Modification for easier tramming


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Thread: Modification for easier tramming

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    Registered momus_cnc's Avatar
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    Default Modification for easier tramming

    I've been meaning to do this for a while, and finally got around to it. The most difficult adjustment to make on the machine is setting the spindle exactly perpendicular to the table. Because the nuts that attach the router mounts are located directly behind the router, it means taking it off to make every adjustment. Every positional relationship changes every time the parts are unbolted, so it can take quite a bit of trial and error. After building the new machine, and using it for a while, I knew it needed better adjustment as I could feel (and see) scallops in one direction when milling flat surfaces. I was also getting some chatter when cutting in one direction. So I came up with this modification to make tramming much easier.


    The first thing I did was make a tramming gauge to be able to measure the spindle adjustment. (photo 1) I used a 6 1/2” length of left over aluminum T-track extrusion from when I made my spoilboard. I installed a 1/4” bolt with the head cut off on one end, and a stud in the other. I sharpened the stud to a sharp point by chucking it up in the drill press and using a file against it. The gauge is used by installing it in the spindle and rotating it to check the gap between the point and the table with feeler gauges. (photo 2) As the gauge sweeps through its travel it describes a perfect plane in space (assuming no spindle runout, etc.)


    Measuring my current adjustment was revealing. Not bad side to side, out about .020” over the 11.5” circle that it sweeps. Front to rear was horrible. Out nearly .100”!


    The mod is basically to replace the two router mount studs with countersunk cap screws that come in from the rear. The router is left clamped securely in its mounts during adjustment. Just crack the countersunk screws loose a tiny bit, and reposition it.


    Here are the steps to make the mod:


    1. Surface the spoilboard. Do this even if the it is known that the spindle is out of square to the table.


    2. Remove the Z axis rail assembly. Remove the router, and the nuts holding the nut plate to the nut plate block. The rail assembly will pull out of the top of the machine.


    3. With everything still bolted together, I installed an additional 1” countersunk cap screw from the front, as seen in the third photo. This will keep everything secure while adjustments are made later. It doesn't have to be a countersunk screw, there is room here for the head of a standard bolt. The Z rail is tapped. The rail block has a clearance hole through it, and countersink.


    4. Remove the two studs.(photo 4) I was able to get both of them out with a large pair of vise grips. One of these later became the pointy stud in the tram gauge.


    5. Drill the tapped stud holes in the Z rail out to 5/16”.


    6. Countersink the rear face of the Z rail for the cap screws. (photo 5)


    7. Fabricate a captive nut plate out of a piece of 3/4” x 2” x 3/16” cold rolled steel (or 1/4” thick if you have slightly longer cap screws than I used.) The two extra holes in the center of the plate are just to remove a little bit of mass from the part. Not needed for anything functional. (photo 6)


    8. Reinstall the Z rail in the carriage.


    9. Assemble the router mounts, using 1/4” x 1.5” countersunk cap screws and the new nut plate.(photo 7) I set the countersink a bit deep to get full thread engagement in the nut plate. 1.75” long screws would be better.


    10. With everything assembled, and the two countersunk screws lightly snug, install the tram gauge. Rotate the router/clamps to set the side to side adjustment so that it is approximately correct, and tighten the cap screws.


    11. Rotate the tram gauge to check the front/rear adjustment. I was able to bring it into alignment by adding some paper shims between the lower mount and the Z rail block. (photo 8) I ended up needing 3 pieces of index card stock, and one piece of printer paper.


    11. With the front/rear adjustment corrected with shims, set the side to side by rotating the router/clamp assembly.


    12. I was able to get the front/rear to within .003” deviation over the 11.5” gauge sweep, and the side to side is less than .001”. I think I could get that .003” down a little closer to zero by adding an aluminum foil shim to the paper ones, but good enough for now. The whole adjustment procedure took about 10 minutes, most of that fiddling with paper shims. I spent about an hour and a half total, making the modification to the Z axis and setting the alignment.


    Of course, a dial indicator in the end of the tram would be even better, but I had no problem getting it to acceptable levels of accuracy using the feeler gauges.

    -Bob

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Modification for easier tramming-1-tram-gauge-jpg   Modification for easier tramming-2-tram-spindle-jpg   Modification for easier tramming-3-added-countersunk-cap-screw-jpg   Modification for easier tramming-4-removed-studs-jpg  

    Modification for easier tramming-5-countersunk-rear-jpg   Modification for easier tramming-6-nut-plate-jpg   Modification for easier tramming-7-mounts-installed-jpg   Modification for easier tramming-8-paper-shims-jpg  



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    Default

    Hey, how come the words "drill press," "vise grips," and "dial indicator" magically have an ebay link attached to them? Grrr. Ebay is infiltrating the entire world.



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    Thanks Bob,

    I had been reading the term "Traming" a few times now and had know idea what people were talking about. This would make a good adition to the current version of the plans. posibly insert the above around page 164/165 of version 2.1

    regards Ryan



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    Ryan,

    This will absolutely find its way into the next revision of the plans. I had actually intended on putting this into the version that is out now (2.1), but I frankly forgot all about it until it was too late. In the meanwhile, does anyone know if it is possible to have this made into a sticky, so it stays at the top? Ryan's the first person to comment about this post, but I think it is valuable enough that everyone should see it. It makes adjusting the machine sooooo much easier.

    -Bob



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    Default Re: Modification for easier tramming

    Quote Originally Posted by momus_cnc View Post
    Ryan,

    This will absolutely find its way into the next revision of the plans. I had actually intended on putting this into the version that is out now (2.1), but I frankly forgot all about it until it was too late. In the meanwhile, does anyone know if it is possible to have this made into a sticky, so it stays at the top? Ryan's the first person to comment about this post, but I think it is valuable enough that everyone should see it. It makes adjusting the machine sooooo much easier.

    -Bob
    Didn't make it into 2.2, either. Wish I had seen this before... I'll work this mod into my 2.2, though.



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    Default Re: Modification for easier tramming

    Relatively easy mod. I used a chunk of aluminum with helicoils for the nut plate, and a couple of stainless steel screws. Works like a champ!



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    Default Re: Modification for easier tramming

    I am in the base and top prime/sand/finish mode and need to revisit the Z mount ro do this.
    Easier done while the gantry in on the bench than later.

    The metal work was much more fun than the mode I am in now.

    -=Doug

    "IT ≠ IQ " Starwalt 1999


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Modification for easier tramming

Modification for easier tramming