Problem Prusa i3 Mk2

[GONO3D]

Hi all !

I have a problem with my printer and I’m not able to find a solution…Printing at 100µm, tempreature 210c, Red PLA, speed 45mm/s, original Mk2.

See attached pictures.

1st print is OK, 2nd print the cylinders are under extruded from the middle and 3rd print from the beginning.

What’s happen ?? Why only the cyclinders become under extruded ?

Thanks all !

David

[Garyg]

Hi

My guess would be that your 1st print was started when your machine had a cold startup.

Your 2nd print was done without cooling your machine down for a few hours.

Your 3rd print was done immediately after the 2nd print.

Basically, you are printing too hot.

After several prints without shutting down your machine, things tend to get slightly warmer.

Printing small towers, like what you have in your design are somewhat difficult if the PLA is too warm or running

at too high of a temperature.

I see exactly what you have when my cooling fans are not set up properly or

If I run parts back to back without cooling down the printer.

…

Just my 2 cents worth

I have limited experience with PLA.

I usually print with ABS, nGen or PCTPE nylon.

I believe you really only have a temperature control issue.

[steveprinters29]

I think the problem could be the brand of filament you are using. Did you take the cylinder test? You should try this and see whether the operating temperature is appropriate or not.

If you are still not fully acquainted, better get a technician to assist you.

[GONO3D]

Hi Gary, Thanks for your answer and your good guess Ok I will try again with a cold startup…1st time I have this trouble I always printed big orders without cool down the printer. Thanks David

[GONO3D]

So I tried to reprint the part with a cold startup and it is working fine…This is still a weird thing It is only for prusa or all printers need to start when them are cooled ?

I have always used the filament I was using for this print and never had a problem. I think I have a pretty good filament.

Thanks for your answers

David

[Garyg]

Hi again

Small towers are always difficult no matter which material you are using.

With PLA - it helps lots to be sure your fans are running to cool the towers.

Another thing would be to try turning down the extruder temperature some.

…

I have a soda straw with a piece of cotton cloth taped to the end.

If I’m making something that has small details like your towers, I manually blow on the towers

through the straw on each layer to cool the material.

It’s very inconvenient, but that has worked for me on difficult 1 off parts.

…

Just another 2 cents worth

[cobnut]

Hi @GONO3D as others have said, I’d look at your temperature and cooling initially. PLA nozzle temps can vary quite a lot from manufacturer to manufacturer - I’ve some that print great at 195C, others that need 210C. I’d suggest 210C is possibly a little high unless you know that’s what’s needed for this brand, so try reducing by 5C at a time (using a test piece). Is your cooling at 100%, it should be for PLA.

I’d perhaps also suggest 45mm/s is a little quick for such detailed work, I rarely print above 40mm/s and then only with simple shapes. Try your test piece at 30mm/s and see if it works, then increase by 5mm/s until it fails (if it does).

I can’t really see how starting cold or hot will make any difference. The nozzle is preheated to temperature at the beginning of every print and while the bits and pieces of mountings, etc. will warm up from a cold start, after 20 minutes or so they’ll have reached a steady temperature. Printers don’t get hotter endlessly the longer you leave them running, so if this print job is anything more than 30 minutes long, the cold/hot start is irrelevant.

[wirlybird]

I agree on these notes. Along with speed I would look at retraction settings. They might be a bit aggressive for the detail work.

[GONO3D]

Hi all and thanks for your advises. I’m only printing the bottom of the part at 45 and after for the details the speed is 25mm. The problem is really the temperature. The head was too hot. 205c is ok. But I have tried the cold start up without changing anything and it works great…I’m a little muddled! Thank you all! David