The Dollar Store: a source for cheap lost foam patterns

For when you just feel like melting metal, but don't actually have any artistic or machinery projects that need parts cast right now...

Sometimes they have some kind of cheezy seasonal styrofoam decorations at the dollar store. Stuff that nobody really wants or needs, much less wants or needs a metal copy of.

But after being cooped up in my house through a too cold to stick my hands in frozen sand January and February, until there's nothing left on Netflix that I haven't binged through already except a few of the lower rated dubbed foreign language series, casting these "patterns" was a good enough way to temporarily scratch the pyromaniac itch I think we all share here.

Spent $2 for a pack of 3 big super special styrofoam snowflakes, a month or so ago. To make it feel a bit more like I was actually doing something original/creative, I cut up one super special snowflake into 3 pieces on the band saw and hot glued some 'feet' made from chunks I cut off the other 2 flakes onto the bottom of the 3 main pieces. The 3 pieces fit together to make a complete snowflake-shaped trivet for hot pots to sit on, or they can be separated to use as 3 coasters or something.

First time I tried using little dabs of paste wax, as sparingly as I could manage, to smooth out the areas where I cut the foamy in 3. This worked really well, those cuts look just as smooth on the final casting as the rest of the cast surface. And these foamies were pretty nicely made, no pits or voids in them between the foam beads anywhere.

I sprued into the bottom of one of the feet (the one nearest the center of the original flake, where there was the shortest path from the sprue to every area of the pattern) on each of the 3 parts, with 2 parts glued onto one sprue and the third piece getting its own sprue all to itself. Cleaning up the gating was super easy as a result, I just ground the one foot smooth on the bottom after sawing the sprue off, then sanded the other 2 feet's bases to match the look of the first.

I "bare-dogged" the patterns as usual (aka no coatings) and a wire wheel cup bit in my drill press cleaned up the castings nice and shiny. My lost foam sand is fine enough that the little bit of texture it leaves behind actually looks nice IMO.

I know it is definitely kind of a goofy project, but at least it's not yet another Hallowe'en skull, right?

Would I rather be doing sand casting and/or making something entirely original? Of course! But it is just no fun jamming my fingers into frozen greensand in an unheated shed in a Canadian January/February. Same thing goes for working on wooden sand casting patterns in my other frozen shed...

This is the kind of thing I can give Mom for Christmas next year. She will love it/them even with the one little casting defect on one of the pieces, and I'll save a few bucks and some time shopping.


A triumvirate of trivets!

Also, whenever I wish for the snow to melt and the sun to come out to warm up the world and thaw out my greensand, we get a blizzard. So I figured why not try to trick the weather into thinking I actually want more winter. Maybe then it will suddenly become summer, or at least spring, just to try and spite me.

I did film the pour and shakeout. Nothing really new here unless you were really wondering how I sift the chunks out of my lost foam sand, or maybe you somehow never saw how I light my furnace before. Maybe some of you pervs just like to watch, how should I know? I'm not judging. For now, this video's the only way to get a look at the feet on the undersides that I didn't get a still shot of. Yet...

Foot fetish video:


Not the first dollar store foamies I have cast. If I can find my pictures of some of the older ones, I'll add them here too with the eventual snowflake trivet feet pix I'll try to remember to take.

Anyhow, this is kind of a fun way to make gifts for old lady relatives on the cheap and easy.

Or it could be a beginner's project. (Don't become yet another youtube ingot polisher! That has been done to death.) Spend just $2 or $3 on cheap patterns like this rather than spend hours carving and sanding original foam patterns. It takes a few tries to get a hang for how fast to pour and learn to recognize the infamous "pause" that tries to trick you into stopping pouring lost foam molds too soon. If you want to make those newbie mistakes on junk practice patterns you didn't have to expend much money or effort creating, just hit up the dollar store. I bet they have a bunch of styrofoam bunny rabbits and/or four-leaf clovers up on shelves right now...

Anyone else used cheap premade lost foam patterns? Post your pix here.

Jeff

 

Those look good Jeff.

Strictly speaking, no, because I've just never quite been able to get my artsy-fartsy on, but I will come out to you on having searched what's out there. Your dollar store must be better than mine, because mine has squat. Just for ideas, try searching Styrofoam on eBay and quickly click through the first 10 pages or so. Polystyrene works too but you have to sift through a lot more crap.

If in addition to Styrofoam if you add the following to the search:

1. Christmas, Halloween, Easter etc you'll get holiday themed items. Santas and Elves etc. I was tempted by a 20" tall set of full skeleton bones. They can be assembled and glued together in positons and grouping suitable for adult viewing/gifts that cannot be purchased .
2. Hollow half ball.......you can get these in any size up to 10". Stick two together and carve through the surface for hollow globes or patterned Christmas ornaments.
3. Animals.........you'll get any and all kinds.
4. Head or Mannequin.....good starting point for sculpture....and they are reasonably cheap. You'd need to hot wire them in half, hollow them out, and glue back together. Just could never figure out what I'd do with the casting.
5. Letters.......4-12" in size.......for plaques and signs but I'd probably just hot wire my own.

or.......just stick to making my own foam patterns for machine and automotive castings.

Best,
Kelly

 

Kelly, I have been trying not to go looking for easier ways to cheat by ordering these premade patterns online - the dollar store's limited selection gives me something to hunt for when the kids drag me there to buy candy, without becoming too much of a slippery slope into only ever making cheap junk out of even cheaper junk. Making and using original patterns is way more fun and challenging, but I'll do stuff like this sometimes between projects just for kicks. Eventually I'm going to have to come up with some sort of hobby that actually requires castings. Other than continually upgrading my foundry so I can more comfortably make more better ?????????, I mean. Maybe I should start on those Gingery machines at last this year, seems like that might be the best of both worlds.

I also made a really quick and dirty one-off lost foam cast aluminum phone stand a week before casting the snowflake thing too. Used some crappy EPS packaging to bandsaw out the pattern from. Didnt even really try to sand the foam too much or anything. Came out kind of rough looking of course, but it works and isn't toooo crooked. I bet some of that wax would have smoothed out the foam pretty nice. It only led to more Netflix induced hibernation though.





I did watch Madmen a few years ago, or most of it. I think I still need to go back and watch the final season, pretty sure it was still actually on TV or had maybe just ended at the time I started streaming it. But we're getting nice (ie. above freezing) days here often enough now that I think my deep winter binge watching season is probably just about over.

Jeff

 

It's actually the same abrasive glass bead blasting media I've been using for lost foam sand for years. Works great for aluminum, but sometimes I have to chip a little melted glass off of bronze castings. It seems to compact well enough just by whacking the buckets a bunch of times. I have experienced a few sand float defects (the bizarre lost foam equivalent of a runout in a sand mold) but I don't know if that would be more or less likely if I used real sand. Certainly better vibration would help.

I originally bought it on the recommendation of Metalbynevin from Alloyavenue before I was able to find nice clean fine dry silica sand for sale anywhere locally. Now I know I can get it in 75 mesh from the pottery supply shop. Much cheaper than the glass bead and comparable grain size, but still not as cheap as I'd like. I heard about a quarry nearby where I can pull up the van and shovel my own bins full for way cheaper, but it won't be pre-dried and screened like the pottery stuff. It's supposed to be the finest stuff they sell though. I plan to check it out and see if I think it would be good for doing this and/or making molding sand.

I don't think bare-doggin' it would be great for casting machine parts (my muller's scraper clamps notwithstanding) or anything with high tolerances. Kelly has mentioned concerns about sand getting stuck in the surface of the castings, which would be an issue in many applications.

But for stuff like this that is decorative at best and doesn't require machining, for me, having to wait for a coating to dry negates the benefit of being able to pour the casting within half an hour of the hot glue freezing up. I don't need a three piece snowflake trivet badly enough to wait that long, but casting one in less than an hour from unwrapping the first snowflake and starting the band saw to shutting down the furnace is a fun little project-between-projects that doesn't take up my whole weekend and cut into family time. I only do this for fun, so if I'm gonna spend significant time on something, I'd much rather spend it trying to ram up a perfect sand mold than spend it waiting for mud to dry.

================

Here are a few more dollar store obscenities I've created over the years.

Easter bunnies AKA rab-bots. I gave the foamies screws for eyes before pouring them.



My Jack O'lamp. This one was fun. It did take a little longer to do the foam work than most of these. I cut up 3 styrofoam pumpkins and glued the pieces back together to make one pumpkin with faces on 3 sides and a lid piece, then drilled a hole through the stem of the lid casting for the electrical wire. The bulb just barely fits inside the pumpkin. Definitely not CSA approved! Hallowe'en is supposed to be a little scary though, right?





I have a few more snowflake things, and a Santa Claus face somewhere too which was one of my very first charcoal furnace and steel pipe crucible castings ever, poured in ladder extrusion alloy in December of 2013. but those are all in a box underneath a bunch of other boxes right now.

Jeff

 

Oh, that could be a whole other thread... Sadly, Michael's has switched to molded plastic skulls for the past 2 Hallowe'ens, at least around here.



Fortunately I have a few left over that I stashed away on previous years that I've been playing around with on occasion.

I actually sold a few belt buckles (3, plus one that I traded for my train track anvil) that I made out of the smaller foam skulls, but they are kind of a lot of work to make.



Jeff

 

I know I said I'd stick with dollar store finds but I went and ordered a bag of bunnies in spite of myself.

Tried to cast the first one in bronze after hollowing it out, but sand float ruined it, as previously shown here.

2nd attemp would be in aluminum. I avoided covering part of the open end of the loose sand core at the bunny's base with gating as I had done with the first one.



I used a little paste wax to put a small fillet around the base of the sprue and fill in the little divots between the foam beads in some areas - I didn't want the casting to look like metal styrofoam. This was the third bunny to be sacrificed so far, so it wasn't the best looking styrofoam specimen that came in the bag. I found that filling the divots all in one coat of wax leads to the wax shrinking and pulling away from the foam a bit overnight, so I did 2 thinner passes to get the bunny all smoothed out nice before letting him hop into his bucket.



Came out just about perfect!





It looks like I didn't conceal the bead texture too well in these pix, but the dark areas beyween the beads is just discoloration on the surface from where the wax burned out. Maybe from whatever makes the wax smell minty?

There were a couple spots where the aluminum penetrated into the sand a little.



nothing a couple minutes with a file and a dremel sanding drum couldn't fix though. Then I used a wire brush bit in my drill press to brush off the "sand", scrub off the dark spots drom the paste wax, and blend the file marks back to look about the same as the cast surface. That worked better than I expected it to. I can still see it's not totally perfect in one little spot, but I think anyone else would have to be looking at it pretty closely and critically to notice. I smoothed out the bottom a bit on the belt sander and drilled and tapped it for a 1/4-20 bolt.



Then I shined it up with some Mother's polish and gave it a coat of wax. Made the base out of a piece of an old shelf, some kind of hardwood.







He looks angry in that last pic. So much so that I started getting ideas. Wouldn't a head like that make a hilarious tiny novelty hunting trophy casting to hang on the wall? Another full bunny would be a bit boring, but I do still have half a bag of bunnies left...

Nah, not a tiny stuffed head. A coat hook!





Do I risk sand float trying for bronze, or take the easy road and just use aluminum again? A bronze longhorn lapinophant would be a fun patina subject, plus the horns and tusks would be stronger, and the head is much narrower than the whole body I tried to cast. thus less likely to float the sand... I think I might have just talked myself into it.

Jeff

 

Bronze!

Best,
Kelly

 

Thanks guys. Since the 4 day weekend has finally begun, the plan is to pour this bunny rabbit demon thing hook in bronze sometime in the next few days.

Any notes or comments about this spruing arrangement? Long enough?



I have a bucket that should be wide enough that's also the tallest one I have, so I could bury it a bit deeper than normal then fill up more sand (glass) around the soup can for a bit more weight. I can use a sander or something to really vibrate the bucket this time too, and I'll lay some heavy wide stuff on top of the sand. So far 2 of my 4 bronze lost foam attempts have floated the sand, so I'm taking no chances (beyond still using the low density glass media, since I don't want to go sand shopping right now).

Here's the video from the bunny casting sessions, for anyone who wants to see the few gory details I left out before:



I'm retiring the crucible I've been using for silicon bronze. It's the one we used at the blacksmith's shop to pour the copper argon condenser. Josh gave it to me before I left that day as it was too big for his forge to handle anyhow. It had already seen better days even then (he'd burned out one of his forges trying to melt that much copper in it before calling me, I suspect that was how the crucible got so thrashed to begin with too). Its surface is cracked like dry earth, and Josh had loaded some kind of flux in it with the copper. There has always been a little bit of glassy lumpy stuff left stuck in the bottom.

When I skimmed the bronze melt for the first bunny, a bunch of sticky nasty goo came out with it. It seemed like more than that junk in the crucible could account for if it had come loose. You can see it in the video a little after the 10:30 mark. I don't know if that stuff was melted crucible or what, but I didn't like the look of it and was already starting to doubt that crucible a little anyhow.

So I ordered a couple of #6 salamander supers, which showed up already. I still have to compare them side by side with my others but they might be a little smaller than the ones I have. Maybe they'll grow in my eyes once I look at them inside my little shed though.



Jeff

 

Looks good. You still have cup height to add to sprue too. Bury to top of the cup! Still going to bare dog it?

Best,
Kelly

 

You wouldn't really ask me to break ALL my bad habits all at once now, would you? I'll think about it, but my 8 year old bucket of drywall mud might have dried out by now. I do have some hydrostone, just not sure how good of an idea that is.

Turns out the new crucibles are not too different from the size of the old ones after all. My fire log pluckers will still fit them just fine. Got one in the oven now.



Lefty's the one I'm calling toast, it looks worse close up but the top 2/3 or so does still ring when I tap on it, about like the others. Why take chances though, I figure. Not a great time to end up in the hospital, in a worst case scenario... Middle is the one that came with my used kiln, it looked brand new to me then and I thought it still did, until I saw it beside righty, one of the new guys. It's turned a good deal redder than I realized.

I've only used the middle one for wheelium, and the inside is still really clean and smooth, the skulls always lift right out almost fully intact, and any foil remaining just brushes out easily by hand.



Jeff

 

I do have one silicon carbide crucible, the #12 I use in the big furnace. It has held up really well through many waste oil powered melts. But they are so expensive... I think the better quality clay graphite crucibles ought to last quite a long time. The one I use for aluminum is still in great shape and from all I've read the salamander supers I just got ought to be really good ones, I'll be surprised and disappointed if they end up looking like the one they're replacing anytime soon.

Sorry guys, the elephabbit's already buried in the sand, sans coating. It's buried deeper this time, and I vibrated the bucket, and I weighted the top of the sand (well, glass). Belt and suspenders and staplegun as they say. But no plaster. I think tonight's the night...

Jeff

 

I don't know what hydrostone is but even totally dried out non-hardening drywall joint compound can be reconstituted by grinding it up and adding water.

Besides preventing sand inclusions on the surface, the coating also keeps the mold surface at the pattern interface stable. You're bound to get some wash of sand at the surface of the mold and especially the sprue and impingement locations without the coating. Since your using glass beads with bronze pours, it will also prevent your liquefied glass from sticking to your casting.

Best,
Kelly