Wax piston sprue extruder?

Discussion in 'Lost wax casting' started by Zapins, May 21, 2018.

  1. Zapins

    Zapins Gold

    The piston is in the mail! Looking forward to getting it next week.

    As for now I printed out that PID controller case. Here it is after 20 something hours of printing. Nearly finished.
     
    oldironfarmer likes this.
  2. Jason

    Jason Gold

    20hrs of printing? Why didn't you fire up that tig machine and make yourself a proper case out of aluminium? Hell, you can get a plastic case from digikey or mouser for 6 bucks made specifically for this. This is my problem with 3d printing.... It's not cheap, takes forever and produces an inferior end user product. I'm all for prototype work, but that's it these days. In 10years from now, it will be a different story.

    Look at kermit the frog here, he makes ugly art with these things and suckers cough up stupid money for this no talent trash. If I can download a file and babysit a printer, It's not art!
    http://www.kevincaron.com/artwork/fine-art-3d-printed~11.php
     
  3. Zapins

    Zapins Gold

    20 hours of printer time. 0 hours of my time though. Perfectly made to spec with back plate and feet in a decent color. Not too bad of a deal. Total cost was probably 3 bucks of plastic and less than a buck of electricity.

    Also I'm in TN and the tig welder is up in CT. I'm away from my workshop most of the year :(
     
    Last edited: Jul 22, 2018
    Rtsquirrel likes this.
  4. Jason

    Jason Gold

    Ahhh.. that's right, I forgot your off at school. You making another bird in TN?
     
  5. Zapins

    Zapins Gold

    Yeah it's already been slush cast in wax and chased. Just need to fit the metal feet to the bird and then sprue it up.

    I try make a second copy just in case. Plus I still have a second pair of feet lying around from the bird that smashed during coating.
     
  6. Zapins

    Zapins Gold

    Having a bit of a problem finding the right part. The controller box I printed out from thingiverse (https://www.thingiverse.com/thing:1679361) uses a K type thermocouple with 2 parts:

    Male: HFMPW-J-M,
    Female: HMPW-K-F

    These parts cost something like $13 dollars each plus shipping and I need 3 sets of them for the 3 PID controllers I bought (a bit pricey). Also these parts are on back order from https://www.omega.com/pptst/HMPW_HFMPW.html & a second website http://www.newark.com/omega/hfmpw-k...fmpw+k+m&ddkey=http:en-US/Element14_US/search

    My question is, do I really need this connector to make the thing work or can I just plug the temperature sensor directly into the PID? I wouldn't mind saving myself like 40 or 50 bucks on these parts if possible.
     
  7. joe yard

    joe yard Silver

    Hi Zapins
    That would work for now.
    You can get the low end connectors from china later cheep. 5 PCS for under $2

    .aliexpress.com/item/DSHA-New-Hot-5-Pcs-Flat-Male-2-Pin-K-Type-Thermocouple-Wire-Connector

    Joe
     
  8. Zapins

    Zapins Gold

    Got some questions about the extrusion dye.

    The hole that does the final shaping of the extrudate, does that need to be at a specific angle? Or just at 90 degrees?

    These 2 seem to be opposite angles, but I have seen other schematics that show the angle of the dye is 90 degrees. Any idea which angle to choose?
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
    Last edited: Jul 27, 2018
  9. Jason

    Jason Gold

    I don't think it matters. You squeeze it and it can only come out the shape of the hole.
     
  10. Zapins

    Zapins Gold

    Alright. Makes sense, but then again who knows reality can be surprising lol.

    What about hooking up watlow band heaters? Do I just attach a 120v wire to them straight from the wall? With the PID temperature controller connected in series?
     
  11. Jason

    Jason Gold

    I haven't tried hooking mine up, but that sounds like it should work.
     
  12. It is called a die.

    And the shape depends on the material being extruded. Materials like aluminum have a sharp edge at the inside face and draft behind so you don't get galling as it is extruded. Wax might benefit from the same design but I'd start with a straight hole then relieve it if you don't get good surface finish.
     
  13. Zapins

    Zapins Gold

    Smart idea. I'll do that with the orifice of the die.

    Do you think I need to angle the area leading up to the die (like the 3rd photo)? Or just leave it flat like in the last photo?

    I'll see if I can find a wiring diagram for the PID controller. I bought 6 band heaters so I'll need to figure out how to wire them, probably in parallel and somehow hook them all up to the controller.

    I think I'll weld a blob of metal, then drill it and insert the thermocouple into the blob onto the barrel of the extruder. That way the probe will more accurately measure the temperature.
     
  14. Zapins

    Zapins Gold

    The PIDs arrived today and I installed them in the case. I also used meshmixer to make a little insert for the temperature controller slot so I don't need to shell out extra cash for that thermocouple connector. Seems to be printing out ok which is pretty cool (my first self designed object).

    I found this wiring diagram which I think looks ok. It looks like the PID itself supplies the DC input to the SSR via the 4 & 5 slots going to the 3 and 4 slots on the SSR.

    The one thing I don't really see on here is how do the heater elements get powered? The neutral and phase power look like the input of the 120v from the wall, but where is the output line? What if I want to wire the thing to a power strip and then plug in my six band heaters?

    [​IMG]
     
  15. In that case you would substitute the power strip for the "Heat Source" in that diagram and connect the power strip ground and neutral to the mains ground and neutral and then the active or "Phase" for the power strip comes via "Terminal 2" of the solid state relay. That way your heater strips get turned off and on via the SSR which is controlled by the Rex controller (Which is a cheap knock off by the way).
     
  16. Zapins

    Zapins Gold

    Ahhh yes good point. I think I overlooked that. Sounds straight forward then. I'll see if I can find a 6 slot power strip and wire it up.
     
  17. The material being extruded has to fail in shear before it assumes the shape of the die. Liquid has no shear strength so a tapered lead in is nice with liquid but I believe it serves no purpose with a solid.

    It should be adequate to strap the thermocouple to the cylinder with a hose clamp. If you like put a piece of cardboard right over the tip and that will insulate it from direct pad heat. In industry it is common to insulate a surface thermocouple. The end cap has plenty of thickness to drill a small hole for a thermocouple.
     
  18. Zapins

    Zapins Gold

    How do you connect/wire kanthal wire? I can't seem to find a diagram or picture of the ends of the wire and what they plug into.

    Also, how do you calculate how thick or long the wire needs to be to provide a given amount of heat without burning out?
     

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