[POC] Compact 90° stepper w/o silicon or rubber

[Didumos69]

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.

Edited October 27, 2016 by Didumos69

[Tommy Styrvoky]

Interesting use of torsion bars.

[Boxerlego]

Impressive setup, looks very functional and integratable. Looking forward for more. 

[Lipko]

That's pretty clever!

I'm waiting for a stepper with no relying on elastic parts at all

Edited October 26, 2016 by Lipko

[Didumos69]

1 hour ago, Lipko said:

That's pretty clever!

I'm waiting for a stepper with no relying on elastic parts at all

Thanks! Something purely mechanical, that would indeed be cool. I had something like the above setup without anything elastic. It relied on friction in the shift axle and the shift lever had to be pulled far enough to make a complete shift and had to be returned manually. But it could result in non-90-degree positions if the shift lever wasn't pulled far enough. I might look into that once more...

[agrof]

Very cool, balancing on legal- and illegal build boarder.  I actually support the use of the properties of materials (like flexibility here). Great solution! 

[Didumos69]

2 hours ago, agrof said:

Very cool, balancing on legal- and illegal build boarder.  I actually support the use of the properties of materials (like flexibility here). Great solution! 

Thanks! I tend to make use of axles as torsion bars more often. But also for me there is a fine line between do's and dont's. I would for instance never - or at least not deliberately - make use of slack in parts to make something work.

[Imanol BB]

I wouldn't think this is a so "illegal" solution, torsion bars are used in real life for many kinds of devices, so why not to do the same with Lego?, for me this is a completely acceptable use of parts because you aren´t "hacking" the parts to make them work, i really like who smooth and perfect it works.

[BusterHaus]

Very good solution, axles are much more durable than rubber or silicone components. I wouldn't worry too much about the legality of the build. Axles are meant to transfer torque, and Lego axles do not have the right cross section shape to resist deformation when they transfer a lot of torque.  It's a shortcoming that's actually a blessing , as it allows for solutions like the one you have here. 

[Didumos69]

On 27-10-2016 at 0:58 AM, ImanolBB said:

I wouldn't think this is a so "illegal" solution, torsion bars are used in real life for many kinds of devices, so why not to do the same with Lego?, for me this is a completely acceptable use of parts because you aren´t "hacking" the parts to make them work, i really like who smooth and perfect it works.

 

On 27-10-2016 at 4:25 AM, BusterHaus said:

Very good solution, axles are much more durable than rubber or silicone components. I wouldn't worry too much about the legality of the build. Axles are meant to transfer torque, and Lego axles do not have the right cross section shape to resist deformation when they transfer a lot of torque.  It's a shortcoming that's actually a blessing , as it allows for solutions like the one you have here. 

Thanks guys! I don't have a problem with it either. I've been using axles as torsion bars in suspension setups for whole my Technic life. Like in the 8845 mod below, haha (note also the Ackermann steering ). Nevertheless, the version of this stepper that does use silicon bands operates more smooth than this one. The nice thing about silicon bands is that they give a fairly constant stress, almost independent of how far you stretch them. As opposed to that, the resistance of axles used as torsion bars does increase significantly when you twist the axle further.

Edited October 28, 2016 by Didumos69

[Victor Imaginator]

I like to watch that evolution of steppers) Always surprising.

[Meatman]

Probably not something that we would see TLC approve of, but still impressive.