Bed levelling and other things to do on new printer or every so often.
I carried out the calibration tests etc on a new pre built printer and found it wasn't perfect out of the box.
Whilst this isn't a guide to achieve perfection, it is a quick guide to help new starters to 3D printing and will help get better adhesion and results.
When the Y axis was driven to the rear, as it collided with the stops the X would ever so slightly move a step to the right and when the Y axis was driven to the stops on the front the X axis would do a corresponding step to the left, these were tiny, but noticeable. Also the Skew was ever so slightly out.
I found the belt tensions were 107 Hz not 85 (I have a specialist belt tension frequency meter which measures down to 0.1 resolution). Now set at 90 +- 0.3, I expect the belts to stretch a little in the first few weeks.
The step to the left and right are no more and the skew appears to be spot on.
I lubricated the Z axis screws with the included lubricant as well as the rods, a lentil sized amount spread on the three Z axis screws then the Z axis run up and down a few times to spread the grease. You shouldn't have accumulations on the top of the plastic threaded part. A rice grain smear on the rods then run the axis so the grease gets spread along the rods, again there shouldn't be large accumulations in front of the bearing seals / wipes.
NOTE: DO NOT USE THE INCLUDED LUBRICANT ON THE LINEAR RAIL!
https://help.prusa3d.com/article/regular-printer-maintenance-core-one_829710
I carried out a first layer test print and observed the Z axis screws which were moving more than I liked, also the surface finish on the prints was a bit rough in places, which can be caused by the bed not being level, this appears more as a matt finish rather than a satin sheen finish.
So I raised the Z axis to 1mm and could see whilst moving the X and Y axis that the gap was varying, granted the bed levelling does a really good job of correcting for this, but it's always better to get things as level as you can.
NOTE: Make sure you can see what you are doing as the print head is close to the surface of the print sheet and can scratch / damage the surface if you drive the head into it.
Now using a business card or similar adjust the screws using disable motors from the control panel and turn the screw with your fingers until the card is just slightly being touched by the nozzle, move the axis after each adjustment using the control panel to check the level in three places nearest to each screw about 1 to 2 cm in from the edge, you can do this a number of times until you are happy the bed is fairly level rechecking the final position without any further adjustment.
As long as you don't turn a screw by hand or crash a print, this should remain level, but is easy enough to check and reset.
Now when you do a first level print you will notice the Z axis screws hardly move when the X / Y axis is moving in a continuous print and the surface finish is a lot more even across the print plate.
The first layer on mine printed at 0.2mm actually comes out at 0.21mm across the board checked using a good micrometer, on the textured plate this ends up being 0.25mm due to the uneven surface so just be aware when checking calibration for height use a smooth surface.
The build plate cleaning, you can and should occasionally wash the build plate using washing up liquid and hot water, just wet the plate, squirt some washing up liquid on it and use a paper towel to clean it and rinse thoroughly. Dry well with more paper towel then once it looks dry, place it into the printer and set the bed heating to 110 Deg for at least 15 minutes, this will evaporate any remaining traces of moisture off, this works especially well for textured plates.
Use IPA and paper towel between prints and avoid touching the plate with your fingers, but once adhesion becomes worse, just wash it.
The reason for this is that some PLA's actually contain sugars, well, they all do as this is what PLA is made from as this is fermented into Lactic Acid, but some raw sugar can remain and you can sometimes smell a sweet note when printing. Anyway, sugar does not dissolve in alcohol so ends up remaining on the plate so needs to be removed when it becomes a problem. If you decide to print with PETG, good luck trying to get it to stick to sugar, you must wash the sugar deposits away beforehand.
Normal people believe that if it is not broke, do not fix it. Engineers believe that if it is not broke, it does not have enough features yet.
RE: Bed levelling and other things to do on new printer or every so often.
Thank you for these tips, and for the bed leveling suggestion in particular. I have always been weary of relying on the software-compensated bed "leveling" only. (Disclaimer: My Anycubic i3 does not provide this luxury anyway, so I don't have personal experience with it yet.) It's reassuring to see that you have reached the same conclusion.
Your procedure makes sense to me -- but am I right to assume that the leveling will not survive a Z homing? In my understanding, the printer drives all Z motors into their physical end stops to define the home position, right? So the base plate of the printer becomes the new reference plane for the bed. One would need to add shims above the base plate (or somewhere in the linkage of each of the three Z nuts to the bed) for a permanent compensation of the leveling, I'd say.
RE:
There's actually three tapped holes in the base where a cap head screw could get screwed in and a locking nut used to set it to the correct height. So this could be used, it looks like it could have been used as some sort of transport fixings to keep the bed in place but was never implemented.
They are in the perfect locations really, Going to go look for some screws and nuts which fit and do this.
Normal people believe that if it is not broke, do not fix it. Engineers believe that if it is not broke, it does not have enough features yet.
RE: Bed levelling and other things to do on new printer or every so often.
NOTE: DO NOT USE THE INCLUDED LUBRICANT ON THE LINEAR RAIL!
It's crazy, I had issue with my X axis (resonance/vibration noises, and "clicking" sound when it moves) and Prusa support asked me to lube it with Prusa grease.
My printer is in its way back to Prusa for repare.
RE:
With linear bearings there are usually greasing holes (Sealed with a spring loaded bearing) into which you pump grease, this pushes out old grease and contaminants which you wipe away, then you are good to go again, so if anyone has greased their linear rail with the incorrect lubricant, just buy the approved grease and injector kit, wipe down the rail and refill the sliding bearing then wipe away what has been pushed out.
This is the way we have always lubricated these type of bearings although they are usually a little larger than the one found in the printer.
I cant see this being any different, lets see what the kit has and what instructions say when they are released.
With grease, it is a carrier often called a soap, which carries the actual lubricating oil and allows slow release as required. Mixing greases can result in this soap hardening or liquifying ruining its purpose, hence why you have to be careful with changing grease from one type to another.
Its a whole subject called tribology is lubrication and greases.
Normal people believe that if it is not broke, do not fix it. Engineers believe that if it is not broke, it does not have enough features yet.
RE: Bed levelling and other things to do on new printer or every so often.
NOTE: DO NOT USE THE INCLUDED LUBRICANT ON THE LINEAR RAIL!
It's crazy, I had issue with my X axis (resonance/vibration noises, and "clicking" sound when it moves) and Prusa support asked me to lube it with Prusa grease.
My printer is in its way back to Prusa for repare.
It's disconcerting that Prusa support apparently gives advice sometimes which is clearly technically incorrect or can even damage the printer. "Tension the belts differently to mask a skewed gantry" falls into the former category, and I am not sure whether "bend the gantry in place, using the Y axis linear bearings as counter support" doesn't fall into the latter.
RE: Bed levelling and other things to do on new printer or every so often.
Actually, the lubrication guidance for the linear rail may not be a case of bad advice from support. Misumi specify that small profiles should be lubricated by applying grease to the rail. Only larger profiles have a grease nipple on the carriage:
Lubricate the linear guide/lubrication intervals
To reduce friction and wear, linear guides such as the profile rail guides should be lubricated regularly. The lubrication interval varies depending on the application and ambient condition, as this depends on many factors. The general recommended lubrication intervals of the profile rail guides are in the range of approx. 6 months. For long strokes, the lubrication intervals are reduced to approx. 3 months or every 1000 km. Here, too, it is recommended to check the lubrication performance initially at shorter intervals and to adjust it to the existing operating conditions. Too much lubricant should not be introduced into the linear guide, as too much lubricant can lead to increased resistance and damage.
For smaller profile rail guides, such as miniature linear guides, the linear guide can be lubricated over the linear rail. For this purpose, the lubricant can be applied to the running surfaces of the linear rail. Structurally larger profile rail guides have a grease nipple to get the lubricant to the necessary areas.
RE: Bed levelling and other things to do on new printer or every so often.
There's actually three tapped holes in the base where a cap head screw could get screwed in and a locking nut used to set it to the correct height. So this could be used, it looks like it could have been used as some sort of transport fixings to keep the bed in place but was never implemented.
They are in the perfect locations really, Going to go look for some screws and nuts which fit and do this.
Hmmm, don't like the idea of putting loading off centre on the Z axis screw guides as this will apply uneven forces across the guide, so going to see if I can measure the difference between actual and manual bed levelling and see what these values are and then see what I can come up with, currently thinking something that is attached at a thin flexible end by these existing screw holes, but which sits around the Z stepper fixing screws and has grub screws to adjust height to get a nice level when Z axis homes against this but so the Z axis threaded parts sit flat on this leveller spreading the load evenly across the part.
It should be OK but always better to try and prevent deflection where it is not wanted.
Normal people believe that if it is not broke, do not fix it. Engineers believe that if it is not broke, it does not have enough features yet.