lost wax casting

Discussion in 'General Engine Discussion' started by abby, Apr 16, 2009.

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  1. Apr 16, 2009 #1

    abby

    abby

    abby

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    My speciality is lost wax casting which I have been doing for over 20 years.
    I got into this from sand casting as I had a need to produce sculptures,
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    business awards,
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    and classic auto spares,
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    but now concentrate on model engineering castings of the more difficult type.
    mostly in gun-metal
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    but also aluminium
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    and nickel-silver
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    I have complex patterns rapid prototyped and have had to become proficient with 3D cad,
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    Most of my equipment and process is designed and built in house by me,
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    [​IMG]
    always willing to help out on a project and if anyone is interested they can see more on my web-site ;
    www.unionsteam.co.uk and forum www.unionsteam.co.uk/forum
    these are hosted on my own server so may be slow at times.
    regards to all.
     
    gabby likes this.
  2. Apr 16, 2009 #2
    Great work , lost wax casting is something i am going to have to get into, what dose the modified ped drill do.
    Rob
     
  3. Apr 16, 2009 #3

    abby

    abby

    abby

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    Hi Rob, the drill press has been converted into a high pressure wax injector , the wax is melted by a small cartridge heater in the reservoir - the copper tube part on the side - and drawn , via a non-return valve , into the cylinder which replaces the quill.
    Pressure is applied by the long top handle onto a piston and the wax is forced into a die ,placed on the table ,through the bottom valve. A band heater keeps the nozzle and ram at required temperature using simple temperature controllers.
    Injection pressures of 200 psi are possible and dies are machined from aluminium , or cast from low melt alloy(woods metal) , or sometimes silicone rubber , even chemical metal can be utilised.
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    the combination of pressure and die produces consistent dimensions in the wax patterns and castings allowing holes as small as 1\16" to be included in the casting , thin wall sections are also more easily reproduced allowing castings to be made that require minimum machining
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  4. Apr 16, 2009 #4
    Abby that's a good idea for the drill press, and you sure are the man to ask about lost wax from the look of your work, I do a fare bit of sand casting so what sort initial of cost would it be to get started with LWC ?
    Rob
     
  5. Apr 16, 2009 #5

    rake60

    rake60

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    Abby I know what it takes to get a positive result from casting.

    Let me say: :bow: :bow: :bow:

    Rick
     
  6. Apr 16, 2009 #6

    abby

    abby

    abby

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    Rob , it need not cost a great amount to set up a small facility but there are two essential items.
    You will need some way of de-waxing and firing the moulds , typically an electric oven of suitable size and able to reach 750°C , you could probably use a domestic cooking oven with extra insulation , or use the elements in a Kaowool lined metal box.
    The oven will need a programable controller , again if you are so inclined you could use a PC , my first oven used an Apple IIe with home made I/O board , but for around 100 USD you can buy a good controller.
    [​IMG]
    Secondly you will need a source of high vacuum i.e. at least 28" Hg in 2 minutes. I have an Edwards laboratory high vacuum pump which new would be over a 1000 bucks but if you look hard enough you can get a used one for peanuts.
    You will need the pump for de-gassing the investment cement and assisting the mould filling.
    Some stainless steel tube large enough to take your castings with at least 1/4" to spare , but mild steel will work, just doesn't last as long.
    I spent almost nothing on my first lost wax foundry , now it is a business I tend to buy what I need unless I can make it better.
    the rest is consumables ,my process uses commercially produced plaster based cements , but you can make your own , not so reliable but it works.
     
  7. Apr 16, 2009 #7

    abby

    abby

    abby

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    Rick...lol
     
  8. Apr 16, 2009 #8
    Well i have a start the vacuum pump i picked up free some years ago to build a vacuform machine witch was never built, i best get scrounging for the rest.
    Great web site, one photo shows Mixing Investment Cement under vacuum is the vessel a modified pressure spray paint pot ?
    Thanks for the info. Rob
     
  9. Apr 17, 2009 #9

    shred

    shred

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    That drill press setup looks a lot like a plastic injection molder.... I scrounged a tiny one several years ago from a defunct high school shop. It's not got a big 'shot', but I think it would work for wax. IIRC, Gingery has plans to make a drill-press injection-molder attachment that could probably be converted. Have to consider lost wax sometime as I also already have a burnout kiln.. alas I passed on the vacuum degasser and flasks as well.
     
  10. Apr 17, 2009 #10

    abby

    abby

    abby

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    Most of my equipment is made from something more readily available , the paint pressure pot is a good example.
    With the current financial situation cash is king and bargains are out there. Bankrupt factory auctions are the place to go but you will need transport and lifting gear for the bigger stuff.
     
  11. May 10, 2009 #11

    pmercer

    pmercer

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    I've not been on here in a long while, and have just updated a thread I started and now have seen this. Absolutley amazing and brings back a few memories. I used to do a lot of loss wax castings in SS and Alu using a theremojet. Had to outsource the castings to get my parts cast for my model gatling gun though as I coudn't do brass(as I found out).
     
  12. Aug 27, 2009 #12

    NeilSM

    NeilSM

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    Interesting.

    I spent some time looking at the cast iron bed of the Unimat 3 and trying to see how it was made. First I thought it was cast with a core but the draft angles were all wrong. Then I thought it was cast in two parts and welded together, however there is no sign of brazing where there should have been a witness line and I can't see them using cast iron welding and not brazing.

    Finally I realized they must have used lost wax. I believe they injection mold two wax pieces (the front and the back) weld the wax pieces with a hot iron, spray coat them and then cast them.

    I was quite surprised at this but it seems to be the only way to do it.

    Almost very other part is either machined steel or injection molded Zamak. The only exeption I can see is the machine vice which has a body of cast steel. The chucks may also be cast steel but as they are fully machined it isn't possible to tell.
     
  13. Aug 27, 2009 #13

    kustomkb

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    Very nice work!

    Also something I would like to try. My father is a retired pattern maker.
     
  14. Sep 20, 2009 #14

    spazman_77

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    wow, wonderfull work and great tips on how to do it, im doing the same thing in lost foam, works faily well.....

    once again great work.....
     
  15. Aug 10, 2010 #15

    Paul Erland

    Paul Erland

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    What are you using for the investment. Purchased product or something home made?
     
  16. Aug 10, 2010 #16

    Dan Rowe

    Dan Rowe

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    Paul,
    Abby has his own forum now and might be a while before he reads this. I know that he uses comercial investment.
    http://www.unionsteammodels.co.uk/forum/

    My opinion on this is there is WAY to much work in some of the wax models I have made and I am not going to take any chances on an expermental investment. I have a thankfully small box of bits that did not work....come to think of it I only kept the sadest cases of something going wrong with a lost wax casting sesion to remind me to NOT do that again.

    Dan
     

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