Reply to "Building a Gr4 replica"

Goodroc wrote,
"Geometry of the Linkage he just needs to make the moving Arm the exact lenght that matches: fully retracted=Doors closed and fully extended=Doors open or visa versa."

Yes, that's true but as I see the problem there are two variables: the length of the "arm" that is attached to the headlight bar and the mounting point/geometry of the linear motor with respect to that arm. Changing either of them can effect either or both of the up and down position. The exact up position end point is not too critical, you just adjust the headlight alignment accordingly. But, if the down position is wrong, i.e. the bucket is closed all of the way before the limit switch is tripped the motor could burn out. Of course the stock system has this problem too but the limit switch stops make it easy to adjust. So, either a geometric solution using fixed limit switches or adding an external limit switch(s) would work. I'm just wondering which would be easier for a given situation.

Actually, I'm surprised that Gary "comp2" has not commented as he was working on this problem in 2009 but never posted his results.
http://pantera.infopop.cc/eve/...77274/m/93610454/p/1
He posted some interesting links. With the right kind of linear actuator (with a Potentiometer) and a "Linear actuator controller" the actuator can be commanded to go to programmed positions:
http://www.slickcar.com/info_linear_actuator.asp
http://www.slickcar.com/detail...ved-door-handles.asp
some more info on the controller:
http://www.speedwaymotors.com/...t-Actuator,7477.html

I've not looked into making any of this work with the stock headlight circuitry and switch. My guess is that using external limit switches would be necessary.

If you don't care about that and are OK with putting in a separate switch to raise and lower the lights then a power window switch approach would work just fine: just hold the switch on until you get to the position you want (i.e. things stop moving when they hit a mechanical stop) and let go. Just make sure your actuator isn't strong enough to bend things!