I’ve just watched "PRUSA live #52 which was a bit of a talk fest about their print head load cell development. In short the data they collect from the load cell is sufficiently clear now that they can technically reverse engineer a model from it. ie they can take the data and build the model of what was being printed.
They are developing it for things like crash and print failure detection, and have a serious team working full time on it AND they have said they will be releasing it into the open source community.
Which leads me to this… Surely commercial CNC machines have incorporated this somewhere in their setups? How hard would it be to adapt?
Given that there are more than a dozen people working full time on Prusa’s firmware, I suspect that there’s a bit involved, which makes their commitment to open source more than admirable I think.
Who will volunteer to set up a triangulated load cell installation in a spindle base, which could automatically correct cut speed (and depth of cut) via firmware in the next gen MPCNC? Is that a project that even interests anyone?
I think it is harder with CNC. You can easily detect a broken bit that way, but the rest is just vibrations. You might be able to figure out exact ideal feeds and speeds. I am pretty sure most commercial CNC;s have something similar built it, or at least a horsepower monitor to see how hard you are pushing your spindle.
Now that you mention it - my son law is a machinist, and even with the squillion dollar machines operates them by ear. It’s actually amazing to watch him reacting to things that are well out of the range of my admittedly defective hearing.
I think there is potential, but real-time use of the data needs a different control strategy and potentially complex software.
One thing that seems doable would be a variable feedrate so it slows down under heavy load. Maybe your stock is uneven and you spend a lot of time cutting air. Or maybe you have stock that is variable density. A load-dependent feed rate could help.
I’m not sure - some would say the same about an automatic gearbox on a car.
I think about what I can do with my printer vs what some of you guys can from entirely different approaches - and I suspect that we’re not too far apart at the end. Yet I have a very limited knowledge (admittedly it’s over the whole process and I really understand the mechanical aspects so I’m more than an average user). The leveller is that I can use the clever bits in the machine and the work of others (software) to produce similar results to the genuine old school tinkering geeks.
I am not alone in saying my biggest stumbling block with machining is knowing where to start - If I could dial in loose parameters and the machine could take away some of the trial and error, I think it would then open up to a whole new world of tinkerers.
I have been pondering a bit of late as to why we have so few females around here yet there’s a fair representation in the 3d printing space - I’m not sure if this sort of deve
Imagine gcode where you set the load you want, and the cnc uses a PID to adjust the died to get close to that load.
I do think there are a ton of challenges. The load from is the same as my kitchen scale and it takes seconds to respond to input. That makes controls very hard.
See this is what happens when you are trying to distract yourself while waiting for you wife to come out of surgery! “No more garbled posts for you today young man!!”
Well, there’s one answer. Wimmen are always whinging and doing medical healthcare nonsense. Menfolk just spit on it and walk it off. When dealing with fully autonomous robotic death machines, the ability to walk off injuries is a key skill. Heck, look at the group photo from RMRRF: total sausage fest. Cool and praise-worthy sausage, but sausage nonetheless.
This was all tongue-in-cheeck, of course, and I hope your wife came through her surgery (or his, since I don’t recall what surgery we’re talking about) with flying colors and is recovering comfortably with a positive outcome!
In my experience once you start spitting out acceptable house decorations and stuff with cnc, women start getting interested. The non-maker type too… as long as they’re the type who doesn’t mind a little dirt on their hands.
That said, load cells are very common on higher end cnc… but similarly they’re not usually used for control feedback. They’re there to tell the operator something if they can’t hear it… and the operator is obliged to react and adjust parameters to fix it. Watching ‘ave’ on youtube, he has some videos showing the load cell feedback on his Haas… the numbers don’t mean much for the operator, other than relative changes. Like “oh nope, that’s where it was last time I broke the bit… need to dial it down”.
