So you have got yourself a Prusa i3 kit? Well I have a had a Prusa i3 for a little bit now and worked through most of the issues. So I will go through most of the issues I encountered and show you my solutions to to fixing a prussa i3. Keep in mind that every Prusa is different and that my solution might not be the best one, so feel free to offer your opinion in the comments. This guide is aimed to help some people very new to 3D-Printing.
Weird Ovals instead of Circles – fixing a prussa i3
So this is a problem which seemed so obvious to me once I realised it however when I was a noob at 3D-Printing I didn’t realise the problem. I didn’t find anything on the web about it either so hopefully this will help someone who is new to 3D-Printing.
So the problem was that whenever I tried to print a circle it would turn into a weird oval that seem to point diagonally. This was very annoying and I didn’t understand at the time what the problem was. It would also affect other shapes but was most apparent in circles.
Well the solution was so frustrating obvious when I realised it. I had to make the X and Y axis exactly perpendicular (90*) to each other. This means that I had to adjust the metal threaded rods and nuts to move the main acrylic/metal/wood frame parallel to the bed. The way I did this was placing a strip of masking tape/painting tape across the printer’s bed. The tape will need to parallel to the X axis. Then you want to use a set square to make a line across the tape and the bed, this line will have to be very precise. Then you want to align the hot-end to the line and move the X axis. So from that you can adjust the X frame to make the hot-end follow the line. This should now fix your circle issues.
Z axis Home – fixing a prussa i3
So I found that I had to adjust my Z home constantly. This was as the home switch would move constantly whenever the Z axis tried to home itself.
So the solution to that problem is to find a new clip to securely clamp the switch down so it doesn’t move when the Z axis hits it. You would want the clip to have a hole for a nut and bolt so you can tighten it down. Then I recommend to make a little small hole in the printed part that rides the Z axis to insert a nut with two bolts on either side. This will allow you to adjust your Z axis home easily and securely. This has made my Z axis homing much easier and much more reliable.
Cable Management – fixing a prussa i3
So my Prusa kit came with no way of managing the cables from the Ramps board to the extruder. A simple yet affective and in my opinion a visually pleasing addition to any printer is a cable. chain. I used 20 links on mine which I sanded and broke in by moving them each for a couple of minutes so they move freely with no resistance. You can install it by gluing it or zip tying it, then I secured the cables going from that going to the Ramps board with metal cable ties that you get with electronics packaging. This cable chain keeps the cables safe and stop them from bending too much which should hopefully prolong the life of your printer. If you don’t feel like printing a cable chain out you can buy a cable sheath which is a fabric or plastic that goes over your cables to protect them although I personally think a cable chain look better.
Z axis Wobble and Inaccuracies – fixing a prussa i3
When I started printing I noticed that I sometimes my layers would randomly shift or move at set intervals, either way it wasn’t right and needed to be fixed. The first thing I looked at was whether the motors were loose and surely enough they were. The bolts provided were too long as they would hit the bottom of the stepper motor screw hole and would allow the stepper motors to shift up and down in during a print. I used a couple of washers to make up for the space as I had no shorter bolts and they worked a treat and fixed all my Z axis issues
Now you may still experience issues but don’t worry there are still more fixes. The first thing you may want to try is to print and install a new nut holder to ride your threaded rod. You can try this anti-blacklash file on thingiverse by Tech2C here. In this you add two nuts per threaded rod and a spring in between them to keep constant contact with the threads. This may solve your issues or you could try another one on thingiverse.
If none of these methods work you may want to check your Z axis threaded rods to make sure they are not bent, this you would want to check first. If they are you may have to replace them or you could try to bend them back but replacing them should work better. While you are at it check your stepper motors to make sure their shafts are straight and not bent as this may also be a contributing factor. Your coupling should help if the shaft it bent but you may want to replace it if you deem it necessary.
So I hope I have helped some of you with some early teething issues of your Prusa i3. Some of your problems may not be here but these are the ones I had and that I fixed, and it is possible there is a better solution to a problem so feel free to express your opinion in the comments. After all these problem I have really fine-tuned the printer and it’s printing really well now:
Another issue that I have seen is that the threaded rods can strip over time, especially if the bolt that they are in contact with is of a harder metal than the rod itself.
I prefer threaded rod made from steel and the nuts made from brass.