My refurbished Coulter

Last month, someone gave me a old Coulter Odyssey, an older mass produced dobson style 10" f/4.5... mid 80s, cheap particleboard construction, but decent optics.

the mirror was moderately dirty and had big gaps in its plating where salt air had etched it away. I replaced a few broken bearings with similar furniture glide bits found at the local hardware store, and it was usable.

the focuser was embarrassing, a crude push tube affair, difficult to focus without moving aim.

I removed and cleaned the mirror with soapy water and dried it with acetone, then handed it off to Bob Fies to be stripped and plated. He did an excellent job.

While the mirror was away, I replaced the pushtube focuser with a 2" crayford focuser, and added a 9x50 erect finder, both found used for cheap locally.

When the mirror returned from plating, since my focuser had added 1.5" or so of height, I added three wooden block risers to the mirror mounting plate, then RTV'd the mirror to these using 3/16" thick spacers til the RTV cured.

Adding a old vinyl LP ("The Birds, The Bees, & The Monkees", don't laugh) to the base bearing and replacing the nut with a nylock 1/2-16 made it usable.

the fan we installed in the base, a 120mm vantec 'stealth' computer fan, works great. take the scope out of my car, plug it in, and in 20-30 minutes, its quite usable. i haven't actually seen any vibration caused by it, even at 120X (currently the highest power I'm using this at)

the 9x50 erect finder directly on the top of the tube is great for homing in on things but i've had trouble finding initial guide stars in it, so I just installed a spare telrad base... a quick driveway test of this arrangement was very successful, I was able to find things in short order.


a mid 80s 'red tube' Coulter Odyssey 10.1" f/4.5


orion 9x50 erect finder, telrad, and orion 2" crayford focuser

Next up is to fix the altitude bearings. Right now, I'm thinking of going with some 10" or so 1" thick birch ply disks with ebony star, and teflon. Rather than rely on 5lbs of dead weight added to the bottom/back of the scope, I think I'll move the pivot point forward some to rebalance things, this will require raising the sides of the rocker box a bit but I'll need to redo that anyways to support the larger bearings.

update - november 11

I've replaced the secondary mount with a curved vane spider from 1800destiny. I chose their lightest 'medium' spider with the optional larger mirror holder... This coulter uses a thick heavy 2.5" secondary, I probably should have gotten the beefier 'large' version as it shifts a bit between vertical and horizontal. however, this should cure the horrible big single diffraction spike the original mount created.