Mould & Tools fabrication


I have been teaching myself solidworks to design some moulds and mounts for a startup I have recently started… We make home-compostable plastic alternatives from organic food waste - can have a look at our website,

I think I figured out what I need but I’m not sure how to go from design to making the real-thing (!) I am super keen to learn any tool / seek advice from anyone in this great community to turn our designs into the parts we need to prototype various shapes we can mould our materials in.

We will need to make the moulds in Aluminum (probably 6061) and the mount in 4140 or similar Steel alloy. The moulds are for a hydraulic press (garage press).

Attached a couple of snapshots of the current designs I am looking to get done.

Happy to discuss options and hear from all the great brains around here to see how we can move forward :blush:

Thank you!

Hi Andy,

It looks like you need a fillet on the top half of the mould, on the outside top edge of the shape. As it is currently, a spinning bit on the CNC won’t be able to machine that, unless the adjacent surface is perfectly perpendicular which I don’t think it is. A fillet there makes machining straight forward with a ball nose endmill. You want a fillet radius that matches the diameter of the ball endmill.

I also assume you are placing a lump of material in the centre then pressing it into the shape - you will want a gutter the whole way around that comes up to a sharp edge, which will trim the “flash” during each pressing operation. The gutter provides space for the excess to flow into/occupy so you can fully close the mould.

Otherwise you should probably talk to @MoltenAluminium about machining it on the Hildi CNC - you will have to buy your own endmills and double check the largest envelope size on the machine, but it should be straightforward.

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Thanks @wixted - this is gold!

How will I find out what the “diameter of the ball endmill” is? I am not really sure how a CNC works tbh…

Love the suggestion to add a gutter around the edge, we are doing exactly what you say and in our current mould (that was done by some tool maker) any excess goes outside the mould and we can never close the mould all the way (and also creates some weird uneven edges that we have to cut off and clean.

Will do these changes tomorrow and see how they look :smiley:

@MoltenAluminium - any suggestions on where to start from with machining these pieces? Would love to start from the simple mount (in the first photo) to get an idea of how the machine works etc. I will also need to source the right materials for it (and endmills?) so any suggestions on where to fnd those would be great :smiley:

Sorry, I have so many questions…! Thanks so much!

Hi Andy

Your project looks pretty solid. More eco-friendly packaging is no bad thing!

Don’t underestimate the effort required in creating quality metal molds, particularly if you want repeatability at scale.

I see you’re affiliated with UQ ventures, you should speak to Blair Knight who is the technical head in the Engineering school. He’s spent decades making high precision tooling and is super friendly. I think he’d be open to an e-mail In any case he’ll be able to tell you the best approach to take before you start cutting metal.

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Hey Sam,

Absolutely! At this stage, we’re not making products / packaging that will be sold.

We have been working towards creating some simple shapes to use as samples of what our materials can look and feel like. We’re not really looking for high-quality moulds, rather cheap(er) prototyping tools… We had one done by a workshop, a small ramekin size bowl, and it cost us $900+ just for machining, so I was exploring other ways we could machine a couple of other designs for less than what a workshop would charge…

But 100% open to other ways to go about it, we’re just starting off so nothing is set in stone :slight_smile: Someone suggested we’d look into 3D printing as there might be materials that can substain the amount of pressure we put the moulds under (currently, 50 tonnes)!

I will reach out to Blair, sounds like he has some great credentials! Thank you so much for sharing his contact :slight_smile:

Took away all your great reccomendations and spoke to a few more people, and everyone keeps going back to cutting steel as the way to make these compression moulds because of the amount of pressure they’ll have to work under… :man_facepalming:

So… Anyone interested in having a chat and see if it’s something that can be done at HSBNE? Not sure where to get materials, and all that either…

Thanks everyone!

For weird steel i tend to turn to Home - voestalpine HPM (Australia) Pty Ltd

they can get you whatever grade in whatever billet you want.

Hildi or the BECNC can most likely do it just fine, it will just be a case of speed. I think they’re both rigid enough.

TOT on youtube has a bunch of good intro to cnc videos we recommend to people who are new to it: CNC Dummies For Routers - YouTube

I’d say go through the videos there and you should have a reasonable idea how the machines do what they do, and answer your ball nose endmill question :slight_smile: from there its just CAD + CAM and then onto the machine for workholding and running the job.

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