Tobho Mott Halloween casting contest 2017

Discussion in 'Halloween Casting contest' started by Tobho Mott, Sep 3, 2017.

  1. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    I'm in. I always cast something for Halloween anyhow! The hard part is going to be finding time, but I'll give it my best shot.

    Last edited: Sep 5, 2017
  2. Jason

    Jason Gold

    Do a spooky dog....
  3. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Lol, I already cast a couple of invisible ones as you know...

  4. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Hmmm... Decisions, decisions...


    This is most of my hoard of Halloween foamies that I've been adding to here and there around this time of year for a few years now, just for goofing around making fun skully spooky things with lost foam casting around halloween time. I've made a bunch of stuff before out of these types of cheap styrofoam decorations that they send out to the craft stores and dollar stores for whatever seasonal holiday might be coming up next. Posting this here now in hopes it might help attract a few more competitors...

    I haven't decided what to make yet this year though. Might not even be lost foam... but I must admit, looking through this collection of "patterns" is making me miss that sweet sweet stench of burning polystyrene more than I ever thought I would. :)

  5. Jason

    Jason Gold

    skulls are too common. do Frankensteins head..
  6. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member


    OK, so much for waiting to see what everyone else is doing, guess I'll start posting my entry first... ;)

    Note: This should be read as a tutorial for a casting project suitable for any casting hobbyist, from the rawest of beginners to those with years of foundry experience (though I have no doubt the latter would have some of his own tricks to outdo me with here). If you have a way to melt and pour molten metal and even just a small collection of typical homeowner's tools, you can make one of these too.

    Throughout this project, you'll see me using a band saw, a belt sander, a drill press, and some fancy sand blasting beads, but those things are not necessary for this project; they just speed up some of the steps. A hacksaw, some normal sandpaper, a drill, and a bucket of play sand would be just fine (though you would want to make sure the sand is dry).

    By the same token, you could also go more high tech if you have bucket vibration and vacuum casting equipment as seen in other entries.

    Coatings like professional casting investment or ceramic shell mold material or even drywall mud could be used to get a smoother finish if a smoother finish is what you're going for. But pouring cooler than you'll see me do later in this thread would also result in a much smoother finish than you'll see on my entry - almost as smooth as a coated pattern can yield - since the pattern I will show is set up to be able to fill successfully even when poured much less hot. I'll try and remember to include an example or two of smoother looking foam castings that did not use any coatings a little later on.

    Now that that is out of the way, on to the project itself!

    Jason suggested I cast Frankenstein's monster's head using one of the bigger foamies shown above, and I was really considering that, but I think David D wants to cast a lost foam bust that would probably end up being a very similar project, so I will be doing something else.

    My best Hallowe'en lost foam project ever was probably the three-faced Jack O'lantern table lamp I made that actually lights up and everything. It'll be out on my front porch this Hallowe'en, hopefully not burning my house down.


    But I poured those (the lid is a separate piece) last year and installed the electricity this spring, so it's not a valid entry for this contest. :(

    I've done a really cool sand cast skull ashtray, um, I mean, candy dish too, it's one of my favourite castings I have made... Sold it a while ago and was going to cast a new one to have it handy for Hallowe'en on Saturday October 28th. I had the mold all ready and everything, but then it started raining. Still hasn't stopped, so I guess that is probably not gonna happen on time for this Hallowe'en, which is tomorrow at the time of this edit.


    I shared many pictures online of how I cast it though - so, also not an eligible project for this contest. :(

    My entry will be a spooky all one solid piece belt buckle, cast using the lost foam method.

    I have come up with this buckle casting method through trial and error, and the way I cast this one is the only method I have come up with that has never failed to work for making a one piece belt buckle using lost foam. All the other examples I have seen others doing used a separate piece of wire attached to the casting to make the belt loop, and in many cases, the belt hook too. If anyone else is making them in one solid piece using lost foam, I haven't seen it, and it's not for lack of looking.

    First you need to come up with an idea. You can see my big pile of Hallowe'en foamies in the pic I posted above. In the past I have made similar belt buckles (shown below) by taking the small (~3") expanded polystyrene (EPS) foam skulls and cutting a slice off of them to use as the buckle. There are a couple of decent angles I have found to cut these at where you can get a pretty cool skull buckle out of it.


    Looks like 2 pairs of identical buckles, but they are not identical - each one is slightly different, therefore completely unique!

    Other old buckle.jpg

    I gave the one shown being worn above to a friend's brother in law for letting me hang out on his driveway for a weekend using his welding machine to fabricate the steel parts of my oil furnace and its cart a couple years ago. Sadly, I was not able to pick up that machine on the cheap at the divorce auction he had last month.

    I am wearing one of the ones I kept for myself right now, and have worn it every day since I got through finishing up sanding it to a reasonably shiny finish a couple years ago. It fits great, never comes unbuckled unexpectedly or digs into my gut or anything when I'm sitting down or what have you. I'm very happy with it.

    But that is not a new project either, so it is not my entry. Just a shameless pic overload strategy to get me an extra vote or two, I hope! :D And it may also serve as an example that others attempting this method might draw some inspiration from.



    Since I have to come up with something new, I thought I would take this idea to the next level and, rather than take one factory made Hallowe'en foamie and simply use a slice of it to make a buckle from as I'd done before (above), I'd cut up some pieces of a few different factory foamies and glue them together in an original arrangement on a base made of a rectangular slab of extruded polystyrene (XPS) foam instead. No actual sculpting skill required... ;)

    In my foam hoard, I found a small box of small glitter-coated skulls. I figured I could make a cool buckle with those. I'd put the face of one skull looking straight forward in the foreground, and a left and right skull profile looking to each side beside it sort of in the background. Should look pretty bad-ass, I figure.

    You could make anything you want though. If you haven't been hoarding styrofoam skulls and stuff for years like I have, and don't have extra slabs of XPS lying around, you can carve something original out of foam packaging material, you just have to be really careful and use incredibly sharp razor blades, plus sandpaper and files etc., or whatever you can think of trying that may work. I have a few tricks for doing stuff like that too, but that is not within the scope of this project, so I will leave it for another thread...

    Blah blah blah, too much talk, need more pictures!

    OK, OK, I get it, let's get into the good stuff...

    I used my bandsaw to cut two little skulls in half to make the pieces I needed. I also cut a rectangle out of a big sheet of XPS to use as the background. This could also be done with a hacksaw, a razor saw, a coping saw, a sharp razor blade, a surprisingly easy to build hot wire foam cutter table, etc. You get the idea. Like I said, this really is a project that almost anyone could pull off.

    Although there was a piece of a pointy stick inside one of the skulls that I had not seen through the glitter; the hot wire would not have liked that... but the bandsaw only slowed down a tiny bit, and only for a moment.



    The blue rectangle was still too thick at this point. I rigged up an improvised fence on my saw and took a thin slice off it to make a border out of later, then trimmed the remaining buckle base down to a more reasonable thickness.


    Next step was to trace out an outline of the skulls in place as I envisioned them, in order to create some guide templates for removing the excess foam from the backs of the heads of the two sideways-facing skull halves. Thank goodness pictures can explain that better than I just did!




    Once roughly cut to shape, they still didn't quite fit together right (see skull on left in next pic). I used the bandsaw again to trim off some of the back of the sideways skulls so they would fit better.

    Sandpaper, files, etc. would have worked too, just a little slower. I'll be posting a couple of videos of how I made this belt buckle later; the first video will show some of the ways I used the bandsaw to carefully munch off unwanted foam and get the skulls to fit (more like the one on the right).


    (both skulls trimmed down)


    By the way, the glitter coating is not a problem, it won't affect the surface finish of the casting other that it will come out of the sand with a black coating that is fairly easily scrubbed off, if desired. But aside from that wooden skewer tip I found hidden by it in one skull, I have come to realize it can cause minor problems in some other ways... They do make it difficult to see if your chosen foamie is relatively neat and tidy when it comes to mold lines and finer foam details, as you will see later on.

    I traced out the skull parts in position lightly with a pencil on the thin slice of XPS I had cut to make the border. I also traced a fairly even border around the edge. I would cut the border out with an X-Acto knife, trimming away a little bit of it at the edges where the skulls were a little wider than I had planned for, so that the skulls and border would not interfere with each other.


    A quick test fit seemed to confirm everything was gonna fit...


    Time to start gluing stuff together!

    That's step 1 I guess; cutting out the pieces and test fitting everything. I haven't explained how the back side of the belt buckle is going to work yet, but that will become clear as the thread continues, I hope. Next up, actually assembling the pattern...

    Last edited: Oct 30, 2017
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  7. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member


    Hot glue guns are a staple of the backyard lost foam caster. But hot melt glue does not give you much time to tweak things and adjust the positioning of different pattern parts!

    This is where the glue stick in your kid's school pencil case comes in handy. They take a good long time to dry, so you have plenty of time to adjust everything so it's perfect. Yet it is tacky enough right off the stick that even while it's still drying, something as light as foam isn't going to slide around when you're off doing something else due to gravity etc.

    You can just smear it on normally from the stick, or with a fingertip, or you can make fillets with a wooden popsicle/stir stick, whatever the situation warrants, but it's probably best to try and keep it to thin coats where possible. I made little fillets with it where the three skull sections met, to plug up any little gaps and avoid sharp corners, but when gluing one piece of foam to another, I smeared it on as thin as I could with my finger, which also helped get rid of any lumps.



    I also used the glue stick to fill in the small gap where the border met the rectangular background. I've seen some people using toilet gasket wax or beeswax-based hand salves to smooth out lost foam patterns and disguise the beaded texture that often comes through in the casting when EPS foam is used, by filling up those little gaps and pita between the beads. Same basic idea here.


    That took care of the front part of the buckle pattern, I let it sit until all the glue dried before I began assembling the gating and the belt loop and hook.


    My trick to get the belt loop to cast in one piece is pretty simple, but maybe a bit labour intensive. I cut the loop right out of the sprue, which I make a bit wider than a normal belt and a bit thicker than I want the loop to be. This is done after the buckle has been cast. Trial and error has proven to me that it is worth the extra finishing work on the casting because done this way, it never fails to fill. I had very little success casting the full loop in place and as thin as desired.

    Certain aspects of how this casting turned out are making me reconsider this approach, but more on that later; this is how I did it this time, and those are the reasons.

    First I shape the sprue, then I cut it into pieces small enough to hollow out on the bandsaw, so the metal can get to the pattern with no delay. Then I hot glue them back together, then hot glue the reassembled hollow sprue into place. You can see them taped together temporarily in some of these pix, that is just because I had misplaced my hot glue gun for a bit there. The hollow sprue is optional, but could be done in other ways. I have seen people hollowing their sprues out with a piece of wire that has been heated up, etc., and many people do not use hollow sprues at all or may even believe it is a waste of time or even counterproductive.
    To me it often seems worth doing, but I don't always bother. I did it here because this is a contest, so I must make sure to use all my best tricks in order to help ensure I don't lose just because my first attempt failed to fill the mold! (Ahem. :p)

    Sorry for the lack of pictures of me cutting up and hollowing out the sprue; you can see some of that in the video, but my hand was too much in the way to pull out any worthwhile stills.

    I also use one drinking straw for these buckle castings. No, it is not a vent, which is what most drinking straws being poked into Styrofoam patterns would be intended as.

    I don't think it would do any good as a vent anyway; not only would the mold already be pretty much full by the time any gases could get into it (just as it becomes plugged with metal anyhow), but IMO you need to build a hollow pattern with a clear path of open air from the sprue all the way through the pattern to the drinking straw(s) for them to do any good as vents. With no coating though, or even with thin coatings, the foam seems to be able to vent into the wide open (ie. completely unbonded) sand easily enough.

    For those who do use straws as vents, here's a tip: See (below) how I used a piece of tape to hold the bendy straw in the fully bent position? It could still vent this way (were it actually a vent) - the open end of the straw will only be under an inch or two of loose sand after all - but this way you don't need to worry about it filling up with sand when you bury the pattern.

    In this case, the straw is just to form the hook to grab onto a hole in my belt though. It will fill at least part way to make a wire, as seen in the older examples I posted above, so if it is a nice fat straw and it is slanted at the right angle, I will just have to cut it to length and file it down to a good shape for keeping my belt done up.

    Here are some pictures of how I shape my belt buckle sprues and belt hook straws to work properly and keep the extra finishing work down to a not so bad amount:




    I use the hot glue gun and a popsicle stick to make small fillets around the sprue base and where the straw sticks into the foam. You can just twist the straw into the foam usually, but because the buckles are pretty thin, you can't stick the stray in too deep; I like having that extra bit of insurance that it won't pop out under the sand during burying.


    That is it, simple as that, and the pattern is complete. Using coatings on lost foam is optional and IMO may be unwise using glitter-coated foamies. I do not generally use coatings on my lost foam castings; I find my very fine sand makes it more trouble that it is worth for most jobs. But that is for the next post... Which will cover how I actually molded and cast this thing.

    Here is a video of the steps in the patternmaking process used to make this belt buckle:

    Last edited: Oct 30, 2017
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  8. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Step 3: Setting Up the Mold and Casting the Belt Buckle

    The way I usually do lost foam casting relies more on really fine sand than on drywall mud investment or other coatings to get a good finish. I use super fine abrasive glass blasting beads instead of actual sand, but real sand that is just as fine would work just as well.


    I fill up the bucket about halfway to support the pattern such that the sprue tops out near the top of the bucket. I try to get a nice smooth layer on top of a reasonably compacted bed, with some more fluffed up sand on top. I take note of undercuts on the pattern and press it firmly into the surface of the sand in a direction that forces the sand to fill up the undercuts... as much as possible. It is best to keep those undercuts to a minimum if you skip coating your foamies like I do.



    I carefully fill up the bucket with sand, being careful not to get any down the hollow sprue. Sometimes I will put an upside down plastic cup over top of it to make sure, but this time I was just careful and scooped in the sand a little at a time. If you have some kind of a bucket vibration machine, now's the time to use it, while you're burying the pattern. But if you don't, just kick or bang on the side of the bucket a little bit every so often while you're filling it up with sand, it helps the sand settle and compact around the pattern a bit, and that'll go a long way to help ensure your casting won't have a bunch of (extra) weird scary blobs sticking out of it.


    Once the bucket is full enough of the sand that it is just below the top of the sprue, I stick the magic head pressure tool (a soup can with both ends cut off. Don't use your favourite one!) maybe an inch or so down into the sand around it, and add a little more sand around the outside of the can. This pic is just before I added the extra sand around the can; I wanted to show that I made sure to get the can between the foam sprue and the top of the drinking straw. I had to bend the can a little to do that, not a big deal. The straw is not meant as a vent, but I do want it to be able to fill with metal. From below, not above.


    Here's the mold all ready for pouring. I stuck another lost foam skull-thing in there too since the bucket is big enough, so technically I guess it's two molds.


    Firing up The Black Dread on waste vegetable oil! (AKA fire porn!)


    After seeing how well Kelly's lost foam casting has been going, I thought I'd try one of his tricks and let the aluminum heat up a little more then I'm used to doing. I use the hot rod dip test to determine pouring temperature, but for this pour I kept it cooking for another minute or two, in hopes that the mold would fill. I have never had one of these buckles not fill, but it's lost foam, anything could happen.

    This extra heat worked really well! Not only did the mold fill, but molten metal came all the way up the drinking straw and spilled across the sand around the soup can! I never had it run so far casting one of these buckles before. This pic actually shows the moment the metal got to the top of the straw and burned through it, you can see the little puff of burning styro-vapour jetting out of it, which only lasted an instant, then the metal metal started flowing out from the top of the straw. Not that I could see that happening at the time through all the fire and black smoke!



    Here is the casting fresh out of the sand bucket, still piping hot!


    And again after I scrubbed it off a little...


    And yet again after I gave it a little taste of a wire brush drill bit... You can see where the drinking straw filled completely in this pic.


    They don't have mouths like I wish they did. I guess I was hoping the glitter on the foam skulls was hiding some nice teeth, but not so much really. You can't get more detail in the casting than was ever on the pattern to begin with! More detailed foamies would have made for a more detailed casting.

    Next post (>here<) will show everything else, from removing the gating to creating the hook and the loop to the finished casting, ready to hold my pants up when I take the kids out trick-or-treating. :)

    Last edited: Oct 31, 2017
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  9. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Lookin good Jeff. I like it. I worked on my entry tonight and hope to pour and post this'll never work...:confused:

  10. Jason

    Jason Gold

    Chase some teeth or mouths on them if need be. Looking forward to seeing the video. (and smoke)
  11. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Hey Jeff, I meant to ask how long you've been using the fine blasting media as mold sand.

    I know we've discussed it several times and I actually looked at aluminum oxide blasting media because it was relatively economical as far as blasting media goes (still $1/lb though). Just could not get myself to spend that kind of dough on foam sand when what I'm using is essentially free. Aluminum oxide would have the added benefit of high refractory for bronze and iron pours. Now If I could find someone that did a lot of blasting and was changing out their old grit......but then the stuff is usually powdery and full of other stuff from blasting.

  12. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Kelly, I have been using the glass beads for a few years now, based on a suggestion from metalbynevin over on AA. It is pricey, but it is what I have, so I use it. Was having trouble finding actual sand this fine anywhere, so I bit the bullet and shelled out to give this stuff a try. Equally fine sand should work just as well; I have used some really fine beach sand from a campsite on a lake where I go with a bunch of friends every September, and our campfire melt / lost foam castings came out great.

    Jason, I could do that (chasing in some teeth), but I feel like it is beyond the scope of this project. I wanted to show how to get a working belt buckle out of the raw casting and show a bit of foam work to give people ideas about what glues to use and how to set up the molds etc., maybe inspire some original designs... Not how to carve details into an existing metal casting. The right time to add teeth was when the skulls were still made out of styrofoam. This is where the glitter coated foamies can let you down a bit, I really thought these guys had teeth hiding under all that glitter... If my write-ups don't, convey that this is really just a demo, and that the more work you put into the foam work and foamie selection, the better the casting could be, I guess ilmhave to do about of editing. Hopefully it is already clear in the video that will accompany my next post, because that is already edited and uploaded... It will be made public when I'm ready to post it here.

    Remember, the contest is to be judged on the merits of how each thread presents the entry, not on who makes the most perfect Hallowe'en casting...;)

    Maybe one day I will do a how-to like this where I carve a foam pattern rather than build it up out of pieces of purchased foam decorations. But the point of my contest entry is to do a simple how-to that anyone, even the rawest newbie, could follow along with and have a usable belt buckle to show for it in the end.

    Thanks for the comments guys,

  13. Jason

    Jason Gold

    Rock on man!
  14. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Could really use some of that on my Halloween entry. It's going to be hard to coat with brush and all I have is coarse sand........

    Last edited: Oct 25, 2017
  15. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Kelly, I have had trouble finding fine sand around here anywhere, I'd have just bought real sand if I could find it as fine as I want, and it'd presumably be cheaper than those abrasive beads! We don't have white silica for sale in big box stores at all here that I've been able to find. Thought about getting the local hardware store to special order me some to try making greensand with, but I am not sure what numbers (mesh, grain size, whatever) to ask for; having trouble finding recommendations that don't all conflict with each other or use different units of measurement, so that doesn't help either. That's how I ended up shelling out for the pricey beads.

    Good luck with your entry, I'm looking forward to seeing what you will make!

  16. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    (Continued from >this post<...)

    Step 4: Turning the Raw Casting Into a Wearable Belt Buckle


    You can start to see how this is going to work here.

    Next I cut off the drinking straw leaving a little stub to be trimmed more and filed down into a nice hook shape later...


    ...and drill a couple holes a little wider than 3 layers of belt, right near either edge of the base of the sprue...



    ...then cut off most of the sprue with an angle grinder/cutoff wheel and hacksaw...






    ...and removed the metal from between the two drilled holes with a couple of cutoff wheels in the dremel. Alternatively, you could drill a bunch of holes and file out the rest by hand or something I guess...


    I have cast several buckles this way and I cut the thin belt loop out of the casting instead of cutting it out of the foam because trial and error has shown it is much more reliable. But with this one, pouring as hot as I did, and seeing how far the metal flowed up and through that drinking straw, I bet I could have cut the slot in the foam on this one and still gotten it to fill... The downside is, pouring this hot, my super fine sand that I've been going on and on about how it gives almost as good of a finish as drywall mud coatings doesnt quite work as well; there was way more sandy texture on this buckle than I expected to see. It would be a lot less work to not have to remove so much metal. So maybe next time I'll think about trying a mud coating with a super hot pour and the loop already cut out of the foam sprue.

    Next step was using a file to smooth off the rough edges and refine the shape of the hook and the loop, and do a bit of sanding.


    Once the shape of the hook seems right and all the rough corners of the loop have been filed and/or sanded smooth, the amount of extra finish work to do on it is up to the individual making the darn thing. You can leave a lot of sand texture showing or sand it up to a mirror shine if you want, it all depends on what kind of look you're going for. In this case, I decided to just sand off most of the sand texture from the border of this one, but not to try and get it looking too shiny new and smooth or do a lot of finishing work on it at all. I also gave the skulls themselves just a really quick going over with a scrap of 220 grit paper just to brighten them up a little; I was really going for more of a spooky just dug up out of someone's grave kind of look...



    I also filed and sanded the back of the belt buckle a bit to try and bring out the lettering I had stamped into the foam pattern as an experiment. Worked pretty good, I can read it quite clearly. No drywall mud coatings used; bare-doggin' it FTW! :D


    Here's a closer look at the finished buckle, front side:


    Reverse side:


    And the obligatory action shot to prove it will actually hold my pants up when I take the kids out trick-or-treating:


    I guess that's about it, that's my entry. That's how I cast my lost foam skull belt buckles or whatever kind of lost foam belt buckles one might be capable of carving out and/or gluing up from chunks of foam. Hope you've enjoyed this little how-to, it's been a fun project!

    Here's the video version of the molding, casting, and finishing bits. Enjoy!

    Vote early, vote often... :D

    Last edited: Oct 31, 2017
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  17. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    OK, I have made all the final edits and tweaks, clarified a few things and added a few extra pictures, etc. If you have read through this thread before now, please consider going over it again before voting.



    Last edited: Oct 31, 2017
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  18. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Nicely done Jeff and congrats on an excellent presentation and result. You'll be stylin' and profilin' with the Halloween celebrations.

  19. Tobho Mott

    Tobho Mott Administrator Staff Member Banner Member

    Thanks Kelly, your spiders turned out really great too. Looks like it might be just the two of us entered before the deadline, assuming it's at midnight tonight. You never know though, maybe David D will get his lost foam zombie head posted in time too...

    Best of luck to you and anyone else who might manage to squeak an entry in under the wire!

    Well, second best of luck anyhow... :p

  20. OCD

    OCD Silver

    My vote is for that creature standing to "your" left.

    That's a cool costume.

    That is a costume, right? :D

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