z travel speed

[alaris2 1]

has anyone played with this setting? the 3mm seems conservative but what range of values makes sense? I'm assuming 500mm/s is out of the question

I tried 5 already but didn't see any real difference..

[Daid 306]

The firmware limits this to 5mm/s.

It can reduce the Z scar a bit, but it's not that important as a setting. However, some machines are experiencing missed steps at the Z at some speeds, so then it's important to lower it.

[rewolff 0]

If the X and Y motors can do 250 mm/sec, why can't the Z-motor?

The answer is that the Z-motor has a different "transmission chain". For a revolution of the X motor, the extrusion head moves 10 teeth at 2.5mm per tooth or 25mm.

The Z axis is different. For a full revolution of the motor, the platform moves down one thread on the big driveshaft. I haven't measured it, but it's about 2 or 3mm.

But if the X motor can do 250 mm/s, it will be doing 10 revolutions per second. So why can't the Z-motor do 10 revs/sec? That would come to 20-30 mm/sec for the Z axis. That would be useful to reduce the blobs tenfold... :-)

I can understand that when it has to push the platform up it can't achieve such high speeds. So I'd be happy having it limited to 5mm/sec in the Z- direction, but a limit of 30 in the Z+ might be useful....

[Daid 306]

People have experimented with 10mm/s but then they had missed steps in the Z direction which is pretty bad for your print.

You are free to set a different max feedrate in Marlin, you can use M203 Z... to set the max feedrate. And use M201 Z... to set the acceleration. Default acceleration is 100, default max feedrate is 5.

The weight of the platform is what keeps the feedrate low, as lots of weight it is harder to move it (Ask Newton for details). But I think if you tweak the acceleration right you can achieve higher Z speeds. However, for the Z blob I don't think it will help because that move is very short and it might never reach full speed.