Upgrading the Super Racer (hereafter called the SR) with the direct-drive LGX-Lite extruder really does improve the results the SR can produce. But there is a unique problem with making this upgrade that will render your SR inoperable when it happens to you. Note that I said “when”, and not “if”. What is this problem? Here’s a photo of it:
See that broken green wire? That wire broke off right at the edge of my LGX-Lite after about 6 months of printing. It broke because of repeated bending caused by the movement of the end effector from the printer’s home position to where it needed to be for printing. This repeated bending will break at least one of the wires sooner or later. The problem is even worse because fixing the broken wire is very difficult. The reason is that the extruder’s wires go directly into the motor’s armature. Consequently there is no connector to unplug the wires and plug in new ones because the extruder motor is so small there is no room for one.
What is important to know is that, once one of the extruder wires breaks, the SR will stop cold with a catastrophic error as soon as it tries to extrude filament. This renders the printer totally inoperable.
The problem is even worse because fixing the broken wire is very difficult. The reason is that the extruder’s wires go directly into the motor’s armature. Consequently there is no connector to unplug the wires and plug in new ones because the extruder motor is so small there is no room for one.
In discussing this problem with Bondtech I exchanged several emails with Jonathan Bondéus about potential fixes. Here is the key thing thing he told me (twice actually):
You can not have it like how you have it in the pictures you send, if you do not fix the cable somewhere, it will break again.
Fortunately I was able to remove the motor’s rear cover and solder a small piece of new wire to fix the problem, but doing this was very tricky and tedious and certainly not recommended.
The good news is there is a very quick and simple fix that will prevent this problem from ever happening in the first place. If your SR has an LGX-Lite configured as direct drive you should implement this fix right now. Don’t wait. My thanks to Jonathan Bondéus for pointing it out to me. It is surprisingly simple and easy to do. Here are 2 photos that show what the fix is, and how I’ve done it on my SR:
That’s it – this 30 second fix will prevent you from having to mess with the extruder motor’s internals – or replacing the entire extruder motor with a new one. If you are reading this – get busy!
21 Jul 2022
Edit: 24 Jul 2022
Someone on FaceBook posted a message with the following link that has a better, though more complex, solution for this problem. For this method you have to print a small STL file from the following link:
The ZIP file at this link contains several STL files for attaching to the LGX lite that provide the required strain relief. The STL I used is named soutien-cable-flsun-sr.stl. It sits on top of the LGX-Lite and looks like this:
Next, the hole in the printed part is too small for an M4 screw. So I used an X-Acto knife to make it a bit larger. Finally, the M4 screws I have are either too long or too short, so I used a longer one but backed it off with an M4 nut so just a few mm protrude below the bottom surface of the part. Fortunately this configuration works just fine and doesn’t look too kludgy.
Once the strain relief was attached it was easy to put all the wires through it, wrap and tape the results, and Voila! A nice, neat solution that works even better than the tie wrap one I described above. Here are more photos of the installation: