im trying a metal casting experiment.

Zortrax M200 General Discussion
#1

we mill 4 axis small metal objects in our factory but we sometimes find ourselves in need of more complex shapes that would require a 5 axis machine.

since we do not get these jobs too often, and since we only make samples, i cant justify the huge cost of a 5 axis milling machine addition.

to solve this problem im looking at trying a lost wax casting approach to this.

the type of work we do is mainly fashion hardware and embellishments so the objects are jewelry like is size so i was looking to perhaps use our zortrax to print the objects and then either use a direct lost abs method or maybe use the printer to make a negative mold that i will cast wax into and then use the cast wax to do a real lost wax casting.

anyway, back to my question…its my understanding that while lost abs works to some extent, it doesnt burn out clean so the surface finish is not as good as lost wax, since the objects i will be casting are quite complex, and like jewlery they will require a nice finish, i dont think this method will work.

what i am thinking, is i will try this…i will print my object in abs , include the spout and air escape channels in my print…i will then tumble this object for several hours to achieve a nice finish ,and further refine the surface with a polishing tool on a rotary device…i will then place the object in plaster, cure it and rather than try to burn out the abs, i will place the finished piece in pure acetone to dissolve out the abs instead…my logic is that this may allow for a much cleaner removal of the abs , thus leaving me with a nice cavity to then cast my metal into(zinc in this case).

anyway, i will be documenting my experiment and if successful i will post the results with pictures but i was looking for advice and suggestions and basically what you guys thought of this approach.

as far as the casting process, im fine with that, i cast zinc in my factory all the time and im fine with that aspect… my concern is more about the properties of the abs and if it will fully dissolve in acetone and if so, what is the time frame im looking at?

im also wondering about perhaps a saturation point of the acetone, like after a certain point it will cease to dissolve the acetone and i will have to change out the solution…again, im not talking about a large object but rather something no more than 1"x1" piece of abs, maybe a little more for spout and air channels…

if this method works i will then look to refine to process, perhaps with another 3d printer more suited to small detail like form 1 but im not sure that resin will be effected by acetone.

ideally a direct wax 3d printing machine is what i need but the cost for one of those is huge.

form one has a fire cast resin but the results i have seen are poor, i dont believe it burns out as clean as wax and while a solvent to remove the material may be slower, if it works i believe the results should be as good as wax .

please let me know what you thoughts are on this method,…my main concern is the abs dissolving…would heating the acetone help?

#2

I think it will take forever to dissolve the ABS as well as saturate or degrade the plaster mold.. If you can PLA with higher extruding temp, that might work better.

#3

There are resins used as direct replacements in lost wax method.  Just print using that resin and proceed to regular lost wax method. For best results use this. Especially for jewlery sized objects.

Also PLA works many times better than ABS from what little information I have gathered on the subject.

PLA seems to give good results for bigger objects.

#4

i dont have a printer capable of using that resin. i printed my part, and its in the tumbler...i think this might work provided the plaster holds up in the acetone..its quite possible that it remains unaffected by pure acetone...it may have to sit in the acetone for a day or two but that would be fine provided it works...we shall see..if it works its certainly going to be better than using heat.....heat doesnt allow for a clean burn out and ash and burnt plastic is whats causing the poor results im seeing...

even the so called castable resin provided poor results based on what i have seen....only wax provides the results i would like and if the acetone can dissolve all the plastic the results should be as good

#5

Send STL to www.printedsolid.com and they will cast it in metal for you.

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#6

hi guys, sorry about the delay but i was on vacation in mexico,…

so anyway, my method worked like a charm…the results were beyond acceptable(i was shooting for something i could live with) i didnt for a second think that the results would be flawless…when i say flawless i mean flawless…the casting came out perfect.

just to sum my method up again…i create my model with my zortrax…i roll the model in a tumbler for 24 hours to smooth out any print lines…i then cast in plaster of paris and after the plaster was allowed to harden for 24 hours i submerged the plaster in pure acetone…i was concerned that the acetone would make the plaster break apart but it didnt at all.

i suspect that plaster reacts to water but not acetone…after 24 hours of acetone i was able to turn the plaster piece upside down and all the abs ran out in a big glob…i then rinsed the cavity with a little fresh acetone 2 or three times.

i used zinc for my casting and when i say flawless i mean flawless…every other 3d printed lost abs i have seen online used heat to burn out the abs and i suspect that the left over ash just creates a junky finish with pitting…my results were literally flawless and by far the best result i have ever seen utilizing a 3d printer to cast metal and the best part is that not only was the result superior, but it required no furnace what so ever.

i will post photos tonight after the metal has had time to shine in the tumbler

#7

i am so shocked and impressed with the result of this “heat free”

method that i believe it will almost certainly catch on, so i am calling my new method the 'feinberg" method…lol

#8

good job, waiting for the pics!

#9

That's very exciting. What media do you use in your tumbler?

How did you make the draining and casting and venting holes in the mold - part of your printed part or added later with other materials?

Love to see details, thanks.

#10

in retrospect i should have just printed my air escapes but i used hot glue to just glue a couple strips of abs off the roll to serve as air escapes but to save time and make the process even easier, next time i will just print the tubes for air to escape…but what i did do this time was to print the funnel right into the object, this made the process very easy…because since i included the funnel in my design, what i did was simply fill a small cup with plaser of paris and basically submerged the entire object into the plaster right up until the tip of the funnel , then when i dissolved away all the abs in the acetone bath, it not only left the void of my object, but a nice clean funnel to accept the metal as well and had i thought to include the air tubes it would have done the same with them…

basically i wanted to try this method because its requires such little man hours because im very busy and i dont have time to create molds and such…this method i just print the entire object(funnel and all) and in about 2 min i add water to plaster, submerge entire object and its done, then the following day i spend 30 seconds pouring the acetone in a bottle and then let it sit over night.

im telling you, my intentions were to create something decent but with less work this way, i didnt for a second think the results would be so spectacular but after comparing this to other lost abs trials i have seen online, it makes total sense …burning away abs just doesnt allow for a clean burn like wax does, the ash and perhaps burning and bubbling process destroys the surface of the mold…this is much more gentle and allows for the finish to remain perfect…i will post pictures in a little while but im not quite sure how to post photos on here, can you tell me?

#11

as we speak im about to experiment with actually an even easier method…i will try to print the actual 2 part mold…i will connect the two pieces and pour the metal directly into the mold.

this sounds crazy but i think with zinc it might work…i have heard some have success using this method with pewter but i have no desire to work in pewter…its an ugly and weak metal imo…it has a very low melting point so it works but zinc has a higher melting point but is much nicer imo and the polished finish is very attractive and its durable.

while zinc has a higher melting point than pewter, its not much higher so there is a chance it might work…if it does then i will use that instead of plaster…that would make the whole process a breeze …i will have an answer and photos with that experiment by tonight as well.

#12

julia is it true zabs uses a hotter extruding temp than standard abs?? if so this method may be zortrax specific if it does actually work…i did some preliminary testing that leads me to believe it can endure molten zinc alloy for a short time but this wasnt enclosed, so im not certain…enclosed the zinc will certainly not cool down as quickly this leaving more time for the mold to distort.

#13

Z-ABS and pp3dp ABS are usually extruded at 260-280C, while "generic" ABS filament usually likes approx 230C.

The plastic will soften at considerably lower temperatures, though. Zinc melts at 420C according to Wikipedia.

#14

If you have dropbox you can upload to there and post link. I use imageshack myself.

#15

The acetone bath method sounds like a winner to me. I have my doubts that the ABS will keep the form long enough before melting or deforming. I would also be worried about the plastic catching fire or producing toxic smoke or fumes.

But people also thought the acetone bath wouldn’t work and it apparently does. So happy experimenting and remember to open the window when you do.

#16

yes it did, in fact,it didnt deform the slightest bit…i now have my method for making metal parts.

the part i cast using the plaster was a very complex part that was not possible to cast using a two part mold. it was so complex it needed the lost abs method.

the second part i cast using the two part(directly cast into abs) was far less complex(it was a simple silver ring shape) that too cast perfectly.

what i did with that was i printed a two part mold with a male and female side that interlocked as well as including the funnel and air vents directly into the mold.

i cast a zinc alloy(melting point is slightly higher than zinc…its something like 800 degrees F…i use this alloy because it is stronger than zinc yet is able to be polished to a fine silver / chrome like shine… this alloy has a relatively low melting point so its easily melted with a torch, shines to a jewelry like silver finish and is durable so i can make functional objects with it and not have to worry about bending or breaking.

my only complaint is that its rather heavy…i would much rather have the option of using aluminum but im certain z abs will melt at those temps.

so there you have it!!! …both methods work, imo the plaster method may produce a slightly better finish but unless the part is one that cant be created in a two part mold, i will likely not be using it because the results of the two part mold are so close and a few hours in the tumbler will clean up the finish to a mirror shine regardless which method you use. its just so much easier.

i do not have dropbox nor do i know anything about it…you cant post photos directly to the site?

id really like to share my results but i dont have dropbox…i will look into it and try to figure it out if i have time…if anyone is interested and wants to see photos right away feel free to pm me a phone number and i cant text you the photos…if you have dropbox you are free to post the results as well. U.S.A . numbers only.

#17

It only takes a few minutes to set up a Dropbox or ImageShack account, it'd be great if you could post photos.

 

It is possible to upload directly to the forum, just click "More Options", then "Attach Files", then Choose FIle then Attach This File. 600 - 800 pixels wide is usually good.

 
What media do you use in your tumbler for smoothing ABS parts?
 
Thanks for posting descriptions of your experiments, very interesting.
 
Julia
#18

Can’t wait to see the photos. Quick patent the method before Makerbot does!

#19

nah Julia all of that is too complicated...

:D :huh: :rolleyes: :P :ph34r: 

It only takes a few minutes to set up a Dropbox or ImageShack account, it'd be great if you could post photos.

 

It is possible to upload directly to the forum, just click "More Options", then "Attach Files", then Choose FIle then Attach This File. 600 - 800 pixels wide is usually good.

 
What media do you use in your tumbler for smoothing ABS parts?
 
Thanks for posting descriptions of your experiments, very interesting.
 
Julia
#20

You can always use http://postimg.org

Just drop a bunch of pictures on the homepage and you get a link to the gallery that you can post here.

If possible, I am very curious about that Zinc alloy, can you please say more about that? Maybe a link to where you source it?

Thanks for the details you posted.