First attempt at 3D printed lost was casting

[Mcgyver]

well, really my first attempt at any lost wax casting. Other than a sand cast pulley blank done 30 years ago this is my first casting. I'd bought the equipment ages ago and never got around to trying it. Gotta jump when a good deal presents itself. My youngest, a Vet practicing in Scotland, was home for the holidays and was interested in 3d printing. Recently I'd bought some printable wax in anticipation of some projects, and the idea emerged to print and cast something. Being a Vet, a simple animal curio/paperweight was what we decide on.

Here's a video giving an overview of the process. There was a lot to this, and a lot of new stuff to understand, stuff to make and marshal etc. It took us overall about a week, but having done it and assembled everything, would probably be less than half a days effort next time (not including print time or the burn out cycle). My son did all the video recording.

 

[kevin.decelles]

We’ll, that makes my setup look medieval ! Stupid question , but does the video have sound? I tried it in you tube and in the browser in my phone just now and no sound. Assuming no, so I have some questions that may have been explained in the video

What temperature for the burn out?

What length of time for burnout?

What is the machine that you put the wet mild on? (Does it vibrate to remove air bubbles)

What brand of wax?

What temperature did you print at?

Very interested in this….. I have tried pla but had mixed results. I have some bevel gears I want to try in brass/bronze next

Nice shop!

 

[gerritv]

Great result. Something that is on my list, I have the furnace and vacuum setup. And Zamak, which doesn't need a ton of heat to get to flowing temperature.

Gerrit

 

[Mcgyver]

Thanks Kevin, was intended as an overview, not a instruction video so lots of missing bits, but happy to answer questions.

No sound. Connor shot the video, a lot of it, and I pieced together the clip - taking seconds from lots of clips, the dialogue of the sound track would be cut up and make no sense. I thought of putting Roy Hargrove to it, but everyone has their knickers in a knot over copyright so chose "silence is golden"

Burn out is a cycle, in F, 300, 700, 1350, then 800 to pour. Each was an hour or two but the 1350 was for four hours. As soon as it settles in at 800 you can pour. There's lots of info these cycles and they do vary by flask and casting size. I don't think, other than it taking longer, hurts things. Total time before 800 was 10 hours

Vacuum caster - gets the air out of the investment and the metal into every nook and crany. You first vacuum the investment, then do it again after pouring the investment in the flask, then you cast under vacuum and it sucks the metal in perfectly. One mistake we made was we didn't have the vacuum turned on when we started to pour....but you can see how the metal got sucked in once I realized this and turned it on.

Wax, Orion I think? will double check when at home

Print temp, 145 C as per manufacture's suggestion. They said to have the bed at 90 which we did, but I've seen videos since that suggest 75. We tried all their suggestions and still didn't get good bed adhesion. the painters tape idea was from some comments on the internet.

I think PLA would be ok outdoors but don't want the stink inside. As it was, the wax didn't melt out like it should. The first low temp cycle is suppose to melt out most of the wax (collected in a can under the flask) then the subsequent hotter ramps burn out what's left. Because so little melted out (assuming that's just a difference of the filament stuff vs real jewelers hard wax) a lot ended up getting burned off and I ended up opening windows and placing fans at 2:30 a.m. after the wife woke up because the house stank so much. While I'm a proud cave man, that was not good. Future endeavors will have a vent on top of the furnace to outside.

The other thing I've heard with PLA is it doesn't burn out cleanly, you can get ash that can show up in casting surface.

Lastly, the print is easily worked like you would any other wax - this makes it easy to add the sprue, make a tree of several small parts, repair, add or modify etc

 

[kevin.decelles]

Thank-you for the intel. Now I'm googling vacuum casters..... Every shop should have one!

 

[kevin.decelles]

What is the type/make of furnace you are running? looks 'purchased' (not home made).

 

[Mcgyver]

Its an Aim. The orginal pid didn't work properly and I replaced the pid controller with a cheapo....figuring out how to make that work was the hardest and worst part of the whole deal. If you're a mean nasty sadistic technical writer who hates humanity, and if the bearing companies turn you away, the last stop before unemployment is the PID manufacturers

 

[Tom O]

Very interesting! So about the vacuum caster does it suck the vacuum through the plaster and how many “ of mercury does it require?

 

[PeterT]

Wow, good job. Looking forward to more projects.
What alloy was the aluminum & did you add any goodies to it during melt?

 

[Tom O]

I just watched a homebuild on YouTube that says 8 to 9 cfm vacuum

 

[Mcgyver]

Morning,
Yes the vacuum pulls the metal into the investment mold - you can see it do so in video. The investment is amazing stuff, holds the detail perfectly, has just the right porosity to hold the metal and achieve great detail while allowing the air to pass through. The unit pulled 25 inches of mercury during casting if I remember correctly. it will bury the needle at 30 easily, but when casting, its also still pulling from the atmosphere - i.e. it pulls from the investment exposed at the top of the flask.

You can see in the video, the metal was not entering the mold until I turned on the vacuum. This is because there are no vents, which aren't needed with the vacuum. The other way to do it is a centrifugal caster, but that would be a bit hairy imo for anything but a tiny jewelry pour. The vacuum is afaik considered the best way to investment cast

 

[GJD Battleford]

Looks very nice.
What kind of investment did you use?

 

[Tom O]

Yes I saw it get pulled in which made my head cock to one side wondering about the porosity of the plaster investment is it pure plaster of Paris or sand mix? I did pick up a Centrifugal casting machine with crucibles a couple years ago for the Granddaughter but her jewelry interest died out so we never did try it She drilled a hole through a polished stone but that was it. Go figure.

 

[Mcgyver]

Tom its call "investment", special stuff for this application. Don't know its composition, but silica is involved based on the health warnings. Nothing added, just an extremely white fine powder that you add a bit of water to and it mixes almost instantly. Not like anything else I've used. They've found the magic balance of letting air through and not the metal

Gerald here is the investment info....not anything I sought out, just what I ended up, came with the package. It gives about 10 minutes of working time.

 

[deleted_user]

Thank-you for the intel. Now I'm googling vacuum casters..... Every shop should have one!

Vacuum casting equipment is now so affordable you are right, everyone should have a set-up. I promised to teach my wife jewelry making in order to convince her I needed vacuum caster.

Also I recommend a cheap ~$200 LCD resin printer for small intricate parts, such as steam valve components.

 

[Dan Dubeau]

Great Job on the Casting Mike! Looks like a great Father Son project as well.

 

[Mcgyver]

Thanks Dan - good to see you here., It was so nice to have a project we were both keen on - spent time everyday working on it together. Other than meals together, the time'll just slip away without finding something like that of mutual interest

 

[Dan Dubeau]

Thanks, This seems like a bit more active place than others. I agree about time slipping away. Seems like yesterday I was bringing my first home from the hospital and now he's 9. I have no idea where the last 9 years went.

Seeing you post that might finally poke and prod me to get off my arse and finish my casting setup and getting back to it.

 

[Tom O]

Tom its call "investment", special stuff for this application. Don't know its composition, but silica is involved based on the health warnings. Nothing added, just an extremely white fine powder that you add a bit of water to and it mixes almost instantly. Not like anything else I've used. They've found the magic balance of letting air through and not the metal

Gerald here is the investment info....not anything I sought out, just what I ended up, came with the package. It gives about 10 minutes of working time.

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That sounds like really fine sand and plaster. If you have one of those cheap sandblasters you could always mix it up in there and not worry about breathing it in.