need some casting help/ suggestions using solus proto

[manakawari]

hey guys, so i work for a product development company..we primarily make samples and prototypes for the fashion industry.

for most of our metal work, i was either using a laser cutter or a cnc machine but since we got our solus, i have been using it more and more and i love it but im having some issues and i was hoping since im not a jeweler and have zero casting experience, maybe some of your guys could offer some suggestions on my work flow to make things easier or better.

so for flat objects that i need in metal, its a fairly straight forward process... i basically just directly laser cut my sheet metal of choice on our fiber laser and i run the pieces in our vibratory tumbler for deburring and polishing...the tumbler takes about a full 24 hours but with a two step process, i can get stainless steel to go from rough with heavy burrs, to a mirror finish..the same for brass only the brass polishes up in half the time...i basically use a two step process for both..first step is ceramic media for deburring, edge rounding and smoothing and then a dry run in treated polishing media...like i said, the parts go from raw metal to mirror finish in about 24 hours with no labor so that is fine....this process i use for any flat metal objects that i need and those that can start flat but are then bent to create the shape i need.

The issue that i am struggling with, is full 3d solid metal objects.

this is where i was hoping to use my solus and i innitally had some success but its limited and im struggling with certain shapes and features.

again, we don't do jewelry so i do not need or want precious metal, i basically need to come up with a solution for making a silver colored metal and a gold colored metal objects and they are usually just samples but quite often i need to do a limited production run of a couple dozen of the same piece.

the pieces are just fashion related objects and embellishments like custom buttons, belt buckles, key chains or small sew on embellishments.

the method i settled on is printing my object in solus proto, vulcanizing the prints and spin casting in pewter or zinc, tumbling and polishing the casts and that's it for silver objects as polished pewter or zinc is attractive enough for my needs but the gold options are then plated.

at first i had a ton of problems as the solus proto did not survive the vulcanizing as my caster uses natural rubber and that is heated to 350 degrees but after some experimentation, i found that heavy post curing and then heating in an oven at around 250 degrees for a couple hours hardened the parts enough that they casted well with no melting or warping but the problem is the surface finish...despite the post curing processes definitely making the prints stronger, they still seem to form tiny surface imperfections that make it impossible to get a smooth finish...i cant tumble out these imperfections in any reasonable amount of time..they seem to be quite deep to the point that they need so much time in the tumbler,and need so much material removed, that any small details in my prints are lost in the process and even if i manage to preserve the details, the process just takes literally days in the tumbler.

so basically, i was hoping to hear from as many people, and as many suggestions as possible , as to what i could tweak in my workflow, to get a better surface finish in my spin castings?

my whole problem seems to stem from these blemishes that form on the solus proto in the vulcanizer.

Its been suggested to use RTV silicone or a low temp vulcanizing rubber but evidently, this is not an option with my caster and because im in manhattan, this guy is the only game in town and he just refuses to use anything other than what he uses for every other job so im forced to try to come up with a solution that works with his available rubber.

i was hoping i didn't have to , but i may need to abandon the solus proto and seek a real high temp resin but i do not know of any that can achieve a resolution close to what solus proto can so maybe someone can suggest something i can try?

aside from that, i was thinking maybe i would use solus proto, and then with the proto printed master, maybe i would create a silicone mold and then cast a bunch of masters in a casting material that has better heat properties than solus proto and use these to directly vulcanize but i am not aware of any casting resins that are specifically high heat.

Lastly, and frankly my favorite option, i was thinking of just purchasing some sort of casting apparatus where i can create RTV silicone molds in house and then do the pewter casting in house...for most jobs i only need to create a 5 or 10 of a specific object, so i wouldn't need anything crazy, and if i do get a large production job, i can still use this setup to create a few pewter masters that i can then give to my caster to make a production mold with and since these masters will be pewter, i shouldn't have any problems with surface quality.

the issue i have with this last option, is not knowing what kind of small setup i can use for pewter casting..i know about the typical 9 inch round rubber mold spin casting machines but they are very large and require large production molds and space for my is a problem...i was hoping to find a smaller method/ setup for making pewter samples but i do not know of what that would be.

I have experimented with rtv silicone and then just directly pouring pewter and the results are promising and ok, but without the aid of centrifical force or a vacuum , small details or say lettering of logos in my objects are not possible and i need very high quality castings where tiny logos or lettering are clear.

any ideas? id love something i can fit on a desktop to use my solus, to create pewter samples of excellent quality using RTV molds..no need for ability to spin production quantity...just the ability to make a few samples would be enough to satisfy most jobs and like i said, i can then use these samples to create a production mold and outsource if i do need production quantity.

Id love to hear ideas as this problem has been plaguing me and i need a solution already!!! thanks for taking the time to read all that.

[Chalamba]

Hi,
Very detailed post, and very challenging task ahead of you .
I have experience with spin casting and lost wax casting and have experienced same problems with Proto.
You have two options in my opinion.
Print, make your own molds with low temp silicon inject wax patterns and investment cast them.
Or spin cast with small mashine ( i have seen really small ones in riogrande).
I would say it is the same investment. You can get very nice budget lostwax vacuum casting machines from aliexpress.
If you make small seriess lost wax casting is maybe your option.
How big are the biggest items you make? You mentioned belt buckles , they can be pretty big and challengind.
Here is something i have made in this way:

[manakawari]

this is a great response and I really appreciate the help.

So your suggestion is to create silicone mold and then use the wax casts to investment cast to make my masters with and then use these to spin cast if I have a production order?

it just seems like a lot of extra work considering im using a low melt alloy/ alloys.

I was hoping perhaps I could just figure a way to create silicone molds that I use to direct cast the pewter as opposed to first casting in wax and then investment casting.

it seems this would be the easiest way to create my 5 or 10 perfect pieces needed to either fill the small sample order, or provide the necessary quantity to provide to my caster to fill a circular spin casting mold.

Its so annoying that solus proto cant handle the heat of vulcanizing...it seems so close and I wish solus would reformulate the resin so that it can..its advertised as high heat tolerant and it doesn't seem at all like it is.

other suppliers sell high heat resin that is capable of withstanding the heat so its entirely possible, I would buy one of those but I do not believe envisiontec sells to the general public and I don't have time to play with the settings to get it to work.

direct vulcanizing resin would seem like a no brainer for a resin and machine directed almost entirely towards jewelry makers...come on solus!! solve this problem!!

[manakawari]

your work is beautiful BTW and its exactly the type and size of work im struggling with.

[Chalamba]

Thank you!
So, correct me if i am wrong, but what i undestood is that you need to show samples to your clients before you start real scale production?
If this is the case, and shrinkage is not an issue?!?!?
Then i would go for B9 emerald, print and cure. Low temp silicon, inject and lost wax cast 10-20 pcs. ( in brass or in pewter ) client approves and doesn't mind 3-5% shrinkage ( you can make the model with the shrinkage taken into account ) send some of the already cast masters for spincast mold making.
As you know models take sereous pressure when mold are made for spin-casting, i dont thing any resin can withstand it.
Proto has some serious issues in my opinion, prints kind of well, but it cracks under heat and presure and thats not all it sticks badly to most silicons, so it need some serious lubricants to be used for mold making at all. I personally have given ip on it.
I hope any of this makes sence to you

[mongerdesigns]

You can make vulcanized molds from the SolusProto resin. Not all rubbers are the same. Some don't need very high temperatures.

This customer has made the majority of their rings using the the SolusProto and then making a vulcanized mold using a castaldo brand rubber.
http://www.bookofalchemy.com/

You can also use RTV silicons, just have to make sure they are tin-catalyzed, so they don't react with the resin.

[manakawari]

maybe it will work with a lower temperature silicone but lower temp and rtv silicones are considerably more expensive so the overwhelming majority of spin casters do not use them...most use natural rubber and that requires 350 degrees F...its just a shame because the resin is almost perfect..if it could tolerate 350 or closer to it, it would be much more useful but as it stands it has limited use.

Perhaps you guys should attempt to reformulate the resin to survive a slightly higher temperature considering how vulcanization is one of the primary uses this resin is intended for ... until that happens im forced to try to find another solution

[rsaldivar]

I agree , more would sell if somehow it can be used for all types of molding , rubber or RTV , as is now , can only be used for direct modeling , if the resin your grew , is the produce you will use , just paint ,

However as stated above , the majority of us mold with it , not utilize the grow part as our product

[manakawari]

evidently the form labs high temp resin can survive vulcanization, I just don't know how the resolution is and I would have to reinstall the uv filter on my projector...just a pain in the ass...envisiontec has a high temp resin that achieves great resolution but I don't think we can buy it without an envisiontec machine.

[manakawari]

I found a high temp casting resin online, im thinking of experimenting with instead of directly printing my master, I will print a mold instead and then cast my masters with this high temperature casting resin.

I can then easily polish up these resin masters and they should work much better in the vulcanizer...just adds another step and I lose an entire day and it also further reduces my print area because the molds are obviously considerably larger than the actual piece but until I find a better solution resin wise, I don't think I have any choice.