Machine Development…….Injection

Please use this Sub category for all posts & information regarding the Injection Machine Development. Thanks 🙂

We’re working on the injection machine at the moment and should have it ready soon! We’ll post updates in our topic:

@rizla and dont forget, the cooling rate will be very fast for thin wall. melted plastic might turn solid.
on picture is my first attempt, the plan is vase with 2,5mm wall. result varying thickness from 2,5-5mm, the thin wall mold might deform due to heat+pressure.
you might want to use thick mold and put extra heater around it.

*my mold capacity is around 75gr HDPE.

186cc is theoretically just about doable if you can pack the barrel solid right up to the bottom of the hopper. But don’t forget injection moulding takes some pressure, and that pressure spread over a large area mould with thin walls will spell disaster! It could take many tonnes of force to hold a mould of that cross-sectional area closed.

Man, i just stumbled onto this project site and the timing was perfect. I’m picking up a CNC kit tomorrow (Shapeoko 3 XL) so that I can mill two part molds to do some prototype injection molding. I have a 3d printer that I use for the “rapid” prototype for fit/function, but ultimately the goal is to get to injection molding. Obviously, cost is a conern, so thats why Im going the DIY route to fully vet the design.

Anyhow, with the injection molding machine I’m wondering how large of a piece you can work with realistically. My design is “large” but has thin walls (355mm x 585mm). I calculated the internal volume of what the plastic piece is and its about 1.859E+05 cubic mm.

Would the injection molding machine be capable of filling that thin cavity?

Anyone can help with injection machine wiring? When i put 2 PID circuit, the temperature going up more than i set. The heater seems to always on even the relay light is off

hi @birdynamnam, try to increase the temperature of the nozzle. That single element has much more mass to heat (barrel + nozzle) increasing the temperature could help to transfer the heat all the way around.

Hey @lyricalpolymath,

Excuse the late reply. In the end I’ve had to buy four of those Chinese-made PID temp controllers in order to get two that work. The gain control seems all out of whack and reading the temp over the length of the tube (with an infra-red thermometer gun), it’s very irregular. I’ve finally got the machine up and running now (it’s been a busy summer!) and tried testing it again today.

The major problem I’ve now encountered is that the heat does not convect from the tube with the band heaters to the reducing bushes, so when you try to inject the molten plastic into a mould, there is a blockage. This doesn’t appear to happen in @davehakkens video, any thoughts appreciated!

Will post a pic in the other thread now too.


hey @birdynamnam, did you manage to try the PID from your link already? how do they work? they look soo “Chinisey” and the price makes me worry that they might turn out to be a completely waste of money.
Dave’s TC Direct TD102 or similar cost 90 GBP, or 120 € if bought from an european reseller.
The price difference isn’t that conforting…especially when buying stuff from the Chinese.
Let us know.

also, has anyone bought and used the PIDs? any suggestions? on brand or things to look for?
the wiki has just a generic intro to the argument but not suggesting any manufacturer

Hey dresdenjack, may be a bit late now, but I bought this SSR with the PID unit and it seemed to work fine. We have had set backs, but that’s more due to my wiring capabilities than anything else I think!


Hi guys, I’m purchasing all the bits and pieces this week and I’m on the hunt for the right SSR but am new to all of this. I can’t find the exact 2-24V SSR but have found this one described below. I think it’s all good but would appreciate advice.

“Solid State Relay 3-32VDC Input, 240VAC 40A Switching”

“This panel mount solid state relay offers 3-32VDC input control, with a switched output rated at 240VAC/ 40Amps.”

I’m not sure if this is the place for my post. First off I think Dave and the team have done an amazing job with this precious plastic project!

Regarding the Injection Machine V2, I noticed in this video: at 3.39 that the machine tips towards Dave as he injects, it seems to me that the base should come out as far as the end of the lever, anyone else think so?