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He's Back (interesting photos)

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  • He's Back (interesting photos)

    OK, last summer I took a leave of absense from the board to work on a "little" project. I've been making a pair of patterns and core box for an OSSA motorcycle magneto cover. Well on Friday I droped the final mounted patterns and core box off at the foundry so I am now free to piss away my free time again on the board shooting the sh!t. The photos of the casting are from a down and dirty test pattern used to calculate shrink and check for potential problems. Also the photos were taken to accent the texture of the sand casting. I'll post photos of the finished casting after I get final approval.

    New url listed below, check out the casting photos too.

    [This message has been edited by Dave Opincarne (edited 06-09-2004).]

    [This message has been edited by Dave Opincarne (edited 06-09-2004).]

  • #2
    Nice Furby.. HA HA.. (sorry I got tickled when he popped up) (cute dog) Has one ghost eye.

    I really like the patterns, good job. I should hope mine turn out so good. Ossa, wasn't that a Spanish trials bike of the 70s? I kinda remember riding one though the haze of the 70s.

    I have a casting outfit here, wish you were closer, I don't have anyone much that I trust to help me pour. (two man flask bar)

    I have been working on a cnc machine to carve sand molds directly to pour.. *(machinery mostly)

    HOW did you calculate the shrinkage factor for what alloy?

    David

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    • #3
      The pooch was a nice supprise.
      The patterns look fantastic. What, if I may ask, is the charge for poruing such castings? I would assume that there is a minimum amount of aluminum that they want to pour at one time.
      Civil engineers build targets, Mechanical engineers build weapons.

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      • #4
        Thanks

        Skye is a constant "help" in the shop. She actualy has two blue eyes but one has an iris colaboma which meens the iris is not fully developed, jaged and fully dilated all the time. But very smart dogs are not always a pleasure to have around. Having a dog that can shut the door behind here is great, but she also gets into shut cupboard doors and find interesting ways to keep herself entertained. She also has a garbage/food/cat sh!t addiction. Smart and highly motivated by food is not a good thing. Like the bumper sticker says: "My austrailian sheepard is smarter than your honor student"

        These were a nice change from the patterns I make at work, smaller and much more complex. They were much more akin to the work I used to do in composite tooling. One thing I learned though is taking on a large job like this and trying to work on it for a couple of hours in the evening or on the weekend is very inefficient. Only half the time is as productive as it should be. Too much time is spent getting my head back into it or trying to remember what I was doing when I left off. My bid ended up being fairley accurate for the time I was acctualy moving forward, but there's a lot of time I can't justify billing for.

        Ossa was a spanish dirt bike of '70s vintage, but I'm not sure what the model is, I'm not the owner of the bike I was just hired to do the pattern work.

        Alloy is aluminum. The standard shrink for aluminum is 1/8" per foot, but that's for an unresticted solid mass. Because the part consisted of thin walls over a solid CO2 core and since the core can restrict shrink, we didn't know how much to factor in. Thats why we did the test casting. Comparing the casting to the pattern used to make it allowed us to come up with a shrink factor.

        We're using a small job shop type foundry. By putting two patterns on a board we were able to get the unit cost down to $35. Since there are other jobs going on at the same time minimum size is not a factor. They're pouring several molds in one heat. This is by no means the smallest job they do.

        Why make sand molds by cnc milling? Seems ineficient to me. Why not mill a pattern and be able to reuse it?

        Dave

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        • #5
          Hi Dave, welcome back!

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          • #6
            <font face="Verdana, Arial" size="2">Originally posted by Dave Opincarne:

            Why make sand molds by cnc milling? Seems ineficient to me. Why not mill a pattern and be able to reuse it?

            Dave
            </font>
            Plus sand is rather friable and doesn't lend itself to good machining. After all that work you finish up with something like the Venus Di milo

            Won't happen anyway, That was last weeks idea and anyway sand's not shiney - opps whasszat ? something new and even shinier - gotta run

            John S.

            .

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



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            • #7
              Thanks Joel - It's very good to be back, I've missed talking to all of you and I hope to get to know some of the new personalities that have arived in my absence too. I just had too many things to do over the last year and I'm capable of spending too much here (you people are far too facinating ) so I had to make myself sign off. In the interum I bought a second Land Cruiser, sold the Revcon motorhome, had the Cadilac hauled off after I pulled the 350 Olds/Turbo 400 out if it, and have a new computer, scanner, and digital camera. I also put the final touches on the fly rod that's been sitting 90% complete since before the divorce and got a good deal on a Marryat reel and spare spool.

              My next projects are going to be finishing the apartment renovation and building a new kitchen island and building a helper drive for my bike. In a couple of months I hope to be working on addapting the transmision into the Land Cruiser (which can be seen in the first photo)

              NEW AND SHINEY!?!? WHERE!?

              Dave

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              • #8
                Here's a new URL for the whole album. Sorry, I'm just figuring out photobucket.

                http://img78.photobucket.com/albums/...carne/Pattern/

                Dave

                [This message has been edited by Dave Opincarne (edited 06-09-2004).]

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