Not long ago, I purchased a da Vinci Jr. 1.0 3D printer from ebay. This printer was being advertised as “For Parts Only” with no real description as to what was damaged on the printer. I decided to purchase it in order to take a shot at fixing it. I purchased it for about $110 with one day shipping, and as you will see, the printer was fairly easy to fix.
The main issue that this printer had when I acquired it was that the machine will only give the user an error code (which I am unable recall at the moment). This error code is usually displayed when the machine has an issue when it boots and tries to home the X and Y axis, but is unable to reach the optical end-stops. The whole homing procedure at startup is not very good, mainly because it could potentially crash the printer if there was a print left on the bed of this printer. Nevertheless, I inspected the printer in order to find the issue that was causing the error.
After inspecting all the axis of the printer, I found that the movement of the Y Axis carriage had little to no resistance. This tend to not be a good sign and it could be either one of two different issues. The first issue that can cause this lack of friction is a loose pulley on the stepper motor, if the pulley on the motor gets loose, it can lead to the pulley rolling on the shaft of the motor, which removes the friction provided by the stepper motor. The second issue that can cause this lack of friction is the carriage being detached from the belt system. If the carriage is detached from the belt, it will freely move on the rails without the friction provided by the stepper motor.
In order to get a closer look at the Y carriage system, I had to first get to the lowest part of the carriage, which rides on the bearings and attaches to the belt. In order to do this, I had to remove the four brackets that held the glass plate in place. Each bracket has a single screw that is fairly easy to remove.
Once the glass was removed, I also removed the three screws which attached the top metal plate of the carriage to the lower plastic part of the carriage. Once this metal bracket is removed, we are only left with the lower plastic bracket.
In order to get access to the lower part of the carriage, I removed the upper part of the carriage cover. This cover helps reduce the amount of dust and other particles that can get to the linear rods and bearings of the axis. This plastic bracket can be fairly tricky to remove, it is attached with some plastic tabs which can be very fragile. To properly remove this bracket, one must disengage the tabs attaching it to the lower bracket and pull the top bracket upwards.
From this view, we can already see that my second theory was correct. The belt is not attached to the carriage at all, and this was because the small plastic part which held the belt on the carriage snapped. To fix the issue, we will need to remove the bracket and find a simple way in which we can attach the belt to the carriage.
In order to remove the carriage, we must first remove the rods on which the carriage rides on. To detach these rods from the plastic lower bracket, we need to remove four screws, two in the front of the bracket, and two in the back, close to the where the motor and optical endstop reside. Once the screws are removed, I proceeded to remove the two rods from the lower bracket and slid out the carriage from the rods.
There were many solutions which could have been employed to solve this problem, I decided to go to the simplest one that I could think of, make a hole at the back of the part that held the belt in place, and then use a zip-tie in order to clamp the belt against this part. I drilled a hole with a 4mm drill-bit right above where the top of the belt would be located. This would allow the zip-tie to rest above the belt and keep the belt properly aligned.
This solution ended up working fairly well and it allowed for the belt to be tightly attached to the carriage. The Zip-tie was also trimmed to size to not interfere with the belt. Zip-ties are fairly common in 3D printers, a lot of DIY printers tend to use them to hold belts in place, as well as hold linear bearings in place, while allowing some small amount of play on the bearings to reduce binding.
After performing this fix, I powered on the printer just to find that it now homed properly all the axis and the error code on the LCD of the printer was removed. At this point, I put the whole Y axis back together, in the same manner as it was disassembled before.
After fixing this issue, I was able to access all the menus on the 3D Printer. One interesting that I found was the lifetime of the 3D Printer, turns out it had only been used for about 100 hours before it was sold, this is quiet a bit of printing time, but not as much as some of my printers have.
Although this is a fairly well built 3D Printer, most of the system is proprietary. This 3D Printer requires filament which can be only purchased from XYZ, the manufacturer of the printer. The printer also requires the use of their own slicer software, which does not have a Linux version available. Because of these limitations, I was unable to print anything in order to test the printer in order to make sure that it works. However, I did end up changing all the main electronic board of the printer for an MKS gen 1.4, as well as an Orange Pi in order to use Octoprint to print remotely. A tutorial on how I performed these modifications will be posted fairly soon.