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Pindaprobe during printing  

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strafplanet
(@strafplanet)
Active Member
Pindaprobe during printing

Hi,

I received my MK3 a few days ago and from the first print on, while eating the Gummibärchen and watching my first 3d print I only had successful prints.

However, I generated a small case for a fridge magnet with little pockets to accommodate the actual (quite strong) magnets, which I inserted during print. This worked in general, however the accuracy is less perfect than without the magnets inserted.
I'm wondering if that is just an effect of the time I interrupted the print and inserted the magnets or if it can be an effect of the strong magnetic field to the Pindaprobe or the printhead while finishing the layers that cover up the magnets pockets.

I guess that the Pindaprobe is responsible to measure the bed geometry before printing and I think I read somewhere that it is responsible for the first layers to be accurate, but does it measure anything later in the print?

Posted : 07/03/2018 2:26 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Pindaprobe during printing

Pinda probe only measures bed height during 9 point bed levelling, after that it is redundant.

Live 'Z' adjusts the Pinda sense height to provide the optimum extruder height based on the Pinda sensing.

the Pinda operates at a distance,greater than the extruder, so you use LiveZ to resolve the issue.

the PINDA MUST be higher than the extruder, otherwise it will snag on the model as it prints...

the absolute Live Z adjustment value is a function of the Pinda Sensitivity and the Pinda height above the extruder.

if your Pinda is a bit low, then your live 'Z' will have to be a larger number in order to give the ideal extruder height. but this is at the risk of curled prints hitting the pinda Probe... during printing

If your Pinda is a bit high then your Live'Z' adjustment will be smaller. which reduces the liklihood of the pinda striking curled print elelments,
if the Pinda is very high, there is a chance of the extruder scraping on the print bed before you have chance to do Live 'Z' adjustment

Live 'Z' changes between different filament types on my printer, so I like the Live'Z' to be in the region of .300 to .600 with PLA, so that I can adjust it for PETG without issues...

In the case of your Magnet pockets, it is likely that the pocket depth is different to your magnet thickness. so it's possible that your model is sinking in the area over your magnets.
Ideally the magnets should be as close to the bottom as possible, and as far away from the top surface as possible.

if there is sufficient height above the magnet pockets, the model will even out the surface level, increasing the number of top layers may help here...

NOTE! if the height above the magnet pockets is say 0.6mm and your layer height is say 0.2mm it doesn't matter how many top and bottom layers you specify, you will only ever get a maximum three layers over the magnet pocket...

however assuming a layer height of 0.2mm, if your magnet pocket top, is about, say 2.5mm above the build plate and the model top is about, say 3.1mm above the build plate, it is unlikely that you will get three layers covering the magnet pocket, because the multiplications of the layer height do not match the model dimensions, so the slicer is likely not to print the top of the magnet pocket, or the top of the model, where you expect them!

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 07/03/2018 3:53 pm
strafplanet
(@strafplanet)
Active Member
Topic starter answered:
Re: Pindaprobe during printing

Hey Joan,

thanks for your help, that's a lot of very useful information and it answers my question thoroughly!

Chris

Posted : 07/03/2018 8:10 pm
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Pindaprobe during printing

Thanks Chris,
good to be of assistance!

regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 07/03/2018 10:11 pm
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