Lots going on in my casting adventures, months of effort setting up and mastering (cleanly and with no odor) SLA printing. Still have some challenges with getting a decent print that will correctly burn out, not cost an arm and leg and will burn out a temp low enough that the investment can handle it, but I am close to success there (after many fails).
Meanwhile, I did the following casting from a filament print the other day. I've concluded the Print2Cast filament is just garbage. It burns out beautifully but it is impossible to achieve good bed adhesion and bottom inevitably peels up and warps. I had some success with the dog my son and I cast, but it wasn't a mechanical item so a slightly warped bottom didn't matter. If someone has the silver bullet for that material, I'm all ears
What I found works fantastically is Polycast filament. Probably the easily and best filament I've printed with and it burns out prefectly.
The story in photos
I tried everything with Print2Cast. With each I tried several times with different bed temps, enclosure/no enclosure etc (had to make the bloody enclosure of course)....this whole process was very frustrating
Prusa's PEI bedplate (heated) which is excellent for most everything else
Painters tape
PET tape
hair spray (even imported a special one someone recommended that was suppose to have the right combination of chemicals, what BS)
FR4, another supposed miracle solution
I even tried emery cloth thinking it might possibly form a mechanical bond
Then I thought an enclosure might help....so I made one, and tried it all again. (hey, no comments on the looks, its "experimental"
)
I'm afraid I have to admit defeat on this awful material. Grrrr.
Then I tried Polycast by Polymaker, the storm clouds parted and golden rays of sunshine entered my basement. This stuff prints and burns out like a dream. The only issue with it is is that its extremely moisture sensitive. To the extent that it will pull moisture from the air and crack and pop as it goes through the hot extruder and the moisture boils. I avoid all issues by running a dehumidifier at its lowest setting (30%) with the door to the room closed. Polycast calls for 20% RH, but there was not issue with 30%.
In addition, its surface can be smoothed with exposure to alcohol mist (IPA not Glenmorangie, its the Print2Cast material you need that kind of alcohol for). That holds potential but I didn't bother....their mister seems a bit silly and expensive and I haven't bother to make on yet)
it comes in a vacuum resealable bag and if exposed to moisture can be fixed by baking it (as per mfg's instructions)
Great print
You need sticky wax (made in myself, rosin and beeswax) to get it stick to a wax sprure
mounted to the base
and fills my largest flask!
investment mixed, poured and ready for vacuuming. The investment mixing is an exact thing, weights of water and invest to better than 1% as well as water temperature.
My casting set up has a number of improvements since the inital cast last December. I made the vent system which temporarily fits in a window (you can't believe how the house stunk after a 3D wax print burnout with a vent). The pick up sits above the oven just the right amount (the goals being 1) get all the fumes coming out of the oven, 2) don't create a draw through the oven and 3) pull in enough room temp air that the vent stays cool)
I also placed the oven on some pieces of small angle iron, it creates a heat break between it and the vent.
I used a cheapo pid with a USB connection (thermomart). While the software and instructions are probably the worst mankind has ever seen, truly remarkable, its still about 1,000,000 times better than keying in segments 4 button key pad. The PID industry is, for some reason, stuck in the late 1970's electronics interface wise.
This isn't the actual flask, but the story would be a lunch bag let down without the obligatory red hot burnout shot.
After the pour (flask is in the vacuum caster which sucks the metal through out the cavity). Notice the cracks in the investment. This I think is my fault. You are suppose to to start the burn out cycle, about 16 hours, two hours after pouring the investment. Life got in the way and instead it sat for a week, a no-no.
Casting was done with the AL at 735C and the mold at 400C
The moment of truth is nigh! The flask is allowed to cool for 15-20 minutes and will still over boilding temperature is plunged into water. The boiling really helps break up the investment
....and did it work? Mostly, fairly well. A few issues, but a workable part. It was a huge effort to make it this far, and while there is still room for improvement, it is quite a thrill to go from computer screen to cast metal part in one's basement. Its a part that would be extremely difficult to make other with investment (cores...and where would you part it) which adds to the fun; new possiblities
There is a lot porosity in one spot
and the investment cracks lead to some flash (that 3 minutes of fettling took care of)
And what the heck is it? A bracket to support table that will let me use the horizontal bandsaw as a vertical band saw
