Updated: Jan 16
Hello, and I hope you are all enjoying the Christmas Holidays. I have taken a few days away from the sim but wanted to show you some of the upcoming projects in the background.
The first project and the focal point of this particular blog are the 3D printed Boeing 737 Rudder pedals.
The first thing was to create the basic design and prove that 3d printed parts could put up with the stresses from peoples feet. I personally know that when new pilots get excited in the cockpit, they have superhuman strength. I really had to concentrate on the pedal structure itself and the supporting pivot that take all the force.
The pedals are the correct size and closely match that of the real ones. I have added a bit of artistic license with the word "BOEING" across them. The pedals have a huge structure behind them and are much thicker than the real pedals. During testing, the pedals seem extremely strong and would match any Plastic injection method. Of course, they are made from plastic and they have their limits.
Prototyping was carried out at 5 % infill, but these split around the square shaft that goes through the base to attach the unit to the pedal base.
Another test print was carried out increasing the wall thickness from 0.8mm to1.2mm and infilling to 20%. This produced an awesome pedal and I am more than happy with these now. The final pedals are now printing and I have to warn you that these take 3 days each to print at high quality. (four in total)
I can foresee the pedal anti-slip ribs around the base wearing just as they do in real aircraft. However, with 3d Printing, these can be replaced with ease. The next main area of concern was the shaft that supports the pedal. Could this support the pedal and side loads created by pushing on it? The only way I could think to achieve these massive stresses was to add metal, in the form of a 12mm threaded rod supported by some big bearings.
The pedal needs to be supported on this shaft, as well as being able to rotate for the brake axis. You can see the pot attached to the back of the pedal base. The forward bar is the parallel restraint bar that keeps the pedal at the correct angle through the range.
In the left image, the restraint bar was secured by a fork from the pedal. This was completely over-engineered and restricted the pedal movement. In the end, I moved away from the fork end to the single-sided lever, shown in the right picture. The spring is what returns the pedal from the braked position.
Another item I am really please with is the 3d printed tie rod with movable ball joints. Printed in a single piece this allows correct movement of the mechanism and moves the other pedal forward as this one is pushed aft.
You can see the gas strut in this picture that provides a "push" feel to each pedal. These have not arrived yet and I can not really progress any further until these arrive and the size can be calculated and the design adjusted accordingly. The idea then is that these whole units will slide back and forth in the pedal housing and be adjusted by another rotating M12 thread rod.
The pedal casing/Housing will be constructed from wood, probably MDF. After creating the control columns, I had so many people state that getting metal work done was difficult and expensive. This is the reason why I am trying to make these units from 3d printed parts.
This is the final pedals printing now, as this design should not need to change.
That's all for this update, kind regards Karl.