After watching my 3D printer take days and days to print all the parts for the MPCNC, I have to wonder if I were to make a second one, and had a 4th axis for my MPCNC, could wood be used to make parts for a MRCNC (mostly routed CNC)?
Or is wood to dimensionally unstable?
I suspect that some of the sections are too thin to be made out of wood, and would have to be thickened.
I am assuming here that it is faster to route a part out of wood than it is to print a part out of plastic.
I love the idea of this and I am always considering a different build type to implement some flat parts. Production wise there are a ton of options, and I am always trying to find a way to produce this for less cost for everyone.
I have recently switched to 0.5mm nozzles and I can tell you right now I will never go back. Half the print time, the parts are stronger, less clogs.
Personally I still like the idea of making silicone molds of the parts, then use two part polyurethane. I’m not sure if the wieght difference will be a problem. I’ve heard of techniques to lighten parts without sacrificing strenght but I’m not familiar with them.
Formlabs keeps advertising a free printed part on YouTube. I wonder just how much better a part looks off an sla machine. If it is as good as they say it is, it might be worth getting a set made then cast those for the molds. There are a rediculous amont of polyurethane and silicones to choose from.
I used some lightweight silicone and tough poly to cast a GameCube shell/case last year. It’s really a viable method. Once the mold is made(hard part) making duplicate parts is easy and fast. Printing, your waiting on the machine. You can make multiple molds and pour all the parts at once. 2 hours later all the parts are done.
Jason> I still like the idea of making silicone molds of the parts, then use two part polyurethane
How would you handle all the holes (bolt holes, screw holes, nut traps) with your approach?DIY molds would make some great parts. From my end, production, it is not nearly as viable as printing. Printing requires about 2 minutes of my time per full set. Mixing, degassing, cleanup, waste, and then you can not make more until those are removed from the mold, and silicon molds don’t actually last all that long.
As a one off or for a few parts, it would be cool. Barry and Dui have made sand molds and poured aluminum parts, that outta get you thinking!
Let’s take the xyz plate for an example. When you cast it, you use metal dowel rod to get the bolt holes. Remove them and pull your mold apart, then replace them and pour again. Like pins.
It gets a little tricky with the rollers at the end due to the way the nuttrap is. I think I would place the 6/32 nut on a screw with the head cut off and wrap the threads with a layer of Scotch tape. The slot wouldn’t be a slot anymore, but will encase the nut completely.
Looking at it, most of the parts would not be too difficult. When making the molds, it’s easier to drill larger than needed holes for the dowel rods in the form, and just mask them closed. Depending on your selection of silicone, it may be necessary to get the right kind of putty for sealing it up. Platinum silicone won’t cure right if it’s in contact with the wrong stuff.
Usually you can get about fifty parts from a silicone mold. Most likely more. I’m taking that number from a company that makes low run silicone molds with platic injection ttechniques. I’m not sure if not having such a high stress usage means they should last a lot longer, or if they simply don’t stand up to the flexing from part removal.
Your right about one thing, if your not careful, it can turn into a real mess. And it’s takes some time and effort to get started.
The real benefit is once all molds are made, you can pour all the parts at once. Or even two machines worth of parts at once. And they have some polys that are as strong as mild steel.
What about milling molds for forced injection? PLA is a fine material, IMO. Ryan is the only one that could benefit from something like that, but how does it compare to a silicone like mold?
Something like this:
Some sorta long videos, but this is what’s in my head. I have no idea if it works that well for larger parts.
Honestly, even if Ryan could do this, I don’t know if he should (and it’s not up to me 
). I like printing my own parts, and I like getting help from Ryan and if he changes anything that works better for a molded part, the printed parts aren’t going to be as good.
It is cool to think about though. I love the idea of making all the parts in like 5 minutes.
You can still do injection molding with casts. Earlier I quoted a company that does small run injection molds using silicone molds. They are a stiff, high temperature formulation of silicone, so usually it means more parts to the molds, where as, with softer silicones will flex and you can realese parts with undercuts much easier. This means fewer steps and less error. Imho, the added mess of dealing with two part plastics is much easier, minus being messy. Your right though, you wouldn’t have to wait as long to pull them out of the molds using plasic injection… actually I’m not sure that’s entirety true. There are additives that really raise the cure rates, but I can only imagine that adds some extra difficulty in working with it.
Milling the molds for these parts would take a lot of time. And difficult. I don’t think it’s something we could do with the mpcnc right now. I could be wrong, but without 5 axis and a lot of clever coding, it would be hard to get all the angles needed to have the right finish. You thinking milling these parts out of aluminum, right? I think give it a try in engineering block first.
In a month or so I might have time to make a a few molds. I think I’d focus on the center carriage. Those are two of three of the more difficult parts. Now if only I could get my hands on some sla printed parts, we could get some good castings…