Need some help from clever builders...

[AK Mongo]

Rack and Pinion was what I was thinking of I just didn't know the name till I looked it up. I was thinking the worm though from a rotational standpoint but your right about the cable from the control. That worm action must happen up front ?[/QUOTE]

Correct.

The handle rotation on the Prop and Mixture controls does not cause the working end of the cable to spin, only move in small increments.

[No Longer Active]

To put it simply, just use linear slide pots attached to your levers and leave out the rotational adjust feature to keep it simple!

Cheers,

Alex

[Ronson2k9]

Well Alex as it's happening up front he will get that too. It's already built into the control. Perhaps there is a way to disconnect the cable from the control and use a different one though if space is a problem and the cable doesn't flex that much? I've got my mind on building one myself so it's flooding over from to time time .. sorry.

BTW guys my remade version of the C172 => C185F of the panel drawing is nearly complete. Based on my calculations the 185 pit is about 10 inches smalled then the 172. The MIP is about 31" across. I had thought it would get a bit bigger then the 172 but smaller then the 206. Also Alex you had the prop / engine mix in the wrong place. Prop goes beside the throttle. I think because they are both related to RPM.

The more I dig into Paint.net the more I like it. Especially the bezier curves.

[Westozy]

This is an easy one. I have used this method to interface the slide motion of my rudders to a small 10kohm rotary potentiometer. I would avoid the use of bell cranks as you will end up with a non linear signal. Slide pots are a good option and they can be mounted upside down so they avoid collecting dust in the tracks, they will last quite a while and they are a cheap option.

To connect a slide throttle to a rotary pot there is a simple solution - attach some fishing trace wire to the end of your throttle slide and then wrap the wire around a small drum on the pot (like a cotton reel shape). Wrap it around the drum about three times and then attach the loose end to a fixed point using a light spring to keep the tension on. When you buy stainless steel fishing trace wire it usually comes with small crimps for making loops on the ends for connecting swivels etc.

To calculate the drum diameter it's good old Pi that helps, I will use 3.142 for Pi and explain the calc. A pot needs to rotate about 3/4 of a circle, usually pots need to rotate about this much to utilize it's maximum efficiency so we need to work out what size circle has 3/4 of it's circumference equalling 60mm.

4 x 60 = 240, 240 / 3 = 80mm (You need a circumference of 80mm)

To find the diameter - 80 / 3.142 = 25.48

You need a drum diameter of 25.48, this is close enough to 1 inch in that measuring system created in the dark ages lol

This will provide a true linear signal from a rotary pot and the wire won't slip if it's wrapped around the drum about three times.

Hope this helps!!!

Gwyn

[AK Mongo]

"To connect a slide throttle to a rotary pot there is a simple solution - attach some fishing trace wire to the end of your throttle slide and then wrap the wire around a small drum on the pot (like a cotton reel shape). Wrap it around the drum about three times and then attach the loose end to a fixed point using a light spring to keep the tension on. When you buy stainless steel fishing trace wire it usually comes with small crimps for making loops on the ends for connecting swivels etc."

Gwyn,
I love this idea...it is thrifty and clever, exactly what I was looking for! Has the advantage of being able to use parts I have lying about instead of using more cash. Would the "pulling" force from the spring or wire cause the pot to fail due to sideload? Can't imagine those things have substantial bearings. Any thoughts?

[Westozy]

[QUOTE=AK Mongo;102105
Would the "pulling" force from the spring or wire cause the pot to fail due to sideload? Can't imagine those things have substantial bearings. Any thoughts?[/QUOTE]

There will be no load on the pot, the light load from a fine spring will all be inline with the wire! The only load on the pot drum will be the wire itself gripping it!


I---------_____________O___________ /\/\/\/\/\/\/\/\/o

Throttle......................Pot........................spring


(how's that for a quick sketch!!!)
Gwyn

[flatlandpilot]

is it possible to make something like this:


travel_dist. = (300/360) * 2 * pi * r

btw if you use 2 pot meters, but only connect 1 electracally,
than you only have to find 2 knobs with the right diameter. (or a little bigger)

potmeters with a metal shaft are bit more durable.

[AK Mongo]

Another great idea! Knew this was the right forum for creative mayhem!