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evidence of a nice tram

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  • evidence of a nice tram

    You should see this pattern every time you mill a cylinder head - if you don't then don't bolt it together,

    This is not evidence of a "perfect tram" because fore and aft tilt of the head could still be way off, although that you will notice in your first "skin cut" and it's also no where near as critical and really means nothing for sealing capabilities,,,

    However the crosshatch pattern does, the side to side crosshatch is evidence of a very good tram and you should see this pattern every time, very critical esp. with todays very unforgiving three piece steel head gaskets,

    if you do not see crosshatch it means only one thing - that you have dished the center of the head length wise, so the extra critical bridge area of the head gasket that does double duty for sealing off combustion gasses/pressure is far more apt to fail.

    I know for many all the above is quite obvious but thought id post for the ones who have not been around engines much and such...

    Too achieve good results always tram your Mill with a wider swath then the actual part you want good results with...


  • #2
    I thought you meant one of these...

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    • #3
      Could be just built-up-edge.
      Not impressed.

      -D
      DZER

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      • #4
        its an insert cutter with a nice radius, no built up edge on anything

        and yeah iv seem prettier done by auto-feeds but the principal stands, this is one smooth flat head and there will be no wimpers on it's end of the bargain...

        now the block on the other hand is another story --- another one of those yee-ha hacks went wild with a power disc on an aluminum block --- all to remove that thin membrane material that comes right off with a scraper,,, definitely not impressed...

        two hours of precision hand stoning and with the perfect head mill I believe im within allowable tolerance...

        AB is that one a wood burner?

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        • #5
          I totally agree with what you posted AK. But the picture is too fuzzy to see the pattern properly.

          To me it's just fuzzy enough that I'm only seeing the arcs running in one direction without any reversed hatching. But it's pretty fuzzy as I said. Or I wonder if it was posted as an example of what NOT to see?
          Chilliwack BC, Canada

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          • #6
            Originally posted by BCRider View Post
            I totally agree with what you posted AK. But the picture is too fuzzy to see the pattern properly.

            To me it's just fuzzy enough that I'm only seeing the arcs running in one direction without any reversed hatching. But it's pretty fuzzy as I said. Or I wonder if it was posted as an example of what NOT to see?
            Yep, looks way off tram and dished in the pic.
            1601

            Keep eye on ball.
            Hashim Khan

            Comment


            • #7
              That's funny because, although it is somewhat fuzzy, I do see the cross hatch. It looks like a good tram to me. At lease in the X axis. Can't say anything about the Y without more testing.



              Originally posted by BCRider View Post
              I totally agree with what you posted AK. But the picture is too fuzzy to see the pattern properly.

              To me it's just fuzzy enough that I'm only seeing the arcs running in one direction without any reversed hatching. But it's pretty fuzzy as I said. Or I wonder if it was posted as an example of what NOT to see?
              Paul A.
              SE Texas

              Make it fit.
              You can't win and there IS a penalty for trying!

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              • #8
                It is a fuzzy pic but if you look between the two coolant ports at the bottom of the pic you can see the hatch pretty good,

                I think it took the camera being directly above the head to see it best as it does not have much effect off to the sides.

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                • #9
                  I watched a vidio yesterday from the Russian guy that goes as factory dragon, he was grinding the dace of the block on a big old stankoimport surface grinder (nice machine from memory), I was told this wasn't a good idea because of sealing, it's too smooth, even though the job looks really nice, not being a car guy apart from the basics does this hold up in practice?
                  It has to be said that stanko machines are built like bloody tanks, stick a gun and tracks on one and you can invade harbour freight single handed
                  Mark

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                  • #10
                    That's nothing. You only need a 50c off coupon to invade Harbor Freight.
                    .

                    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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                    • #11
                      Oddly enough if I squint a bit to fuzz it out even more and to make the bright areas darken a little the fairly broad cross pattern does come through. More between the lower coolant ports as you say.

                      It's the sort of thing where if we saw it in person it would be obvious. But with the lighting in the picture it doesn't really leap out at one.
                      Chilliwack BC, Canada

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                      • #12
                        Looks good to me-RUN IT!
                        I just need one more tool,just one!

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                        • #13
                          Originally posted by boslab View Post
                          I watched a vidio yesterday from the Russian guy that goes as factory dragon, he was grinding the dace of the block on a big old stankoimport surface grinder (nice machine from memory), I was told this wasn't a good idea because of sealing, it's too smooth, even though the job looks really nice, not being a car guy apart from the basics does this hold up in practice?
                          It has to be said that stanko machines are built like bloody tanks, stick a gun and tracks on one and you can invade harbour freight single handed
                          Mark

                          http://www.felpro-only.com/blog/gask...urface-finish/
                          Location: Saskatoon, Saskatchewan, Canada

                          Comment


                          • #14
                            I saw those, but they looked straight, where the others looked curved as you would expect.... maybe an illusion on my part, I see one just inboard of the RH triangular port that is curved as I expected. OK.
                            1601

                            Keep eye on ball.
                            Hashim Khan

                            Comment


                            • #15
                              Arcane, thank you, not only do I now know the surface texture to aim for but also the block flatness, a very useful thing, more so once I get a new straight edge, or surface plate and make one.
                              Seems grinding a head is quite ok, possibly better than fly cutting, I've seen quite few blocks whose surface after machining exceeds r50/60, no suprise of the gasket failing , usual thing, damn these cheap Chinese gaskets, last time I heard that was on an Audi I had done, the part was OEM from Germany, but it explains a lot.
                              I still have my old Taylor Hobson tallyvel roughness comparator from work, needs new battery pack though, we used to check the surface of steel coils, having one you could put in your pocket was easier than cutting a sample and carting it back to the lab every time there was a problem, though one was later on when doing the tensile strength tests etc.
                              Mark

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