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Tramming aid

Discussion in 'Concepts and Ideas' started by Alex Chambers, Jun 15, 2019.

  1. Alex Chambers

    Alex Chambers Openbuilds Team
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    Tramming aid 2 v1.png Tramming aid 2a.JPG Tramming aid 2b.JPG Tramming aid 3 v1.png For those using an Openbuilds router mount attached directly to a C-beam Z axis with angle brackets.

    I couldn't work out how, when tramming the router mount to the bed, you could hold the router mount still while tightening the fixing screws. I thought about modifying the end plates on the Z axis of my workbee to allow screw adjustment to the height of the router mount on either side - then decide that this modification would get in the way, so thought that a removable attachment that would do the same thing would be a better idea.

    To test the idea I designed and 3D printed a plate to attach below the router mount - see pics labelled Tramming aid 2.

    The concept worked, but the plastic (PLA) was too flexible and moved too much under the weight of the router to be reliable (I rather suspected this would be the case), so the final version will need to be made in aluminium. I have designed this (Fusion 360 and Sketchup files attached) but can't test it until I have ordered some suitable aluminium - if anyone wants to try this before I get around to it please post the results here.

    Holes in the plate are tapping sizes for 5mm (for angle bracket) and 6mm (for screws to adjust/support router mount).


    Alex. Tramming aid 2a.JPG Tramming aid 2b.JPG Tramming aid 3 v1.png
     

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    #1 Alex Chambers, Jun 15, 2019
    Last edited: Jun 18, 2019
  2. Alex Chambers

    Alex Chambers Openbuilds Team
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    PS - before you make one of these check clearance for your router/spindle - the one I have designed clears my Makita clone and I think should clear a DeWalt, but I haven't checked this.
    Alex.
     
  3. Steveathome

    Steveathome Well-Known
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    Looks really good Alex.

    Cant wait to see it in aluminum.

    Only just now noticed the bottom angle brackets on the spindle mount, I never thought of that for my Sphinx 1050, just used the router depth ring to force it.

    Going to order some brackets now.
     

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  4. Alex Chambers

    Alex Chambers Openbuilds Team
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    Hi @Steveathome, if you mount your router that far up your Z axis doesn't the bottom of the Z axis tend to hit the workpiece? - I've mounted mine so that the collet is roughly in line with the bottom of the Z axis.
    Alex.
     
  5. Steveathome

    Steveathome Well-Known
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    Never had a problem with that, probably because all my work is less than an inch and a half.

    If I switch to a spindle I probably will adjust it down.
     
  6. Alex Chambers

    Alex Chambers Openbuilds Team
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    Will be a while before I do this in aluminium - I haven't got any machineable alloys and I haven't cut any aluminium with my workbee yet - so I have some experimenting to do. (also I don't actually need to tram my router at the moment - I surfaced some Ash recently and it's flat within +/- 0.01 mm - more than good enough for me!)
    Alex.
     
  7. GrayUK

    GrayUK Openbuilds Team Elder
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    This has given me the idea to drill and tap two holes in the bottom of my aluminium spindle bracket, use two threaded rods of EXACTLY the same length with a flat bar, maybe 300mm wide, on the end. Then, in theory, lower the spindle till the flat bar touches the bed and should up show any tramming needed. In fact, if I put a cross on the bottom I should be able to read the X and Y tramming situation.
    I'll give this some more thought. :rolleyes:
    Thanks :thumbsup:
     
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  8. Alex Chambers

    Alex Chambers Openbuilds Team
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    How about one 1/4 " rod screwed into a plate (absolutely square obviously) and fit the other end in the collet - then you would be tramming the router rather than the router mount.
    Alex.
     
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  9. GrayUK

    GrayUK Openbuilds Team Elder
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    Good Idea!! SIMPLES. :thumbsup::D
    Wonder why no one else thought of that? :rolleyes:
    Are we missing something? :oops:
     
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  10. Alex Chambers

    Alex Chambers Openbuilds Team
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    Because fitting a rod into a flat plate ABSOLUTELY square in all directions is easier to say than to do, and a dial gauge on a stick does the same job without having to be accurately made. Of course the plate (cross shaped?) could be rotated in the router and any discrepancies measured and allowed for (shims?) but you would need to set this up on a router that had already been trammed. Tramming has always seemed like a chicken and egg situation to me - you need to surface your spoiler board before tramming, but that will only work properly if your router has been trammed.
    By pure luck my own set up is far more accurate than I would hope to set it to by adjustment so I'm leaving things alone until I need to adjust it.
    Alex.:D:D:D
     
  11. GrayUK

    GrayUK Openbuilds Team Elder
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    It is said you should Tram the Z-axis off the X-axis, and the X-axis off the Y rails? Or is it the reverse order? :(
    Then the Spindle off the baseboard.
    Or am I just getting muddled? :duh:
    It could be an age thing!! :rolleyes: My Grammarly program has had a lot of extra work to do lately. :banghead:
     
  12. Alex Chambers

    Alex Chambers Openbuilds Team
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    The aim is to get the base board parallel to the X and Y axes and the Z axis perpendicular to both. The question is where to start - the Y axes need to be parallel to each other - the distance between the X axis and the Y axes needs to be the same both sides (and at different points along the Y axis?) - then you need to ask yourself whether the bed supports are parallel to the X and Y axes. Only if all that is true can you adjust the Z axis. On our machines with their aluminium extrusions there will be some sag on each axis which (because of the way the extrusions are made) won't even be predictable - dimensions and stiffness will vary very slightly along the length of an extrusion - so we have to accept a large amount of compromise.
    As always you have to balance the amount of work involved in setting up against the desire to produce a finished item.
    I can't think of many (woodwork) jobs where +/- 0.5mm wouldn't be acceptable.
     
  13. Rob Taylor

    Rob Taylor Master
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    From a machinist/metrology perspective:

    Parallel Y: lock one side up with your cross-braces and make sure the V-wheels are nice and tight. On the other side, the end brackets are snugged but not tightened, but one end tighter than the other, so you can tap them around but they don't otherwise move. Run an indicator from the gantry against the looser y-rail, tapping the rail in as you drive back and forth, just like tramming in a vise. When the needle stays still, lock in the tighter end and maybe an 1/8 turn on the looser end, and then do a couple more runs. Last couple taps if necessary, then lock in that last corner. You now have two parallel rails, connected by two unknown-angle cross-beams. But the connectors don't need to be perfectly square, technically.

    Perpendicular X: perpendicularity in terms of racking (ie. rotation in C, or about Z) is a function of the wheels and the connection method to the gantry uprights. If the connection is perfectly square, and the wheels are nice and tight, the lowest-energy state of the system is perpendicularity; it'll settle there naturally. Once you get the belts and motors hooked up, that gets a little more complex; you really need to sweep a square based off the master y-axis rail, though cutting x and y lines and measuring the squareness is probably sufficient for most purposes. The one that can need doing depending on how your uprights are configured is also the X axis tilt in B. Sweeping a flat surface supported by, or otherwise coplanar with, your base rails and adjusting the height of one side of the X rail works for that just fine. Tilt in A, ie. rotation about its own axis, has to be addressed when tramming Z.

    Perpendicular Z: Simply sweeping a 1-2-3 block is how I did this:

    [​IMG]

    None of this seems very helpful in text format, but hopefully it got some of the point across. I have all the video but haven't done anything with it yet, maybe I should get on that.
     
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  14. jamin35008

    jamin35008 Veteran
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    Alex, your design looks like it will tram left and right but can it also do front to back?
     
  15. Alex Chambers

    Alex Chambers Openbuilds Team
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    No - because you tram that router mount left to right by adjusting the fixing to the Z axis C-beam. To adjust front to back you would need to insert shims between either the router mount and the C-beam or the Z axis plate and the X gantry plate. Having adjusted left to right my gadget would maintain that setting if you needed to loosen the router mount fixing screws. I would be inclined to adjust front to back first and then do left/right.
    Alex.
     
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  16. Peter Van Der Walt

    Peter Van Der Walt OpenBuilds Team
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    Or loosen the side plates, "twist" the gantry :)

    Please watch video below, around 5min 10 seconds onward has really good insight


     

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