I have been running my Prusa Mendel 3D printer for almost a year now, and thought it to be a pretty good time to outline the kinds of repairs I have had to perform. Since I built my printer from scratch, the first six months involved lots of trial and error as I worked out the best components. I am going to call that all part of the construction phase and not really part of breakdowns and maintenance. If you are buying one of the awesome RepRap kits that are floating about these days, you are going to avoid most of this pain. Plus if you build an open source printer - you truly own it, and will develop the skills to repair it!

However after you have constructed your 3D printer and worked out how to use it, how often is it going to breakdown? I had four major breakdowns last year:

A photo of a broken computer power supply, and some busted 3D printed parts

Breakdown #1 x-end-idler

Most of the parts in my printer were made after getting a friends printer working, some of the first ever prints that I performed while also experimenting with homebuilt hot ends. The print quality was terrible, and the parts were weak. The [x-end-idler]( idler.png) started to show signs of fatigue almost immediately after installation. Towards the end, it was held together with cable ties and fencing wire while I printed a replacement. This was an important lesson. The very first thing you print? A set of replacement parts. That way, if you have a printed part fail. No worries, you have a set of spares on standby to swap in.

Breakdown #2 RAMPS1.4 power coupler

This was probably most worrying breakdown for the year. I had been printing for about 10 hours non-stop, a whole bunch of stuff for the Rise of the Machines print a robot workshop. I was away from my printer, and when I came back I had one mess on the build platform and a horrible burnt smell wafting from the RAMPS1.4 board. What on earth had happened? Reset the print, and nothing would power up and I couldn’t connect to the printer. Uh-oh. I thought the whole RAMPS1.4 and Arduino setup had been fried. After 10 minutes of that heart in my mouth, this is toast feeling. I found that it was the power coupler from the ATX power supply to the RAMPS1.4 that had shorted (the little green thing in the picture above). It had shorted so badly it had welded closed, I couldn’t pull them part. I desoldered, replaced the coupler and crossed my fingers, hoping that it hadn’t caused widespread damage. Powered it up. Phew. It was all good.

Out of all the breakdowns, I wish I knew more about this one. What caused the short? Is it going to happen again?

Breakdown #3 ATX power supply

I seem to be poison to computer power supplies. They like to burn out and die around me. This was an easy fix, and cheap courtesy of some donated replacements from my good friend Michael.

Breakdown #4 x-end-motor

The death of another printed part, the x-end-motor. I already had a replacement on standby and it was a pretty easy deal to swap it out.

Regular maintenance

About every two or three months I perform some regular maintenance. This usually takes around 10-20 minutes, and involves:

  • Tightening the x-axis and y-axis belts. I have found that the y-axis belts don’t come loose as often as the x-axis, and I have only tightened the y-axis belt once in the year. This is good news, because the y-axis belt is a real pain to tighten and involves a considerable amount of disassembly to get at the belt clamps underneath the build platform. Using nylock nuts will help alleviate this problem.
  • During this routine maintenance I clean and oil all the smooth rods that the LM8UU linear bearings ride on. I use a fine machine oil or ‘singer oil’.
  • Re-calibrate. I make sure the build platform is nice and level, print out a calibration object and make any tweaks to firmware as needed.

Reliability rule of thumb

After building and repairing my printer a few times, as well as helping out several others with their own printer problems I came up with “Freeman’s law”

The more colours your RepRap is made from, the more reliable and better it will be.

Generally you get a set of printed parts, all as one colour from a friend or part of a kit. Then you build your printer, making tweaks and changes as you go. Maybe something breaks, maybe you install an upgrade. When you come to print those parts, it is always with whatever you have in your printer at the time. Invariably it is another colour from your original parts. The number of colours in your printer becomes a bit of a history of all the different times you made a change or upgrade. More changes mean the more times your printer has had to evolve and improve.


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