This is my first personally written blog, so come with me as I learn this art. This is a guide to making better 3D prints. There are links off-site and other bits and bobs we have learned over the years. Please note we can not control the off-site content.
So in this picture you can see the print is pretty clean considering it was printed on a STD Anet A8 plus. So it shows a cheaper printer can preform well if set up carefully.
Through this blog, I am not going to take you through every mistake you can make. Just the ones I have documented over the years of running the print farm and working with clients on their machines.
Z-wobble in only one axis.
This is an example of one of the trickiest things we ever came across, it was on an Anet E16 large bed printer.
Z-wobble only in the y-axis plane. Please look at the image below, here you can see the y-axis is the direction the bed moves and the Z-axis is the plane of the table. Normally when you see Z-wobble it is in both the x and y planes which is why this one made the post.
In this case, the problem was the bed on the printer was tightened too much on the bed leveling springs. The way this was discovered was a runout meter was moved over the bed of the printer and readings of the surface were taken at various points and mapped out. From these readings, we could determine the bed was bulging in the center. This was putting extra stress on the linear bearings and causing the whole y-axis to stick and torque around the sticking bearing.
Loosening up the bed leveling screws and adjusting the limit switch instead of using the bed leveling springs to change the nozzle height. a moveable limit switch is something we recommend in general as an upgrade to any printer, you can see this in our recommended upgrades post soon to be added.
Blob sculpture on the tops of a print.
In this case, the print had gotten stuck to the nozzle and stopped the printer from being able to move in the x and y-axis and so while it continued to extrude it created a blob that encased the nozzle.
It was sufficient to speed the print up by 50% on the last few layers. This meant the nozzle moved more quickly over this section and so did not get stuck to the surface. This is a balancing act and sometimes to achieve enough cooling on a slender part you may need to have a wipe tower.
Bottom of the print is not flat
The bottom of the print is not flat
Depends on how far you need to go with this one but normally you find that the bed is clearly damaged. There is also a chance you can save it by facing off the AL build plate again if you have access to a mill or grinder, but most people don’t have access to those kinds of tools.
Replace the bed or cover it with glass or an ultra base. The glass can be purchased very cheaply from a normal window glass shop. Please be careful not to cut yourself as these shops usually break the glass and don’t grand the edges round and smooth.
Infill on the outside
The infill was showing on the outside of the material.
The surface of the print was showing the internal strcuture of the print.
Changing the slicer settings. In Cura the wall thicknesses were too small, they were increased and it fixed the problem. The setting was also changed to adjust to print the edge before the infill.
Stringing, all those little fluffy bits.
The print has strings that go from an area where the nozzle lifts off the part and onto another part of the printed surface. This is not straight forward, there are multiple reasons for this:
1. The nozzle is too hot. (Picture of the valve)
2. The printer is not retracting the filament fare enough.
3. The filament is of poor quality. (Picture of the beetle traps above)
This is one of those things that takes a little trial and error. The solution to the diagnosis above by the same number below:
1. The nozzle temperature should be reduced.
2. The printer retraction settings should be changed in the g-code generator. This one is not always simple, more and faster retraction should be better, but there are limits. The material is no-Newtonian in the melt zone and so there is a magic window. This for me using our PLA is about 40mm retraction at between 40mm/s and 60mm/s.
3. Change the filament. I hate this one, the material is not free and any waisted plastic is a hole in my heart. But this is one of those things that if you have a bad roll of filament can turn your printing experience from a feverish addiction into a nightmare.
There are levels to this one and the reasons for each of the problems. So I will give them and hopefully a solution for the right one.
1. Poor quality filament.
2. Bad extruder nozzle. The nozzles sometimes are not assembled correctly. If this is the case the filament stick in the nozzle and you will not get a continuous stream of filament. This one is pretty rare but I have seen it.
3. Bad thermal regulation. If this is the case the filament will burn and clog the nozzle.
4. Filament expanding in the extruder throat. If this is the case the filament will expand and clog the throat normally because there is not enough cooling on the heat break.
1. Change the filament.
2. Change the nozzle.
3. Ensure the extruder hot end is properly assembled.
4. Ensure there is enough cooling on the heat break. Make sure the fans are all working before changing the hot end for a new one.
Wobbly layers in Prints
The thread on the screw is not tightly toleranced enough.
The edges of the prints are poorly toleranced and the layers are not laying directly on top of one another. The reason for this in this case was the belts were not tight enough. The funny thing about this was that this modification was to fix the problem.
Tighten the belts in the x and y axis, when they are too loose the introduce backlash into the system. Also add belt tensioners were and when you can. Anything that makes tightening up the belts easier is a great thing.
The stepper motor does not step the number of steps the controller ‘thinks’ it has stepped. The controller has no way of knowing where the printer actually is, you home it and then it prints. The open-loop nature of most printers is part of the issue here. The stepper motors have distinctive steps and if they don’t step a step and instead step 2 when they should have stepped 1 or they step 1 when they should have stepped 2 you get what is knows was missing a step.
The layers don’t line up at all and after the incident the print prints relatively normally. Reasons for this happening:
1. Printing too fast.
2. An obstruction.
3. Belts too loose.
4. The belts are too tight.
5. The motors are not strong enough.
6. Cables are not well connected.
1. Slow the print down. The motors can only handle so much change in inertia at once. If this doesn’t work then you have to look at .4.
2. Don’t put things in the way. I have done it, I have seen it done.
3. Tighten those belts.
4. I know I just said those belts have to be tight in the last problem solving, but not a guitar string, remember they are timing belts.
5. Get more powerful motors or drivers, this one needs some analysis, most machines on the market are well-tuned and the engineers have designed them with inertia calculations and spent a lot of time building the control boards to work with those motors. If you are working with an older machine you probably have motors that are larger than on the newer machines, so then look at the driver currents and how much the motor is rated for.
6. The machines vibrate like crazy and over time cables work loose!
Also remember to be Kind to your machine, just because it can doesn’t mean it should be doing the work it is doing!