Botfarm issues
So I run a small botfarm to print out parts for an open source project that I run. My previous printers were Taz 5s but I have purchased two MK3s (one was a kit, one pre-assembled) and initially was incredibly pleased, so i actually moved to PETG. I printed for about 200 hours each with PETG, getting consistently good results. Just cleaning the bed with windex between prints. In the last week things have been getting pretty bad... I have been having 3 issues:
+ inconsistent z offset - I find myself having to frequently change the z offset. I go vary ~.1 offset print to print.
+ offset layers. I get a few layers in then get offset layers.
+ Tearing - this is a less frequent issue, but I have been seeing it.
I am wondering if there is a maintenance step that I am missing? Or if there is some other issue? I read a bunch of the other posts, like bed leveling etc... but what bugs me is that I got 200 hours of good printing out of each printer before the wheels came off.
Re: Botfarm issues
Thought about replacing your nozzle? A wearing out nozzle can cause your symptoms.
Re: Botfarm issues
I had not considered that... but at 200 hours, I would assume the nozzle would be okay? would that cause the z axis issues?
Re: Botfarm issues
This is consumer FDM printing, never assume anything 😆 Mine starting giving me trouble well before 200 hours.
As for z axis issues, if you are seeing uniform displacement of layers (a definite and consistent layer shift) then perhaps not. If the layer shift is irregular then quite possible.
But if you are getting ripping, blobs, slight blockages, issues with first layer etc then these could all indicate a worn nozzle. The fact that it's been getting progressively worse, and you haven't changed much else is another sign.
In any case, nozzles are cheap and easy to replace so give it a go. If it turns out that the nozzle isn't the culprit you haven't really lost much.
Re: Botfarm issues
I guess, since you have two machines and it's fairly quick to do, you could perform a firmware reset, redo a complete calibration, make sure you are at the latest firmware level etc, on one of the machines. It's a bit like "turning it off then back on again" but it can't hurt 😉
Re: Botfarm issues
Thanks, that is good advice. Do you recommend a replacement tip. I see people talking about ruby tips and nickel plated tips...
Re: Botfarm issues
Nickel plated copper with its low surface resistance and high thermal conductivity is intended for use on high temperature or flexible filaments. In either of those two situations it is the best one to use. As you are printing PETG in a commercial setting I would avoid the nickel plated copper nozzles. They are great and the PETG flows better with more consistency but they come with a drawback. As copper is a better conductor of heat than brass even at a lower print temperature the exterior of the nozzle runs hotter and really attracts PETG. For example with a brass nozzle and aluminium heater block with sock I could print a first layer at 10mm/s no problems. To get the same consistency with the nickel plated nozzle and block combination my first layer speed is now 5mm/s and the sock is absolutely essential to prevent first layer ripping. However once passed the first layer you will be able to print at lower temperatures and push the speed on infill. Also I spoke to E3D at wear rates on the nickel plated copper and it is only slightly better than the brass ones. So you would be paying just over twice as much for a nozzle that at most would last 10% longer meaning your running costs would be almost double.
From what I have heard the ruby nozzles tend to give a slightly rougher finish and have a higher back pressure on the extruder as well as reduced heat conduction at the tip. So they have to be run slightly hotter and slower. Their main use is if you are regularly switching to and from abrasive filaments. However with the reduced tip temperature they should be able to lay down a PETG first layer faster as they would be less prone to ripping. Also they would be very long lasting and regular scheduled replacement should not be needed for a PETG print farm.
A hardened steal nozzle will defiantly last a lot longer and even with it being 3 times as expensive as brass the nozzle maintanence costs are less. However it is not as a good conductor of heat as brass so you will have to raise your print temperatures and the maximum volumetric flow rate will reduce meaning slower infills. It will however be likely to print a first layer faster than a brass one due to its poorer thermal conductivity giving it a lower external temperature.
In conclusion printing mostly in PETG in a commercial setting a brass nozzle is the best to use and change it every 180 to 190 print hours to maintain print quality before it wears out to much.
Regards,
Martin
Martin Wolfe
Re: Botfarm issues
I would stick with the standard brass nozzle, for most (if not all) filaments. They give the best heat transfer per unit cost. There is nothing special about printing PETG either.
There is another discussion going on at the moment about the Ruby nozzle, with not so many flattering comments. And added to that the cost I wouldn't bother with it at all.
The good old brass nozzle will wear out a lot more quickly than the hardened nozzles when printing composites (like carbon fibre, wood etc) but I have printed some stuff with both filaments and the nozzle still appears in reasonably good shape. When it finally "lets go" the fix is easy and cheap. 🙂