Had the same thought. Seems like it would be so much faster so I suspect the reason not to do that would be very interesting.

My guess is weight reduction, so your mold is basically a shell 20mm thick rather than a solid block.

Milling from a block would use considerably more material. 3D printing allows us to overprint and cut with less wastage.

The printer is more efficient than milling tooling foam. And you can build internal structure and make a large mold , like a wing skin mold, that is lighter.

Steel and tooling foam are hardly cheap. Also they're very heavy. Invar for tooling us extremely expensive. Tooling foam is also a pain to use for high temp curing because its cte. This process works great for prototype molds and one offs. I wish i had this tech whilst building molds.

Don't get me wrong I love 3d printing technology(have 3 myself) but surely the 7 axis CNC can do all the work(and faster). It really just looks like the 3d printer is creating a big chunk of plastic in the rough shape(ie a coarse milling pass). Why not start with a block of plastic and mill it, particularly for simple shaped molds like that one.

@@lach808 cause it's wasteful and slow? Having made and used molds in a prototype situation, i wish i had access to this tech. The turn around on a mold from this new process is going to be faster for prototype and short runs. Ive also done parts with invar tools and carbon tools, they are great. Every process has its application. You wouldn't use a hammer to drive a screw 🪛 it's nice having options. Look up thermwoods LSAM, they use a printer and mill that are separate. The parts can from machine right into the autoclave. Their mold also have more of a structure. Again each process could be useful to the right application . My 2 cents 😅

@@lach808 also, with a high temperature mold, controlling the thickness of the mold is critical in ensuring even temps in the oven. With a monolith piece, they need to be pocketed, which flipping a 5000+lb piece of metal is probably fun. These printed parts are lighter and dont need flipping around. So its not just the simple form on ine side that gets machined.

​@@samuela6271 I think you may confusing me with the original poster with respect to steel molds. I never suggested them, the plastic versions clearly work beautifully. I just accidentally replied to the thread :) I understand for complex parts and prototyping the 3d-print and mill process would be amazing (I watched a few of those LSAM videos, very nice!). I was just commenting on the application they showed here - using it for a relatively simple convex shape such as the rudder mold. I thought milling it from plastic stock would be quicker - for this shape. Thank CNC cuts it like a hot knife through butter. Anyway, I'm sure they have more complex shapes in mind. Also they said they reuse any plastic scrapped, so not as wasteful to mill a large chunk of plastic. Very exciting stuff though.