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Limiting rotation to 900 degrees with off the shelf parts.

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BadMouth:
Looking for ideas for limiting rotation to 900 degrees with off the shelf parts.

I can think of ways to do it if I were a machinist or wanted to pay one, but are there some thingamajigs that I might not know about that can do this off the shelf.  Best idea I've had is a screw drive with stops, but the parts are still expensive and aren't quite perfect for the application (steering wheel).

Got any ideas?

DaOld Man:
Hmmm, thats a good one.
So you need the wheel to turn 2.5 turns? (900/360=2.5)
How about a small gear on the steering wheel and a big one on the stops?
For every 2.5 turns of the steering wheel, the big gear turns 1 turn.
You could probably do it with cheap nylon gears, but you need to use math to figure out how big the gears need to be. Of course keep in mind that you will need some side room for the big gear.
The screw idea sounds good, just use some threaded rod and have a threaded piece (nut?) move up and down on the steering column. You could have adjustable stops and it wouldnt require much more room than the column.

BadMouth:
This would end up being attached to a big happ ffb motor that the user would be fighting, so plastic gears probably aren't a good idea.

Gearing isn't a bad idea though.  If all the gearing were done on the steering wheel side of an already existing Happ setup, then the happ stops could still function.

I'm just kicking around ideas for hacking arcade controls to a logitech G27 which uses an optical encoder and turns 900 degrees.
If it doesn't get an acceptable number of pulses during automatic calibration when the pc starts up, it disables itself.
The limits on the original wheel are set by a rack and pinion setup that slides back and forth inside the housing.
The rack slides back and forth until it runs out of room in the channel it rides in. 
If it's one tooth off when re-assembled, it fails calibration.

To just attach an optical encoder to where the pot goes on a happ wheel (1:1 ratio, no gearing) and trick the G27 pcb into thinking the wheel was moving through the full 900 degrees, I calculated that I'd need a 3,000CPR+ encoder!  Only ever seen a couple that high and they were crazy expensive.
I guess it could also be done with gearing on the encoder if we weren't interested in the wheel still moving 900 degrees.
I screwed up the math when I hacked a different wheel that used an optical encoder though and spent $90 on one with a count slightly too high.
It would be nice to have adjustable stops to compensate for my poor math skills.  :lol

This is just a mental excercise and maybe coming up with ideas to help others. 
I sold the G27 I used for tinkering in the past because it seemed there were just too many ob$tacle$ to overcome.

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