MOTORIZE- ROLL OFF ROOF

Once I started using CCDAP4 for automating my imaging runs, it became quickly apparent for a need to automate the roof opening and closing . Especially, with Winter and the rainy season coming up.

There are commerically available systems out there, but somewhat pricy. After searching the web I found a great idea for a roll-off roof that used a modified electric hoist motor. "Thanks to Mike @ mikesastro.com."

See Mikes site on how to modify the Harbor Freight 440 lb electric hoist motor.

Amateur source: Mikes Website

Motor source: Harbor Freight

Spur Gear Source: McMaster Carr

Rack Source: McMaster Carr

Control System: Foster Systems

12 vdc Relays: Altronix RDC12

MOTOR MODIFICATION WITH BEARING BLOCK
I machined and added a custom bearing block for better strength and support of the spur gear drive shaft.

MOTOR MOUNTING AVOIDS START-UP JOLT

I mounted the motor on a 1/4" thick x 12" x 18" steel plate. Using a 1/4" steel plate allows the motor mounting to flex slightly, avoiding the sudden full-on impact jolt that these motors exhibit because they lack a soft start.
FOSTER SYSTEMS MC-100 PROGRAM DASHBOARD

The AstroMC software will handle remote roof control and also interface wtih CCDAP4 or ACP plus any weather monitoring such as Boltwood or AstroMC's own weather sensing system. AstroMC system
ADJUSTER BAR

Added a 1/2" x 1/2" steel bar with cap screws for fine adjustment of motor/ spur gear position.

COVER IN PLACE

Covered with matching indoor/outdoor carpeting.
RACK INSTALLED

Rack shown engaged with spur gear.
amc
cover
cover

FULL OPEN & CLOSE LIMIT SWITCH CONFIGURATION

Shown below is the Fully Closed limit switch. The Full Open limit switch is located at the rear of the observatory and offest ~ 2", so that "Closed Trip Cam" will clear when it passes by.

15 amp roller/snap action switches were used for the full open and close limit switch safety stops.

Plastic project boxes were used to cover the switches & wiring connections. I made appropriate cut-outs in the boxes to clear movment for the switch travel. The trip cams were machined from aluminum blocks ~ 3/4" thick.

CONTROL BOX & LIMIT SWITCHES

The control box houses a manual toggle switch (DPDT spring centered- replaces original motor control switch) for manual motor open and close. Also, inside are (2) DPDT 12vdc relays that are controlled via AMC-100 software.

On the outside is a 5 amp fuse with a 0-5 amp meter to monitor current load. Opening and closing pulls about 3.5 amps. I installed motor limit switches on full open and full close to prevent any possible roof over-runs.

The near limit switch is for "Roof Close Stop" and the far limit switch is for "Roof Open Stop." The roof is in a midway position, so the switch trip cams are not in view. Also, note the ~2 " offset between both switches to avert trip cams from activating switches from the wrong direction.

WIRING DIAGRAM (click on diagram for enlarged view)

Two DPDT relays are used to automate roof opening and closing.

FOSTER SYSTEMS AMC-100 ROOF CONTROL

Roof control circuit board installed along with a 12vdc supply.

CUSTOM FIT COVER

Designed with quick hang-on hook/ hole & clip for easy access.

cover

ROOF IN ACTION

Roof opening has (2) limit switch/ trip cam positions. The position shown is a partial opening when using the imaging scope only. This position still covers the desk/ computer, minimizing potential dew in that area. A full open position may be set to fully exposed my other scope for visual activity.

TROUBLE SHOOTING PROBLEM- "Roof closing short"

I have two motor cutoff limit switches, one for roof opened and one for roof closed. Also use two magnetic sensors that are used to sense roof open and roof closed positions. (See wiring diagram on this web page.)

The roof was stopping about 3/4" short of making the motor limit switch cut-off. The problem was only occurring on roof close. The roof open seemed to be alright. I noticed that the magnetic sensors on the roof open position were spaced farther away from each other. They were lined up on full open but offset (See Pics below of MagSensors).

After numerous trials of adjusting "switches/ sensors" back and forth, with no luck, I decided to move the magnetic sensor for roof close, sideways similar to the roof open relationship. This seems to have done the trick! The roof now closes all the way making the Motor Limit Switch cutoff. I guess the magnetic field is now only strong enough when Magnet and Sensor are exactly aligned side by side giving the roof movement a little more time to make the Motor Limit Switch. Another issue is that these switches are kind of mounted in the wrong direction. I think they should be turned 90 deg. so they would by bypassing over there short distance, not lengthwise...........Due to various clearances on my roof design, I had to mount them lengthwise. Anyway...........PROBLEM is now fixed!