hello is it possible or has anyone done a stepper load management in marlin ?
was thinking if its able to make a shut down if the router is going rouge.
or if its possible to have speed set on some type of shipload resistance.
/mikael
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Maybe it should be easier to monitor the router RPM ? My makita 700C has a variable speed drive and I’m pretty sure the rpm are being monitored by the driver.
Thinking about Closed Loop Stepper Motor, or something else?
problem is with wood it has different hardness like when you hit a branch spot “dont know the word for it”
i need to step down, also i like a failsafe for a automatic shutdown.
i built a 5 meter lowrider to be able to get full size wooden planks. after a few a few changes its got closer to reliable, but im not realy there yet. i like to be able to go deeper than 2mm per pass with a 6mm tap. so something to make it slow down or/and shut down if necessary.
a closed loop would be the best. but now im only thinking of the Amps drawn how smooth the motor goes, so when its taking a totaly different path it shuts off or slows down. and not just generate heat.
16.5 feet long LR2 or LR3?
Thinking of measuring, and dynamically tuning feedrate based on stepper ampage draw using tmc2209 diag pin stall guard feature? And/or measuring router ampage draw from mains supply (smart meter), or optical rpm reader, and/or something else?
The current is constant if it is sitting still, moving, or moving through load. The motor does have different back emf based on speed, which results in different voltages needed to keep that current constant. But it is a subtle thing to measure, and very subtle at the slow speeds we mill at. The sensorless homing on the tmc drivers can detect skipped steps using that measurement. But it can be pretty fickle.
There is no reasonable replacement for being in the room listening and sometimes watching the work, ready to kill the power when it goes rogue.
I have my reservations on closed loop steppers too. The precision of open loop steppers is very very good. If you used the encoders to only detect skipped steps, you might get the best of both worlds. But relying on the encoders to determine the desired location for the motors will result in reduced precision, IMO.
its not for leaving the room. its more not to completely destroy the piece.
usually i think its the motor or belt that skips. my belts are 5meters so there are some bungy lash involved.
usually the problem is when you use a 6mm bit to get a 6mm line there are no tolerances. i know it but it still i messup.
LR2 i have no idea how its gonna be made, all sounds like good options to me 
Stepper motors have magnets on the shaft that align with the elecromagnet in the case. Those magnets align every few degrees. Skipping steps happens when the magnets jump from one alignment to the next or previous. It sounds like crunching gears, but it is just the shaft skipping to the next alignment (possibly a few times quickly). The belts rarely jump teeth and there aren’t any gears anywhere.
5m is very long though.
On this it’s the opposite. It skipps fast when building slack on the backside. I tries a lots of belts but the ones with minimum flex is steel braided but they don’t like the small gears or sit in tention, they separate in just a couple of months. Best for me is glas fibre thin flimsy ones. In the next build i go with double belts.
Course i also go for long periods making the motor bracket. Plasticise when putt to much pre tention it bends in time. Now i have heat treated the pla it works better but haven’t pushed my luck, also added some peltier coolers to the steppers.
Also i run the maximum current to the steppers.
But when the disaster comes at 20mm down motors also skips.
The steel belts fatigue fracture inside the belt and you can’t tell except they stretch.
Hopefully you know more than me about it already. 5m is a very long belt.
Yes it’s to long to run single. Just Don’t do it 
Also the axels in the router is burning fast of those 6-8ohur passes. Even though i run it in 1-2mm passes.
I’m in upgrading plans but i don’t know if i go for the V2 or V3 rebuild.
I’m planing on a slightly bigger router water-cooled.
And more belts. Thinking of putting doubble bearings on the stepper axels so have a bit more pre tention and not put that load on the motor or the motor support.
But it would still be nifty with that load failsafe.