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Thread: ducati cylinder head patterns

  1. #11
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    Looking good. Will be interesting to see how you gate it, an what the core look like.

  2. #12
    IMG_20171130_171654081.jpg

    took a pic of the port cores, I 3d printed them and made some plaster molds to make them from sodium silicate bound sand. I finish primed the side fin parts and did some tests with catalysed chembond resin, had some decent success as the sand pulled from most of the fins well, I dusted the pattern with some talc and graphite which seemed to help with the release.

  3. #13
    Good progress on the cores. How are they held in place in the mold? Do they include core prints. Besides release agent, a good finish on the fins will help a bunch but also be susceptible to abrasion. Always used a spray graphite release with air set binders.....tough to get good coverage deep in the fins.

    Best,
    Kelly
    My furnace build ----- I toil and fettle then foam turns to metal!

  4. #14
    do you have a source for spray graphite release? I read about something called nix stix, but couldn't find it available for purchase

  5. #15
    Quote Originally Posted by smp4616 View Post
    do you have a source for spray graphite release? I read about something called nix stix, but couldn't find it available for purchase
    I did acquire some nix stix from a forum member and over the course of a few weeks it evaporated from the plastic bottle it was stored in. What was left was graphite powder. From smell, I'd say nix stix is merely graphite suspended in Naptha and the graphite settles in just a few minutes so you need to frequently shake it to keep it suspended. The common graphite based dry film lubricants work, you just need to make sure it is dry film and the solvent/propellant is compatible with your pattern finish. McMaster Carr or probably your local hardware or big box stores will likely have aerosol dry film brands. The foundry graphite release formulations seem to apply a little thicker and adhere better but you need to have an account and buy it a case at a time from the foundry supply houses.

    Other spray mold releases may work fine too but as always, I'd suggest experimenting on small samples. I never experimented too much and always just used the graphite based stuff because that's what my foundry friends used on sodium silicate, and resin bonded sands. I will tell you that once applied the stuff is seems to get everywhere and you'll never handle your pattern again without getting it all over yourself.

    Best,
    Kelly
    My furnace build ----- I toil and fettle then foam turns to metal!

  6. #16
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    I assume something like this would work:



    CRC Industries 03094
    "Success is 99% determination"

  7. #17
    IMG_20171201_075038553.jpg
    IMG_20171201_155310816.jpg
    after priming the patterns, I stacked them and pulled some tests with bonded sand, I think some of the fins go a bit deep, so I will probably modify the pattern and have the mating patterns make the deeper sections of those fins, I'm running a 3 degree draft on surfaces, so it tends to wind up with very little mold material on the deeper fins, if I get some practice I might try 1.5 degrees. also started working on the rest of the fin pattern, the fin section of this part will be made of 4 molds, then one mold on the bottom to define the combustion chamber and hold the port cores

  8. #18
    I have had good luck with Spray-On brand dry graphite. Ran out on a weekend so I got some B'laster brand but has too strong of a solvent and applies more like paint. I just found this place but haven't used any products or contacted them. Its aluminum and silicone like Nix Stix NB.
    http://foundrychem.com/no-bake-mold-release-agents/

    One has acetone, one has toluene, and one has a $30 haz mat charge.

    Good luck with the head. They are a lot of work but its pretty sweet when you fire it up for the first time.

  9. #19
    Making 900 engines that have old 600 Pantah style intakes in the center/exhaust out the back of the rear head?

    Neat project - looking forward to the (successful) finish!

  10. #20
    Senior Member Spelter's Avatar
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    Since you're using bonded sand, why not do the finned section as a stack of bonded slices? 5 internal slices, parted down the midline of each fin would eliminate all deep draws and allow close inspection of all surfaces. Do it all as 'cores'.
    "The former lives of objects need not interfere with their current use."

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