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Sieg X2 spindle alignment

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  • Sieg X2 spindle alignment

    I have finally acquired a mill! Well sort of a mill anyway since it's actually only a bench top mini mill but I still don't have my new shop yet and this is all I have room for until late this Summer. I have disassembled and cleaned everything and now I am in the process of checking the alignment and addressing the very common "head drop" problem but more about that later. Using a ground/polished test bar and a DTI I have determined the spindle to column alignment is out by .002 over 5 1/2" in both the X and Y axis. What could be considered good? I can make adjustments by shimming the head and nudging it in it's mounting bolt holes but how close should I realistically expect to get it?

  • #2
    I got mine within .0005 over 4".I used news print paper soaked in Loctite 271 as the final shim by tightening the bolts and sweeping an indicator until it was at the .0005" over 4" I was shooting for.Once the Loctite setup it was tightened down rock solid.

    You might want to slip the gibs out and look at them first though.On mine they were really rough and I ended up putting them back in long enough to use the mill to make a better set out of cold rolled flat.
    I just need one more tool,just one!

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    • #3
      I took the gibs out and cleaned all the parts thoroughly then I then coated the gibs with layout dye and honed them lightly to remove burrs and look for high/low spots, except for some burrs and raised spots around the adjustment screw indentations they were in really good shape. I sort of thought the .002 on both X and Y axis was a bit too much and I was going to attempt an adjustment but to be honest I just didn't know what I could realistically expect.

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      • #4
        Considering that 5.5" is close to the largest part you could fit on an X2, I'd say .002" out is neither surprising nor, depending on what you do, worth worrying too much over. YMMV but many people new to the hobby think "more precise" equals "better performance." It's one thing to practice making a part to +/- .0005" so that you know how, it's another to make everything to .001" tolerances when .010" will do more than adequately. Nothing wrong with working to improve the tool but there is always a tradeoff between working on your tools and working with them.

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        • #5
          There are two jobs in particular that I plan to do on a repeat basis that I would like to be as close to perfect as practical it's just that I didn't know what to expect from this little machine, however I certainly don't expect miracles from a toy mill! Basically I just needed to know if I would be wasting my time trying to get it closer than it is but apparently I can do better so I am going to give it a try. I know this thing is limited but it's what I have for the time being and I would like to make the best of it, I am willing to work within it's limits and to spend the extra time it will take to achieve the best results I can.

          Newsprint paper soaked in Loctite, I made a note of that.


          Now about that head drop problem, have any of you guys who have one of these things dealt with that yet? I have not tried to use this mill yet but from what I have learned the backlash in the rack&pinion that moves the head is a source of problems that has been addressed in several different ways. There is a gas cylinder kit for support to replace the spring arm that came from the factory and I have heard of people actually even using counter weights but it looks to me as if this is taking up the back lash in the wrong direction?

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          • #6
            To be sure, you can band-aid the head drop problem by using a powerful air spring or heavy counterweight to raise the head. But as you noted, that takes up the backlash in the wrong direction so now you're just depending on the strength of the air spring (or gravity) to counteract the endmill's tendency to suck itself down into the work. Admittedly, this often works "well enough" for most things, at least until you take a heavy enough cut to overwhelm the system.

            From what I can tell, there are three ways to totally eliminate the head drop. One is the lock the Z axis for every cut. Simple.

            Another is to eliminate the head retract mechanism entirely. Now gravity will take up the backlash in the "correct" direction. Of course, this also means you have to muscle the head back up all by yourself and then lock it in the raised position while you change cutters or work pieces. Maybe that's no big deal for some, could be annoying for others.

            The final way is to use use cutters without a helix (insert endmills, flycutters, face mills) or with a reverse helix. The reverse helix cutters don't like plunging or deep slotting though...

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            • #7
              Originally posted by tylernt View Post
              Another is to eliminate the head retract mechanism entirely. Now gravity will take up the backlash in the "correct" direction. Of course, this also means you have to muscle the head back up all by yourself and then lock it in the raised position while you change cutters or work pieces. Maybe that's no big deal for some, could be annoying for others....

              I was thinking along those lines but I thought maybe I could use a version of the counterweight system and instead of applying a lifting force directly to the head it would instead be used it to counter the down feed handle. The plan would be to allow the head to travel downward freely even if it means adding extra weight to make it do so smoothly and then use the counter force for the down feed handle to balance it out.This would keep the back lash in the right direction, or so it seems to me but at this point have just started to consider options for the problem.

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              • #8
                Sounds intriguing. So, add a spool for the counterweight string to the feed handle hub, basically? I'm doing mental gymnastics to see if that would work, depending on if you wound the string clockwise or counter-clockwise... and what diameter the spool was to change the amount of leverage applied... yeah I think that might work.

                Pretty clever if so -- way to think outside the box there!

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                • #9
                  I address the Z backlash in a pretty simple way: lower the head with the coarse feed until it's about a 1/4" above the work. Engage fine feed and turn it a few revolutions downward while pushing down on the head with my hand. Sometimes you hear a clunk as the backlash is suddenly taken up. From that point on, it works fine. Crank it down to the desired height then lock the axis. I always lock the Z axis.

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                  • #10
                    Originally posted by lwalker View Post
                    I address the Z backlash in a pretty simple way: lower the head with the coarse feed until it's about a 1/4" above the work. Engage fine feed and turn it a few revolutions downward while pushing down on the head with my hand. Sometimes you hear a clunk as the backlash is suddenly taken up. From that point on, it works fine. Crank it down to the desired height then lock the axis. I always lock the Z axis.
                    If you don't take up the backlash, is the Z lock not strong enough to protect from head drop?

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                    • #11
                      The problem with just trying to get by with the head lock is that plunge milling is, I have been told, usually an exercise in futility and drilling has the problem of the drill snagging and pulling the head down until the backlash is taken up, usually enough to cause annoying problems.


                      I have given it some thought today and I think the counterweighted handle just might work, this will allow normal vertical movement when using the handle but will (should?) keep the rack backlash preloaded in the right direction at all times. Of course this is all coming from someone who is just setting up his mill and has yet to have actual experience with the thing so at this point everything I have been saying is purely speculation based mostly on info from the internet, I am certainly still open to suggestions! My goal is to make this little machine as accurate as possible and I am willing to spend the time and money, within reason of course, to do it right.

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                      • #12
                        Originally posted by tylernt View Post
                        If you don't take up the backlash, is the Z lock not strong enough to protect from head drop?
                        The Z lock is plenty strong enough. You don't have to lock the axis after taking up backlash and moving into position, but I have had the head creep down slightly during a heavy cut, so I always lock it now.

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                        • #13
                          Looking at mine today it has very little in the way of back lash in the rack and pinion,but it does have maybe .010"It hasn't been a problem,but it would be easy enough to remove simply by shimming the rack.You could even shim in some preload.
                          I just need one more tool,just one!

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                          • #14
                            I solved a lot of the Z axis pain with a new removable depth stop and a small ground plate on the headstock. The depth stop also holds an indicator arm shank. Touching off on the work, and setting the depth stop with a parallel or gauge block usually gives better results than depending on the fine feed. I also bought the extended rack and air spring kit from LMS. I installed the rack and shimmed it, but haven't done the spring yet.

                            I've had the Z axis slip when locked and a drill grabbed. A bit of crud had found a home behind the gib. The extra resistance from the depth stop was enough to stall the motor long enough to hit the E-stop and save the day.

                            I always lock Z when milling and usually Y as well.

                            As for the X axis gib... Get it as close as you can. The mini mill is already enough of a wet noodle that it raises hell with endmill life. The duller the tool, the worse it gets. Using a fly cutter will cut down a lot on tooling expense.

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                            • #15
                              Originally posted by WCPenney View Post
                              The mini mill is already enough of a wet noodle that it raises hell with endmill life. The duller the tool, the worse it gets. Using a fly cutter will cut down a lot on tooling expense.

                              Did you do anything to stiffen the column? The first thing I did when setting up the mill was to mount it solidly on a steel plate then use a heavy angle plate to stiffen the column mount. I did this by extending the mounting plate past the back of the mill then I bored a hole through one side of the angle plate for the column mounting stud to pass through. The nut and belleville washer were then reinstalled and tightened down, this gives a two point mount support and it made a huge difference in how much flex the column had before and after.

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