Ask HN: What Are You Working On? (June 2025)

I went Yak shaving.

For my 3D audio project I need an affordable way to make plastic cases. I felt like injection molding services are way overpriced, so I decided to make the molds in-house. Turns out, CNC milling is overpriced, too. As are 5 axis CNC mills. So in the end, we built our own CNC machine.

And like these things always go, I found an EMI issue with my power supply and a USB compliance bug in the off-the-shelf stepper control board. But it all turned out OK in the end so we now have the first mold tool that was designed and machined fully in-house. And I learned so much about tool paths and drill bits. Plus it feels like now that everyone has experienced hands-on how stuff is milled, my team got a lot better at designing things for cheap manufacturing.

That's a pretty big yak to shave! Building a 5 axis that gives good results a big task. How long did it take you to get that working?

Why do you need to make so many molds?

Would love to see your machine! Any pics or write up?

Got a link or blog we can check out?

Yeah! I would absolutely love to see a write up about this too!

Great to get experience in CNC! I've been working on how to market my GatorCAM for CNC. So I'll give you a copy! 2 birds!

It is easy to select multiple holes/pockets at once so if you iterate, you don't spend time redoing CAM! It does traveling salesman to solve for efficient paths which even the expensive packages don't get right. Calculates v-bit paths too.

On me: https://sites.google.com/view/gatorcam/home

There was something in this video about not being able to get moulds made in America:

https://youtu.be/3ZTGwcHQfLY

Yes, it's difficult to find someone with both the skills and the machinery. And contrary to software, bad g-code in a CNC mill can easily cause $100k+ in damages if, for example, the spindle head crashes into a solid steel block ... Which is why they will not let outsiders do the programming, even if you think you could do it.

That looks great for 2D engraving setups. Or for cutting parts out of sheet wood/plastic/metal. But based on the videos, I don't think this is suitable for 5-axis milling yet.

Also, in the video where you cut out the circular logo coin:

https://youtu.be/mGd7EIkCK3g?feature=shared&t=108

it looks to me like you're using a metal cutter bit (with corncob grinding surface) on wood. You might get a lot less burr (that furry stuff on the sides of cuts) by using an asymmetric one-blade bit. They look weird, but they'll cut the wood fibers with a carbide blade instead of trying to rub them off with diamond fragments. You usually want separate tiny chips coming off the material. If it starts stringing - like in the video - then usually it's either the wrong bit or too fast spindle speed (and material melting rather than cutting).

Correct. This is only for 3 axis milling.

I'll have to keep an eye out for a bit like that. I usually use my 30 cent eBay bits with blue tape to avoid the frizzies. But i didn't want to hide the workpiece with tape in the video.

Wood be good to not have frizzies in the demo videos!

Btw fxtentacle...go grab a copy on me! Thanks for the kind word!