Large blob on wipe tower  

RE: Large blob on wipe tower

the standard operation with M600 is... 

Model prints to colour change layer, using the first colour, 
M600 occurs. 
Printer finishes queue'd moves, then movesextruder to the front right hand side of the build area and unloads the filament, or requests a manual unload... 
the user removes the filament, confirms success, then the printer requests insertion of the next filament. 
Either Auto load, occurs, or the printer requests manual reload, again depending upon how the printer is set up. 

Normally, the printer then feeds the new filament through the nozzle and asks if the colour is clear... 
you can answer 
not loaded, not clear or yes...(If I remember correctly. )
At this point there is usually a length of waste filament hanging out of the nozzle. and the temptation is to remove it, and click Yes, to continue... 

then just to wind you up, the printer extrudes another squirt of filament, as it progresses back to the print area
IF you can hold yourself in check, and simply grab the waste, then click yes to continue, the printer will extrude the short length of waste filament, which will remain attached to the waste that you are holding, and pull off the nozzle as the printer returns to the model. 
(this saves you having to chase the waste filament with tweezers or pliers... )

BUT... you are using the waste tower, so I suspect the blob, is the additional squirt of filament mentioned above... 

I disable the waste tower if I am doing manual filament changes. you might choose to do the same

regards Joan

RE: Large blob on wipe tower

Hi Cornmeister, any luck with solving the blob issue? I have the same exact problem as you, I don't think sitting at your printer for 7 hours and doing a manual change of filaments is the answer... Thanks very much in advance!

Posted by: @cornmeister

Hi All,

I've just started creating multicolour prints, Mk3s+ without MMU,Every time I resume printing after a filament change (M600), the printer drops a large blob of filament at the wipetower. 

https://imgur.com/6nFCSeP

Why is the printer doing this ?

RE: Large blob on wipe tower

Same problem here... when then nozzle its the blob, it stops with a collision error... 

RE: Large blob on wipe tower

Posted by: @cornmeister

Hi All,

I've just started creating multicolour prints, Mk3s+ without MMU,Every time I resume printing after a filament change (M600), the printer drops a large blob of filament at the wipetower. 

https://imgur.com/6nFCSeP

Why is the printer doing this ?

have you had any luck figuring this out? i am in the same boat. i get the huge blob while using the wipe tower. 

RE: Large blob on wipe tower

That's the printer letting you know who is in charge,,,    Lol... 

with an M600 colour change the process seems to be:-

the printer runs normally until the position for the colourchange, where it moves the nozzle to the front right side of the build plate, and raises Z a little, Then it Beeps to attract your attention and instructs you to press the button and remove the current filament. 

You comply and the filament is fed out into your hand...   
Now if I recall correctly it asks you to confirm that the filament is out, and to insert the new filament and press the button... 
You comply and the printer grabs the filament and feeds it towards the extruder,   
If all is well, the new filament flushes the old filament out of the extruder, and causes a wormcast on the build plate or a dribble of filament in mid air, depending upon how tall the model is... 
Beware, this is the Printer Teasing you... 
The printer will ask if the colour is clear, and give you the option to extrude more filament if needed, and It will ask you to press the button to continue, if all is well... 
At this stage there is an almost impossible urge to pluck the waste off the nozzle...   

Resist the Urge...    trust in the 'Force'      and simply hold on to the waste... 
Press the button with your other hand. and the printer will insolently squirt another length of filament out, before returning to the model... 
If you have resisted temptation, this extra squirt will be attached to the waste that you are holding, and the nozzle will pull away, leaving it behind. and all will be well. 
On the other hand, 
If you have fallen for the temptation and removed the waste, the printer will still squirt out the extra filament in defiance, and the extruder will run away and dump this waste in the most awkward place... 

this is caused by the Marlin Firmware priming the nozzle for you... 
Another irritating feature of the firmware is the nozzle returning to the last point of the print, and touching the  nozzle to the existing print

this often causes a little 'Beauty Spot' on the previous filament surface, which is another irritation

Marlin Firmware does have a supplementary command   M600 N

https://reprap.org/wiki/G-code#M600:_Filament_change_pause

But this does not appear to work with the Prusa Mk3 series printers... never tried it with a Mini, or the newer printers...
I now do the colour change one layer higher than normal, so that the touchdown position for the beauty spot, is under the print area of the new colour, and the beauty spot is never seen.
regards Joan

RE:

Very frustrating problem. If I recall only one setting needs to be changed to prevent this. 

When you added your multiple extruders under the printer settings, tab a new item is added, "Single extruder MM setup. There is a filament parking position setting that defaults to 92mm.  Set that value to 0 and see what happens.  

RE: Large blob on wipe tower

Try this setting. Worked for me. With and without MMU.

Let me know if it works!