A while back I had a rod builder with a request for an automated reversing dryer motor on a timer.
After several different options, I finally finished the design last night for a timer to reverse the DC gear motor dryer direction in times of 1-90 seconds. With a typical dryer speed of 10 rpm, this will give a partial to several rpms of drying before reversing the direction of the dryer.

The thought was that by reversing the drying direction, especially for the first couple of minutes of drying time, that the end result would be smoother, more level and of overall better quality.

The proof will be in the pudding, so to speak , after it is put into use for some testing.

I had never thought of trying this before, but it was an interesting project to get the timer built up and checked out.

It will be up to the client to test the timer with various times and finish applications and technique to see if the timer results in a better quality rod guide finish.

Essentially the final design is a 555 timer chip based printed circuit board, driving a pair of relays, which in turn drive a 12 volt dc gear motor. The entire timer is supplied by the same 12 volt power that powers the dryer motor. Switches are in place to reverse the motor direction manually, turn the motor on and off, and also to enable the automated timer with its own reversing circuitry.

Time will tell if this system results in a finish that pleases the client.


Be safe
Roger

Let us know how it goes. Sounds interesting.

How about one that would turn the rod 180 degrees at adjustable timing?

Phil Erickson Wrote:
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> How about one that would turn the rod 180 degrees
> at adjustable timing?

There you go. And with a sag sensor. :)

_________________________________________
"Angling is extremely time consuming.
That's sort of the whole point." - Thomas McGuane

Phil Erickson Wrote:
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> How about one that would turn the rod 180 degrees
> at adjustable timing?


a servo motor (basically a windshield wiper) would fit perfectly for this app. it would be tough finding one with a low enough turn ratio. i know that you could series a few resistors in line with one to accomplish the same effect, but idk if it would still have the torque to turn the rod. especially at 12v.

also 180 degrees would make where you would have to control exactly where the chuck attached to the rod. no slippage. that way the lag on stop start would oppose each side and prevent build up. to start i would have the quides straight up and down at reversing positions.

Phil,

Actually to make a dryer that would turn 180, stop for a timed period of time, then turn another 180 could be done with reasonable effort, a stepper motor and motor controller and a microprocessor.

Take care
Roger

A windshield wiper motor does not go cw/ccw in 180 degree changes. That is done in the linkage going to the blades. the motor turns one way.
below is a link that shows the idea
[auto.howstuffworks.com]

tom in indy

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tom in indy

im fairly certain it was at one point done with a step motor (servo) at least i was told as much by one of my teachers. im also pretty sure the rear wipers on modern vehicles still use them. however i could be mistaken.

Daniel,
Here is your answer:

[triumph.daveola.com]

Roger

thank you for the link roger. i forwarded it to my teacher who now claims he never said servos were present in anything except, robotics, some kinds of clocks, and sometimes highly automated process control systems. im not sure exactly where i got the notion of them being present in windshield wipers but, either way i am glad to be corrected.