Z18 levelling jig by luben111

Last crawled date: 3 years ago

Hello,
Few weeks ago I purchased Z18 in excellent condition for a good price (bargain) but in the same moment I joined the club of the dissapointed Z18 users. I have to agree - the printer mechanic is great - linear rails, isolated heat chamber, everything to the highest standards. But when you see the print results, you start to reconcider your purchase. The most obvious things which are concerning the quality are :

You can't print without rafts, Z18 is much slower compared to Replicator 2 but when you add the rafts + heating the chamber the print time doubles and tripples compared to my older and reliable Replicator 2. If you try to print without rafts - the filament doesn't stick to the plate and you finish with mess

Layers are shifted - I'm talking about small shifts 0.1..0.2mm in any direction. My guess is that this is caused by two reasons
a/ Z18 uses CoreXY configuration and the belt is probably 3m long
b/ the idler pulleys are smooth (no teeth) despite that the belt teeth are facing the pulley. Like result the teeth are pushing the idler pulley smooth surface and can introuce small legth variations of the belt tension
As an owner of Z18 the worst I found is the Smart Extruder - this is probably the worst combination of well made hardware with bad concept in the same time. Z18 Smart Extruder (also 5th gen printers) uses the nozzle to measure the surface level. Nozzle is not fixed to the body but uses spring and sophisticated mechanic to move up a little bit up and by using magnet and Hall sensor to detect the moment when nozzle touches the surface. You can imagine how small drop of filament on top of the nozzle will shift the levelling, Hall sensor is not that precise and nozzle can't return always to the same place .
The non perfect surface detection of Smart extruder affect the levelling of the build plate - what I found is that the build plate will have at least +/- 0.3..0.7mm difference between different points. This explains why MakerBot recommends for Z18 and 5th gen printers to always use rafts. I my not against using rafts in some cases, but there is something wrong if you can never print without rafts. And the solution to avoid rafts in Z18 includes two things:
B) Platform levelling should be done by using dial indicator attached on Smart Extruder place (instead of using the Smart extruder).
A) Use Z offset in the Z18 settings. Personally I use the Desktop software instead of Print because Desktop slicer is much better and Desktop brings access to some advanced settings. I found that whatever I did, the nozzle is about 0.5mm higher than it should be and only by using the Z offset I was able to bring the nozzle back to the right height.
After using A and B, now I'm able to print on Z18 mainly without rafts, I use rafts only for large objects where maximising the adhesion to the build plate is highly desirable.
About the Z18 levelling jig - it uses D10x8 magnets to attach to the Smart Extruder place, magnet holes have draft angle which allows the magnets to stay in place once inserted. Ensure the polarity of the magnets is correct when inserting them into the holes. I copied the Smart extruder design from another place and I found that positioning holes are not 100% precise - be aware that the jig will require little filing and tweaking before it fits in place.
The dial indicator holder STL and SLDPRT files are attached to the project.