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Thread: Mill tram sanity check please

  1. #1
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    Default Mill tram sanity check please

    I've just put a solid column conversion kit on my Sieg SX2 mill. I'd like to have gone bigger but I just don't have the room. The ultimate plan is to put some riser blocks under the solid column so I get more height but I need it together to surface the chunk of steel when it arrives - looking at a single piece of 2" plate as a riser.
    I thought the tram was only out by 0.06mm side to side....but didn't realise I'd just hit the end or the DTI scale Put a plunger style gauge on and it's 0.45mm out (about 18 thou). I'd ordered in some brass shim that's about 0.025mm thick (roughly 1 thou) as with the original tilting column, that's the sort of amount I was out front to back. Adding a piece of that has changed the tram by 0.05mm so I'd need nine thicknesses of it which seems like a bad plan. Should I be ordering some 8 thou steel shim so that 8 thou plus the 1 thou brass shim should - if my maths is correct - get me about on tram?
    Or is this far enough out that something else is likely to be the cause?
    Should I instead be trying to cut down the high side something like this guy did http://mikesworkshop.weebly.com/mill-fixed-column1.html although this is an SX1 rather than an SX2 but the theory is similar.

    Many thanks,
    Gareth

  2. #2
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    Do you have the table locks tightened?
    Andy

  3. #3
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    Obviously pull the column and check for chips and irregularities. Shims can help, but I wonder since you are machining a column spacer if you can machine it in one direction and flip it to install. Of course if you later remove the spacer because you decided it added to much flex to your machine your problem comes back. Just thinking out loud. Need more coffee.
    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

  4. #4
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    If there are not chips or other obvious causes for the lack of tram, I would machine (or have machined) the column to fix most of the problem. I would not use very much, if any, shim.

  5. #5
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    Thanks guys.

    Table locks are tightened and the same for the head - entire head moves and there's no quill.
    Also tried lowering the head and raising the indicator to ensure I got the same result - ie the head isn't canted.

    I had planned a piece of 2" steel plate bridge all four mounting pads on the base as that seemed strongest. Metal supplier said they could order it in cut to size but that now doesn't seem to be possible. I can find aluminium in 2" bars, even 3" but I'm not sure it would be rigid enough - would it?

    I did take a file to the edges of the pads to ensure there were no burrs. I have to confess that I can't remember whether I did the same to the bottom of the column or not but I did almost everything else. Damn, I'm gonna have to take that apart again to double-check now. It's awkward with the head attached and more awkward to remove it.

    The column is probably the most difficult part to machine as there aren't really any datum surfaces to measure squareness side-to-side from. I think you'd probably only be able to from dowels in the dovetails and I've got nothing that would handle that sort of size.

    I like the idea of machining the spacer to automatically compensate for the tilt. A single piece block of metal could be fly-cut and then spun 180 if I can find such a thing. Presumably I could do the same if it were two pieces as long as I cut them mounted so they are held at the same distance apart as they would be when in place, right?

  6. #6
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    Getting metal should be no big issue. Its just a matter of price.

    Metal yards really want to sell full bars / sheets / extrusions. My local one will sell me half a bar if I ask. Small pieces I can only get by walking out and inspecting the drops racks.

    Some like Alro will sell you a cut piece just about any size, but the price is quite high unless you are buying a lot of material (in which case its often quite low). I always try to buy more material than I need so I can do it twice if I have to. I have lots of 1x6 oversize 4140HT on hand for that reason. For small pieces guys like Speedy metals can be a source, but they are often high enough that its not worth overlooking industrial suppliers like McMaster or MSC for similar small pieces.
    *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.

  7. #7
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    FWIW, Stephan Gotteswinter has a video on his youtube channel about using epoxy to tram his mill in. Seems he ran into the same issue, it might be an easy/cheap way to go and seems plenty strong enough.

  8. #8
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    Let's first look at the parts diagram for the X2

    I see two possible sources for side to side issues. Well... more than that but these first two stand out strongly. One is the hinge for side to side tilting built into the base of the column. Second is the power head "box" where the front and rear halves join together.

    When you're tracking down something like this you really want to start with the basics. Without going TOO deep I'd start by using a suitable mic to measure the table thickness along the front and back edges between the table's top and the flat lower edge that rides on the flat faces of the lower cross slide block. Actually if you want to do this really right you'd be pulling apart the entire lower table system and measuring the thickness between the flat ways of the cross slide block as well... but let's fix the major stuff first. I suggest measuring the table because someone else with a Seig X2 found it to have a surprising amount of taper. So much so that LMS took it back and replaced it for them. You want to check that you're not in the same boat too.

    If the table is decently the same thickness end to end and front to back then it's time to move on. Using a decently square see if you can extend the table back with some sort of jigging to allow you to check the rear column for square to the table surface in both directions. Adjust that tilting joint to zero out any side to side issues and then shim it to do the same for nodding. Do not trust any indicators or setting devices. It's also too early to try the usual tramming off the quill with a swinging arm because there may be an issue in the power head box joint as well. The two would mask each other. So you have to KNOW that one is as good as you can get it first and set the other to suit.

    With the table tested and passed in all regards and column squared up as best you can NOW you can check the tram in the usual way. And if it's out I'd suggest loosening the screws that hold the two halves of the box together and adjust that as much as you can.

    Really though if you're testing to this degree it would not be a bad option to start with the basics. As in a full tear down and start by mic'ing the thickness of the cross slide block. Heck, start by checking that the flat deck on the base is truly flat first. Then check that the cross slide block (#35) is the same thickness to within .02mm all around. And check the table for consistent thickness between the top and flat faces of the dovetail ways. In fact I suspect that it would be best to square up the column for side to side tilt using the flat upper faces of the dovetails in the cross slide block so you're not messing things up with any table thickness variations. Now if the table DOES have some thickness variations then that would be something that you'll need to address. But you really want the column to be square and true to the MOVEMENT of the table. Not the upper surface as such. At least that's what we want if we don't want to cut tapered parts all the time. Anyway.... assuming things tested out within a reasonable tolerance so far then tram the spindle to the table by adjusting the upper box joint. Note that there could be both side to side and some nodding issues all in that joint. But again, you don't really want to adjust the column to compensate since that means the movement in the column isn't square to the table.

    Along the way in all this I suspect that you'll either fix the tram or at least find the "unfixable" culprit.

    Note I haven't suggested what instruments to use since I don't know what you've got for such things on hand other than a DTI and a dial gauge. If you have a good range of bits to hold the gauges then they could be used as impromptu square testers. Especially if you can rig up a way to sneak in from both sides so you're just looking for the same readings if you do not have a way to calibrate it to being square. So some imagination or more detail on options might be needed.

    I know that's a lot of work. Hence the suggestion to trust most of it and just check the table thickness all around which is easily done with a mic. And to adjust the side tilt without trusting the angle indicator. Then shim out any nodding.

    With all that done you should be pretty good.

  9. #9
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    Quote Originally Posted by Bob La Londe View Post
    ... but I wonder since you are machining a column spacer if you can machine it in one direction and flip it to install. ...
    If you only need to correct for one direction, I think that will work. Imagine the column is tilted to the right. making the cut (full width) using the Y axis
    will match the angle of the tilt. Turn the piece 180 degrees and it should offset the columns tilt. If the column also leans forward (or back), I think if
    after the first cut you prop up the low end of the piece so the top surface is once again parallel with the table and do a second cut using the X axis,
    you will have matched both angles. Turn the piece 180 degrees and your column should be straight.

  10. #10
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    This idea of a corrective spacer sounds like an interesting concept.

    The head of my mill needed some shimming to get it set up correctly for tram. I'm thinking that if I cut out a suitable ring from plate stock and face one side on the lathe then do the flip side in the mill with the shims removed then I could simply rotate it through 180 to put the errors into the points where they become corrections.

    Note that this means one side just starts out being skimmed. Then that becomes the reference surface. From there you don't want to flip it at all. Rather you just turn it through 180 so the front becomes the rear and the sides exchange. Any high points when put between the base and column are now where the spots were for any shims that were needed.

    Rich, you have the right idea. But I really don't think it needs any sort of second pass or propping. I'll have to think about it a bit more but with the flat 180 rotation it seems to me that all the proper high points in the block will now be in the low spots and fully mirror imaged correctly.

    Note that this can't be done with a flycutter though. To fully mirror any wedging that needs correcting we want to use the smallest diameter end mill we can without making the number of passes become very tedious. We really want a point cutter like an engraving or ball end to most accurately copy the errors. But that would need a crazy number of passes. So instead I'd suggest a 3/16" cutter or similar.

    In this case a solid block might be a good idea but we don't want a whole seating. So the middle of the top and bottom of the riser block should be relieved somewhat to leave a 3/8 to 1/2" wide edge around the block on both sides

    Cenned, you still have two possible sources of tramming error though. I'd still start with a better tweaking of the column squareness to the table for at least the initial setup. Do NOT trust that wonky little angle indicating tape for more than the coarsest of measurements. Square it up yourself and then adjust the indicator in some manner to something you can easily see. And even that won't help if there's play in the center pivot of the base. Ideally that hinge pin and nut on the back would be used in conjunction with tapered parts that self center very accurately and serve to remove any play at all... But as we all know things are seldom so ideal.

    Basicallly trust NOTHING on any machine to be what it should be until you have checked it with suitable instruments and methods.

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