemed to be more consistent.

Too be honest, I'm going to wait a bit.  Wait for the iron to relax.  Then take another cut and measure again.  4 tenths isn't bad for this class machine, although I'd like it a tiny bit better.  Tapping the headstock with my machinist hammer seemed like it was doing nothing.  But it took off about 0.0005 of the error!  From my former, non-machinist point of view, this would be black magic.  Now I know better.

Need the level for the next step.


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## mikey (Sep 3, 2020)

Okay, at least we're making progress. The important thing is that you now understand how to do this. I did want to point out that bolt #1 is your pivot and once you move the head, locking down that pivot first will hold your settings so that tightening bolts 2 and 3 will not move the head.

How much more accurate the alignment needs to be is up to you. You may get to the point where you may not have enough play in the hard points to allow for much more accuracy. At that point, you either have to accept it or take out your file.

This was a good lesson, I think. There are a number of ways to do most everything in this hobby but the ones you trust are the ones you test yourself and prove them to be valid. This might be one of them.

EDIT: Whatever you do, do NOT remove your rod from the chuck. This is a first operation and as long as the chuck is not loosened then you can rely on the results from subsequent cuts. I know you understand this; just making myself feel better by saying it.


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## WobblyHand (Sep 3, 2020)

mikey said:


> Okay, at least we're making progress. The important thing is that you now understand how to do this. I did want to point out that bolt #1 is your pivot and once you move the head, locking down that pivot first will hold your settings so that tightening bolts 2 and 3 will not move the head.
> 
> How much more accurate the alignment needs to be is up to you. You may get to the point where you may not have enough play in the hard points to allow for much more accuracy. At that point, you either have to accept it or take out your file.
> 
> ...


On the fence on further alignment.  One wouldn't think much more movement is possible.  However, I thought that initially, and got 5/10ths improvement. 

Understood on moving, tightening, un-tightening whatever from the chuck.  It's good to restate the obvious.  

Tomorrow, I'll take another cut to see if the answer is substantially the same.  If it is, then for giggles, I might do the RDM again. Ideally, the numbers should be smaller than what was measured before.  Might be a revealing test.

Level is on order.  Taking a chance on a less expensive one.  If it doesn't work out, I'll get something else.

For the tailstock what do you suggest?  I've seen the test with a bar between centers, taking a cut at both ends.  Is that what you recommend?


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## mikey (Sep 3, 2020)

WobblyHand said:


> For the tailstock what do you suggest?  I've seen the test with a bar between centers, taking a cut at both ends.  Is that what you recommend?



No. I have an article I wrote some time back on how to make a tailstock alignment test bar. I'll try to clean it up and post it.


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## addertooth (Sep 3, 2020)

I would agree that you don't know for sure how true your lathe is cutting, until it is leveled.  I just got in a Starrett Machinist level (today) and it showed me something that surprised me.  My lathe rests on a 3/4 inch marble slab, which rests on a wooden workbench.  When I took the level to the marble slab it was flat, but the wooden table underneath was "sway backed".  i.e.  The middle was a notably low point, with the wood surface slanting upwards towards the legs.  It made me glad I sprung to get the marble slab for under the lathe.  My bullet level I had used before, lacked the resolution to see this.


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## WobblyHand (Sep 3, 2020)

addertooth said:


> I would agree that you don't know for sure how true your lathe is cutting, until it is leveled.  I just got in a Starrett Machinist level (today) and it showed me something that surprised me.  My lathe rests on a 3/4 inch marble slab, which rests on a wooden workbench.  When I took the level to the marble slab it was flat, but the wooden table underneath was "sway backed".  i.e.  The middle was a notably low point, with the wood surface slanting upwards towards the legs.  It made me glad I sprung to get the marble slab for under the lathe.  My bullet level I had used before, lacked the resolution to see this.


Wood tops just don't hold up under machinery.  They are pretty and all, but they sag.  I had a solid core door on saw horses for a while.  I had a small drill press on it.  I was amazed at how much sag there was when I replaced that set up.  Steel stands/benches are so much better.

Carpenter levels are not very sensitive.  The level has to move quite a bit before the bubble seems to move.  One really needs a much better grade level to measure the tiny differences we are trying to correct.


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## addertooth (Sep 3, 2020)

WobblyHand,
I could not agree with you more on the flex of wooden tables. I was just surprised how visible it was with a higher resolution level, it was painfully obvious.   I live in a very small town, and purchasing metal stock here is very pricey.  For the most part, you are forced to get it from a hardware store (If you are unwilling to take off work and drive 3 hours round-trip to get to the "big city".  I had a local guy trying to sell some 1/2 inch steel 24" by 48" plate, but it would be fair to say he wanted a premium price for it, very premium.  I may end up having to build an edge up 2x6 bench if a good steel source cannot be found (fingers crossed).


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## WobblyHand (Sep 5, 2020)

Re-did the measurements after cutting with a TCGT carbide tool.  I got a better surface finish on the aluminum, less grooving.

I really wasn't happy with the finish that I was getting with the HSS. I think I managed to get a bad lot of steel.  The edges micro-fracture after a short time, and give a bad finish.  I looked at the edge, which I know was really nice and it has some really tiny defects in it now.  I have a few pieces of cobalt steel that aren't from that lot, maybe I'll grind another tool.

With the TCGT tool and a recut, I am getting 1.939635" average at the tailstock and 1.939170" average at the headstock.  This means the tailstock measurement is 4.65 tenths larger than the headstock.  I am more confident in this measurement than the previously reported on, because 1) had more practice, 2) remembered to lock the mic, 3) took more measurements, and 4) the standard deviation of the measurements was quite low.  (0.000087" for the TS, 0.000095" for the HS).  In any case, the measurement is pretty close to post #44.  (4.2 tenths vs 4.65 tenths).

Still waiting for the level to show up...  Might make another try at reducing the error, although suspect that the HS is up against the rails at this point.  Not quite sure how or where to safely remove metal to get a little more movement.  Nor do I want to induce any vertical error..


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