Spruing and gating is always an interesting part of the process for me. I like to make net shape castings wherever possible and have this tendency to want to gate into the part where the gating is easily removed and on a surface that will be machined, so it is not visible on the exterior as-cast surface of the finished part. Of course, those locations are not always the best places to gate the part for casting/filling and in lost foam, mold stability, packing, and metal flow. On the handle I kind of ran the gambit from one extreme to the other. The first attempts had minimum contact area which would have made it very easy to degate and clean up but maximized molten metal travel distance while minimizing the contact area where vaporizing foam could vent……not a good combination for a very long thin part. The approach that succeeded did just the opposite. Because the long gate was skinnied down to ¼” width at contact, the degating and clean up wasn’t too bad, if you have a good band saw, belt and spindle sander. As commented earlier in the thread, the handle may have been a better candidate for a different casting process, but the other pieces of the project would have either required complex parting lines and cores (spout and handle mount) or were more simple and quick to do in foam (base and knuckle) compared to other processes for just six pieces. I like projects that push the/my limits. Gives me an opportunity to learn and improve. Best, Kelly
I'll have to try that some time Mark, though I must say when it comes to anodizing, I've never had much luck when it came to cosmetic coloring of cast alloys; wrought yes, cast not so much. Best, K
Congrats on another impressive lost foam success story! I knew you'd get that sucker eventually Kelly. I remember some old posts on AA where people had not had much luck anodizing cast aluminum alloys, just as you say. As I recall, people reported seeing spots where the colour would not take. Mark, if you can find the time at some point, maybe you could write up and post something about how you got it to work? Jeff
Nearly all the test anodising I did with castings was for alloys supposedly hard to anodize. As I recall I gave the samples a good working over with a wire wheel almost to the point where you start to smear the surface and I think that filled in any porosity and maybe removed any surface silicates which will only normally come out with a hydrofluoric acid dip. From there is was into a mild caustic soda dip to etch and degrease and then a few minutes in 20% nitric acid solution to eliminate any grey smutting and brighten/whiten the alloy as well as kick-start the oxidation layer. Then it was a normal DC anodize and then dye with food colouring to get bright blue, red, yellow, gold and silver. I didn't have nickel acetate sealer so I made do with heating it up and a coat of beeswax. The only UV stable colours are from the AC process which gives bronze, gold and silver during the anodize process.
Very nice! When you go for the kill you don't mess around. I was going to suggest casting horizontal with a single gate in the middle but was having too much fun watching you. Since you're set up, how about trying one in this orientation but with a normal size gate?
Considering the travel distance of the first two non-vacuum assisted attempts, I suspect that's right on the verge of what would fill. I'll make a couple extra patterns for experimenting later. Best, Kelly
Managed a little more progress. Successfully poured two more handles. ……and made four more handle patterns, sprued, and coated them. Next casting session should finish up the castings for the project. De-gated and cleaned up the two castings from today. Good to see them multiplying. Best, Kelly
I only used the ingot on the first handle casting and that was remelt from the sprue of the previous intake manifold lid pour. Everything else is (mostly) wheelium and engine castings. I have ten water neck patterns and two more intake manifold lid patterns I previously made in waiting. I plan to use ingot along with Sr and TiB on those. I was going to buy some silicon master alloy to add to the ingot for ornamentals with fine detail but wasn't too impressed with the piston alloy attempt at the handle......but then again, what alloy is that stuff? Best, Kelly
The rest of the handles were cast without issue. Casting for the trophy project has been completed! That was quite a bit of casting, at least for me……5 different parts and 30 pieces total not counting the 3 handle fails. I was pleased with how my furnace performed……charge the crucible, flip the switch, and go about the business of making patterns and molding until pour temp is obtained. There were a couple quirky things. The six-foot-long thermocouple cable I use to connect the contact pyrometer to the handheld meter failed. The TC was reading ~900F when I knew I had molten metal at 1300F+. I determined it was just the cable after swapping out thermocouples and various other things with no remedy until I connected the meter directly to the male TC mini-connector without the cable and it read correctly. I’ll have to check the connections to the mini-connectors on that cable. Another subtlety I observed; the last two handles cast much cleaner than the previous four handles, and all the other castings for that matter, with much less of the black residue on the surface. It comes right off with light/soft wire wheeling but still... Process-wise everything was identical except, I may have cast the cleaner one slightly cooler (~1500F versus 1570F), and the metal was from a different cast automotive rim than the one that comprised the majority of the rest of the casting stock. Hmmmmm? After I get this project done I’m going to do some more lost foam process experimenting and development. I think I can pour much cooler than I am on most parts. Anyway, time to do some light machining, assemble and finish’em up. Best, Kelly
Thanks for the posts and likes fellas. Still some finish work to do but as always, it turned into a bigger project than I bargained for......in for penny, in for a pound, and some additional learning and experience under my belt. Best, Kelly
Looks great!! You did not by chance change batch of foam on the cleaner items? I understand same foam, but same boards? I really enjoy your analyses of the foam process. Great work!!
Thanks Fellas. All the pattern foam came from the same 4' x 8' sheet of Owens Corning Foamular 150. As near as I can tell the amount of residue seems to be related to pour temperature (more with higher temps), namely when temps are 1500F or better. It's likely the foam. There's an outside chance it's actually something in the mud I'm using instead of the foam. Some of the drywall top coats have additives (like vinyl) to make them lightweight and finish better. Other than surface residue, I really can't detect any other ill effects regarding the castings, and though the high pour temps certainly increase success rate wrt to full pours, I would eventually like to reduce pour temps as it can only help metal quality. Best, Kelly
Closing in on it fellas. I owe the club four of them. They want them painted red I like'em as is. After paint they need to be mounted on Walnut base and then.....done. Best, Kelly
"Throw a little hot rod red in there", I think a clear lacquer would be perfectly fine but somebody always has to have some input on things or they're not happy.