A tale of the leftover wood DOB.
Orion was straight out from my side porch and the 10 inch gave me excellent views of the nebula. There were parts
that looked like pulled apart cotton and the nebula stretched out with two wisps forming at 2 o'clock and around 7
o'clock and going out to the limits of the field of view in the 18mm eyepiece I had in.
I had used Polaris to test the inner and outer focus star images before I viewed Orion and the planets. The images
were as close to the same in both directions as I could tell with the seeing that night. There wasalso good snap to
focus. Stars were not refractor like by any means but looked very nice in ten inches of scope.
12" had to go away. Bills you know. Wished I could replace it with a good sized, good optics dob, but not likely.
What would you like for your birthday dear? I would like money honey. Got some old parts out and sold them to
raise some more cash. So with a few hundred dollars burning a hole in my pocket I was off looking for astro stuff.
Eyepiece? Camera stuff? Books? Decisions, decisions. Glanced at the atm section at astromart and hello, there
were optics for sale. 10 inches of coated mirror. Wow, is that a secondary too. And a spider and holder for the
secondary. Gasp a 2 inch focuser too. Owner said the mirror was testedat Woden Optics at close to 1/10th wave.
Should I go for it and take a chance? Hesitated for all of 15 seconds, and then a "I will take it"
went out. Sent him the cash and waited. Box came. All the parts looked good.
Got a concrete form from home depot $8.00 Made a plywood mirror cell. Got carriage bolts, springs, and wing nuts
for the cell. Put it together attached the mirror dropped it in the tube. Springs provide the collimation ability for the
main mirror. The spider contains a three screw adjustment for the secondary mirror and needed a plywood ring to
stifen the thin concrete tube enough for tighten the spider.
Got the freeware Newt program to layout where the secondary mirror goes, and that defines where to cut the large
hole for the focuser. Measure twice cut once. OK, measure four times. Alright measure six times, cut once. Ahh, just
right. 4 or 5 inches of tube in front of the secondary is good to help with dew and stray light. Tube has mirror,
secondary, focuser. Time to collimate. Looks like it's close. Test it on the distant trees across the valley. Get the old
barlow and take off the optics end to provide extension above the focuser. I brought the focus point well above the
stock focuser requiring an extension to achieve focus with an eyepiece, but it allows my cameras to focus. A pain to
balance the focus while not causing vignetting. Think I got it, but still need to check it out with flat field images.
There is a bunch of leftover 1/2" plywood, from other home projects and shipping pallets. Looks like an altitude
bearing box to me. Two hours, and there is the first pass at the box.Screws no glue. Altitudebearings with Formica
from an old dob that never got finished are added and I'm done for now. Assorted scraps of 1/2" plywood and 2x4's
will make the base and a place for the Teflon pads for the altitude bearings to runon. In the back of the garage is
the Formica sink cutout I had planned to throw out at every garage cleanup for the last twenty-four months.
Glad I did not. The Formica became the bearing surface for the bottom Teflon pads, and now I had everything but
the ground board. Morelooking in the junk/leftover pile and there at the bottom of a bunch of cutoffs is 1/4" plywood
just big enough for the ground board. Three blocks oftwo inch thick mahogany from the dumpster when a lab was
renovated at work one year for three feet, and the mount for the tube was ready topaint. Let's see. Got some gloss
black enamel form the porch chairs.Looks good to me. Plus there was just enough for the base. OK on to the tube.
Wanted royal blue. Found nice gallon of white latex house paint. Tubes should be white I guess, and it's already in
stock! White tube looks good. Alright that's that.
Final touches. Altitude box needs a bit more clearance as there is some drag on it at close to zenith. A bit of belt
sander and it's all better. Nice smooth motions from horizontal to vertical. Balance is just about correct. Got an hour
to do a quick star test and adjust the mirrors. Wonder if it will hold. One thing about the tube from Home Depot it's
really too thin to be stiff enough without the large altitude bearing box. That thing is almost as heavy as the optical
tube itself, and needs a date with a hole saw at some point. Works though, and the OTA and box can be carried
with one had using the LARGE handle I bolted on it. It's not fun but works and the scope and mount base can be
moved together when I feel the need. Don't get me wrong. Not moving yards, just a few feet. It is by no means an
Views are all I had hoped. The scope lives on the porch. That was the goal after giving it some thought. I wanted a
quick look scope of reasonable size. It takes about one minute to set the scope up. It's already at ambient
temperature since it's outside all the time. When monsoon season here at the ranch is over the base can stay in the
yard all the time. Hope it does not look to much like a planter. Alas, some risk must be accepted.
Scope is cheap in terms of investment and if lost (I hope not!), I will be in pain, it's a great scope, but not bankrupt
as the total investment for a 10 inch f4.7 telescope is a couple hundred dollars plus less than twenty dollars in
hardware total spent,and more room in the garage for more scrap wood cut to size. I did not desire a masterpiece. I
wanted basic mechanical goodness and a good mirror.
Something I would not fear leaving out on the porch. I admit I slapped it together and it was fun to do that way.
Came out better than I hoped. Not a bad deal at all.
Took a while to get this written up, but wished to
share an observing session I had. A wonderful
clear night on Wednesday, with the just finished
dob I built, provided some of the best skies I have
had here at home in some time.
Saturn had belts on the globe, The rings were
clean and crisp, and Cassini was visible around the
There was a pale yellow tint to the planet and rings,
and the view held pretty steady at about 400x
which was a wonderful verification for the optics.
This was one of the finer views I have been given
the opportunity to see.
I got to look at Mars, and when the seeing allowed,
was able to glimpse surface detail, which when I
looked at Cal sky's previewer showed features in
the right place from what I had seen.