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Thread: A water pump pattern

  1. #1
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    A water pump pattern

    This should be of interest to some of the beginners. The old pros can do these in their sleep... (oh to be an old pro!) Several years ago I was asked to create tooling to replicate a water pump from a 1912 International pick up truck for a collector down south. All I had to work with was the remains of the original pump. It was complete, in a sense, but the critical surfaces were shot in the pump body and the impeller cover. Nonetheless I took it on. The first series of photos show the original pump:

    1 by Chuck Hancock, on Flickr

    2 by Chuck Hancock, on Flickr

    3 by Chuck Hancock, on Flickr

    5 by Chuck Hancock, on Flickr

    6 by Chuck Hancock, on Flickr

  2. #2
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    The remaining photos will show the creation of the tooling for the pump body. I also created tooling for the impeller, the impeller housing, and the seal flange though I would have to dig around to find pics of that portion. To explain, I was working as a professional patternmaker at the time and so rarely photographed my work. This was kind of a special project though, so I made the effort. However, it was for my own amusement and not intended as a document for instruction so there are large gaps in the steps you'll see. That said, here's what I recorded:
    The first step was to generate a series of drawings. As many of you know, replicating a part yields the advantage of studying how the original was cast. Parting lines, remains of gates and risers, signs of pins removed, etc. all speed up the process. No need to reinvent the wheel after all.

    9 by Chuck Hancock, on Flickr

    This was a simple split pattern whose parting plane goes horizontally through the piece you see here. This is the beginning of the coremaster.

    10 by Chuck Hancock, on Flickr

    Lots of steps missing, as I said. This is fast forward to the coremaster after the volute has been radiused. This was done refering to a table of dimensions that I calculated for points at sixteen stations and using a dial caliper to check progress.

    11 by Chuck Hancock, on Flickr

  3. #3
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    Here's another shot of the coremaster. Also notice the bag of potato chips. These are a valuable aid to concentration...

    12 by Chuck Hancock, on Flickr

    Here you see a core print which will void out the body where the impeller resides.

    13 by Chuck Hancock, on Flickr

    Another view.

    14 by Chuck Hancock, on Flickr
    Last edited by Chuck H.; 03-13-2012 at 07:25 PM.

  4. #4
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    Now the beginning of the pattern itself. Same procedure as the coremaster.

    15 by Chuck Hancock, on Flickr

    Here you can see the old pump body on the table in the background.

    16 by Chuck Hancock, on Flickr

    The volute is shaped and the impeller side is now opened up to it's final diameter and recieves the flange which will provide the mating surface for the impeller housing.

    17 by Chuck Hancock, on Flickr

    The pattern on the left, the coremaster on the right.

    18 by Chuck Hancock, on Flickr

  5. #5
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    This is the first stage of the turning for a piece which will be used in the creation of the pump body core box, the pump body pattern, and the impeller.

    19 by Chuck Hancock, on Flickr

    I placed the piece in a jig of body filler and plywood and screwed it to a face plate so that the opposing side could be turned.

    20 by Chuck Hancock, on Flickr

    The finished piece.

    21 by Chuck Hancock, on Flickr

  6. #6
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    The flange and stud boss are now added to the body pattern.

    22 by Chuck Hancock, on Flickr

    On the left you can see that the previous small turning has been incorporated into the impeller shaft side of the body pattern. Prior to this a female mold was created from the turning which will come into play at several points later.

    23 by Chuck Hancock, on Flickr

    The flanges on both halves of the body pattern.

    24 by Chuck Hancock, on Flickr

  7. #7
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    We're now looking at the impeller shaft side of the body pattern and the original pump. Notice the mounting flange running tangentially from the central column to the outer edge of the body, and the various bosses for mounting, compression flanges, etc.

    25 by Chuck Hancock, on Flickr

    Here the central column and mounting flange have been roughed into place.

    28 by Chuck Hancock, on Flickr

    The bosses on the shaft column are designed to detach from the main body pattern as it is withdrawn from the mold and are withdrawn separately, one at a time. The vertical white lines on the column are saw cuts. The bosses have metal blades which slide in these cuts and are held in place temporarily with pins during the molding process.

    29 by Chuck Hancock, on Flickr

    Here you see the bosses in place.

    30 by Chuck Hancock, on Flickr

    And here are the bosses faired and pinned in place.

    32 by Chuck Hancock, on Flickr

  8. #8
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    In this photo you can see the blades on each boss. (recycled band saw blade...)

    33 by Chuck Hancock, on Flickr

    The final boss being added.

    34 by Chuck Hancock, on Flickr

    And fast forward to the finished pattern. Note the whiter core prints, one from the impeller cavity and one from the outlet.

    35 by Chuck Hancock, on Flickr

    And more views...

    36 by Chuck Hancock, on Flickr


    38 by Chuck Hancock, on Flickr


    39 by Chuck Hancock, on Flickr


    41 by Chuck Hancock, on Flickr


    42 by Chuck Hancock, on Flickr

  9. #9
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    Pump body core box.


    47 by Chuck Hancock, on Flickr

    Here's the core box for the pump body, opened up. Also, note the little bent wire tool sitting on the table just to the left of the lower half of the box. I made this to aid in ramming sand into the box.

    46 by Chuck Hancock, on Flickr

    Here's a finished core. The mix is half silica, half olivene, both of 100 grit. I can't remember the exact binder I used, maybe Sta Set at 2 ml/lb. The gold colored protion is stock 3/4" core added during ram up.

    54 by Chuck Hancock, on Flickr

  10. #10
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    The cope half of the mold. Blind risers are vented through the top.

    56 by Chuck Hancock, on Flickr

    The drag half.

    57 by Chuck Hancock, on Flickr

    The core in place.

    58 by Chuck Hancock, on Flickr

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