Adjusting Z axis while printing??

While my prints are running, I've noticed that after a while, the nozzle slowly moves closer to the surface it it printing. During small circles, it actually hesitates every few mms on the horizontal. I think that if I could just raise the nozzle .3 mm while it is printing, it would solve the problem. It looks like the filament is causing the nozzle to stall, as there are little filament "balls" along the exterior wall of the print. Is there a way to pause the print, sent a G command telling the Z axis to move up and then continue printing? I've paused the print before and raised the Z axis, but when the print continues, the Z axis goes back to the spot where it left off. Thanks

Not sure about altering the z position while paused
But have you fine tuned your Z steps/mm, make sure that telling Z to move 100 mm actually does move 100 mm.

Which firmware are you using?

Repetier and marlin (I think Marlin supports this, I know repetier does) support something called 'babystepping' where you turn the dial and the print head moves up and down while printing. I find it a very useful feature.

Babystepping would work, and is easy, but to answer your question yes you can pause and then send G92 Z(current height-0.3). You don't even need to pause, assuming you're running off a pc/Octoprint just dial your speed back to 10% and send the G92 Z(current height-0.3).

This moves the coordinate system so that the firmware now considers itself to be 0.3mm lower than it should be. When you restart it moves up 0.3mm before continuing.

But +1 for checking your calibration, if after a reasonable number of layers your nozzle is digging into the previous layer then either your z calibration is off, or you are over extruding.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Cool, I'll give babystepping a try.

I'm using Repetier and Marlin, and I'm still not getting the result I'm looking for. While running, I've typed in G92 Z(current height-0.3). the extruder, just climbs up and the filament keeps going??? I'm using the Z axis indicator in the manual Control screen to determine where the nozzle is on the Z axis. It seems like there is a lag time or something, but I've tried it 3 times now, and all 3 times, it just seems to take off up the Z axis...omt, I'm using a laptop as I have yet to figure out how to make my 2004 Display work...

Edited 1 time(s). Last edit at 01/15/2017 01:14AM by Flyer.

Can you video what it's doing and YouTube it? When you say it climbs up do you mean 0.3mm or more?

Just to check are you sending literally G92 (current height - 0.3) or G92 Z99.7 (assuming current height is 100)? Sorry if this sounds like a silly question.

There will be a delay as there is a command buffer in the firmware it will take 2-3 seconds to respond thats why I suggested turning the speed down.

Babystepping is a better method as it just sends extra step pulses to the z axis to move up or down this is instant.

Edited 2 time(s). Last edit at 01/15/2017 04:57AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Thanks so much for the replies. I'm going to play around with it today and see what I can figure out. I'll set up a camera, and will take a few stills. I'm sure it is something simple, just can't wrap my head around it.

Quote
DjDemonD
Can you video what it's doing and YouTube it? When you say it climbs up do you mean 0.3mm or more?

Just to check are you sending literally G92 (current height - 0.3) or G92 Z99.7 (assuming current height is 100)? Sorry if this sounds like a silly question.

There will be a delay as there is a command buffer in the firmware it will take 2-3 seconds to respond thats why I suggested turning the speed down.

Babystepping is a better method as it just sends extra step pulses to the z axis to move up or down this is instant.

I'm sending G92 Z100-0.3 using the same example, When I looked up "babystepping" (and I'm using a laptop) it seems like I'd have to do a lot of editing of one of the Marlin files?? Is there a simple way to activate babystepping?

If using marlin - its in configuration_adv.h just uncomment appropriate lines, dont bother with babystep x and y its never needed.

Reupload, then when printing has begun, go to tune menu on LCD and turn the rotary encoder knob for up and down adjustment.

Edited 2 time(s). Last edit at 01/15/2017 02:13PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

No LCD, using laptop.....how to do with laptop?? Feedrate?? Flowrate??

No as far as I am aware you need a rotary encoder. Get your Lcd working it's not that hard just enable it in configuration.h you just need to uncomment the one line that refers to your Lcd and get the exp1 and exp2 cables the right way around, trial and error works fine here.

You're sounding a bit exasperated, don't worry it's a steep learning curve but you'll be an expert in a few months time.

Although please bear in mind what was said earlier if you're digging into the last layer after a while you're over extruding try turning flow down 1 to 2% or your z axis is lifting too little with each layer and plastic is building up verify your steps per mm is right and check your pulleys/couplers are not slipping.

Edited 2 time(s). Last edit at 01/15/2017 03:19PM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Install Matter Control and use the babystepping inside that, babystep right from PC, I dont remember needing anything set in firmware to enable it.

Master Control doesn't seem interested in communicating with my Folgertech i3.

Matter Control, Check com/usb ports/ change usb port, make sure its configured in all right places, but when you plug new printer in it normally runs through a little setup where you name printer, not sure if the folgertech is incompatible for any reason ie board?