Getting Started on my 'Dob'

 

or ... What I did on my summer vacation

(even though it was actually winter and I wasn't on vacation).
  • Saturday 2001/12/08 - Went to the show!
I went out to the Von Braun Astronomical Society planetarium and observatory to watch the Christmas Star show and join the club.
  • Tuesday 2001/12/11 - I bought a 48 inch long 8 inch diameter concrete form.
  • Wednesday 2001/12/12 - I bought a Meade 26mm Super Plossl telescope eyepiece on eBay for $40.
  • Meade Super Plossl 26mm.
  • Meade 8 x 21 finder scope.
    • Wednesday 2001/12/12 - I bought a Celestron 29mm (1.14 inch) Secondary mirror on eBay for $5.  
      My theoretical goal was 1.247 for .5 degree field but it was cheap and I still have ZERO experience with scopes.
    • This focuser was in pretty good shape. It needed cleaning and adjusting and it still wobbles just a little.
    • Friday 2001/12/14 - I went to meet with the observatory director and got a mirror and a focuser. He also made me a collimating tool from a plastic film cannister and suggested a design for an adjustable focuser (my realization of that design shown below).
    • Ok, I've got a cardboard tube, a focuser and a mirror. I feel like a kid with a new toy and I can't wait. Here's what I did...
    • My first experiment was to set the newly acquired mirror upright in my garage and try looking into it with a (junk .96) eyepiece. I also tried using a 2x2 mirror to move my head out of the way. No joy.
    • My second experiment: I wanted to point the mirror up. I knew that my light cone would stop an the top of the tube, so I put a paint can under the mirror to push the focal point out of the tube. I set my new tube over both of them. Then I taped a 1x2 board across the top of the tube (like a spider) and taped my 2x2 mirror at a 45 degree angle on that. Then I tried my eyepiece again. Very shaky, but something looking like stars was there.
      I knew that my light cone would stop an the top of the tube, so I put a paint can under the mirror to push the focal point out of the tube, then taped a pocket mirror on a stick at the top of the tube. Then I got one of those miserable toy .96 eyepieces and wrapped a paper towel around it so it would fit the 1.25 opening and braced the focuser on the top lip of the tube.
      • I raised the mirror by setting a roll of box sealing tape on the paint can. I got one of those miserable toy .96 eyepieces and wrapped a paper towel around it so it would fit the 1.25 opening and braced the focuser on the top lip of the tube. Now I could see very poor quality star images from directly above.
    • Saturday 2001/12/15 - Mirror mounted on a plate.
    I couldn't get the back off and there were screws there already so I just used the screws to mount the mirror to a backing plate.
    • Monday 2001/12/17 - Postman brought the secondary mirror, the finder scope and the 26mm Super Plossl! I attached the mirror to the almost complete spider.
    • The spider I build from Wes' idea. (This was before I actually saw the secondary mirror).
    • I mounted "L" brackets and 2 inch #8 screws on the tube.
    • Mounted mirror plate to "tail end" of main tube.
    • Close up of collimation bolts.
    • Tuesday 2001/12/18 - Attached PC slot covers to the spider. Cut hole for focuser and mounted it. Mounted spider. Colimated scope. Took it out into the night for it's first test, sans mount (that means I set it on a door mat and leaned it against the BBQ grill).
    • Finder scope and focuser mounted on tube.
    • Thursday 2001/12/20 - Invented the "Shopsmithsonian Mount".
    • Shopsmithonian mount. This photo has 'tube box' installed, but I used it without the box for a week.
    • ... with DeWalt counterweight.
    • This worked amazingly well. The trouble was switching objects; it was a lot of work. Returning to horizontal, for example, was performed something like a bear hug...
    		This is because the counterweight only holds the base from falling off the little cabinet, but does not really balance the scope.
    • Friday 2001/12/21 - Bought some more eyepieces on eBay. All are 1.25" diameter.
    • Tuthill Astro 18mm, Celestron 25mm Kellner, Celestron 6mm (unknown) and Meade Modified Acromatic 9mm.
    • Saturday 2001/12/22 - Worked on the base of the Dob mount.
    • About 80% complete Dobsonian mount.
    • Sunday 2001/12/23 - Worked on the bearings for the Dob mount.
    • I used a 4 inch PVC coupling for each bearing. I cut out 1.5 inches in the middle to have a lip for the wood to sit on. There's a 1/4 inch ring for the pipes to bottom out on and I left 1/4 inch pipe on one side (towards the tube box) and 3/4 inch on the other side.
    • Tuesday 2001/12/25
    • Bolt for pivot and rocker boards installed.

     


    Lunar occultation of Saturn - Friday morning, December 28, 2001

    • My scope is still not done yet. It's not painted inside and I want to make the spider smaller. I get some spikes and glare from that, I think. Also, I only have the one lense so far. The others are on order. The camera I used was a HP Sureshot 210. No mount, just held it over the eyepiece. I tried a pair of sunglases for a filter in one of the moon shots. Just so you'll know what to expect...
    • I labeled 'em, but any astronomer worth his or her NaCl would recognize them!
    • Jupiter and four moons.
    • Saturn.

     

    • Monday 2001/12/31 - New Year's Eve
    • We had a talent contest at my church instead of a wild drinking party.  I didn't perform, but instead announced that my talent was a telescope I built and I could show Jupiter, Saturn and the Moon to any interested folks.  A lot of people came out.  Many oohs and aahs were heard and one person even asked me if that wasn't really a picture taped over the end of the scope...
    • Tuesday 2002/01/02 - Got my shipment of eyepieces.
    • Got the five eyepieces pictured above and also a GTO 40mm, a 2x Barlow and a variable polarizing filter.
    • Unfortunately, my focuser bottomed out before any eyepiece (other than my Meade 4000 Series 26mm Super Plossl) came into focus. When I got home, I moved the focuser back by 2.5 inches. I think that would have done the trick except it was very cloudy. What I had now was in range, but I think the clouds gave the apperance of out-of-focus.
    • I got some very short glimpses of Jupiter, Saturn and the Moon, but I didn't want to move the focuser and replace the spider both, so the spider upgrade will have to wait till later.
    • Tuesday 2002/01/08 - Installed the new spider - finally.
    • Front end of 1/2" spider hub with small knurled screws and a 4" 3/8" diameter bolt.
    • 1/2" PVC coupler with 3 PC slot covers.
    • 1" coupler spider next to 1/2" coupler spider.
    • Notice how much of the spider hub is visible around the mirror.
    • I trimmed off the dowel, drilled a small hole and threaded the 4" machine screw into the dowel.
    • You can see that the mirror now covers up all but the tips of the screws.
    • Painted the inside of the tube flat black (right over the wax and everything).
    • I also put the 'center dot' on the mirror. Then I tried collimating; but something feels 'funny'. I think I may need a bigger shaft for the spider adjustment bolts to sit on.
    • Was up till the 'wee hours' adjusting and trying the different lenses. I guess I'll have to try some pics to see if the difference is measurable, but I don't see as much 'glare'.
    • Monday 2002/01/14 - Got a new toy from an eBay purchase in the mail.
    • This is an Orion ShortTube 80mm refractor. It came with an H20mm eyepiece and a Celestron StarFinder instead of the finder scope.
    • This is a picture from the Orion web site. I didn't get the finder scope or mount.
    • Sunday 2002/01/20 - Started experimenting with a right angle finder scope.
    • 1.25 PVC "T" fitting.
    • 1 inch cap.
    • 1 inch to female threaded.
    • Sunday 2002/01/25 - Won an eBay auction for a returned Orion Explorer 90
    • I bought this as a gift for my sister.
    • It has a 910mm focal length and an altaz mount.
    • I'll probably put the Kellners that came with this scope with the ShortTube (that's what it's supposed to come with also) and sell it on eBay. I don't need three telescopes! (not for very long anyway!)
    • Sunday 2002/02/14 - Sold the ShortTube 80 on eBay - like I said, with the Kellners
    • I put the Kellners and the finder scope with it and sold it on eBay.
    • Now I have to find some replacement eyepieces for the Explorer!
    • I think I about 'broke even' since I sold it with more than I bought it with.

    More pictures coming soon!


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