The Melzi II is built around ATMEGA1284P. To use the board with Arduino IDE, burn the Bootloader with an Arduino acting as an ISP.
I didn’t explore micro python yet.
The Melzi board could be used to make an automatic start for a generator.
Here is the specs for the motor.
https://www.kysanelectronics.com/Products/cat_pro_rev.php?recordID=9388
It is pretty much a generic arduino with a bunch of mosfets to control steppers. they can do whatever you want them to do. 3d printers/routers/laser engravers/plasma cutters/etc are all pretty much just a microcontroller with the stepper controllers to control everything.
A lot of the pattern could be made as sections and glued together.
Yup, old time wood pattern makers would glue all sorts of pieces together. For disc shaped pieces they would usually use six pie sections. This would allow the pattern to stay round even over long periods of time, and prevent cracks. Poplar and winter cut hard maple were commonly used.
Rindert
Hi Brian,
Here’s another trick foundry guys use; a horn sprue. It will allow you to gate into the middle of the part from beneath. This might solve some of the problems here.
Rindert
Looks a little tricky to mold up. I assume the horn needs dug out of the sand and that part becomes part of the top sand. Coping down or something like that I think it was called.
Part of the reason I made the dimple in the center was to possibly locate a vent or the pouring sprue itself but just adding a second riser seemed to work.
Well, no. The horn sprue will come out of the drag, or bottom as you call it, without disturbing the sand. Just drill a hole for a wood screw in its big end. When you want to remove the horn sprue, just thread the screw into the hole, rap it a little, and lift and rotate the horn sprue out.
Rindert
We’ve talked about casting for the last month or so, and 3D printing.
One neat thing about some Slicer programs is you can make a Mold out of the 3d image.
Also one of the easiest ways to cast metal is the Lost Foam method.
This guy has made some incredibly complex automotive parts using Lost Foam. He shapes the pieces himself, but I’ve wondered if I could 3D print a mold, then use a 2 part expanding foam to cast the sacrificial part. If you have 1 mold that was a successful print, you don’t have to worry about repeatability or accuracy than if you were 3D printing investment wax parts.
Using refractory coatings, you can just use plain fine sand and retain high detail. No plaster to worry about cracking up or an expensive kiln to heat up that mold.
I believe General Motors used the Lost Foam method when casting blocks and other parts for Saturn.
Of course you could just cut out your foam pattern if you only needed to cast a part once.
Cody,
Those refractory washes prevent sand inclusions. But you can still make useful castings just with foam patterns. That blue small celled foam you can get at building supply stores makes the nicest smooth surface.
I was able to use a battery charger set on 6V and a piece of .035 flux core wire to make a hot wire foam cutter.
Yup, Saturn’s blocks and heads were made using lost foam method.
To get started I used all sorts of foam shapes I found laying around, cups, cup-of noodles bowl, etc.
Great Stuff foam adhesive can be used to glue foam pieces together.
There are lots of ways to use 3D printers for foundry; lost wax, 3D printed molds, 3D printed patterns. If you can imagine it realistically I’d say it’s probably been done. 3D Printing for Metal Casting | 3D Systems
I thought myfordboy on youtube had some more reasonably doable projects for regular folks.
Rindert
2 part expanding foam is usually polyurethane and I don’t think it works the same as styrofoam/polystyrene in the casting process.
You MIGHT be able to use ABS as a mold for polystyrene. Boiling water is under the 200c melting temperature…
@r_wesseling 's post about looking at aircrete for a foundry, got me poking around. I ran into this formula which explains how to make aluminum firebricks.
They apparently make alumina firebricks.
However, while trying to figure out how they make those because aluminum oxide is a powder… I ran into Sodium Aluminate, which has a melting point of 1650C. It is used to accelerate the solidification of concrete which seemingly makes it a good addition to aircrete if you are looking at using it for a foundry brick especially if it was used to like powder coat the outside.
Sean, super interested in what you find. I’ve been researching DIY foundry insulation and construction with an eye to using the same methods for maintaining heat in a gasifier hearth and shielding nozzles.
So… fire brick, cast’able refractory, water glass seals, facing coatings (radiant reflective ones), rockwool, rockwool stabilizers. Happy to socialize what I’ve found.
It can’t take super high heat but “Hempcrete” or similar (foamed concrete, perlite/vermiculite mixed concrete) would be decent+cheap secondary insulation.
This is pretty interesting, if you are interested in seemingly a drop in replacement for portland.
Calcium aluminate cements aren’t great refractories, but not bad compared to portland cement. You can get close with rapid-setting cements.
Courtesy of Home Depot (no endorsement either way 
)
https://www.homedepot.com/p/Rapid-Set-55-lbs-Cement-All-Multi-Purpose-Construction-Material-02010055/202188447
From the MSDS:
Identification Name Weight %
CAS number: 12004-14-7 Aluminum calcium oxide sulfate 10-25%
CAS number: 10034-77-2 Dicalcium silicate 10-35%
CAS number: 7778-18-9 Calcium sulfate 1-12%
CAS number: 14808-60-7 Silica, crystalline quartz 40-70%
CAS number: 50-00-0 Formaldehyde <0.01%
It seems better than portland cement when mixed with perlite and some fireclay, but I wasn’t very diligent in testing, and no long-term testing. Quick and easy, though.
I suspect it is better then portland by a bit because it seemingly should be able to handle higher temperatures.
More interesting is the aluminum oxide brick is most likely synthetic corundum, which is manufactured in a process similar to synthetic ruby which also has a high aluminum content. Which someone on youtube was doing it in the microwave, but they weren’t getting good results although they were able to make some small beads which -might- be a good aggregate material. Apparently it is already used as such.
Since I am going down the rabbit hole. Aluminum oxynitride has a melting point of 2150C and apparently has some bulletproof qualities. That might have more SHTF appeal, then just forging. The wikipedia article just mentions it is similar to manufacturing of other ceramics. and a refractory index of 1.79 which is in the ballpark of aluminum oxide.
After having and building foundry furnaces for decades, I have always found that if you do a bit of a search,. You can find a refractory supplier within an hour or two. Even here in rural Pa, if I drive about an hour towards Cleaveland there is a foundry supply house that will sell me whatever I want.
My old melt furnace is sitting outside and I will never use it again. It is free to who ever wants to haul it off. It comes with lifting tongs and a pouring shank, it does need a new electric motor for the burner blower. It was built to hold a #70 crucible.
kent
Now that I’ve got a little bit of 3D modeling under my belt I’m considering using this ability to either sand cast or Lost PLA cast. I’m leaning towards sand casting and printing in two parts.
I’d like to finally make a water “carburetor” for adding a more even mist on charcoal gasifiers and to do that I’ll need to make a Venturi chamber. Of course any printed material would melt, I believe the best resin prints can withstand about 400°F but who knows what effects thermal cycling would have.
You probably already thought I’d this but. If you are going to make that venturi that you posted. I would just cast the restriction part and slide it into the pipe. You might be able to make it out of sheet metal as well.
It will be easier to cast and polish, and easier to change the design later if you want or need to.
Yeah that’s what I was planning. Just a tight fit inside pipe to prevent having to do any threading etc. Maybe seal it with muffler sealant. It can handle super high temps and can tolerate getting wet once it’s cured.
I was thinking of casting it in Aluminum-Bronze because of its high resistance to oxidation in high temps and it’s high corrosion resistance.
I don’t think i would seal it. I think I would just pin it or set screw it. The closest I would come would be like an anti-seize compound.
The more tricky part is if you don’t have a lathe, because you will have to spin it to shape it for the last little bit.
