Static paddles with 2 shifters per paddle

[Elaphe]

I once 3D-printed long paddles ala Ferrari or Lambo, conceived to work on a fixed position (not moving with the steering wheel), and installed with custom clamps attached to the front of my Mige. They worked fine, but any minimum flex (even using ABS with 100% infill) when pressing on the top or the bottom made the activation a little harder. It also induced some torsional force on the shifter's mechanism, which ended up adding some play to it.

So, now I've come up with this idea: installing 2 shifter mechanisms for each paddle. I've made a rudimentary test and it works better because the forces are better distributed. I will make a prototype print and see how it goes.

 

[AccAkut]

How does that work with both pivot axis' pointing in wildly different directions? Shouldn't this add a lot of torsion to the paddle on actuation?

 

[Elaphe]

How does that work with both pivot axis' pointing in wildly different directions? Shouldn't this add a lot of torsion to the paddle on actuation?

That doesn't matter at all. They are following the shape of the paddle, so that's why they are not straight, but that's just for aesthetics.

 

[RasmusP]

That doesn't matter at all. They are following the shape of the paddle, so that's why they are not straight, but that's just for aesthetics.

Ermh... Your design bends the paddle into a curve.
If the mechanisms have enough play, it might work but it's really not great.

Btw 100% infill makes the paddle easier to flex. A tube is way stiffer than a full cylinder.

What might help instead of using multiple mechanisms would be some ribs from top to bottom.

 

[Elaphe]

Sure, everyone knows the less infill, the stiffer the piece XD. That's why jail bars are hollow XDDDD

 

[AccAkut]

Sure, everyone knows the less infill, the stiffer the piece XD. That's why jail bars are hollow XDDDD

Rasmus is partly right, a hollow tube is stronger than full material, AS LONG as the actual cross section of the material is the same. As in a wider radius tube compared to a full material rod. It's first semester engineering stuff.

Still can't see how your mechanism works without putting extra stress on everything, even if you just have millimeter paddle actuation.

...you made me grab my random hardware box

 

[RasmusP]

Rasmus is partly right, a hollow tube is stronger than full material, AS LONG as the actual cross section of the material is the same. As in a wider radius tube compared to a full material rod. It's first semester engineering stuff.

Whoops.. yeah it was a long day lol... I mostly work with mass vs material vs stiffness kind of things without tight restrictions on the measurements.
So my instant thought was "make it hollow and add ribs"

I'd still rather add some ribs on one side than adding a second mechanism...

...you made me grab my random hardware box

At least my inner virtualization was working correctly today

 

[Elaphe]

As I said, the angle of the shifters doesn't matter because the force applied is perpendicular. Try to stretch your arms and move them up and down. It doesn't matter if they are close together or opened in an angle.

The best position of the connection would be between the center and the tips of the paddle. That way the force is better distributed. If you put them close to the center you have the same problem of using just one single shifter. If you put them on the ends of the paddle the force applied on one end is too distant from the other so one of the shifters would tend to move before the other, specially if some flex occur on the material. This is the reason why the doors have two hinges and not one and why they are placed where they are.

The reason for the angle in my design is also a matter of room. Making them point in differrnt angles allows the mechanisms to be close, while the connections are still on a better position. Take a look a the attached picture. Imagine you have to place the shifters inside the red box.

I have also redesigned the part of the paddle where it connects to the shifters. This will make it even stronger.

 

[GeekyDeaks]

Try to stretch your arms and move them up and down. It doesn't matter if they are close together or opened in an angle.

If you have your arms open (i.e. not parallel to each other), then the distance between your hands changes as you move them up and down unless you also twist your upper arm to change the axis of your elbow to accommodate. I believe this is what @RasmusP and @AccAkut are trying to explain. With the small distances and materials involved, it probably won't make a practical difference, but it's something I personally would have avoided doing.

 

[Neilski]

As I said, the angle of the shifters doesn't matter because the force applied is perpendicular.

Hmm, I think you should take another look at this picture @AccAkut posted:

The force may well be perpendicular to the plane of the paddle, but that's not the issue. The issue is that the axes of the hinges are not colinear, so you will create strain as soon as they rotate away from the starting position.

With the small distances and materials involved, it probably won't make a practical difference, but it's something I personally would have avoided doing.

I'd agree though that it probably won't make a lot of difference

Edit: Btw, I like the general concept, apart from this niggle. I'm assuming the second shifter is acting purely as a mechanical support and is not plugged in?

 

[GeekyDeaks]

Btw, I like the general concept, apart from this niggle.

I have a fair few 'it might not be right, but it still works as intended' contraptions floating around the house!

 

[Elaphe]

Hmm, I think you should take another look at this picture @AccAkut posted:

The force may well be perpendicular to the plane of the paddle, but that's not the issue. The issue is that the axes of the hinges are not colinear, so you will create strain as soon as they rotate away from the starting position.

I'd agree though that it probably won't make a lot of difference

Edit: Btw, I like the general concept, apart from this niggle. I'm assuming the second shifter is acting purely as a mechanical support and is not plugged in?

That piece your made has nothing to do with paddle shifters. Those hinges are too small. I don't know how to explain it well, but I think the point is that we are dealing with circular shapes. See the attached image. I'm sure the extreme angled shifters on the right would work perfectly with no stress.

 

[GeekyDeaks]

Those hinges are too small

It's not the size of the hinges that is the problem it's the fact that the hinges are not in line. Like @Neilski said, at the distances of movement you are dealing with, it's likely the stresses will be fine, but there will be some.

I'm sure the extreme angled shifters on the right would work perfectly with no stress.

Taking that latest example where they are angled at 45deg, try pushing it to the extreme and imagine the hinge could be moved 90deg (yeah, I know it physically cannot, but it should hopefully explain why and where the stress exists) and then ask yourself the following question: What would be the distance between the two points they are attached to the paddle?

Honestly though, what I would do is take one of the shifters and try and wiggle it left and right. If there is a bit of give, you are golden. If not, you are probably still ok and the compression on the paddle might even help the return

 

[AccAkut]

I'm sure the extreme angled shifters on the right would work perfectly with no stress.

it would not. I mean it would probably work with the few degrees of movement, but its a system full of tension/torsion and not engineered correctly

 

[Elaphe]

it would not. I mean it would probably work with the few degrees of movement, but its a system full of tension/torsion and not engineered correctly

That animation is completelly wrong. That's not the way the rotation occurs.

 

[GeekyDeaks]

That animation is completelly wrong. That's not the way the rotation occurs.

Erm... that animation is 100% correct.... it's trying to show you how the plane of rotation for the two shifters is not aligned. It might be extreme in the rotation, but I'm pretty sure @AccAkut purely did that to highlight misalignment

It doesn't really matter if the design is working for you, but I would recommend taking the time to understand what is wrong with it as you might need that knowledge for future projects

 

[Neilski]

If the rotation of the shifters is only a few (up to say ten) degrees, then you'll probably get away with it with no problems at all or at worst an occasional need to retighten the bolts. (But I'm puzzled that we're still not on the same page about the thing that's making a few of us wince about the design...)

 

[mclarenf1papa]

That piece your made has nothing to do with paddle shifters. Those hinges are too small. I don't know how to explain it well, but I think the point is that we are dealing with circular shapes. See the attached image. I'm sure the extreme angled shifters on the right would work perfectly with no stress.

Just imagine the shifters being able to rotate 180 degrees. You can see that their ends would be closer together than they are at 0 degrees (as drawn in your picture). Thus the paddle would have to deform to allow the design to work.

As others have said, it might be fine at small angles, but it is certainly putting unnecessary stress on the system and violates design principles.

You can also look at another extreme - imagine the hinges were collinear and opposite (one pointing up and one pointing down), it would try to break the paddle in half.

 

[AccAkut]

Erm... that animation is 100% correct.... it's trying to show you how the plane of rotation for the two shifters is not aligned. It might be extreme in the rotation, but I'm pretty sure @AccAkut purely did that to highlight misalignment

its basically the most extreme version @Elaphe drew, just something I wipped up in a few minutes to show how each halves connected to the respective hinge would want to move in an ideal play-free case.

We all have brain farts from time to time, but I think with now four people telling you it won't work right... try building the mechanism out of things you have laying around, some cabinet hinges and wood if you don't believe my animation.

the left variant here will work perfectly fine, as long as both hinge mechanisms are lined up right, with both axis colinear.

 

[Elaphe]

I trust my own intuition, so I will install the levers with an extreme angle as a test. Then I will see if there is any of that stress you all imagine. I will record a video.