Can the printer detect when the nozzle hits something and stop?

After crashing because I had forgotten to remove a previous print and suddenly I heard a terrible banging because the current print was causing the print head to bang on it, I have a couple questions and a possible suggestion.

Bambu printers do plate calibration by touching the nozzle to the plate. Does that mean that the print head has some kind of strain gauge in it?

If there is some way to measure pressure on the nozzle, maybe during a print when there should never be any pressure on the nozzle it could be used to detect a collision problem and pause the print with an error. Even if a strain gauge is calibrated for vertical pressure, I would expect that will the kinds of collisions that I saw there would be enough of a vertical component to trigger crash detection.

The potential for hitting something on the print plate isn’t just limited to forgetting to remove a print. It can happen if a part shifts, tips or any number of situations.

Thoughts please?

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The force sensor is in the bed, not the printhead. But the printer (at least the X1) does a bed scan before starting to look for previous prints (except on the textured bed). I suppose if the old print was large, that would not help avoid crashes.

What the printer COULD do is sense excessive current caused by sideways load on the printhead. It already does this for X and Y homing.

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I’ve no idea if the crash detection actually works. Based on the number of bent nozzles I’ve seen posted here and elsewhere, I do wonder. I know that if you pick ludicrous mode, it warns you that it will disable crash detection.
Under print options in Handy and Studio you can set AI monitoring of printing to low, medium or high with no explanation of whet that means. It is for the spaghetti detection so won’t help with a print left on the bed. Another setting is for recovering from step loss. I’m not finding mention of that in the wiki so I don’t know if that means it will stop and rehome then try again which isn’t going to help if the previous print is still on the bed. If it pauses and asks for confirmation, that could help as you would need to look at the printer to press OK.

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Thanks for the info. I know that some printers use the print head for the strain gauge. It makes the bed much simpler.

(I have been too busy printing to take the time to disassemble the printer and find out how it ticks.)

i have an issue where i print something, insert a 30mm x 30mm x240mm aluminum profile and want to continue printing.
However the printhead does random movements and collides with the wall, but continues printing.
Even if i add custom Gcode to home after i inserted the profile it collides with the wall.

Does this have to do with the printer in the printhead?

other “orange” printers just use the motor drivers to detect collisions. no strain gauge needed. I just got back to a 10 hour print that had a collision and continued to print with a very big offset in one axis

As far as I know, Bambu printers also use motor current sensing for this, in addition to homing detection in the X and Y axes. Like the newest “orange” printers, a strain gauge is used for Z homing.

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Motor current is proportional to motor torque. The homing process relies on the motor’s stalling when they’re jamming the printhead in to the homing corner. A stalled motor is when a motor draws the most current. But under high acceleration, motor torque (and current draw) also goes way up. So if you want to use motor current to detect collisions with something, without that collision producing enough force (= motor torque) to damage anything, the threshold has to be very low, which would mean that acceleration had to be very low so the “crash detection” wouldn’t get confused between the forces generated in normal operation vs. a collision with something on the build plate. So lower speed printers can probably do this more easily than high speed.


I think the easiest way to detect if the plate is empty would be with the camera. Even so image recognition in general is complicated the difference between an empty plate and a plate with some object should be relative easy detectable.

Every time after a print finished the printer asks if I wish to repeat the print. I never said “yes”. I am afraid that I would not have a chance to remove the model.
Has anybody used it? How does it works?

I use it all the time to repeat prints, I get the option to select which spool to print from, and if I want Bed level, Flow Dynamics or time laps on the new print. Works very well for me. I usually select re-print even before removing the plate to save time. The bed will move a little and then stop but I have plenty of time to remove the print and clean and re-install the plate before it is need to start the next print.

My printer was on silent mode. Similar to prusa maybe collision detect doesnt work in silent? Too bad i cant find documentation…