Mechanical stuff printed in PLA? Hmmm... PLA might not really be the first choice.
But since it is widely available, easy to print and rather cheap, - and especially the fact that I have plenty of rolls lying around in my workshop, I decided to start the "Sequential shifter Projet" as some sort of "proof of concept" in order to find out if it is feasable or not
I am using Autodesk Fusion 360 as design software, Autodesk Meshmixer to create the STL and finally Ultimaker Cura as well als Slic3r as Slicers.
Starting with a simple sketch
It all started with a few hand drawn sketches..
While Autodesk Fusion 360 is one awesome piece of software it needs to be mastered. I am more a "Learning by doing" guy, so after watching numerous YouTube videos and a couple of play-projects I quickly started the "real deal", always following the rule "Keep it simple".
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| Autodesk Fusion 360 - Meshmixer and Cura |
And here is the finished part. Printed on a Prusa i3 MK3 with 0.15 mm layer height and heavy 45% infill both pieces are of excellent quality. The material seems (at first glance) to be resistant and thus suitable enough to fulfil the task. Final testing will show if my first impression is correct.
Since I tweaked down print speed in order to obtain the best possible print quality, it took me almost 7 hours to print one piece.
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| The first two parts as designed |
The Shifter Lever
I wanted to design a really cool Shifter Lever. However, the following was the best I got. There were quite a lot of 3D Printing related design constraints (Object height, complexity of the object itself, print bed adhesion, avoidance of support structures, sturdiness of the final object etc...) that I needed to consider, so the final shape was not as cool as I initially expected., but nevertheless not that ugly either.
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| Shifter lever Version 1 designed using two distinct bodies (main lever and header part) |
As you might see in the above picture the header part has a slightly different color. The upper part is part of the shifter lever, but has been designed as a distinct component. This allows me to print it separately which reduces the size of the printed parts so that it perfectly fits the print bed. Additionally since the upper part is a cylinder it allows me to place the part straight up on the print bed, thus avoiding the printing of support structures.
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| Here we go for another 6 hours overnight print session. Shifter lever first layers printing |
This is how the final Shifter will look like
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| Fusion 360 Assembly Design |
Pre tension adjusters
The shifter is intended to be fully adjustable in terms of force that is required to shift up or down. Additionally, we need to make sure that the shifter is well calibrated. In order to be able to make adjustments on the fly, I will include a pre-tension adjuster. One challenge tough is that this part will have to withstand a constant high pressure from the coil. In order to make sure the parts will not break apart I will bury a 8mm nut during the print process into the pre-tension adjuster.
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| The Nut will be buried into the component during print time |
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| View on the pre-tension adjuster |
I tweaked the gcode file to pause at layer height 11.6. During the pause with the print head stepping to le left I got access on the unfinsihed object and just inserted the nut. Fits perfectly!
The pre-tension adjuster is printed with 0.2 mm layer height and 100% infill. Print Speed could be bumped up since draft print quality is not an issue for this part.
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| The finished part with coil added |
The Shifter Knob
A shifter knob is not really something spectacular in terms of design. The biggest challenge here is to keep the knob sticking on the bed for many hours during print. I also added a second challenge which is printing while mixing different color. Turns out that the result is pretty awesome:
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| Last top layers need user attention in order to manually change filament |
The Actuator Carriage
The actuator carriage is the linkage between the shifter handle and the pre tensioner assembly. The carriage will not be printed in one piece , but build as an assembly. Here is the left panel of the carriage, of course in multi color...
Here is the finished assembly of the carriage with push rods attached
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| Carriage with Lever and Pre Tension adjuster installed |
Almost finished
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| The assembled shifter prior ging through first mechanical tests |
The Shifter assembly looks great. Overall the Shifter seems pretty robust, and even though it is made out of Plastics, it does not look cheap. Lever action feel is quite nice and the Tension adjustment works like a charm. No grease has been applied on any parts so far. Minimal friction of the tensioner has been noticed and needs to be addressed.
Update:
A new pressure plate that offers enhanced attachments has been designed
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| On the right the new design with enhanced attachment possibilities |
Added a shifter base and slider that activates the microswitches
The base has four 8mm attachment points
While waiting for the microswitches and Joystick controller to be shipped I started the handbrake addition...
The Handbrake Project
The Handbrake is designed to be part of the shifter assembly, however a stand alone version will be made as well. Starting with the lever and the knob. This is work in progress! I provide a few pictures what has been designed and printed so far.
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