Bruce's 2dof fullframe rig aka: the "Ratrod"

this is for reference. these are the pots I use and needed to order more. i killed the bourns i had testing this timing belt motor position setup(dumb pots with stops). I had a hard time finding the link so i'm putting it here. they are 360degree no stop magnetic position sensors. they are about 13.00 dollars each here.
http://www.mouser.com/ProductDetail...j%2b3zvCGcSKF0VHw8x%2bu4HC6rf9y6iuK8kPMMG4Q==

Been rockin those Halls for essentially the whole life of my rig, Even the One that Jammed up twice is still Hard at work. You SERIOUSLY have to do something wrong to break those bad boys.

we shall see @Nick Moxley . i have two in operation they are amazing........ but my new problem, at least testing with the bourns pots, is the lateral force on the pot shaft from the belt tension burned them both up in about two hours. even the bourns pots never broke on my rig. With the geared setup there is little force on the pot shaft. I have an idea though. two pulleys(motor and free) with the pot sprung into the belt in the middle. this will reduce the load on the shaft. I gotta build it then ill post pics. im just not good at drawing it out, better in my head.

Why not Flex Couplers ?

Possibly.....

I want the freedom to quickly change feedback to motor ratio for different style tracks.

Different style tracks ? meaning what exactly ?

superspeedway (daytona or talladega) larger and a little slower movements. short track high bank (bristol or dover) short and slightly violent movements. i dont really do roadcourses. I do race a little watkins glen or sonoma but only out of necessity. At the very least this should help me dial in the overall movement even if I decide on 1 ratio. So far I've printed up 2.22:1, 2:1 and 1.6:1. The 1.6 is pretty extreme and may be too much. I'll know more when the new pots arrive. I'm not stealing the ones off my rig lol.

Crude but it doesn't oscillate.

Interesting way to go about that Bruce, How exactly do you move the pot over or flip the gear i should say ?

Different size gear on the motor it's a pain to switch out. So I don't. I did a couple times when I first built it. But not in months. Flip one swap the other. Takes a half hour by the time it's done and set up.

iracing in joliet illinois. chicagoland speedway.

Hi Bruce, Another option you have if using SMC3 arduino driver code, enable the scaling option and add an extra POT/Knob to adjust the scaling you want on the fly. Should have the same effect and was designed for this purpose.

@RufusDufus , very interesting I will mess with that later today.

ok I hooked up a pot for scaling and I like it so far. I especially like how i can now dial down the sim instantly when headed for a painful wreck. This will be useful while pacing and pitting during long races to save some abuse(me and equipment). So in the end I will probably settle on the 1.6:1 pot setup and scale from there. Update coming.....

Great to hear. I haven't had any feedback on the scaling - did you use linear or non-linear scaling option? Which did you prefer?

linear, ran a long one at atlanta tonight no problems so far(140 or so laps cause i wrecked). makes it way easier to race long ones. i turned the movement basically off while pacing and pitting. turned it up and down a bunch. ill test non linear and report back.

Thats kinda cool i have to admit, Essentially a volume knob on the motion, Very handy im sure.

@RufusDufus SMC3 pot scaling imho is a very useful tool. the NON LINEAR is my favorite in that it seems to retain most of the detail while dialing down the overall force. @Nick Moxley that is exactly what it is i can dial down to 0 movement and back up to full blast in just seconds, as well as in between, while on the track turning laps.

On a side note i was thinking of trying to install some sort of limit switch for movement. Now my first thought was to run a line from 5v+ to the appropriate feedback input on the ard separated by a normally open switch. so that when the switch is closed it causes 5v to trigger the software limit shutting down the motor. Will I need a diode on the feedback to prevent damage to the magnapots? Does this sound right or am I all wrong with this?

@bruce stephen , that's good feedback. I also prefer the non-linear mode but wondered if might get different results from sim to sim?

Did you know that SMC3 already shuts down the motors if they go beyond the set "max limits". You have to reset the arduino (or use SMC3Utils) to turn them back on as a safety measure. The SMC3 will apply braking (reverse motors) when they go outside the "clip limit" ranges and then if momentum or something causes them to go beyond the "max limits" they shut down.

Limit switches would be a fail safe if the software goes wrong I guess but probably aren't required.

ty @RufusDufus , yes the mechanical stops would be just an additional fail safe and I dont plan on them for this rig(future 6dof if i get the time and weather). they really would only be used when testing and pushing the limits. sometimes when cranked way up my motors will shoot past and free wheel, if it doesn't hit limits it can just be pushed to the point where the software grabs the motor again. I believe this is because i am using these helical gear boxes that can be turned by hand while off(with leverage). So when I'm testing in the future, the stops may save me a little grief. also I'm planning to bump up my power to see if the peak draw is the issue for the "free wheel". An additional 50amps and 1 more monster should ensure that it isn't caused by low voltage. I don't have access to anything that would measure the draw real time. My cheap equipment isn't fast enough. My sim runs great and I'm not really having problems but I like to tinker with it and push its limits. canei..........constant and never ending improvment.

here are the stl files if you want for the belt position sensor setup