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Thread: zeroing in on components

  1. #13
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    Default Re: zeroing in on components

    I’m in the process of building my first router so take my opinion for what it’s worth, but this is how I understood the difference when evaluating what to go with. I went with the spring loaded design.

    I believe the spring loaded design helps to compensate for wear. It also doesn’t require you to have the system as finely adjusted because it can compensate for slight misalignment (ie, distance between the pinion pivot point and the rack not being consistent).

    A rigid system might need regular adjustments as the rack/pinion wear to keep backlash out of it. The more wear you have equals more slop; and more slop means it wears faster. So it would be important to have the alignment set just right and maintain this regularly to extend its life.


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  2. #14
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    Default Re: zeroing in on components

    If you are a metal worker and can build accurately, forget the spring loaded pinion. I was advised not to do it by a couple of guys who make tables for a living and have no backlash anywhere. Here was what was said:
    https://forum.linuxcnc.org/30-cnc-ma...-drive?start=0

    My X axis (gantry) uses 40mm x 80mm x 3mm Ally RHS with R&P and two HGR15 Rails (I think 1 would do and save some weight)
    The Y (table) uses HGR25 rails (one each side) and R&P. The rack and rails on the table are mounted on full length laser cut plates and lots of holes. Because the holes were laser cut before they were tapped by hand with a tapping jig, everything is in perfect position. The laser cut plates are sitting on set screws each end to allow levelling before they are clamped off along the length. Gantry ends are laser cut and folded 6mm ally plates to keep weight down.

    Rod Webster
    www.vehiclemods.net.au


  3. #15
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    Default Re: zeroing in on components

    I’m not a big fan fan of spring loading a pinion into a rack!

    However if you do a rigid mount it needs to be done with high precision. Technically there is only one proper distance, center to center, to mount a gear eet. Now obviously a rack is different in that it doesn’t have a center but the fact remains you need proper meshing to prevent wear. Proper meshing also reduces backlash. If you don’t have the equipment to mount the rack precisely parallel to the plane thelinear bearings ride on then it might make sense to spring load the pinion. The reality is though that a dial indicator and a few other tools to do the job are likely cheaper than a spring loading mechanism.

    Oh one more thing as somebody above mentioned there is a type of pinion that is considered an anti backlash solution that is spring loaded. This is an entirely different beast and may be worth implementing. I don’t have a picture which would certainly be worth athousands words here but these are years designed to take up clearances in the mechanical assembly. Not mounting errors but clearances in properly mounted components. .



  4. #16
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    Default Re: zeroing in on components

    Quote Originally Posted by wizard View Post
    I’m not a big fan fan of spring loading a pinion into a rack!

    However if you do a rigid mount it needs to be done with high precision. Technically there is only one proper distance, center to center, to mount a gear eetProper meshing also reduces backlash. If you don’t have the equipment to mount the rack precisely parallel to the plane thelinear bearings ride on then it might make sense to spring load the pinion. The reality is though that a dial indicator and a few other tools to do the job are likely cheaper than a spring loading mechanism.
    Far better to take the time and do the job properly. Going with a spring loaded pinion breaks those proper clearances and leads to premature wear. I will say in my view that helical racks are much better than straight ones. I've used both on my machine.

    If you read up on the Hiwin installation guides, the rails should be mounted ona machined surface with the master rail registered to a machined lip. The second rail is mounted once the master rail is perfectly aligned with the carriages attached and joined together. The rack should also be on a machined surface...

    Quote Originally Posted by wizard View Post
    Oh one more thing as somebody above mentioned there is a type of pinion that is considered an anti backlash solution that is spring loaded. This is an entirely different beast and may be worth implementing. I don’t have a picture which would certainly be worth athousands words here but these are years designed to take up clearances in the mechanical assembly. Not mounting errors but clearances in properly mounted components. .
    I think also might be worth a few thousand dollars too! Maybe not quite but they are expensive!

    Rod Webster
    www.vehiclemods.net.au


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