Capricorn Bowden Tubing XS Low Friction 2,85mm

This is the original from Capricorn in USA, and not a china copy as many sells. 

Til 2,85mm filament

Prisen er pr. 10 cm. Så hvis der ordres 3, får man et stykke på 30cm.

our extruder system has a finite amount of pushing force. You want as much as possible of that pushing force to be used to generate pressure in your HotEnd, as it’s what causes the molten filament to actually extrude from the print-head (crucial to 3D printing!).The friction of filament sliding its way from the filament drive to the HotEnd saps away some of this force, leaving less force to create useful pressure. When we use a bowden system the filament has to travel on a longer and more convoluted path, and so we get higher losses to friction. While standard PTFE is slippery enough to mitigate this effect, it does not eliminate it.

Another error source in extrusion systems is the compression/buckling of the filament. As we apply pressure to the filament in order to extrude it will bend a little (but a little is all it takes) between the extruder drive wheel and the HotEnd melt zone. Because of this spring-like compression we can advance the filament by 1mm at the drive wheels, but 1mm’s worth of filament will not immediately exit the nozzle in perfect synchronicity. In a bowden system this filament-spring is “softer” due to its much increased-length. The subsequent deformation under force results in extruder motor speed changes taking longer to be reflected at the nozzle, and the errors being greater in magnitude. 

Capricorn XS bowden tubing helps with both of these issues. It is made of pure PTFE that has been treated with a special additive to reduce friction. It is also made to highly precise standards, with an extremely tight internal diameter to improve filament constraint between the extruder and the HotEnd.

The friction of filament sliding its way from the filament drive to the HotEnd saps away some of this force, leaving less force to create useful pressure. When we use a bowden system the filament has to travel on a longer and more convoluted path, and so we get higher losses to friction. We tackle this by using a tube made of PTFE (a very slippery material indeed), which reduces but does not eliminate friction. This problem is fairly easily mitigated by ensuring you have an extruder mechanism which can exert enough force on the filament.

Friction in a standard v. Capricorn bowden tube: More friction in the tube means less force pushing filament through the HotEnd

This leaves us with the rather more complex matter of response and control. A printer needs good control of the amount of flow from its nozzle in order to accurately build parts. It also needs to be able to carefully control when extrusion starts and stops. We maintain this control by using a stepper motor, which moves the extruder filament drive wheels very precisely. However, there are still some errors that occur.

The first is what we might call “pure backlash.” This might be something like backlash in your geared extruder, or slack in the couplings of your bowden system. To counter this you have to increase your retraction distances to take up the lost motion upon direction change, and when doing so there is some delay.

Another error source in extrusion systems is the compression/buckling of the filament. As we apply pressure to the filament in order to extrude it will bend a little (but a little is all it takes) between the extruder drive wheel and the HotEnd melt zone. Because of this spring-like compression we can advance the filament by 1mm at the drive wheels, but 1mm’s worth of filament will not immediately exit the nozzle in perfect synchronicity. In a direct extruder with a well-constrained filament path there is very little flex and so our control system is very “stiff”, with changes in extruder motor speed being quickly translated to changes in nozzle flow. However with a bowden system this filament-spring is much “softer” due to its much increased length. The subsequent deformation under force results in extruder motor speed changes taking longer to be reflected at the nozzle, and the errors being greater in magnitude.

You can read more about it on our blog!

Key Features

• Inner diameter of just 3.2mm 
• Outer diameter is 6.35mm
• Highly consistent - perfectly round
• Treated with a unique friction-reducing additive
• Capricorn™ XS branded quality
• Perfect for softer and more flexible filaments
• For use with 2.85mm filament only
• Buy from Filament23D in lengths of 100mm - add more to your basket to receive longer lengths!