Small time production of plastic goods?

>>1121530
>Am I shit out of luck?
Yup.

>>1121530
What kind of features do you need to be "sub-mm precision and accuracy"?

>>1121532
Fine details for scale models

>>1121533
https://1d4chan.org/wiki/Casting
Some techniques here even a grognard can find success with.

>>1121536
The parts may include very thin strips or working joints, so crafts store resin in a jerryrigged mold probably won't work.

>>1121530

What's wrong with acrylic resin?

Sure it has easily acquired contact allergies, but it hasn't stopped millions of women using it for their nails. Don't be a pussy.

>>1121530

How many, how big, and how well could you make a master?

If you can make suitable masters, don't need too many, and are a bit loose with your definition of "acetal-like", casting them will be trivially cheap in terms of set-up, but will probably be more per-unit, depending on what resin you use. It will also be slower, since you'll need to wait for the resin to cure before de-mold.

If you cannot make a good master and/or need more than a few, consider manual injection molding. See if you can find someone to make a mold for you for under your budget. This will depend entirely on the size and complexity of your part. I'll admit, you're going to struggle to get someone to make a mold as detailed as those for models at the upper and of your size range. Even half that might be difficult.


Really, those are your only options for production. Like you, I'm inclined to think casting is the way to go in your case, since you can't really afford the tooling costs for even one of your larger models. If this is a serious business venture, the best option would be finding a loan or investor. Otherwise, you're stuck either spending a lot of time hassling with casting, or just plain SOL.


As an aside, what you need isn't really precision or accuracy, just detail. Unless there are interlocking parts involved, nobody's going to notice that a 15cm model is a millimeter shorter and wider than it's supposed to be. This is important to remember, because you will pay a premium for requesting an unusually high-accuracy mold (if you decide to go that route), and there's no point doing so if you don't need it.

That being said, even China-tier modern CNC machinery can manage tolerance better than you need without even trying. Most start out at better than a few tens of micrometers.

>>1121541
I'll probably have masters 3d printed from SLA printing service and use those to make molds. Or get it printed in clay and finish it by hand and then make molds from that. Either way the parts are digital so I'll have to have them produced first.

I think resin is the easiest path too but I really think I need tougher plastic, it's just too bad the good stuff is so toxic. I'm okay with paint thinners and stuff but what the manufacturers suggest on their site these industrial resins are pretty dangerous before curing, both to store and use. So with that in mind I'm not sure if it's the best idea for me. I have basic safety equipment but once I start needing to store resin in dry nitrogen to prevent explosions due to moisture during curing I get skeptical.

The volume probably won't be more than a few dozen, it's just a hobby.

How would a manual injection molding machine work for details? Doesn't it need several tons of pressure to push the plastic into all the right spots? I did look at some of those manual injection molding machines, and thought I could use it with a 3d printed mold, made with formlabs resins. Then I could injection molding the parts that need durability and resin cast everything else in a "safe" resin.

You can buy a manually controlled injection press for less than $2000, and then each mold can be made for a few hundred dollars depending on what you make it out of. Do some research on that, if you want to make any significant number of parts, injection is the way to go over 3d printing. Will require less surface treatment too.

>>1121677
I don't really want or need to make a significant number of parts, I just need it to be strong and detailed. Of course the option is nice

The ultra cheap way to go about it is Milkstone but the results can be slightly random, will require sanding and polishing (but you can be exact with that) and you may have limitations on colors.

Milkstone is made from vinegar and milk, it smells horrible, but it yields a gummy shapeable glob which will harden into a brittle kind of plastic.

Kids can make this crap in the kitchen so that's cheap.

Also before bakelite came about people often made things like knife handles and novelties out of it as cheap alternatives to Ivory, so its seen industry before.

Youtube it

>>1121836
I'm looking for something that is slightly soft, i.e it can elongate around 20% before breaking. I don't want a brittle plastic specifically because I'm dealing with things that might be under stress, like for example a sculpt of hair.

File: model_digitalmaterial_comb.png (83KB, 360x240px) Image search: [Google]

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Have fun with mold design:
http://lcamtuf.coredump.cx/gcnc/

>>1121680
Then just use stereolithography or another 3d printing process

>>1121538
Redesign so that you don't have thin strips, these will be hard to manufacture

>>1121916
>> slightly soft
Objet machines can print a rubbery like material

>> hair
Fucking why.
>> under stress
Why do you need to stress a scale model?

>>1121986
>Why do you need to stress a scale model?
I'd be willing to bet he's either garage kitting Gundams or toys.

>>1122077
Original designs but basically yea, gundam and mecha kits.

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Order a 3D printed (polyjet or sla with abs-like resin, not shit tier FDM) mold for plastic injection and use a desktop plastic injection machine to produce your part.

>>1122098
That's what I'm thinking would be best, but will these manual injection molding machines have enough pressure to mold the stuff I want properly? I'm talking very fine details like panel lines and rivets on like a 1/72 plane. And will it be able to inject acetal/delrin?

>>1122121

Yes they will, not sure about that specific machine but you can certainly get one that is good enough.

https://www.youtube.com/watch?v=QI83Ni-XhRk

>>1121530
Jordan?

>>1122183
Who?

>>1121530
Join Tech Shop ( $1500 for a year) . Take cnc and injection molding classes.

Cnc your own mold . And inject plastic using their plastic injection machine.

>>1122234
That sounds good but I'm in NJ.

>>1122237
What are you actually trying to make? Organic mecha designs that are posable?

>>1122239
Waifu, mechs, and spaceships

>>1122245
I mean more specifically, give an example of something you want to build with this magic material

>>1122249
The best comparison would be a 1/100 gundam model kit. Jointed elbows, knees, shoulders, feet, wrist, etc. And capable of holding up external accessories.

My first project will in fact be a Guncannon Detector. I've done some testing with a 3d printer but the dimensions always come out inaccurate. I'll know more once I've completed modeling all of the parts and printed them, but things like eyes and small gun barrels aren't going to work with a fdm printer

I've been reading up on injection molding and I've seen some claims that those manual plunger-style injection molding machines might not reproduce fine details due to non-uniform temperature of the plastic.

Has anyone used a manual injection molding machine before?

I'd be willing to put this off for a few years if it means getting a better machine.

On a related note, how is the PocketNC?

>>1122543

If it was just for a few parts couldn't you just heat the mould?

>>1122555
How hot would it need to be to get it to get everything to flow in well?

>>1122556

I'm just applying common sense here, but if it was a thermoplastic any temperature which keeps it liquid?

>>1122559
Yea, it makes sense, it just seems like people would've just done that already if it were so easy to solve the problem with plunger machines.

Wouldn't you need to maintain pressure to keep it from shrinking back as the mold slowly cools down?

>>1121540
Women are hardcore crazy when dealing with beauty chemicals, is not only the acrylic resin, they then stick their hands on cancer lamps, put irritants on purpose near the eyes, wear steel strips that can stab the chest in an air bag incident, but cry like bitches when see a mouse...

>>1121540
Pretty sure PT8902 is more dangerous than acrylic nail polish or w/e

>>1122543
k you are stepping outside your league very quickly with this

when doing injection molding there are 3-4 key parameters
, injection pressure, temperature , and velocity

because plastic is a non newtonian liquid , its viscosity changes as the pressure changes

model style molds are inherently difficult because of the unbalanced nature of their molds

but honestly, you arent gonna get a better molding machine than the hand plunger so you might aswell fuck around and do some trial and error

>>1123082
Yea I think I'm getting out of hand. I'll have to consider things more carefully. On a second look it doesn't seem the safety sheets for industrial resin is particularly worse than regular resins, though I'm sure there are some other nuances.