Marlin "Power-loss recovery" Feature

Mostly Printed CNC - MPCNC Advice
#1

I see that there is a feature in Marlin to have power-loss Recovery enabled? Is this a viable feature to try and use on a MPCNC with a Makita or Dewalt Router?

One of my 3d printers has that feature and it works well and saved quite a few large 2 day prints when hit by unexpected power cuts (load shedding they call it in South Africa).

I guess it is unlikely that the MPCNC will ever be routing a job more than an hour or two but the material is a lot more expensive if it does go wrong.

With our dodgy electricity company letting us down frequently, wandered if it was a rabbit hole I wanted to go down. Is it viable feature in this case? I am thinking of problems like if the power goes off, the Z axis will probably drop.

Has anyone tried it?

#2

We haven’t tried enabling it in the firmware. I’m not sure what the hardware requirements are, but I don’t think a standard board will just work out of the box.

I honestly don’t see the benefit, because any power outage will probably make a real mess. Also, the starting location (origin) isn’t always repeatable.

But it could work, with a few caveats.

#3

That is what concerned me as well, the repeatability. It works well on my 3d printer but it does not have that mass of the router to deal with.

#4

I think another thing you might be overlooking ingredient is the bit… during a power outage the bit would be engaged in the wood, loosing power would kill the steppers holding torque almost immediately, but the bit spinning at 30k rpm would not stop as fast so it could pull and make a nasty spot in the wood. Let alone the issue of repeatability you already mentioned.

If it’s a really big issue (happens multiple times a week) I would probably buy a battery backup and implement a primary power detection circuit. So if the power goes out it has a period of time for it to detect the outage and park the router at a safe location. Then as long as you where using the duel endstops for your home position you could restart the job after power returns.

#5

Yes, I can see that being an issue with the router.

We have had to put 3 UPS’s in just to maintain the basics like keeping the business computers running and having lights & TV internet etc. Once I dont owe for those I will try justify another one with “the handbrake” (Wife)

We do get “load shedding” schedules through cellphone app, but they cannot even be unreliable reliably and you schedule a job to run, and they change the schedule for the outage. Most frustrating.