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Re: Best place to shim when tramming Y-axis?

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  • Adam
    I can think of a couple factors you would use to guide your decision: - Inspectability - can you check to ensure the shim is still there? - Is it a joint you
    Message 1 of 4 , Apr 30, 2008
      I can think of a couple factors you would use to guide your decision:

      - Inspectability - can you check to ensure the shim is still there?

      - Is it a joint you will be accessing or is it needed for other adjustments, routine maintenance?

      - Could the shim fall out or rattle loose somehow?

      - How thick a shim would be required?

      So while its a good idea to shim what's wrong, that isn't always what's done or even what's
      best 100% of the time.

      Now I'm not exactly sure what 4 smaller bolts you're talking about. To get Y really correct
      I had to shim two spots:
      1) under the column assembly
      2) between the head and the gear box

      The spacing between the three bolts at the column assy mount is such that I had to use a
      small portion of a .002" al shim to get the column square with the table. I think I put
      .004" shims under the lower gearbox bolts. I used slotted engine mount shims from
      McMaster. They made the job easy. You really need to keep track of how much shim you
      stick in there.

      If I didn't have a belt drive, I would have sought another solution at the gearbox. Its my
      understanding there are parts in there that need access. I tore all of mine out when I
      installed my harrison kit. You don't want to have to redo that shimming (I spent the better
      part of an afternoon tuning that head and tramming it) every time you break an internal
      gear.

      Sorry if I misunderstood the question.

      Adam
      > What's the best place to shim the column to get the Y-axis trammed?
      > It seems that the two possibilities are either between the "pivot
      > plate" and the base (which is held by 3 cap head screws), or between
      > the "connecting strut" and the column (which is held by 4 smaller cap
      > head screws).
      >
      > Is one location better that the other? Why?
      >
    • johnw887
      Thanks for the info. The column as measured had been leaning forward by about .002 /inch. I decided to shim between the pivot plate and and the base, thinking
      Message 2 of 4 , May 4, 2008
        Thanks for the info. The column as measured had been leaning forward
        by about .002"/inch. I decided to shim between the pivot plate and and
        the base, thinking that I would put a thin shim near the front. When I
        took the three screws off, though, I noticed that the oil film left at
        the interface was "wrinkly" and thick, where the plate had separated.

        Obviously, there had been a lot of space for that much oil to accumulate.

        Using some blue "high spot" paste , I could see that near the back of
        the base there were some areas that were higher. When I scraped these
        areas down with my $4 Enco machinist's scraper, and bolted it back
        together, the column turned out to be plumb!
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