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Thread: Tapered Bronze Valves

  1. #36
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    Default Re: Tapered Bronze Valves

    Quote Originally Posted by Garret View Post
    I've checked 'em in a drill. IOW3,467 turns... I do go both directions though.

    Different strokes?
    I will suggest you got lucky

    There is a problem with that technique, in the manner that a spiral drill bit or a single bit boring bar will indeed make a round hole, the lapping pattern may look good but the parts wont always exactly mate and seal in the desired position.
    Hand lapping of non-rotating parts should be done so the working surfaces mate into the position they are designed to work.
    When I had to lap 500cc single cylinder MC engines to use a solid (thin) copper head gasket you could only "get-it" by working back and forth within the space of the head bolts or about 60
    (On quarter turn valves you should worth between the finished open and closed positions)
    Flat surfaces can be lapped differently

  2. #37
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    Default Re: Tapered Bronze Valves

    Could be I did. If so, it was on 3 different seacocks. However, you have far more machining experience than I!
    "If it ain't broke, you're not trying." - Red Green

  3. #38
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    long beach, ca, usa
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    Default Re: Tapered Bronze Valves

    While I'm waiting for the lapping compound I thought I would share some photos. This is the directional valve that I am practicing on. You can see scoring on the plug and uneven wear. You can see that the plug probably needs some material removed at the large end to fit deeper into the valve. I think. Maybe I need more machining than the lapping compound will remove. We'll see.
    P1010780.jpgP1010781.jpgP1010782.jpg

  4. #39
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    Default Re: Tapered Bronze Valves

    There is no shoulder, it should just seat down further in the bore as you lap it.

  5. #40
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    Default Re: Tapered Bronze Valves

    Theoretically, a shoulder will be created as the lapping removes material along the plug but not the whole length. I'm hoping not enough to matter.

  6. #41
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    Default Re: Tapered Bronze Valves

    I doubt if it will drop more than two thousands of an inch. Machining taper fits is always interesting.
    (You can do a little kitchen table math to determine dia vs longitudinal axial distance to better visualize this.)

  7. #42
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    long beach, ca, usa
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    Default Re: Tapered Bronze Valves

    Well, I got the lapping compound and the grease this morning and tried them. I think they worked fantastic. I did ten turns clockwise with the compound. Much better. I did ten turns counterclockwise. Even better. I did ten more clockwise and I think it came out great.
    The material should last for a hundred applications.
    The grease is nice. That should last for a 1000 maybe, lol.
    I don't think the valve will leak at the top or bottom. It might leak a little in the middle between channels because the there was no lapping contact. That's not a problem. I don't think it would be a problem if it was a two way valve instead of three.
    Thanks for all the help.

    P1010783.jpgP1010784.jpgP1010785.jpgP1010786.jpg

  8. #43
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    Default Re: Tapered Bronze Valves

    I think that the 320 grit is way too aggressive for the lapping compound. Probably less turns would have been better, also. Glad I have this valve to practice on.
    But there is a balance. The surfaces should be rough enough to hold the grease. Maybe 600 or 800 grit particles.

  9. #44
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    Default Re: Tapered Bronze Valves

    I didn't realize Spartan's compound was that coarse. Regular valve grinding compound is much finer - 500 or 600 equivalent? Not sure, but definitely finer than 320.
    "If it ain't broke, you're not trying." - Red Green

  10. #45
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    Default Re: Tapered Bronze Valves

    Quote Originally Posted by Garret View Post
    I didn't realize Spartan's compound was that coarse. Regular valve grinding compound is much finer - 500 or 600 equivalent? Not sure, but definitely finer than 320.
    I was expecting 500, 600 or finer, myself. But that's the information I have from my reading and 320 is how it felt. I've hand polished a lot of metal for microexams in my career and I know what the different grits feel like. I was surprised how coarse Spartan's is. I do plan to give Spartan a call to sort it out. The valve could easily have been ruined from over lapping it. I will be much more careful with my more critical valves.
    I do understand that the valve surfaces need to have texture to hold the grease but this seems to be a bit too much.

  11. #46
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    Default Re: Tapered Bronze Valves

    Lapping compound is readily available in grit from 16 on through 2400.
    It can be obtained as a finer compound than 2400 but that stuff is expensive. This is something I routinely use to "rebuild" old school diesel fuel injectors.
    (The finest I have in stock is red colored, dry (mix with oil) and leaves a mirror finish)

    McMaster-Carr
    https://www.mcmaster.com/lapping-compounds/

  12. #47
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    Default Re: Tapered Bronze Valves

    Quote Originally Posted by Canoeyawl View Post
    Lapping compound is readily available in grit from 16 on through 2400.
    It can be obtained as a finer compound than 2400 but that stuff is expensive. This is something I routinely use to "rebuild" old school diesel fuel injectors.
    (The finest I have in stock is red colored, dry (mix with oil) and leaves a mirror finish)

    McMaster-Carr
    https://www.mcmaster.com/lapping-compounds/
    I should have searched McMaster. Oh well, next valve rescue.
    Interesting comment about adding oil, I was thinking about doing that. The product I got from Spartan is like a sample size bottle without enough oil or whatever they use. It could go a lot longer way. Mineral oil? Glycerine? Sewing machine oil? I think I'll try some sewing machine oil.
    My choice to try next would be around 800 grit.

  13. #48
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    Default Re: Tapered Bronze Valves

    Success. Installed the valve and does not leak a drop. Turns easy.
    Neighbor said he uses rubbing compound. Why not. I guess. Not sure what the grit size is in rubbing compound but I would guess 1 micron. Or what the condition of his valves are/were.

  14. #49
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    Default Re: Tapered Bronze Valves

    Excellent!
    "If it ain't broke, you're not trying." - Red Green

  15. #50
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    Default

    Quote Originally Posted by keelhauler View Post
    Success. Installed the valve and does not leak a drop. Turns easy.
    Neighbor said he uses rubbing compound. Why not. I guess. Not sure what the grit size is in rubbing compound but I would guess 1 micron. Or what the condition of his valves are/were.


    Rubbing compound and polishes comes in an array of grits, though its usually labeled coarse, or heavy cut, or finishing etc, rather than by grit. Perhaps examination of fine print in documentation or a call to customer service could provide a grit cross reference.

    Kevin


    Sent from my iPhone using Tapatalk Pro
    There are two kinds of boaters: those who have run aground, and those who lie about it.

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