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[POC] Compact 90° stepper w/o silicon or rubber
Didumos69 posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
If you don't like things that use axles as torsion bars, then please skip this topic. In the march of steppers, shifters and limiters, here's my throw at a 90 degree stepper without silicon or rubber. I started off with my compact 90 degree stepper which uses silicon bands for returning the shift lever as well as for limiting the shift axle to 90 degree orientations. Because the rotation movements that had to be limited are quite small (max 10 degrees), using axles as torsion bars seemed to be a valid option that wouldn't put too much stress on the axles involved. After some trial and error I found a setup that actually works. It uses 3L axles with knob and half pins (also with knob) with a flat round 1x1 tile attached to them as stoppers and pole reverser handles as torsion levers. In idle state, there's practically no torsion stress on any of the involved axles. Only when you pull the shift lever, the axles get twisted, but not more than about 10 degrees for the shift lever and even less for the 90 degree limiter. The casing had to be made quite strong to prevent any other bending then the intended axle torsion. LXF-file here. -
[POC][WIP] Compact 90° stepper w/ instructions
Didumos69 posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
After shortening the travel required to shift gears in my improved paddle shifter unit for the Porsche (42056), I put some effort in trying to use the same concept - a lever knob gear driving a central knob gear - as a base for a 90 degree stepper. I was able to make a compact setup with the shift lever directly operating the shift axle that could in turn drive the clutches of a gearbox (the gearbox is not part of this unit). By using the knob gear inside the shift lever, the rotation speed of the central knob gear is twice the rotation speed of the shift lever itself. As a result each shift requires only a relatively short travel. The stoppers that catch the upper knob gear when shifting are the crucial part of this mechanism. They had to be reliable when it comes to catching the knob gear and needed to allow for a smooth return at the sane time. The whole setup relies on its interaction with the simple 90° limiter., which has been integrated in this unit. I'm very happy with the result. EDIT: I've been working on this a little more. I'wasn't completely satisfied about the return of the shift lever. It requires a lot of silicon power and I couldn't get it working with a new set of red silicon bands. Apparently the old ones (+/- 8 years old) are stronger. So I decided to skip the auto-return completely. The return is not needed for a full shift and a completely manual operation of the shift lever gives a nice feel. Returning the lever can actually be postponed until the next shift. This also allowed me to make an even more simple version of the stepper. In that simple version a different 90° limiter now operates directly on the lower knob gear. The limiter allows for some free movement of the orange paddles, but my guess is that this won't give any trouble when they operate the clutches of the gearbox. So all together I now have two versions: The compact stepper with separate 90° limiter and the simple stepper with limiter directly applied to the lower knob gear. Compact 90° stepper with separate limiter (LXF-file) Simple 90° stepper (LXF-file) Comments and (suggestions for) improvements are welcome! -
Simple 90° Limiter for Axle
Didumos69 posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
I just posted about this in the Porsche MODs and improvements thread, but I think this might be worth sharing with everybody. In an attempt to further improve the definite character of the selecter axle in the Porsche gearbox I found a very easy way to limit an axle to 90° positions. I think this video tells the whole story (don't bother the bevel gears if you're not interested in the Porsche gearbox). (Actually I don't really know what the name is of this kind of mechanism. ) Without the bevel gears this is all there is to it: LXF-file here.