# Injection moulding woes

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#### Dr_Doggy

##### Well-Known Member
not really electronics ... but. .. for my circuits I need custom plastic housings.
Its very hard to get an abstract quote, but from what i am getting it seems that for my hollow housing that is about 5in x 5in x 1.5in will cost me about 10-20 thousand dollars for the tool alone.. assuming the worst price if I run 100 of theses the overall price is about 250$per unit. Which would never fly no matter how good the circuits were. Increasing the yield to 1000 brings the price down closer to 40$/unit (at 40000$total this is my best bet so far). and at 10,000 = 20$/unit.. but brings my total costs up to 200,000$. Some vendors have suggested that I am at a prototype stage and that I should consider 3d printing, but the last time i got a quote it was like 500$, so i expect this project to be at least 200$per unit. So not sure what my best move is? Can anyone relate? And where can/do I go from here? Last edited: #### alec_t ##### Well-Known Member Most Helpful Member Are there no off-the-shelf housings which are 'close enough' in size? #### Dr_Doggy ##### Well-Known Member unfortunately to use what i am using now for my test models would be considered copy written material. I'm pretty sure it would get me in to a lot of trouble to use them. ... sorry to not elaborate but its more than just a box so to speak #### shortbus= ##### Well-Known Member Most Helpful Member If your "handy" you could cast your own in poly resin. Make the form that you want to reproduce in plaster of paris, sand very smooth coat with polyurethane varnish and then the casting. You need to make sure you add 'draft' on the sides to allow the finished part to be removed from the mold. And no under cuts allowed. TenK to twentyK wouldn't get you a very complicated mold back when I was building injection molds. But maybe prices have come down since many today are made in Asia. https://en.wikipedia.org/wiki/Resin_casting One of many sites on casting. Google is full of them. https://www.resinobsession.com/resi...and-silicone-resin-molds-whats-the-difference #### Reloadron ##### Well-Known Member Most Helpful Member If you can't find something turn key off the shelf you start looking at money. Injection molding would involve making the die which is time and money and to run a small batch the setup cost on the machine will eat you alive as you have discovered. I would be looking high and low for an off the shelf solution or redesign into something off the shelf. While I can appreciate you wanting to keep your project confidential I would be looking at a design change where you can use something already out there and inexpensive. Ron #### aardyvarky ##### Member Can we assume that the shape of the enclosure is functional and critical (e.g. a hand-held radar gun... er, let's hope it isn't a hand-held radar gun!!)? Or is it that you just need to make it a different shape from an existing product? Edit. How about blow-moulding for a short run? #### Pommie ##### Well-Known Member Most Helpful Member Here in Brisbane there is a hackerspace area at the local library where you can go and use the equipment. One of the guys there had built a small rotocasting machine using the available 3D printer and was using it to cast novelty chocolate eggs but also did some polyurethane models. The item to be cast was 3D printed and then moulds were made from the 3D printed form. There are lots of youtube videos of rotocasting - mainly by sculptors but the principle is the same. There's also a few pages describing how to make one. Just a thought. Mike. #### Dr_Doggy ##### Well-Known Member For prototyping I used an off the shelf model, like all my doggy designs , "I have improved it", and working closely off the original, I have drafted a clone in CAD, this way i can change things enough to get over the copy write hook. I bought these off the shelf, gutted them and re-wired , I would ideally like to resell them as modded device and in fact this way would prove simplest & cheapest again closer to that 40$ mark, but wouldn't that have similar issues which bring up topics like "royalties" ????
... besides that problem I would have no problem using the pre made model I found, since the originality is in the guts.

yes, some of the shape is functional and critical and needs to be somewhat aesthetically pleasing, I dont think blow molding will work for me, it looks like it needs it die too. .. and a thicker shell .. but i did wonder how they made bottles and such

Imagine like a tv remote, it needs to be enough of a rectangle to fit the hand, but can be different from others, and so far using that type of plastic enclosure too.
Plus there are actually several parts to mine, such as lid, cover, body, base, -- not all 90deg not all perfect squares/circles.. ie cones and pyramid shapes there too!

Or is it that you just need to make it a different shape from an existing product? "i mostly just fear getting sued using the original!"

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#### JonSea

##### Well-Known Member
Most Helpful Member
Check out enclosure manufacturers. There are many boxes designed to get handheld that aren't simple rectangular shapes.

#### crutschow

##### Well-Known Member
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Have you looked at the cost of a 3d printer that can make the part you want?

#### ClydeCrashKop

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#### shortbus=

##### Well-Known Member
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Clyde, as a retired die/mold maker(did both) that site is really good. Did see why they can do it cheaply though, their proto molds don't use any cooling. Doesn't hurt most finished parts and cuts the cost way down, thanks for the link.

#### Dr_Doggy

##### Well-Known Member
1) do you guys think I am actually infringing if i take the existing shell, mod the core then resell?

2) also it took me a sec to get what was being said, but one direction that could work well is if i 3d printed my unique design then used the printed prototype for the resin cast! But is resin casting quality comparable to that of injection mold? I would like my products case to be comparable to that of a cellphone or tv remote or even similar to the shell of my pickit2. it is outdoor product...

3)also are there pro resin casters out there i could pay?

#### JonSea

##### Well-Known Member
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Let's see. How about buying a bottle of Coke, adding a drop of your "secret ingredient" and calling it Koke Plus?

Get serious. Of course they would mind. If you put any product similar to theirs in an enclosure that even looks the same as theirs, expect a lawsuit. If you are taking their intellectual property, making a few mods and selling it, geez. What happens when your secret sauce is a bust and people blame the original manufacturer. What happens if it really works and people buy one from the original manufacturer and complain when it isn't as good. What happens when your device breaks and they return it to the original manufacturer?

If you are modifying their circuit board or selling your own do-dah in their enclosure or your own enclosure that looks enough like theirs to be confused with it, you're going to end up violating the law in some regard.

Your best (only?) option is to sell a modification kits to purchasers of the original device.

#### Dr_Doggy

##### Well-Known Member
yes, that is what was aiming at, sell a modification kits to the original device.... already installed! this way im buying the plastic shape and paying company for their losses at point of retail. back to the tv remote example, it would be similar to buying a remote, cutting a few buttons out and resaling as " simpler and improved "! Is it still intellectual property theft??? since I am NOT copying the design and printing myself?
... just questions!

anyway.. if I can find some resin that is similar to the abs used, and a company to make a nice cast and/or product this would be the ideal and most cost effective way to go!

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#### JonSea

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I don't think that will fly.

#### alec_t

##### Well-Known Member
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Is it still intellectual property theft?
If your product outwardly resembles theirs and could easily be mistaken for theirs then they would have cause for a "passing off" action (in the UK at least).

#### Dr_Doggy

##### Well-Known Member
I will assume its the same laws in Canada, ... still going to check out these resin places Monday

Maybe its the fact that things are made in China where the looser rules are, is how so many clones of things make it out to market.

#### aardyvarky

##### Member
Yes, the other company WILL sue you if they can show that your design was theirs, or that you have copied any part of their product.

Advise? Do you mean advice?
MD? Medical Doctor?
Red Green???

#### Dr_Doggy

##### Well-Known Member
Lol yes!
yes im not any form of doctor
google it , Red Green is an engineer of his own class!

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