Bowden Tube Upgrade – Capricorn Mod


Hello everybody and welcome to another video. Today well be covering a very simple upgrade, which is to replace the standard Bowden tube with a Capricorn tubing instead. As always, do this mod at your own risk, and I’m in no way responsible if any damages may occur.

So why do this upgrade at all? Well, as it turns out, it can often prevent problems before they appear. As some of you may already know, there’s quite a few cloned hot ends on the market, and this does create quality control issues as a result. I’ve actually had the Bowden tube of my CR-30 and Sovol SV1 constrict so much that they completely stopped extruding material. In most cases this can be a minor inconvenience, however in other’s it can be more serious. On my CR-30, the Bowden tube was actually burnt within the hot end and caused the filament to puncture the Bowden tube itself. Most standard Bowden tubes are known to release extremely toxic fumes when heated past it’s recommended levels, so this was a great concern to me at the time. This issue is caused by the heat from the heater block creeping up the Bowden tube, and this is known as heat creep. This is pretty common in most hot ends that come with questionable quality control, however it can also happen to higher end models as well. On my CR10 V3 for instance, I had the same issues when I had added an all metal hot end from a well known company. The most common method to dealing with these issues is to upgrade the Bowden tube to a Capricorn one and is something that I recommend most people do at some point since it’s a very simple upgrade. The Capricorn tubing is made from high quality PTFE tubing along with normally some lubricant within the tube itself. Since the tolerances are much tighter, there tends to be fewer chances of the filament bending within as a result. A standard Bowden tube has a maximum temperature of 230 while the Capricorn one can go as high as 260.

In order to do this upgrade, you should only need one tool, however you have two options available. The first is to use side snips pliers to cut the tubing to the correct length, and then re-open the opening using the tip. You’ll re-open the tubing by using a circular motion to gently reshape it to its original opening size. The second method is to use a PTFE Teflon Tube cutter to get a clean cut on the ends of the tubing. Although the tube cutter does give a cleaner cut, you may still have to re-open the opening of the tubing slightly after having cut it down to the correct size.

The fittings which help hold the tubing in place are what allow for movement in only one direction when they are fully functioning. Putting the tubing into place is the easy part, however to remove it you must apply downwards pressure on the collet of the Pneumatic joint. Applying this pressure helps move the gripping teeth out of the way, which in turn allows tubing to be removed.

Before start swapping out the tubing, we first need to prepare the machine by doing a cold pull. A cold pull helps remove any debris that might be in the hot end and is a highly recommended step to help ensure that the tubing goes in all the way during assembly. Although I prefer to use some TPU while doing this, PLA will also work, but you’ll have to be careful not snap it in the process. To start things off, if you don’t have any filament already loading into your machine, you’ll need to preheat the nozzle so that you can feed some filament through the hot end. Once the filament has been feed through, you can then let the hot end completely cool down. Once it’s Cooldown completely, you’ll restart the heating process while tugging on the filament at the same time. As the hot end heats up, any residue will be dislodged when the filament is pulled out at a low temperature. As you can see, I did this process with both TPU and PLA with the same results. Once again, just make sure not to snap the filament while doing this step.

To replace your Bowden tube, you’ll first remove the existing tubing from your device. Some machines use a small clip to hold the collet into place while other’s sometimes have a zip tie as an alternative, so make sure to remove these before taking out the Bowden tube. You’ll then take this tubing and use it to measure out the replacement Capricorn tubing. By either using a set of side snip pliers or PTFE Teflon Tube cutters, you’ll cut the length of tubing required for your particular machine, making sure to keep the cut as level and clean as possible. If needed, you can use the side snip pliers to reshape the tip of the tubing so that it’s round. You can then begin feeding the tubing into the hot end assembly, making sure that is put all the way in, followed by the extruder.

I hope you guys found this video useful and that you are now more comfortable undertaking this simple modification on your machine.


Yasmeen completed both the 2D and 3D animation course at Algonquin College and worked in the animation industry as a freelancer for a number of years before being hired to manage the 3D printing services at ItsYeBoi. While using the Alias of "Jenny" during her services, she was responsible for the testing, maintenance and upgrading of the machine while also filming and developing 3D printable assets for various projects.