Arduino - poznámky

Verze z 7. 6. 2017, 15:00

Frekvence pro Seben RA motor 12.67Hz

Post-Printing

Instructions: 1.use drills and countersink bits to clean all holes and notches. 2.Insert the M3 nuts into the gears, and thread the M3 bolts. 3.insert the ball bearing into the gears holding plate. 4.insert the holding plate both polar axis shaft and elevation shaft. 5.put the stepper motor in place with M3 bolts. use M3 washers to avoid print crushing. keep them loose for the moment. 6.insert both small and big gears into the polar and motor shafts (small gear into the stepper, big gear into the polar shaft as shown in photos. 7.tight the gears bolts. do not overtight. 8.use a plasting bag as a gauge between both gears. hold both gears together and start tightening the motor bolts in a star pattern. 9.with a stepper driver of your preference, and a arduino, connect your stepper and let it run for 20 minutes at a moderate speed, to the gears will wear a bit. this process is called breaking in. 10.finally use a brush to clean both gears. add a little of grease to lubricate the transmission. it will run quietly. 11.according to my calculations, the final transmission including the equatorial mount worm gear:

144:1 (worm gear) and 2.05:1 (printer gears) = 295.2:1. with a A4988 in a 16 microstep mode, a 200 steps motor will run at 3200 steps/revolution. if polar axis should run roughly at 23 hours 56 minutes y 4,0916 seconds (sidereal day) per revolution, this gives a 82800 s + 3360 s +4.0916 s = 86164.0916 seconds /rev. of the polar axis.

for each revolution, the steps count for the motor will be (3200 x 295.2= 944640 steps), wich gives a (86164.0916 s/944640 steps) = 0.091213681 seconds/step, or 10.9632676703 Hz.

this ~11Hz signal can be generated using an arduino. to keep costs low, a NE555 can be used. for a fast feed of the equatorial mount, a higher trigger frecuency can be used according t desired feed speed.

a switch for direction changing of the stepper. is also recommended