Mert
Carpal Tunnel
Reged: 08/31/05
Posts: 1800
Loc: Spain, Pamplona
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That's a wonderful job Ed, very inspiring!!
Please let us know how it performs! 
Regards and thanks for sharing
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Mert
42º49"N 1º38"W
3" Polarex refractor
6" F12 SW Maksutov,CS2-S
EQ6 + EQMOD 
SPC900NC/DFK21AU04.AS
My web-page don't laugh, I should make it better! 
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reiner
super member
Reged: 09/28/05
Posts: 100
Loc: Freiburg, Germany
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Hi Ed,
can you tell me more about the motors? Are these DC geared motors? Could you post a link to where you bought them?
Thanks
Reiner
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Reiner
22" and 14" Dobs on EQ platforms
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Luigi
Post Laureate
Reged: 07/03/07
Posts: 4938
Loc: MA
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Looks like a really nice, clean implementation! I've been planning to build at paltform once I get my shop set up (I'm moving) and this is a nice as design I've seen.
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17.5" f/5 Dob. IM-715 MCT. 120ED. Lunt 60mm Ha.
Zeiss, Leica, Fujinon, Nikon, Pentax, Bushnell bins
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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The motors i used are 1/15 RPM AC timing motors CCW rotation 110 volt 60 hz 1.35 watts by Sonceboz. I just checked Apogee's website and sorry they no longer have them it seems. However Herbach and Rademan has this motor for $18.95.
here
It is clockwise however which means the motor must be mounted in front of the north bearing.
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Ed Jones
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reiner
super member
Reged: 09/28/05
Posts: 100
Loc: Freiburg, Germany
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Thanks for the information, Ed. I like your platform design.
R
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Reiner
22" and 14" Dobs on EQ platforms
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ren hoek
member
Reged: 09/22/07
Posts: 73
Loc: Burlington Ontario Canada
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Ed, would you consider building one of these for a price $$$
or perhaps a kit
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Skywatcher Dobsonian 10" F4.7
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Almagne
member
Reged: 02/25/08
Posts: 33
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A bit more information on the motor drive would be helpful. Is there some kind of control to vary the speed of the motors?
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Note my workshop is a picnic table! I expended a lot of wife's good will on this project, I know not to push her limit. 
For a motor drive check out this thread.
here
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Ed Jones
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Wes James
Post Laureate
Reged: 04/12/06
Posts: 3454
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Ed- Any suggestions for driving stepper motors? I picked up a couple, and haven't found an independant, speed controllable circuit or kit. Most of what I found was meant to be run off a couputer, and that's not in my agenda.
Thanks, btw for documenting this as you did... I'm one of those to whom EQ platforms are somewhat magic, not that I can't build- or do jigs, but the whole concept is right on the edge of understanding. The Yahoo EQ group has some good intro's in their files, studying them... am relocating from Florida to NY (upstate) within the next year or so, so not in a rush- want to have one for NY's latitude, so am slowly planning mine out. Bought a couple of stepping motors for it.
Wes
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Tom L
Reged: 01/07/04
Posts: 30838
Loc: Sunny Oregon
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Thanks Ed! Just added this to my thread watch list. I love the way you made the bearing on the table saw.
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Tom 
Tele Vue 102mm f/8.6 on an EzTouch
Vixen 80mm f/5 A80SSWT on a grab-n-go mount
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Wes,
The only stepper driver I've messed with is this WZ Micro
It doesn't do half steps or microsteps. Steppers are more noisy than timing motors and need more battery power.
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Ed Jones
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epee
professor emeritus
Reged: 11/30/06
Posts: 697
Loc: Suh-van-nuh, Jaw-juh
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Ed,
You may have inspired my next project. There goes the house painting for another month....
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Jim Girardeau
Orion XT12 Intelliscope
Celestron 11X80mm binoculars
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Wes James
Post Laureate
Reged: 04/12/06
Posts: 3454
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Thanks, Ed-
Wes
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Good luck, my wife found my paint brush today. What a way to spend Memorial day, painting the deck.
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Ed Jones
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reiner
super member
Reged: 09/28/05
Posts: 100
Loc: Freiburg, Germany
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Ed, I just read your thread on the speed control for the AC motors. This is a great idea.
I use for my platforms generally geared DC motors and a small voltage controller circuit, such that everything runs from a pack of four AA cells, which last "forever". I don't like step motors partly for the same reason as you (noise, high current, and complicated electronics). These AC motors and the frequency controller are really a new twist. What kind of battery is required to run the inverter?
Reiner
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Reiner
22" and 14" Dobs on EQ platforms
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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That inverter comes with a cigarette lighter plug for a car although any 12 volt battery will work.
One other note on timing motors. The ones I bought for my last eq platform ran fairly hot so I put resistors in series with them to drop the current. I put 2K or 4K resistors I think and they still didn't stall under load. Saves battery too.
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Ed Jones
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Mark Harry
Post Laureate
Reged: 09/05/05
Posts: 3125
Loc: Northeast
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On the large piece of wood you use and made for the south(?) bearing:
Do you find it necessary to line it with something to keep the wood from developing a "divot" or "flat spot", or is the maple hard enough to accomodate the 1/2" shafts? And, any problem with traction between the motor shafts and wood?
Mark
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So many projects, so little time!
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Mark Harry
Post Laureate
Reged: 09/05/05
Posts: 3125
Loc: Northeast
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My latitude is 42.5 degrees. I'm wondering if I could simplify things by using just 45 degrees, and making up the difference with leveling bolts/pads?
Mark
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So many projects, so little time!
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RRavneberg
professor emeritus
Reged: 12/02/05
Posts: 634
Loc: Columbus, OH
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Ed,
Looking forward to seeing your handiwork. Will you have it at Apollo Rendezvous?
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Ron Ravneberg
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Mark,
I have used maple wood, walnut wood and now maple plywood for bearings. Normal usage in my first 2 platforms hasn’t created any problems with divots. I don’t know how much banging around it would take to cause a divot but certainly more abuse than you’d want to put your scope through. I know others put metal on the bearings but I think this is overkill. I don’t get any slippage with knurled rods and 2 motors and I’m fairly sure these unknurled posts will not slip as well on wood, stay tuned, I’ll let you know.
There was one case where I did get a divot but it wasn’t normal use. I left my platform running and it actually ran off one of the rollers and the causing the other roller to run in the same spot. The knurling did grind a divot but would have on metal too I think.
I’d recalculate the platform for a different latitude, that part’s easy.
Ron I will have this and hopefully my 12 inch at Apollo.
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Ed Jones
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