Beaker's center-stick project!

Beaker · Post by **Beaker** » Thu Sep 17, 2009 5:24 pm

It's been too long since I've had a hardware project so I thought I'd give building a center-mounted joystick a try.
I'm building it around a motorcycle's universal joint, using 4 20lb springs for tension and Leo Bodnar's BU0836A chip with Hall Effect sensors for the axes. (Those will be tough to mount.) The current grip (which can be swapped out) is an old friend of mine, a Thrustmaster Top Gun USB. I enlisted a friend to help with welding. It's not what you know, it's who you know!

Total costs are around 200 dollars so far.

Post by **Ray** » Thu Sep 17, 2009 6:29 pm

Man that's a great idea - I've thought about trying to make something like that as well. I really prefer a center stick, feels more natural. I had a TM Top Gun HOTAS many years ago, was a great feeling stick.

I've got my stick setup on a makeshift wooden platform that I stick between my legs - it's an interesting looking contraption, held together with lots of glue, tape and a few nails.

Keep us updated!

Luse · Post by **Luse** » Thu Sep 17, 2009 7:37 pm

Looking good there Beaker

Post by **Gunner** » Thu Sep 17, 2009 7:44 pm

Now since your arm will be resting on your leg, does this mean you will no longer be able to wear a G-suit?

Beaker · Post by **Beaker** » Thu Sep 17, 2009 9:18 pm

Thanks guys...!

Gunner wrote:Now since your arm will be resting on your leg, does this mean you will no longer be able to wear a G-suit?

Darn, I guess not! I'll have to work on my AGSM. And get my blood pressure up. Actually that last one is easy, just become a Cubs fan or something.

Post by **Gunner** » Thu Sep 17, 2009 11:02 pm

@Beaker - I can't remember where I read it, but a while back I heard the description of the perfect body type to handle Gs...chubby, short, high blood pressure. First time I've ever felt like a perfect specimen!

BTW, your stick is very clever!

Beaker · Post by **Beaker** » Fri Sep 18, 2009 12:46 am

Thanks man! Yeah I've heard the guys who have a thick build with a high blood pressure (i.e. the guys who eat tons of red meat and drink tons of beer) do best.

Rhino · Post by **Rhino** » Fri Sep 18, 2009 2:25 am

Gunner wrote:@Beaker - I can't remember where I read it, but a while back I heard the description of the perfect body type to handle Gs...chubby, short, high blood pressure. First time I've ever felt like a perfect specimen!

Luse · Post by **Luse** » Fri Sep 18, 2009 4:08 am

Good Speed and Angels quote also, Two birds with One stone

Beaker · Post by **Beaker** » Tue Sep 22, 2009 1:10 pm

Got a little work done!

Now it has some tension. It's too light for now, hopefully I can find some stronger springs (more than 19.1 lb but still around 1.5in long when compressed). Tension is very smooth however, increases linearly right out to the edge of the axes.

Joker · Post by **Joker** » Tue Sep 22, 2009 11:57 pm

Looking good so far! Keep it up Beaker!

Post by **Gunner** » Wed Sep 23, 2009 9:59 am

Have you thought about adding an additional spring at each corner? You could use the same hole on the top plate and angle another spring to the outside corners of the bottom plate. Having eight springs would also give you more options for tweaking the resistance.

Beaker · Post by **Beaker** » Wed Sep 23, 2009 4:40 pm

I have thought about that, but it would certainly ruin my ability to add a case/box around the internals at the base. The "box" is what will restrict the range of motion of the stick, so that part is pretty much non-negotiable. I've been considering adding a spring at each of the midpoints on the sides of the upper plate...

Good idea though, I'll look into something like that also.

Post by **Ray** » Wed Sep 23, 2009 5:34 pm

Yea I was going to suggest the 8 springs.

Just give the case box a large opening on the top for unrestricted movement and put some kind of a rubber / leather boot over it to clean it up.

One idea that I had about making a stick like yours was to have some kind of a ring with bearings that would slide down over the stick and position it to the lower portion of the stick and then somehow weld on many little hooks in a radial pattern around the outside of bearing ring, and weld the mounting hooks for the springs on the base plate in a circular pattern, all equidistant from the stick base.

That way you could have 32+ springs packed tightly together in an even radial pattern radiating from the bearing ring and the equal tension of the springs opposite each other on the base is what would hold the stick in the center.

The bearing ring in combination with the equal spacing of so many springs spaced equally apart would provide a near frictionless feel, and would allow the stick to move in any direction without and kind of X/Y axis uneven tension/clunk.

Not sure if that makes any sense or not, maybe I should have made a MS Paint drawing, lol.

I was bored, I had to draw it.

There's probably some blatant mechanical obstacle that would make it very hard to create that I didn't think about, but it seems like a good idea.

Beaker · Post by **Beaker** » Wed Sep 23, 2009 5:56 pm

Ray-

The top opening you described is exactly my plan, when I have the tools/materials again. (Christmas break! lol)

The radial spring arrangement was definitely something I considered, but I wasn't able to put it together in my head. I have a few more ideas how to make that happen now! It might be something to switch to, actually, it just requires a larger base and case box. Another difficulty with using that many springs is making sure they aren't brushing up against each other at any point. Other than that, the only other reason was that I'm not the first person to have used this basic design, and it has worked for others in the past. I'll have to look into that though, it's certainly feasible.

Just a thing to keep in mind for planning if you haven't already... No spring should ever compress to its relaxed state. It'll register as a 'click' in the movement and you'll lose the linear tension feel. I have all of these springs at about 175% extension and they can't possibly ever contract entirely.