# Mini-Mill Spindle-Column Alignment



## rudydubya

After reading an earlier thread about off-center drilled holes *HERE*, I checked my Harbor Freight mini-mill and found that the spindle was not in alignment with the column, apparently not uncommon with the Sieg X2 machines. From what I've read, the only practical way to align the spindle and column is to shim the spindle housing where it mates with its carriage for Y-axis corrections, and to wiggle it about on its mounting screws for X-axis corrections. Either adjustment requires getting to the housing mounting screws, located behind the carriage and hidden by the column. You have to remove the head from the column to get free access to the screws (shown later below). It sounded like a challenge, but turned out to be relatively simple. Here's how I did it. But before I start, the photo below shows what I'll be calling the spindle housing and the carriage that make up the mill head. Your nomenclature may vary. Also, all my measurements are in inches, taken on import tools.





Aligning the mini-mill spindle with the column basically just involves putting a test bar in the spindle and adjusting the spindle housing until the test bar is parallel to the column in both axes. I used E. T. Hackett's alignment procedure except for the choice of a test bar and the measurement method (see the files section of the Yahoo GrizHFMinimill group or at http://www.machinistblog.com/?p=991 for his writeup). Mr. Hackett used an aluminum precision shaft from McMaster-Carr and measured along the length of the shaft after it was turned to midpoint of indicated runout. I used a 7" long, .500 diameter steel shaft salvaged from an old inkjet printer instead, and used Rollie's Dad's Method to do the measurements and alignment (see the link in steamer's post *HERE* for more information on Rollie's Dad's method). The beauty of Rollie's Dad's method is that the test bar doesn't have to be perfectly straight, and runout of the chuck or collet won't affect the results either.

*Safety Note:* If you try this and you've never removed the column and head assembly from your mill before, be forewarned that it's heavy, and top heavy, and can hurt you if you're not careful or can't handle the weight. Also, the head counterbalance arm is spring-loaded, don't let it spring back and whack your knuckles or your favorite dial indicator when you let it loose.

First, I removed the mill column, laid it on a workbench, and removed the motor, the control box, and the electrical box so the head would be easier to slide off the column. I also removed the Z-axis stop and the bolt that connects the spring-loaded counterbalance arm to the carriage. I let the arm swing back and rest against the benchtop.

Next, I did some baseline measurements to see how much out of alignment the spindle was and where adjustments would be needed. The photos below show my test and adjustment setup. The test bar is in a 1/2" collet, but a drill chuck could just as well been used. For the Y-axis checks and adjustments, the DTI point was set on top of the test bar with just enough pressure to get about a .015 reading on the dial. Then, two sets of measurements were taken, one set at the collet end of the bar, and the other set at the far end of the bar. I started my measurements at the collet end. I locked the carriage there and rotated the spindle 360 degrees, and wrote down the minimum and maximum readings from the dial indicator, and then found the average of the two measurements (added the maximum and minimum reading together and divided the result by two). Then, without changing anything about the indicator, I unlocked the carriage and wheeled the head back up the column so that the indicator was at the other end of the bar. I locked the carriage, got the maximum and minimum readings there, and averaged those two measurements. Then I compared the averages. The difference between one end's average and the other end's average was the total misalignment for the distance along the bar. (That's Rollie's Dad's method.) I repeated the procedure for the X-axis, with the indicator point at the side of the test bar, as shown in the second photo.







My initial Y-axis measurements indicated about .0055 misalignment, the spindle axis being tilted downward slightly toward the column. For the X-axis, I couldn't get an exact set of readings because the DTI was hitting its stops as it got close to the bar end, but I estimated that the misalignment was at least .020, more or less, the spindle axis being skewed slightly to the right.

Now, knowing the nature of the adjustments required, I proceeded with the alignment. I did the Y-axis first. I removed the head from the column and loosened the four spindle-housing cap screws (shown in the photo below) so I could put a piece of shim stock between the spindle housing and the carriage. For my mill, the shim needed to be at the bottom of the spindle housing so as to raise the far end of the test bar just a little. I didn't know exactly how thick the shim should be, but since the Y-axis was only off by .0055, I tried a strip of .003 brass shim stock first, figuring that would be a good place to start. I slipped the shim in under the spindle housing where it joins the carriage, tightened the spindle-housing screws, put the head back on the column, and repeated the Y-axis measurements. As it turned out, the .003 shim was a good choice, reducing the Y-axis misalignment to less than .001 over the length of the test bar. The second photo below shows the shim location, just barely visible at the joint. Note that any Y-axis adjustments need to be made first, otherwise any X-axis adjustments that were made would be corrupted when the screws were loosened to insert the shim.







For the X-axis adjustment, I removed the head again and loosened the screws so that the housing could be moved by hand slightly side to side (without significantly moving the shim), and put the head back on the column. I set up my DTI for X-axis measurements again and then moved the spindle housing side to side on its mounting screws to adjust the alignment while monitoring the readings on the DTI. When the alignment was right, I moved the head to the top of the column until I could get to the upper two housing screws from underneath and carefully tightened them. Then I removed the head completely, tightened the two lower screws, replaced the head, and re-checked the X-axis alignment. It took me a couple of tries before I got the bar alignment within .001 of the column axis, because the housing tried to shift a little when I tightened the upper screws. After I was satisfied with the alignment I re-checked both the Y-axis and X-axis alignment to make sure nothing had changed, replaced the motor and boxes, and put the column back on the mill. A final alignment check after the mill was back together indicated less than .001 error in either axis over about 5" of head travel.




I hope the above is of value to anyone considering adjusting their mini-mill. I did a search of the forum but didn't find anything about how to do such an alignment, but if it's there and I missed it, my apologies for the repetition. I'm still a novice on these little machines, and my methods may not be correct and are certainly not the only ways of doing these things. This is just the way I did it. I didn't go into detail on how I removed the column from the mill, the electrical boxes, the motor, etc. either, but if anyone has questions, I'll try to answer. Thanks for reading.

Regards,
Rudy


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## zeeprogrammer

Thanks Rudy!
I have one of those machines and your post is very very helpful.
I know I'll be using this thread as a reference.

Thanks again for the well detailed process.


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## tmuir

Thanks a lot for that.
I read a bit about this on other peoples websites but none of them actually showed where the shims needed to go and I've been afraid to touch mine in case I make it worse.

I'll print this out tomorrow and when I go to fit my airspring I think that will be a good time to do this and I will even use a 1/2 inch SS rod I just got from a printer I pulled apart to. ;D

Most helpful post I've seen on aligning the head of an X2.
Thanks


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## Diy89

Great Job, Thanks for sharing. Now i have the incentive to work on the mill.
Great photos to.


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## jmshep

Thanks for that - I will now have another go at aligning my mill using some of your ideas. 

How did you check that the column was aligned in both axis to the table when reassembled ? 

Has anyone come up with a method of locating the spindle housing and carriage so that they stay in alignment rather than relying on just the four screws. 
Similarly any good methods to add fine adjustment to the column to make tramming easier and locating it once set. (mine always moves as I tighten it).

Regards
John


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## rudydubya

Guys, thanks, I appreciate the feedback.

John, I just trammed it normally. No problems with the X-axis tram, but my column wasn't exactly perpendicular to the table in the Y-axis, something not so easy to correct. Others have loosened the three cap screws holding the pivot plate to the base shown below and shimmed underneath the plate, either at the front or back of the plate, to get the column straight, but I couldn't get the shims to work for me. I finally corrected the Y-axis tram when I was stiffening up the column to reduce flexing. I plan to post an explanation and some pictures on how I did all that in a day or two, but essentially I just put a little stress on the bottom of the column to force it into alignment. It didn't take much, the misalignment was only off about .004 before I fixed it.




And John, I haven't had a problem, at least that I'm aware of, with the spindle housing moving on the carriage. Have you seen movement with the screws tightened?

Rudy


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## ksouers

Rudy,
Very nice write-up on aligning the spindle. This seems to be a common problem with the X2 and I'm sure many owners will appreciate the effort you went through to document the process.


Kevin


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## 4wheels

Hi to all the other X2's,

I have been enjoying my X2 for a few years now only doing small minor jobs but very enjoyable never the less. 

Then a few months ago I read a magazine article about the lack of rigidity in the X2 so the next use I finished facing a surface then with the mill still running I placed a finger on top of the spindle housing and without leaning on it I made a noticeable cut. I reckon I could operate the Z axis by mind control only!

The problem was deemed to be the rotating joint at the base of the main upright member and the offered solution was to add bracing from the four mounting points and the large bolt which the upright rotates on. They still allowed the ability to tilt the upright 45 either side. Once I get the upright upright the last thing I will want to do is rotate it. So my plan is to extend the bracing to some distance up the upright. Instead of fixed attachments at this high point I would use adjustable screws which will allow for fine tuning to the squareness of the upright.

Having just feeling good about that problem I had the same problem described on this thread i.e. started a hole with a centre drill then replaced it with a longer drill and then started the hole a mile away. I went through all the thoughts as described here and noticed that the paint at the joint between the spindle housing and the carriage housing was disturbed and was obvious that the spindle housing had rotated.

My thoughts were that to set the two units back to their start position was there would be no guarantee that they would stay there. They would be held by fiction alone resulting from the tension of the four securing bolts. I went along the lines a some sort of pining or keying but I worried about the testing for alignment procedure as I would hate to key it in the wrong place. The testing procedure was solved by the previous reply and thanks for that. The other great idea was the shim trick.

To hold the spindle housing after the alignment test I intend to securely bolt three bars to the carriage housing two top and bottom on one side a one in the middle of the other side these would overlap the spindle housing by 10mm or so with a bolt through each to contact the spindle housing to adjust and hold the alignment until the four holding bolts are tightened. They would also hold the housing from twisting when one is trying an over zealous cut.

Two problems two solutions. Your good, bad or indifferent comments most welcome.


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## jmshep

4 wheels
 I have been thinking on similar lines to you re making sure the head stays in x axis alignment and also to improve the alignment process. Prompted by your post I had another look at my mill and came up with this idea : 

Drill and tap a hole in each of the back corners of the motor mounting plate. With the four screws that hold the two sections together loosened slightly, screws in the new holes in contact with the carriage top surface will then be adjusted to "rock" the spindle housing into alignment. The screws can be then held in place with lock nuts and the four fastening screws tightened.
This method might not stop the spindle housing moving but it should help, provide a reference if it does and make the alignment procedure easier. 

Before I start drilling can anyone see any flaws in the idea?

John S


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## jmshep

Since my last post I have had a look at the underside of the motor mounting plate and its shape does not lend itself to being drilled as I had hoped.
Plan B is to mount a bar onto the end of the plate as an extension and do it that way.

John S


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## 4wheels

Hi John S,

I popped into the shed yesterday for a look at your idea and thought that a couple of screws would fit OK but I will have a closer look today. If the underside is not suitable then maybe a shaped plate on the top surface of the motor bracket would help? 

My idea of the 3 bars is still on for me as I have drilled and tapped all the required holes in the CI housings and the bars. If it is possible to do your idea I will do that as well. Bit like belt and braces!

Brian


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## jmshep

I have now done the mod I mentioned in my previous post to give fine adjustment to the x alignment on the X2.

It works well and takes all the hit and miss out of the alignment. I just slackened the 4 bolts holding the carriage and spindle housing slightly and was able to make fine adjustments with the two set screws using the measuring method described by Rudy. When I tightened up the 4 bolts and there was no movement. 

After having some doubts how well it might work I am pleased with the result and it only need two 6mm tapped holes in the motor mounting plate casting. 

John S


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## 4wheels

Hi John S,
I have made the bar as you show and am part way thru' fitting but I have already fitted the 3 bars of my original idea so "belt and braces" prevale. My thoughts have now moved to the rigidity of the rotating joint at the base of the column. Currently leaning on the spindle housing moves the Z by about 5 thou. Not a good look. Any thoughts?
Cheers,


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## jmshep

Hello 
I have read several posts that suggest that the domed washer on the column contributes to lack of rigidity. I replaced mine with one made from a piece of steel about 1/4 x 4 x 4 and that does improve things. Another suggestion is to fill the bottom 6 ins of the column with an epoxy and sand mixture but I have not done that (yet).

Another mod I have tried to improve getting the tramming right (as opposed to the head alignment discussed earlier) is to mount a vertical bar on the RH side of the base of the casting and with an adjusting screw in contact with the side of the column near the top to act as a fine adjustment and stop. It is not entirely successful as the bar flexes even though it is 3/4 square steel. I does however make things easier and gives something to push the column against when tramming. With your solution I don't think you will need this.

John S

BTW since posting the picture of the alignment aid I can report that it it was worth the effort and works well.


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## compressor man

Oh great! another thing for me to stress about. I had trammed my mill and built on to the column/base joint to sustantially beef it up. Having done this I sat back in great satisfaction knowing that my mill was just as it should be. Now I learn that there is another and much more involved adjustment that must be done. :wall:

Well, now that I know about it I cannot let it go...it must be done. After reading your post I went out and put a DI on the side of the quill bottom and lowered the head, and yes I watched the DI move, grrr. 

At least I know how to do this now, although ignorance was bliss .

 Thankyou for your very informative and helpful post on this. A kudos point for you sir


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## rudydubya

Thank you Chris, appreciate it. Good luck with your alignment. Please let us know how you make out. 

Regards,
Rudy


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## compressor man

Well, I aligned my mill today as promised. In hopes that it will help somebody I will describe how I did it. I accomplished this in a slightly different manner from Rudy but I am not saying this was a better method at all just different. I gave my initial check in this manner: Chucked my rod into the mill, set an indicator against it and ran the head down about 4-5"
 I determined that my x axis was off about .020 !!! My Y was so close that it did not bear fooling with. I unwired the motor and took the whole assembly off of the column and loosened the 4 bolts Rudy described. Putting it back on the column and setting up my indicator again allowed me to get real close to plumb but I was unable to twist it enough to really get it right. Scratching my head a little I decided to take the plunge from which there is no turning back, I cranked up the drill press. I determined that the holes for the 4 alignment bolts were a little too small and would not allow enough movement. I drilled the holes in the carriage out to 5/16 which is a little bigger than stock. A quick reassembly showed that this was enough to allow me to straighten things up. 

I noticed while doing this that I could insert a shim under one side or the other of the motor base. This would allow me to twist the spindle housing to a new axis and hold it there, quite steadily (is that a word?) for a test measurement. Two pieces of aluminum flashing was just right. I pulled the housing off the column and locked down those 4 bolts and reinstalled and remeasured. Everything was still straight, yah! Tomorrow I hope to rewire the motor and retram my column (I was really tugging and twisting before redrilling those holes and almost surely got it off tram).
Hope this helps someone.


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## spectre

I've got a question (sorry if it's a dumb one). It concerns the rollie dad method. Let's say I'm measuring the X or Y axis as rudydubya did in his post. At the collet end, rotating the test indicator moves...say 0.001 total run out while rotating (moves +/-0.0005 each side of zero). I move the carriage up to get a reading on the far end and it reads 0.012 total run out but the center of the reading is on a different point on the dial indicator since i didn't change anything or re-zero (lets say +/-0.006 on each side of the 5 on the dial for simplicity). 
  Does this mean the axis is off by 0.006 -0.0005 = 0.0055? I think the fact that the rod is rotating around a different center point is throwing me off (esp on the x axis). Oh yeah, I'm using a 1/2" piece of drill rod from enco so it should be about the same diameter along it's length. If this is confusing let me know I'll try to explain it better. It always makes sense in your head but it doesn't translate so well into words sometimes ;D .


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## zeeprogrammer

Whoa!
I can't help with your questions...I'm a newbie.

But welcome to the forum.
Post something in the Welcome area about yourself.


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## spectre

Haha, ok will do. Thanks anyway!


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## rudydubya

Spectre, welcome to the forum. I'm still a newbie too, but here's my understanding of Rollie's Dad's Method: Average the minimum and maximum readings at the collet end (just add the two readings together and divide by 2), and then average the minimum and maximum readings at the far end. If the averages are different, then the alignment is off by the amount of the difference. In your case, the average at the collet end is zero, while the average at the far end is 0.005, so the far end is 0.005 off-center. If it were perfectly aligned, the average of the minimum and maximum readings at the far end would be the same as the collet end, zero in this case. Hope this helps.

Regards,
Rudy


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## chester179

Thanks for posting this rudy. Very helpfull.
One thing that i would add is to check the adjustment of the column/carriage assy for correct fit - mine had discernable movement that interfered with reliable measurement and adjustment of the spindle. 
Simple adjustment of the 4 adjusting screws corrected this problem. 



I torqued the 4 spindle housing bolts to about 20 lb.ft probably a bit on the low side but i didnt want to risk damaging the threads.


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## dgjessing

I'm so glad this thread was resurrected - this explains what's wrong with my mini-mill! I'd get the thing trammed just perfect so a fly cutter would make the nice "()()()()" pattern, but when drilling, changing from a short center drill to a long drill bit would throw the center off... WTF? I thought. This explains it! 

Mine is .025" off over 4" in the X axis, but good in the Y axis. Off to do some minor surgery...

 :bow: to the OP

.... after surgery... ;D Much better!!!


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## rudydubya

chester179 and Dave, glad this old thread was still useful.

chester179, thanks for the feedback. I see that was your first post here on HMEM. Welcome. When you get a chance, stop by the welcome section and tell us about yourself and your shop and your equipment and your projects and your interests. Great bunch of folks here, and they would all like to meet you. And you probably already know we love pictures.

Regards,
Rudy


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## chester179

Thanks Rudy.
Your method got the spindle head lined up with the column.
Trammeling the mill revealed that the column/spindle was not in perpendicular alignment to the table/base. It was discernably tilting forward - presumably a natural consequence of the front heavy spindle head weight on the column. 
The method i used to remedy this was to build a wooden brace with a steel bolt between the brace and the top of the spindle column. The mill was the trammeled and the adjusting bolt was tightened up to counter the forward stoop.




This corrected the alignment to acceptable levels.


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## rudydubya

Interesting solution to correct the tilt, chester179. Thanks for sharing. I corrected the tilt on mine with a small plate and some bolts at the bottom of the column while I was trying to minimize the column flex. You can see what I did and see some other solutions here: http://www.homemodelenginemachinist.com/index.php?topic=6075.msg64571#msg64571.

I see from the picture that you've installed the air-spring mod as well, or did that come with your lathe? Any other mods that we would be interested in? Lots of folks here on the forum with mills like ours.

Don't forget to stop by the welcome area and start a hello thread so all the members can meet you.

Regards,
Rudy


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## chester179

Very interested to read the link to how you solved the problem of column flex in your mini mill rudy. Seems we both had the same problem ; forward tilt due to top frontside weight on slightly flexible column. You opted to strengthen the column while i opted to counterbalance the topheavy weight causing the stoop. I guess combining both methods might get the best results. 
My mill is standard as it came from the factory , ive only recently got it and up to present have just been trying to get it all aligned with sufficient accuracy for use. Now i can start using it but will keep a close watch on the forward tilt as things settle into place , particularly with the wooden construction. Have you found the alignment on your mill has remained stable or have you had to adjust it subsequently?
Mines a Chester Conquest (UK) btw.


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## rudydubya

chester179, my setup appears stable. I checked the tram this afternoon to see how much it might have changed over the last several months, and it was only off about 0.0005", about like it was when I last trammed it, as I recall. It hasn't seen much use over that period, and most of that was light work. It will be interesting to see how your wooden brace holds its tram over time. What kind of projects are you planning?

Regards,
Rudy


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## chester179

Rudy well a week down the line and it seems stable. One thing i did notice was that my x axis trammel varied on the lhs depending on if the spindle head was tightened or not indicating the carriage was fitted loose enough for it to move on tightening. I tightened up the carriage adjusters. Fortunately the x axis alignment still seems ok. 
Originally i noticed that the forward lean on my mill could be corrected by leaning on the spindle housing so rigged my setup as a permanent way of counterbalancing this tendency to lean. 
All ive done with it so far is milling retaining bolts and drilling holes. Originally it was an expensive response to needing to do some precision drilling but subconsciously maybe i was also ready for a new hobby. 
Rob


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## rudydubya

Rob, glad your mod is working for you. As for the head movement when locking the gibs, I saw that also while I was getting used to my machine, especially when setting or adjusting the head height. I now keep the gib screws adjusted tight enough to offer a bit of resistance when cranking the head up or down. But even so, I always assume the head may move a thousandth or so when I lock the gibs, and watch for it if I'm trying to do something that requires that kind of accuracy. Adding my cheap DROs have made that a lot easier to monitor.

When you decide on a project be sure and keep us informed. I only wish I had started on this hobby many years ago.

Regards,
Rudy


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## Goldigger

I tried aligning the spindle to the column tonight...I should have started at 6am then I might have got it finished..
For my test bar I used a bar from w printer, thinking it would be perfectly straight and round.
Seems not, rotate it 180 degrees and its off by 0.20mm
If I measure at the top and set the dti to 0, move the spindle to the bottom of the z axis...its now reading -0.60 on the x axis...

So my spindle appears to be pointing to the right on the x axis. That might explain my issue on my rotary table.
With the rotary table centered and spindle aligned to 0.0 x and y..move the x to the left say 20mm and drill a hole..then move the rotary table through to -20mm on the x axis and drill another hole.
I should end up with a hole 20mm either side of the centre of the work piece..the hole to the left is always a shorter distance..

I have a problem with taking the head off to get to the 4 bolts..I have to loosen my gib just to move the head off the end of the column..


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## Goldigger

Can someone confirm im doing this correct please...
Im pretty sure my Y axis is only off by 0.03mm so I'm going to just adjust the X axis

I have my test bar from a printer in a 1/2" collet..
With the head at the top of the column, i take a reading off the DTi at the bottom of the bar...I have 0.15mm runout
With the head at the bottom of the column, i take a reading off the DTi at the top of the bar (just below the collet)...I have 0.02mm runout 
(When i move the head from top to bottom the DTI goes from 0 - 0.50mm)

With the head still at the top of the column, i rotate the spindle and zero the dti so that when i rotate the spindle and read the dti it will read -0.01 through to +0.01
Rotate the spindle so that the dti reads zero
Move the head to the bottom of the column, rotate the spindle and if my X axis is square my readings on the DTI when rotating the spindle should be -0.07 through to +0.07
?

edit..if my method is correct then the Y axis is out by 0.07mm
Where can i find shim stock in the uk? i was tempted to use kitchen foil?

I've found shim stock on ebay, is there a reason why some people have used brass rather than steel shim?
how about this shim tape?
http://www.ebay.co.uk/itm/Stainless...938?pt=LH_DefaultDomain_3&hash=item2314e83e22


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## rudydubya

Hello Goldigger, hope your day has been a good one.  I'm not sure I understand exactly what you're aligning now, and maybe I'm misunderstanding your axis references, so maybe a question or two before I give you my opinion.  First, I think you are still working on aligning the spindle with the column, and not the table, is that correct?  Second, when you say adjust the X axis, do you mean adjusting the head slightly from side to side when looking at the front of the mill, or is it back and forth?  I was thinking it was side to side, but then your question about shim stock made me wonder (the older I get, the easier I am to confuse).  As far as shim stock, I think either brass or steel would work, I used brass because I had some I found at a hardware store, but I think steel would have been fine.  As a source, have you considered sacrificing a simple feeler gauge, which should be available at an auto parts or tool store, for their thinner leafs?

Regards,
Rudy


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## Goldigger

Hi Rudy..
Yeah sorry my explaination wasn't to clear..
I'm trying to align the spindle to the column..when i referenced the X axis i mean spindle side to side/left to right..when looking at the head from the front

The shim stock was for the front to back adjustment, or the Y axis as the spindle is pointing backwards by 0.07mm
I found plenty of options on ebay, some cheap shim from modelling shops
http://www.ebay.co.uk/itm/BRASS-SHI...UK_Crafts_Other_Crafts_EH&hash=item2c5e23cf45
Hopefully me pic helps..

Im tempted to buy a test bar from Chronos in the UK for £39..3MT 250mm long
http://www.chronos.ltd.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww%2echronos%2eltd%2euk%2fcgi%2dbin%2fss000001%2epl%3fpage%3dsearch%26SS%3dmt3%20test%20bar%26PR%3d%2d1%26TB%3dA%26search%2ex%3d0%26search%2ey%3d0&WD=bar%20test&PN=XMAS_GIFT_IDEAS_6%2ehtml%23aGX13#aGX13


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## rudydubya

Hello Goldigger, yes, now I understand, thank you.  That brass shim assortment is similar to what I found at a local hardware store.  Always handy to have some around.  As far as a precision test bar is concerned, I always thought one would be nice to have, but I haven't gotten to the point where I felt I really needed one yet. Granted, I'm an amateur with no practical experience, but I used Rollie's Dad's Method with a bar from a printer and got satisfactory results.  My bar was fairly straight, but not exact, and the diameter was consistent along its length.  A straight test bar is not required for Rollie's Dad's Method, but to keep the procedure simple it should be the same diameter at the points you use for measurement.  By its nature, Rollie's Dad's Method eliminates the need for a bar that's exactly straight.

I went back and re-read your post of 11/11 and it sounds like you're on the right track.  If I understand your procedure correctly, you secured the DTI on the column and measured the runout of the bar at a point close to the spindle when the mill head was at the bottom of the column and got 0.02mm runout.  You then adjusted your DTI dial so that it read from -0.01 to +0.01 as you rotated the spindle.  You then moved the head up to the top of the column without moving the DTI and measured the runout near the bottom of the bar.  I don't think you mentioned the maximum and minimum readings you got there, but if you added those two readings together and divided by two the result should be how much out of alignment your spindle is from the column. For example, if your measurements at the bottom of the bar ranged from -.05 to +.12 as you rotate the spindle, then your alignment is off by +.035.  If your measurements ranged from +.05 to +.12, then your alignment would be off by +.085.

I assume you put your DTI so you were measuring the front (or the back) of the bar for the measurements when checking your Y axis alignment.  Repeating the process with the DTI touching the side of the bar should give you the X axis alignment error.

I'm no expert, but that's what I did when I aligned my mill.  Hope this helps.

Rudy


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## Goldigger

Hi Rudy, sorry for not replying sooner..
I shimmed the housing to align spindle to the column in the y axis, pretty much the same as yours..tightened everything up and checked..
0.01mm out so happy..
Aligning the spindle to the column in the x axis (left to right) took ages, but got it pretty much spot on.
After torqing the bolts up and checking, the spindle alignment to the column is 0.04mm out in the y axis. 
Spindle to the column in the x axis (left to right) is still spot on..

Do you think the 0.04mm mis alignment is Acceptable?

I've modded my column so that I can adjust column nod with two bolts at the bottom of the column brace..but I believe that doesn't solve the problem, spindle to column needs to be adjusted in the way outlined in your thread first..


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## rudydubya

Hello Goldigger.  Yes, your bolts at the bottom of the column brace should help with the alignment of the column with the table, but not the spindle with the column.  As far as 0.04mm mis-alignment being acceptable, you'll have to decide if trying to reduce that  0.04mm is worth the time and effort needed to re-shim and re-align, based on your projected use of the mill and what you're going to  accept for accuracy. One consideration in your decision might be the distance over which that 0.04mm was measured.  If the distance over which you measured the error was, say, 8 inches, then that's only 0.005mm per inch (sorry to mix those mm and inches).

Personally, if I knew or suspected what might have caused my initial alignment to go awry, I'd try again, but I'm probably more obsessive than most...  If you do decide to re-align, make sure your gibs are locked tight during your measurements and be aware that any paint or filler at the joint between the spindle housing and the carriage could get into the joint while the housing is being moved about and confound the shimming adjustments.

Hope this helps.  Let us know what you decide and how you make out.

Regards,
Rudy


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## Goldigger

Hi Rudy,
I pulled the mill apart again today..
I atempted to align the spindle in the y axis (front to back)..tigened it all up and still out.
So i unbolted the spidle housing completely, and removed all paint from the mating surface..
Shimed and tightened it all up and 0.01mm out

So loosened it so i could align the left to right X axis alignment..
Same thing happened again when i tightened it all up..alignment in the Y axis is thrown out..0.04mm.

I've put the mill back together and tramed it..tramming the y axis was a bit of a fiddle, but just used the bolts on the column mod to pull the column back.


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## smarston

Could someone please check my math from the spreadsheet?
I don't want to show how I've arrived at the answers (just yet). I'd like for someone to come up with their own answers by whatever means they deem necessary and compare to mine.

Hopefully this will be of some use to us down the road. 

View attachment Shim Calculator V3.xlsx


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## SilverSanJuan

I haven't had a chance to go through all the math yet, but I'm confused by some of your measurement definitions.
Specifically the "NEAR spindle" and "AWAY from spindle" measurements.  What is the base of those measurements?  Is it the bottom of the head?  Your dimension lines seem to indicate that the measurement is taken from the top of the head.  It's just confusing the way it is drawn.

I'm looking forward to testing it out though as I'm still trying to get my alignment trued up.

Todd


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## smarston

Good feedback!
1. Move the spindle with the test rod downward on the column near the base
2. Place the dial indicator at the bottom of the column touching the rod and lock in place.
3. Take the "Near Spindle" measurements
4. Move the spindle with the test rod upward on the column near the top
5. Take the "Away from Spindle" measurements
Hope this helps.
I will add clarity in Rev 4.
Thanks,
Steven


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## SilverSanJuan

Ok.  I think I got ya now.    I'm in the midst of moving from one house to another.  I'll be needing to re-align my mill when I get the shop set up.  I'll run the numbers through your spreadsheet and report back.

Todd


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## SwarfMuncher

Very handy info here! I am going to work through these procedures as I prepare my X2 mill for the installation of a column stiffener plate.


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