Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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My latest scope needs a new eq platform because of the high CG. I'm almost done with this one except for some sanding, varnishing and bolting down the motors but so far it's cost only $29.5. That doesn't count the maple plywood I already had, ball bearings I had and some screws and leveling feet I need to get yet. It'll be done before the scope!
2 motors from Apogee @ $4 each
2 3 inch Newport SS rods @ $6.60 each
maple from Home Depot $8.30
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Ed Jones
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rmcpb
Carpal Tunnel
Reged: 11/16/04
Posts: 1606
Loc: Blue Mountains, NSW, Australia
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Ed,
What is the layout on the bottom board?
Looking good 
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Rob Browne
8" & 13" Dobs
Equatorial Platform
Couple of Panoptics and a handful of BO/TMBs
9x60 binocs
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The bear
scholastic sledgehammer
Reged: 02/11/08
Posts: 824
Loc: rushville, indiana
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yes ed enlighten us to your good owrk this would be ideal for a poor child like me.
doc
might have the motors already hehe
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Longitude -85.42786 Latitude 39.59153
"current build 6 inch F6.5 "Little Toe"
"if all else fails use duct tape "works for me"
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Here is the bottom board. The 1/15 rpm motors from Apogee are CCW so they must go behind the north bearing. I drilled our the smaller tapped hole on th post to 4 mm to match the motor shafts on a lathe. The SS posts from Newport are 1/2 inch so the radius of the north bearing is 23.93. The CG above the middle of the board is 17.6 inches. Total height 4.25 in. If you want I can start another thread on how I made it.
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Ed Jones
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The bear
scholastic sledgehammer
Reged: 02/11/08
Posts: 824
Loc: rushville, indiana
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yes please this would be very informative and excellent instructional to us all.
doc
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Longitude -85.42786 Latitude 39.59153
"current build 6 inch F6.5 "Little Toe"
"if all else fails use duct tape "works for me"
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Jason D
Post Laureate
Reged: 10/21/06
Posts: 3302
Loc: California
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How well does it perform?
Jason
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XT10 classic with premium optics
Tri-knob CR2 with compression rings
Round Table Platform
4.5" StarBlast
6" StarBlast6
TV EPs
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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As you see it isn't finished yet but it's almost exactly like my first platform (which tracks great)except that I'm not going to knurl the Newport posts. I don't think it'll be necessary. I can always knurl it later if need be.
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Ed Jones
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Biff
Carpal Tunnel
Reged: 09/04/05
Posts: 2372
Loc: Courtice, Ontario
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Quote:
If you want I can start another thread on how I made it.
Isn't this that thread? And yes I'd like to see all the details too, namely how you setup to cut a VNS with such a tight tolerance for the radius!
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Ryan
Antares 200mm f/6 Dob & 130mm f/5 Travel Dob.
Projects on the go...
- a couple 80mm SS refractors on the back burner.
- a few small mirrors awaiting polishing
- 260mm f/7.15 mirror... still polishing
Member of DRAA
 My house.
 DRAACO
Edited by Biff (05/25/08 10:16 PM)
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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OK well I'll start from this thread.
My latitude is 39.25 degrees and my rocker box is 18 inches square so I started with a platform 19 inches wide and long.. Shown below is the cross section layout. The south bearing is 11.91 inches radius spaced 18 inches from the north bearing. The mid platform CG is 17.6 inches from the platform but my computation for the scope CG is 14 inches, 3.6 inches lower but I don’t think it’s a problem at all.
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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I cut two boards with a 50.75 degree bevel about 4.5 inches X 20 inches. On the back side I tacked a ¼ inch scrap piece of plywood and measured from about where the tape is to a 23.93 inch arc from each side. I drilled a hole for a finishing nail to pivot on at that point
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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On my table saw I bolted a ¾ inch piece of wood with my finishing nail pivot a little more than 24 inches from the blade. The blade was tipped at 50.75 degrees and lowered all the way down. I raised the blade a 1/16 of an inch at a time and swung the board into the blade slowly pivoting on the nail. I raised it another 1/16 th and repeated. Eventually the blade was above the board and it was roughed out. I then switched to a sanding disk and continued, moving the part a small distance into the disk each time until the radius was 23.93 at the midpoint. This makes beautiful smooth bearings (and I have fun doing this as well).
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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I made a trapezoid board 19 in. long by 16 in . on one side and 19 in. on the other. I drew a mid-line perpendicular to the middle of the small side (on the bottom).
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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I glued a block with a 50.75 deg. angle on the mid line for support.
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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The south bearing comes out pointed so finding the mid-point is easy. I align the midpoint with the mid-line and glue and screw it together.
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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With a square set to intersect the curve on the north bearing near the edge, I mark both sides then find the mid-point.
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Ed Jones
Edited by Ed Jones (05/25/08 11:53 PM)
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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I made an obtuse triangle to support the back, lined up the mid-point and glued and screwed it together as before. A support block on the other side would have been easier.
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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I glued a 1.5 X 4.5 inch piece of maple to the inside of two 24 X 2.5 inch pieces. This is for mounting the motor. I drilled a ½ inch hole in two pieces of teflon and cut them into for bearings. 2 cross-pieces of maple were glued for strength. (I taped the posts and bearings in place temporarily to figure out where the cross pieces should go.)
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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3 pieces of maple were cut to hold the bearings. The rear bearing block was easy, the other two were compound angles and it took a number of tries cutting pieces on a band saw to get the angles right so that the ball bearings races ran flat to the bearings. These little pieces were the trickiest part of the project.
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Ed Jones
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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The rest is sanding, varnishing, screwing the teflon and motors down, wiring etc.
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Ed Jones
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ZachK
professor emeritus
Reged: 08/21/05
Posts: 709
Loc: Israel
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Thank you, I was planning something exactly like that and I think you gave me what I need to get going. I need to figure out how to do this without a table saw though. I have a jigsaw and a router.
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Zach Kessin
Ariel Israel
Meade ETX 127 Mak-Cass
15x70 Celestron Skymaster Binoculars
Sinar F 4x5 view camera
Rolliflex Camera 80mm F2.8
Pentax K-1000 Camera 35,50 and 60--300mm zoom
4 kids
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Mert
Carpal Tunnel
Reged: 08/31/05
Posts: 1792
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: 4934
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: 3453
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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: 3453
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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: 3124
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: 3124
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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The bear
scholastic sledgehammer
Reged: 02/11/08
Posts: 824
Loc: rushville, indiana
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i know this might sound stupid but how do you get your latitude?
doc
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Longitude -85.42786 Latitude 39.59153
"current build 6 inch F6.5 "Little Toe"
"if all else fails use duct tape "works for me"
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Look it up on a world map, GPS, Google latitude US cities.
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Ed Jones
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The bear
scholastic sledgehammer
Reged: 02/11/08
Posts: 824
Loc: rushville, indiana
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thanks i got it
doc
--------------------
Longitude -85.42786 Latitude 39.59153
"current build 6 inch F6.5 "Little Toe"
"if all else fails use duct tape "works for me"
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The bear
scholastic sledgehammer
Reged: 02/11/08
Posts: 824
Loc: rushville, indiana
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when you use the ac motors then you use a battery pack when you are in the field could you post or send me how you hooked all this up as i am a little electronics challenged and trying to configure al this stuuf so i know what to get when i build my scope(s)?
doc
you are great for helping us out with this soon we will all have eq mounts.
 
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Longitude -85.42786 Latitude 39.59153
"current build 6 inch F6.5 "Little Toe"
"if all else fails use duct tape "works for me"
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Bear,
Here is a shot of my 8 inch on the finished platform, you just plug the motors into a DC to AC converter (about $20) which plugs into a car battery or power pack. I was able to try it out last night but it was almost a disaster. I wired up the motors, plugged it in and the left motor didn't run! Of course it was the motor I hadn't previously tested and now these motors are no longer available. Fortunately these motors can be taken apart so I took the motor off the gear box and freed up the motor shaft. I put it back together and it worked fine. I took it outside and put my 8 inch on it (my 12 inch will be a bit heavier). I plugged it in to my extension cord, focused on a star and watched for drift. The star drifted right across the field. #&@!! Man this thing doesn't work at all, then I chased down the other end of the extension cord and sure enough the wife had unplugged it. With the motors running the stars were rock steady, slowly drifting north or south. I had only roughly pointed it north, later I will make a laser holder to do this more precisely. It looks like it works as designed and the shafts don't need to be knurled.
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Ed Jones
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kfrederick
professor emeritus
Reged: 02/01/08
Posts: 662
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that is a cool scope i like the wood is it maple ?
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Yes, all maple except the octagonal bottom tube which is Baltic birch.
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Ed Jones
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JasonNB
member
Reged: 11/21/06
Posts: 98
Loc: Spring Hill, TN
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Subscribing to thread.
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Zhumell 8" Dob
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RedIrocZ-28
Pooh-Bah
Reged: 09/18/05
Posts: 1175
Loc: Grand Rapids, Michigan
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Ed, seems there is a problem with the link to the motor drive circuitry you posted. It goes to the archives and then has an error when you click the link to go to the archives.
Can you give the name of the post that the info is in? I would like to look this up because I need to get my EQ table back working after the DC motor control circuitry burned out last week...
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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I've never post a DC motor control, AC yes but not DC.
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Ed Jones
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RedIrocZ-28
Pooh-Bah
Reged: 09/18/05
Posts: 1175
Loc: Grand Rapids, Michigan
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Ed, I had a DC motor on my platform, that worked "ok". I was able to track Mars for 4 minutes but not much beyond that. I was then tweaking the gearing and during testing the damn hand controller burned up a resistor. So, I decided to switch to either AC or Stepper motors. And I noticed that you were using AC. So I'd like to see whats the story on your design
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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My link doesn't have the post number either, looks like CN has dumped it or something. Too bad that speed control post was pretty neat. Maybe Mike can help, it was called "How to make a cheap speed control". If not I still have the pictures I took, basically all I did was replace one or two resistors and wire in one in series and one parallel with push buttons in a commercial inverter. If CN can't help should I post it again?
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Ed Jones
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stardustborn
member
Reged: 11/30/07
Posts: 54
Loc: LI, New York
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For those who want to get started down the road, TL Systems sells a kit for an eq platform with stepper and controller. I made the kit and it worked fine for my xt10 but I then canabalized it for my current mount. The kit rollers,parts and such may be minimal but at least you get the motor, controller and basic idea. I found it confusing and frustrating trying to get my mind around the whole thing and finding parts to make my own so the kit worked well for me.
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Orion xt10i on an ugly homemade english fork eq mount
A stepper motor,wires and stuff
Push to digital circles(COL) into "The Sky"
"The Noble Turkey Observatory".... (a small shed)
http://picasaweb.google.com/stardustborn/NobleTurkeyObservatory
Orion Starblast 4.5 imaging scope
Meade DSI 2 pro mono
...and a piece of space to peer into
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RedIrocZ-28
Pooh-Bah
Reged: 09/18/05
Posts: 1175
Loc: Grand Rapids, Michigan
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Ed, found the link
http://www.cloudynights.com/ubbarchive/showflat.php/Cat/0/Number/2062609/page/0/view/collapsed/sb/5/o/all/fpart/1/vc/1
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Great! I see that Jensen still makes a 180 inverter but it's a different case color. Maybe it's the same board inside. You can get one for about $22.
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Ed Jones
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arpruss
scholastic sledgehammer
Reged: 05/23/08
Posts: 854
Loc: Waco, TX
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Two questions:
1. What would happen if you took one of the motors out of the design? Would there be more slippage? Or would a single motor not handle the weight?
2. Would you be able to post a photo of the whole underside of the top board? I am kind of confused what the three bearings at the back bear on. Thanks!
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Coulter Odyssey 13.1" split-tube
Coulter Odyssey 8"
Home-made 7.8" F/4 dobsonian travel scope
Home-made 68mm F/5.3 achro (typically used as finder on 13.1")
Skymaster 15x70
BPTs4 8x30
32mm Plossl, 30mm Rini, 27mm Kellner, 13mm Hyperion, 6mm TMB/BO Planetary, Owl 2X Barlow
Palm TX with AstroInfo and RescoViewer
Edited by arpruss (10/29/09 08:41 AM)
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Initially I used only one motor but I often use other scopes with different COGs. One scope is top heavy and the motor would slip on one side because there was little weight on it, 2 motors fixed that problem and heck they are only $19. If you only use the scope it was designed for then you can use 1 motor. If you use 2 motors I found that you can wire them in series to use even less current and they still work fine.
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Ed Jones
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arpruss
scholastic sledgehammer
Reged: 05/23/08
Posts: 854
Loc: Waco, TX
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Quote:
Initially I used only one motor but I often use other scopes with different COGs. One scope is top heavy and the motor would slip on one side because there was little weight on it, 2 motors fixed that problem and heck they are only $19. If you only use the scope it was designed for then you can use 1 motor. If you use 2 motors I found that you can wire them in series to use even less current and they still work fine.
Makes sense. I will be designing for my 13" with ~25" high center of mass, so this may well come up.
If you do have a photo of the whole underside of the top board, that would be appreciated. I am guessing that you have a smaller beveled sector at the south end?
Is there anything useful here that could be done with the steppers and gears from a dead Roomba?
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Coulter Odyssey 13.1" split-tube
Coulter Odyssey 8"
Home-made 7.8" F/4 dobsonian travel scope
Home-made 68mm F/5.3 achro (typically used as finder on 13.1")
Skymaster 15x70
BPTs4 8x30
32mm Plossl, 30mm Rini, 27mm Kellner, 13mm Hyperion, 6mm TMB/BO Planetary, Owl 2X Barlow
Palm TX with AstroInfo and RescoViewer
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Here is the bottom side of the top board. The north bearing is parallel to the ground, the south bearing has a 15 degree tilt I think to it to keep always against the ball bearings. Note the stick on the north bearing to stop the platform at the end of travel, the smooth shaft can't climb it so it stops. I just push it back to reset, I doubt if any other platform is this easy to reset.
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Ed Jones
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arpruss
scholastic sledgehammer
Reged: 05/23/08
Posts: 854
Loc: Waco, TX
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Nice!
Do the 1/15 rpm motors have any speed adjustment options?
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Coulter Odyssey 13.1" split-tube
Coulter Odyssey 8"
Home-made 7.8" F/4 dobsonian travel scope
Home-made 68mm F/5.3 achro (typically used as finder on 13.1")
Skymaster 15x70
BPTs4 8x30
32mm Plossl, 30mm Rini, 27mm Kellner, 13mm Hyperion, 6mm TMB/BO Planetary, Owl 2X Barlow
Palm TX with AstroInfo and RescoViewer
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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Arpruss,
Synchronous motor speed is determined by the line frequency. I don't need variable speed because the tracking speed is correct. If I were doing photography then I would use the variable frequency inverter mentioned above but then you would need a second axis motor too.
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Ed Jones
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salies
member
Reged: 08/10/09
Posts: 31
Loc: catalogne france
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hola ed! you work is very good for me!
j am envoy see your build
congratulations!!!!
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sempre andavant ,mai morirem !
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arpruss
scholastic sledgehammer
Reged: 05/23/08
Posts: 854
Loc: Waco, TX
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Ed:
How thick is the maple ply that you used?
I am still in the planning stages. What I really like about this design is that it doesn't use a single-point south bearing like most of the other designs on the net. For my scope with a 25.5" high COG and about latitude 30, a single-point south bearing would require a ridiculously long platform--about 58" long.
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Coulter Odyssey 13.1" split-tube
Coulter Odyssey 8"
Home-made 7.8" F/4 dobsonian travel scope
Home-made 68mm F/5.3 achro (typically used as finder on 13.1")
Skymaster 15x70
BPTs4 8x30
32mm Plossl, 30mm Rini, 27mm Kellner, 13mm Hyperion, 6mm TMB/BO Planetary, Owl 2X Barlow
Palm TX with AstroInfo and RescoViewer
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Ed Jones
Pooh-Bah
Reged: 04/06/04
Posts: 1415
Loc: Sin-sin-atti
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I use some old maple wooden flooring 3/8 thick and doubled it to 3/4.
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Ed Jones
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arpruss
scholastic sledgehammer
Reged: 05/23/08
Posts: 854
Loc: Waco, TX
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Does anyone have any spreadsheet for the measurements? I made one (I'll post a link once I know it works) but I'd like to double check its calculations against someone else's before I start to cut.
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Coulter Odyssey 13.1" split-tube
Coulter Odyssey 8"
Home-made 7.8" F/4 dobsonian travel scope
Home-made 68mm F/5.3 achro (typically used as finder on 13.1")
Skymaster 15x70
BPTs4 8x30
32mm Plossl, 30mm Rini, 27mm Kellner, 13mm Hyperion, 6mm TMB/BO Planetary, Owl 2X Barlow
Palm TX with AstroInfo and RescoViewer
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