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To Shim or Not to Shim

Discussion in 'General Talk' started by Adam Filipowicz, Jan 5, 2016.

  1. Adam Filipowicz

    Adam Filipowicz Veteran
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    Are there any general guidelines on when you do and dont use a precision shim when mounting a wheel to some vslot of a plate.
     
  2. Slobberknocker

    Slobberknocker Journeyman
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    For me, the shims act as a spacer between any surface and the bearing. I use shims on all my bearing applications to transfer the compression load to the center race of the bearings. Without a shim, any compression applied to the bearing will be carried equally between the inner and outer races causing binding.
     
  3. Adam Filipowicz

    Adam Filipowicz Veteran
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    what about alum spacers. if i was mounting a wheel directly to some vslot. I would have the teenut, then an alum spacer..
    or should i have a washer before the alum spacer?
     
  4. Adam Filipowicz

    Adam Filipowicz Veteran
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    Do you still use a shim, on top of a alum spacer? they are the same diameter
     
  5. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Spacers alone aren't very stable on V-slot as they aren't wide enough to span the groove properly. Best practice is to set a Slot Washer first.


    [​IMG]
     
  6. Slobberknocker

    Slobberknocker Journeyman
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    In that specific case you would want to bridge the gap of the slot. Openbuilds sells specific washers for this. The precision shim wont effectively bridge that gap.
    20160105_202543.jpg
     
  7. Slobberknocker

    Slobberknocker Journeyman
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    Some aluminum spacers have the exact same ID and OD as the shim. If you dont need the extra space provided by the shim, then as long as the spacer sits on the bolt and centers properly on the inner race, you would be fine.
     
  8. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    Yes and no and depends on the combination. I don't use them with 1/4" spacers as there is no need. The 1/4" spacers provide enough of a gap that there is sufficient space between the plate and the extrusion to have bolt heads running backwards through the back side of the plate. Not so with 6mm spacers so I have to add a shim if there are any conflicting bolt heads (and thus I rarely use 6mm spacers as I am too cheap to pay for all the additional shims).

    As for diameters, shims come in 8 and 10 mm sizes. Imperial sized spacers are 3/8" diameter and metric sized spacers are 10mm.
     
  9. Makerparts

    Makerparts Veteran
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    A visual reference guide I am starting to create, to make it easier to determine lengths required.
    still a work in progress.
    Screw-Length-Guide-M5-v1.jpg
     
  10. Makerparts

    Makerparts Veteran
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