Todays casting adventure.

[SLK001]

They used to cast the Saturn engine with a lost foam process. Just ram up a foam model of the block, then pour in the aluminum. The foam would vaporize upon contact with the molten metal and the process would result in a beautiful casting (if anyone would ever call a Saturn engine beautiful).

Isn't there a filament that you can use to create a foam model?

[Dan Dubeau]

Looking at parts can always tell the tale of how they are made. On EPS lost foam cast parts you can see the "styrofoam" surface finish left from the foam. I always found that pretty neat. On my little parts you can also pick up the layer lines in places too. With finer sand I'm sure the details would be more pronounced as well.

There are guys doing lost PLA, but it requires a burnout. I don't have the means to do that, and as a "total time invested" process IMO I think I'm better sticking with rammed sand. I'd like to try it one day though. There are also wax filaments that are good for investment casting too, as well as resins for SLA printers. I don't currently have the means to do investments, but will pursue it eventually.

I'll try machining some foam on the tormach, but having flashbacks of all the renboard I used to machine at work and what a total mess of the machine it makes I really have no desire to introduce something equally as messy to my machines. I think this would be a good application for those tiny little CNC routers on amazon. Just stick it in a box with a vacuum hose out the side and machine away.

I've done a bit of research on EPS foam, and would like to buy some un expanded beads for some experiments in the future. I have some ideas I'd like to try, that may, or may not be fruitful for the home shopper like me. No idea when I'll ever get to that though.

I gotta get off the computer, and finish machining those brackets. I'm stuck in a youtube trap right now lol.

[Mcgyver]

There are guys doing lost PLA, but it requires a burnout.

Better still, use filament designed to be burnt out. Its a little more expensive and a pita to get good bed adhesion with, but you get a complete burn out, no soot molded into the surface of the casting. Its smelly enough on burnout that I'm putting in ventilation, but I believe its a far less than burning out PLA

[Dan Dubeau]

What filament are you using for investing? I haven't bought filament in about 4 years, so my knowledge of what's out there now is massively out of date.

[Mcgyver]

Using Orion Composites Print2Cast wax filament. No complaints except adhesion. Couldn't tell you if its great or sucks compared to others but its what I tried. I'm currently working on a sort of enclosure thinking that might help. Even with PLA I can get some adhesion issues if the room (basement) is cooler (which it is the dead of winter). A higher ambient temp is suppose to help so an enclosure is one way to get it...not something airtight, just enough so it'll be warm inside and the minimize the effect of drafts

[Dan Dubeau]

Thanks, I'll look into getting a roll when I get setup to do investment eventually.

I really noticed 3d printers are sensitive to temp too. That's why my little kingroon FDM sits on a stand next to the breadmaker in the kitchen . I bought a heater "kit" to put in my Mars enclosure so I could print in the winter time, but was just never motivated enough to get to finishing it this winter. Resin is way more sensitive to ambient temp. Even spring/fall is too cold in my basement, and my results drop off. Too many projects on the go right now.

[Dan Dubeau]

Machining done. They're taking their turns in the tumbler right now. I purposely left some a bit rougher/slopier, as I want to see what I can get away with in the tumbler. Have never used one before, so I'm not sure the extent of sins they erase . Good parts to experiment with, as they really don't matter to anyone but me, and even I don't care as long as they hold my tools up.

Got into a nice rhythm and finished up all the machining in both ops in almost exactly 2 hours. All manual machining with the jog wheel. No G-code was harmed in the making of these

Then I used a 100g flap wheel on the angle grinder for the bulk of the flash, and files for the rest. Sanded the plates up too with the DA and some 220g.


This one (on the left) was in the tumbler for 30 minutes. I've got a batch in there now for 45, and will try the last one at an hour. Just a cheap vibratory tumbler from Princess auto with the green plastic media, a little water and squirt of dish soap. From what I read, there are a lot of variables with these things. I'm sure it'll take me a while to get the hang of it to get repeatable results. First batch came out pretty nice though IMO of course .


Now for the bad part. I don't have enough 1/4-20x3/4" SHCS to finish them all up tonight. Argh.

[Dan Dubeau]

Swapped them out for the last batch, and will only run them for 30 minutes instead of an hour now.


45min vs 30min. If you guys can tell which one is which I'll buy you a beer. I think I found the point of diminishing returns on the first go (with this media anyway). It also doesn't hide as much as I thought it would. Maybe If I left them in there for a few hours, but that's a waste of time, I'll just put more effort into file work.



After handling all these parts today while machining, I'd have to say, this one was the best overall example I got out of the entire batch of 12. This is the one that came from that "magic" batch of sand yesterday too, so there is definitely a correlation between good sand and good parts . If I can just get better at pulling the patterns from the sand I think I can minimize the flash a lot more too. I did have a few parts that were pretty good with almost none in spots. Ironically the one part with the big sand collapse has the least flash along that front rib, almost none. I've seen oldfoundryman use guide blocks before so I might try that, and he also says he prefers odd side molding vs split patterns too so that's something to try in the future as well. A lot to learn.


And through the course of making these I realized I hate the layout of my shop. I will be making some changes (again) in the coming weeks and moving some iron around again. Something might be leaving too.....A big heavy thing. I want a dirty side and a clean side. There's only so much you can do with a single car garage, but I think it'll work. It does in my head anyway, but my back is already disagreeing.

[Dan Dubeau]

Not one to let projects drag on for very long...I dug through my mixed containers of hardware and found enough cap screws to finish the job tonight.


Here is the impetus for this whole project. I hated this tool holder that I got from the previous owner of the Tormach, and wanted something closer to the machine that was wall mounted. I also wanted the bench space for my little foundry. So lets make tool racks using the foundry.....






I think that's a wrap on this adventure. On to the next one....

[Hawkeye]

Great thread Dan, thanks for sharing! Right now the excavator is digging the hole for a swimming pool in my backyard. Based on your comments about sand, I’ll be saving some of the super fine sand that starts about 2’ below the surface of my yard for future casting experiments.

[A.K. Boomer]

This is a great thread thanks for posting - lot's of prep work and some good results Kudos....

Casting kinda reminds me of painting - so for me something to avoid lol lot's of prep work then usually the inevitable "oh no" followed by "fuquing june bug" im sure castings got it's share of pitfalls too...

June bugs are the tractors of the insect world --- they will even dredge up under primer and track it all across the hood,fender whatever - and they don't die - they just keep on going....

[Dan Dubeau]

Great thread Dan, thanks for sharing! Right now the excavator is digging the hole for a swimming pool in my backyard. Based on your comments about sand, I’ll be saving some of the super fine sand that starts about 2’ below the surface of my yard for future casting experiments.

Thanks, If you value your time and money, I'd say skip making your own greensand, and just buy some to start with. I know it's kind of a right of passage for the home shop foundry, but having been there, got the tee shirt, I'd rather buy a known entity than waste that time again making my own. Good learning experience sure, but.....

[Dan Dubeau]

This is a great thread thanks for posting - lot's of prep work and some good results Kudos....

Casting kinda reminds me of painting - so for me something to avoid lol lot's of prep work then usually the inevitable "oh no" followed by "fuquing june bug" im sure castings got it's share of pitfalls too...

June bugs are the tractors of the insect world --- they will even dredge up under primer and track it all across the hood,fender whatever - and they don't die - they just keep on going....

Thanks. Yes, there is a lot of prepwork, but I did get pretty fast at molding over the course of these pours lol. Ironically the quicker molds poured the best.

I hate painting for that reason. All the prep work and something dumb like that can wreck it. I do have some projects to drag out side and paint here shortly. Dreading it like you wouldn't believe.

[Jon Heron]

Dan, that is awesome, good job!
Cheers,
Jon

[SLK001]

Great thread Dan, thanks for sharing! Right now the excavator is digging the hole for a swimming pool in my backyard. Based on your comments about sand, I’ll be saving some of the super fine sand that starts about 2’ below the surface of my yard for future casting experiments.

If you're going to make your own green sand (and I recommend that you do), SIFT the DRY sand first to get a consistent grain size.