Slamming bed after print

[Pavel]

Hello MakerGear Users,

I am a complete rookie in 3D printing (4 days with a 3D printer). I like M2 very much and I already printed out a few prototypes for my side projects. The problem I keep running into is that the bed slams down after each print and, I think, causes the printer to un-home Z-axis. Is there a g-code sequence that slowly brings down the bed?

And a related question - do I need to put a nut on the homing screw to keep Z axis always at the same level?

Thanks

[jimc]

some of the guys here do have an ending gcode to bring the bed down. some other put a rubber grommet on the threaded z-rod above the z axis stepper. some one will chime in im sure on their code. you do need a locking nut on your z-stop bolt.

[Toby]

Welcome to the fun!

I have a simple end script to deal with the problem of bed free-fall:

Code: Select all

M104 S0 ; turn off extruder
M140 S0 ; turn off bed
G91
G1 Z1
G28 X0
G90 ; absolute mode
G1 Z198 ; get lower before cutting power
G4 S10 ; pause 10 seconds
M84 ; disable motors

This takes the bed down to within 2 mm of the bottom, then pauses for ten seconds in case you're around and want to lower the last little bit by hand after the motors quit. I've been meaning to add some cushioning as well, but this works pretty well and I don't have a problem with the bed being knocked out of alignment any more.

There are much more involved end sequences. I believe Dale's is the gold standard in that department, and IIRC it's been included in the M2 tips thread here: viewtopic.php?f=3&t=12

There's lots of other useful stuff in there as well.

[Dale Reed]

Toby,

You are too kind. I did try, however, to comment the code so people can understand it without having to go to the RepRap wiki G code page (http://reprap.org/wiki/G_code) to manually parse it.

Pavel,

Here's a link directly to the G code in question: viewtopic.php?f=2&t=10#p94 . There are various parts of it you may find useful. It retracts the filament out of the hot end and filament drive. It turns off the heat to the hot end and the heated bed. It runs the bed fan full speed, then moves the extruder and fans back and forth along X several times to cool the part and bed. It runs the bed out to about Y max to "present" the part to you, and it runs the bed down to about Z max before turning off the power to the fans and motors. It's designed to finish printing a part unattended and leave the machine in a "reasonably" low power state. (If you want to go even further and wire up a relay box to control power to the M2 to completely shut it off when done printing, check out viewtopic.php?f=9&t=238 ).

Finally.... Toby: You stole my line!!!! Hey, Pavel! Welcome to the fun!
Dale

[Dale Reed]

I guess you can't go wrong with PS3, Adidas, Oakley and NASCAR... except on this fine forum!

Too bad I don't know phpBB -- I'd offer to help moderate this stuff into oblivion.
Dale

[Pavel]

Dale and Toby,

Thanks for your advice! I am back at it and I will try suggested end codes. I am currently using one of the codes from the "Getting Started" thread, but I guess I messed it up or something.

I am excited to try it all today.

[Capt. John]

Second the motion on adding moderators. Pretty sure that was a bot sneaking in.

I use S3D and the bed comes down kinda fast, but no slamming.
My April purchased M2 has a this rubber washer on the z axis rod.