What type of motor?

[Cam]

Im thinking of making one of these I found on STARGAZERS LOUNGE

http://stargazerslounge.com/diy-astronomer/175350-simple-homebrew-electric-focuser-newt.html

Ive had a look on Ebay and found these little motors in both 6v and 12v and ranging in RPM from 6RPM right up to 1000+RPM any input on what would be a good choice for a 10:1 Crayford??? Thanks Cam

[bojan]

6 rpm

[Cam]

Thanks for replying Bojan.. Do you think it would be best in 6v or 12v I usually have both scopes out. The refractor I power with a jump pack that has 12v and usb. Although sometimes I take just the Dob out so for this reason thinking of making it a handbox that runs on batteries.. maybe a toggle switch to control?

[alistairsam]

Hi Cam,
That would depend on the rating of the motor.
the speed is usually specified for a specific input voltage. you can vary the voltage within a window and output speed would correspondingly vary.
it'll be good if you can get a 3v geared motor as there are wired remote controlled toys that have a small box with two buttons to move the car forward and backward. they just reverse the polarity. that box would be ideal.
but have you thought of manual adjustment in case you ever need it? you might need some sort of slip clutch for that.

[Cam]

thanks for the input Alistair,, wondering if you are the Alistair I met at Snake Valley lol.. Maybe a slip could be as simple as pulling the belt off lol

[Cam]

P.s checking the lil ppls remote control cars lol

[bojan]

Cam, you can also consider driver electronics, it is discussed here:

http://www.iceinspace.com.au/forum/showthread.php?t=51301&highlight=focuser+motor

[alistairsam]

Yep, that's me

[RAJAH235]

I made one for my 10" dob, years ago & a couple more for other people.
I used an old servo (from a radio controlled boat), that had failed.
Simply dismantled the gearbox & removed (filed off), the stop tabs, so that it rotated 360º & made up a quick & nasty speed controller in a small Zippy/Jiffy box.
I had a friend machine up a small pulley to fit the servo output shaft & used an
"O" ring as the drive belt.
Powered by 2 AA batteries that just fitted inside the box & it worked fine.
I used one single pole switch to turn it on/off & another (2 pole change-over/centre = Off) to control the In/Out focus.
I also included a small pot to vary the speed slightly.
Total cost was around $6.00.

Pic is here > http://www.iceinspace.com.au/forum/attachment_browse.php?a=552

[Cam]

Thanks for the input guys

[alistairsam]

Hi Cam,

Whilst this is not precision stuff, here's one possibility to salvage IR toys
http://www.youtube.com/watch?v=gA-wQFrSTGY&feature=player_embedded#!