3D Printer Upgrades

 

CTC Dual printer, fresh from the factory.

I brought a very cheap 3D printer from eBay a few years ago. I was expecting it to be barely functional given the price that I paid for it, but to my surprise it wasn’t as bad as it might have been. The printer has been sitting on my desk for the last 2 years and I’ve been nursing it through the occasional print jobs that I needed to create. I’ve made one or two modifications to improve the quality, but it’s largely the same as it was when it came from the factory.

I’ve been spending more time making things recently, and I find that I’m relying on my 3D printer more than I used. A spate of failed prints, crashes, and other small frustrations made me realise that it was time to rebuild or replace the tool with something more reliable. I opted to rebuild rather than buy a new machine because it was substantially cheaper, and I would feel more secure about using a machine that I’d rebuilt myself. Here are some of the changes I made:

Basic Modifications

I printed some simple upgrades for the printer when I first set it up. I’d already added corner spacers, added a filament guide and a support bracket for the cables running to the extruders. I’d also printed a Z-axis wedge, to hold the Z-axis rails more rigidly in alignment and improve the overall stability of the print bed. The acrylic windows I’d fitted to the side of the case helped control the temperature in the print chamber, and reduced the noise from the fans slightly. I reduced noise further by redesigning and printing some anti-vibration feet.

Extruders

MK8 Drive block (image attribution: THRUIT00, Image shared under creative commons share-alike https://creativecommons.org/licenses/by-sa/3.0/)

I’d replaced the 3D printer’s extruder mechanism with a MK8 sprung lever extruder within a week of buying it, and it was one of the most important modifications I made. The stock extruder relied on a pressure from a PTFE block ti hold filament against the drive wheel. This arrangement was far from ideal, with filament prone to slip or jam in the head. The replacement MK8 spring lever applied more pressure and prevented slippage of the filament, while the lever release made it easy to remove the filament quickly or clear jams. However, after a long period of use, one of the extruders started under-extruding, and the issue appeared to be somewhere in the filament feed. It took me a while to realise that the grub screw holding the feed gear onto the motor’s shaft had stripped, and the gear itself -rather than the filament- was slipping on the shaft. Replacing this screw solved the problem and after I recalibrated the height of the nozzles, I had a printer with 2 working extruders.

Cable Routing

As I mentioned earlier in this article, the 3D printer occasionally crashed, and had to be reset. I thought at first that the problem was the length of USB cable I was using, so I switched to printing from SD card and the problem seemed to be solved. A few weeks later, the machine froze again, and I started to doubt my initial diagnosis of the problem was incorrect. The problem got worse over a few days, and eventually I found most prints would freeze the machine after a few minutes. After a large amount of jiggling and poking in the printer’s nether-regions, I found the problem was caused by a loose connection to one of the stepper motors. A few minutes tightening plugs and re-routing cables underneath the printer fixed the problem, and a judicious dab of hot glue made sure that the plugs couldn’t come loose again.

Swapping the Blue Tape for Glass Plate

Glass bed held in place with printed clips. A 3mm spacer is fitted to the bed to accommodate the glass thickness when homing the Z axis.

I’d been a fan of blue painter’s tape for some time, but it wore out quite quickly on the print bed, and it was sometimes difficult to get the tape flat across the bed. The heating and cooling cycle of the print bed made the tape wrinkle after a while, and occasionally the edges of the tape would curl away and snag on the head. I’d seen and heard good things about printing onto a glass plate, so I headed over to thingiverse and downloaded some corner clamps and a Z-axis spacer that could hold a sheet of glass to the bed. I used a 3mm sheet of borosilicate glass. After levelling the print bed and beginning a test print, the effect of the glass was clear. The bottom layer of the print adhered perfectly, and the layer thickness looked perfectly even. I purchased a box of alcohol wipes to clean the glass before printing, and I haven’t had a single problem with bed adhesion since switching to glass.

Reducing Noise

My 3D printer was loud, and most of the noise came from the fans fitted to the electronics. The stepper motor controllers on the printer were cooled by a 24v, side mounted 40mm fan, while the 24v power supply was cooled with an internal 60mm fan. Both of these fans were extremely loud, so I decided to replace them with something a little bit less disruptive.

The 40mm stepper motor controller fan was replaced with a 120mm 24v fan. The larger fan hung beneath the electronics enclosure, but the modified feet I used to reduce vibration lifted the entire printer by a couple of centimetres, and that was enough to keep the fan clear of the desktop and provide adequate space for the air intake.

The 60mm fan was slightly more complicated to replace, because I was replacing it with an 80mm 12v fan with a step-down voltage converter. I removed the existing 60mm fan from the power supply and cut a hole in the metal case to accommodate the larger fan. I fixed the fan to the outside of the case, just as I had with the 120mm stepper controller fan. Again, the anti-vibration feet provided the necessary clearance for the fan.  I headed back to thingiverse to create some appropriately sized fan grilles. The whole printer is so much quieter now that the fans aren’t having to run at full cycle to move enough air over the electronics. I’m considering replacing the extruder fans with larger versions, but the mechanics of that modification are substantial, and I’m too busy to think of doing it at the moment.

Internal Lights

Inside the build chamber, with LED strips visible in the edge of the shot.

I added 24v LED strip-lights to the inside of the build chamber. This made it easier to see prints without annoying shadows from the chassis obscuring the view. The lights were attached directly to the 24V PSU, and were held in place with hot glue. I didn’t care about being able to turn the lights on or off, and just assumed that I would always want them to be powered on. The current drain from the lights doesn’t cause a significant problem, and the lights themselves provide a visual reminder that the printer is running even when the workshop door is closed.

Other Modifications

I wired a 5v regulator to the 24v PSU, adding a USB socket to the back of the printer. I used a Raspberry-Pi running OctoPrint to control the printer, and the USB socket provided a convenient location to plug the Pi into. I added a Logitech camera so that I could monitor prints remotely. I made a mistake here, and I entered the workshop to be greeted by the smell of burning electronics. I’d used an inadequately powered 5V regulator, and it had overheated. I’m currently in the process of modifying the OctoPrint server to run continuously, and control the power of the 3D printer with one of the GPIO pins and a power relay. This will make it possible to turn on the printer remotely and start a print without even entering the workshop. I moved the spool holders from the back of the printer and mounted them on the wall nearby, using a handy print from thingiverse. I could have made something from scratch for this purpose, but I like the idea of reusing the existing spool holders by fitting a wall bracket to them.

With all of these upgrades, the 3D printer is running better than ever. I felt so confident about the newly refurbished unit that I brought simplify3D to handle my slicing. I am extremely happy with the software, and recommend it to anyone who does a lot of 3D printing. I haven’t had a failed print since I upgraded the system, and with the exception of burning out a 5V PSU, the whole process ran smoothly.

 

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