Slow Pan Servo Modification

Dennis Foster, Commerce, Oklahoma, USA       October 5, 2001

Front View Back View Perspective View -Extracts from Emails-
I have been reworking my entire KAP rig and hope to finish it tonight [Oct 5, 2001]. I installed a gear reduction assembly, the one from Hobby Lobby, to get the Pan speed down. It now makes one revolution in 14 seconds, about right I think. I got the idea from Brooks Leffler on using the gearbox. He has one but drives it with a servo. I did something fairly neat here. I took a servo apart an extracted the circuit board and trim pot. I have those mounted in a small plastic container with the leads extending for the receiver and the motor drive. I am using the motor that came on the gearbox as it is rated at 4.5 volts which is about what the battery pack supplies to the motor in the servo.

I used a piece of phenolic as a hub [for the picavet]. I drilled through the bottom of the cross and attached the hub with 4 #4 screws and then drilled the hub to accept #6 screws to secure it to the output shaft of the gearbox. I also added the thrust bearing to carry the weight of the rig and let the gears run freely. You can see the long #4 screws I have holding it in place [Font View] but, that's all I had last night and will replace those with allen head set screws today.



I more or less retrofitted it, using the same mounting holes as the original pan servo was attached to, that way I can remove this and change back if need be, also, it would be easily adapted to other rig's!

The two photos are attached, a front view and a back view. You can see the circuit assembly on the back held in place with double stick foam tape. I used a small plastic box that "ear plugs" come in. I can open it up to adjust "null" if necessary. On the front side, the gearbox is pretty much just like it came from Hobby Lobby. I did add a .01 capacitor across the motor terminals to cancel motor noise generated by the brushes.


I got the gearbox from Hobby Lobby International out of Brentwood, TN. The model number for the gearbox is, HLH 7917 and it sells for $14.90 plus shipping!.

Dennis can be contacted by email at: kk5py@rectec.net

UPDATE - October 21, 2001

Threaded Output Shaft [Ed.- Dennis sent this picture with the short email message below about an improvement to his "Slow Servo Modification"]

Just a short note to attach a photo of yet another modification to the KAP rig. I did some scrounging this past week and found a metric die, 3mmX50 to thread the output shaft of the gearbox drive (Circled). I believe that this gives much more insurance against a "bombs away" than the hub with set screws did.