I am using an MPCNC as a 3d printer, but find the sudden stop at the XY end stops a bit severe, so I wonder what I need to alter in the firmware to introduce a ‘deceleration to a stop point’. Is there a fix?
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I think hitting the end stops is always going to have to be a sudden stop because overshooting can crash into something and be worse than the sudden stop.
The only remedy that comes to mind is to slow down the homing speed.
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I have the homing speed set pretty low (30mm/s and 3mm/s) but you can pretty easily turn it down. Line 1337 1338 of config.h
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Thanks, but I don’t wish to reduce the homing speed, its 520 x 220 mm work area so like the speed.
The axi’s don’t hit the stop, the jerk comes with the switching so will persevere with a solution.
When you home, it does not know where it is so it can not decelerate to hit a switch since it has no idea where the switch is.
You can very easily move the gantry by hand close to the endstops and use a slower home and lose nothing but a second or two. No need to make it home from the far side of the build.
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Or depending what is easier, you can jog over at full speed until you’re close to your home position. Mark off increments on your rails and you would know the distance to home accurate to within say 10mm and move that much before homing.
I can do those, but the object is to make it automatic. I think I know how.
I had fitted a pendant as decribed in Thingiverse by Slavulj,
so feel I can add a second microstop working through the Pro Mini Arduino, one which triggers a speed reduction, before the end stop acts. I’ll see if there is any arduino coding which might do the necessary - I have adapted the INO file to include hot end and bed on/offs since it is a 3D printer, just got to figure what to do with the end stopping.
If it can be done, it must be done!
How is it going to know it’s close to the end stop?
The end stop could act on the ramps board as normal, but also switch the pro mini to move at a slow feed rate for , say 2 to 3 more mm or so. I do not know the answers but figure there may be a solution somewhere. I’ll try experimenting but it takes a bit of time.
The normal homing behavior in marlin is to move toward home at full homing speed. Hit the switch and bounce back a set distance like 5 mm. (That is set in the config adv.h) Then do the actual homing at a much slower speed. Also set in adv config.
I suggest you use this setup. Keep the default faster homing speed. Then set your bounce distance to something you like. 3 to 10 mm. Then set the reduced homing speed for that final distance.
Thanks, I will do that as a starter.
I guess I’m not understanding what you’re trying to do. Once the stop is triggered, any more movement will crush the switch.
I was going to bend the switch lever out a lot! It’s flexible.
As is it should not hit the actual switch body. If it does a little bed would help.