Guest MichaelDurban Posted September 12, 2014 Share Posted September 12, 2014 Well..Every dob owner remembers the perils of the night...When one's hand moves slowly but determined towards the focuser knob, blindly.., eager to feel.. Stretching out your fingers slowly towards that micro adjuster, hungry to feel that cold touch of steel ..You're not sure, you just remember the approximate direction..and hope.. Your eye is transfocused on that elusive DSO, you don't want to look away now..just a tiny tweak to get it into focus..Then..when you touch it..you instantly know you have failed. You find your aim was way off, your fingers fumble, and fold inwards against the wheel...You bump, rather than the intended fluid motion you had envisaged, that vibration free movement whichyou only see on youtube... Your hard fought DSO dissolves into a shaky mess of black and grey intertwining nothingness..A soft curse breaks throughout the night.. Ah yes.....as you move your head away from the eyepiece..you are convinced beyond belief you needthat US$ 400,- geared focuser with microstepping and feather touch 11:1 ratio, buttery smooth..You even look at your hips...How much for a kidney on ebay? Or..Do you?Simple solutions await us...and mine is probably no more simple than any other described on this website.Take one (Chinese made) plastic gearbox. It's a cheaper alternative (for South Africans at least..) to buying one online... Next, dissasemble the focuser wheel from the axle, a little grub screw holds the wheel and the axle together. Then..find any suitable gear/sprocket...I canabalised my old Xbox... With the help of some..very strong adhesive..I simply stuck the gear wheel on the axle. Next, assemble the little gearbox, and solder two wires to the terminal ends of the servo motor. I used an L-bracket to glue the gearbox onto it...and secured it with some plastic tie-downs. the little yellow gear (at the end of the shaft) fitted perfectly on the large black gearing wheel (focuser axle). although there is some play in the gear shaft as it turns, I overcame this slipping effect by letting the glue settle a bit and then switching on the gearbox. As the shaft rotated (and slipped against the larger black gear) I adjusted the angle and length such that the little driving gear was now fully engaged on the larger black gear. Then I let the glue harden overnight..and hoped.. I switched on the gearbox the next morning and although there is a little bit of play (lag) the whole setup works like a charm ! No slippage.. Finally I bought a little black electrical box, a holder for 2x 1.5V AA batteries, a three way switch and a 10k potentiometer (pot meter). With the help of youtube I soldered everything together and connected the terminal leads from the gearbox to the little control unit. Yes..it looks a bit messy (it looks 'Lionel') but this is my first attempt at soldering actual electronics. Then I bought a cheap GPS holder (the one with the big suction cap) and took that apart..much to the dismay of my wife. I took a deep breath and drilled the GPS holder with three small wood screws into the rocker box. Added some velcro and voila !!! (sorry for the upside down pictures...was also my first time using flickr...) Finally everything is complete..it took me a saturday morning to put it together. Performance? well...it is a leeeetttle bit noisy... But it works like a dream, I can finally micro adjust....and without any vibrations !!!! Cost? In South African Rands about R 200,- Which (converted) is about GBP 10,- It takes a little bit of determination and perseverance, but in hindsight this project was so easy, I can't believe I put it off for so long.. Hope you enjoyed my rather (long) story.. And this concludes my very first post on EMS !!! Cheers!!! Link to comment Share on other sites More sharing options...
Rusty Strings Posted September 12, 2014 Share Posted September 12, 2014 Looks great! May well try that one myself. And welcome to EMS Link to comment Share on other sites More sharing options...
Doc Posted September 12, 2014 Share Posted September 12, 2014 Dobs are so easy to DIY it makes them perfect for the tinkerer amongst us. It looks great just needs a little tidying up, but the most important thing is it works. Well done. Link to comment Share on other sites More sharing options...
Daz Type-R Posted September 12, 2014 Share Posted September 12, 2014 Congratulations on you mods, I have modded mine as much as I can, nothing left to do now. As for the focuser, I chickened out and bought a Moonlight. Link to comment Share on other sites More sharing options...
Guest MichaelDurban Posted September 12, 2014 Share Posted September 12, 2014 oooh...a moonlight man !! haha... I understand.. I would have done the same thing.. But my salary is paid in Rands, so I have no option other than to make this stuff myself.. eventually, some day..a moonlight will come my way Link to comment Share on other sites More sharing options...
Daz Type-R Posted September 12, 2014 Share Posted September 12, 2014 A lot of my other mods I have done myself or with help, my last mods were flocking the OTA and cleaning the primary. Made a big difference to the contrast. Link to comment Share on other sites More sharing options...
Guest MichaelDurban Posted September 12, 2014 Share Posted September 12, 2014 Yes..modding is the best..I love tinkering and solving problems.. I'm also going to put my other mods in the diy section.. But I don't want to bother everyone with my stories.. I Promise, I'll keep it short. Link to comment Share on other sites More sharing options...
Doc Posted September 12, 2014 Share Posted September 12, 2014 Michael the more the merrier. The DIY section gets a lot of hits so we need content to keep everybody happy. Link to comment Share on other sites More sharing options...
Guest MichaelDurban Posted September 12, 2014 Share Posted September 12, 2014 Souds good.... Wiil get cracking...thanks ! Link to comment Share on other sites More sharing options...
Tweedledee Posted September 13, 2014 Share Posted September 13, 2014 That looks like a nice job, and keeps it cheap. Well done Link to comment Share on other sites More sharing options...
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