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Possum Pass Observatory* |
* Yeah, yeah, technically it should be "Opossum Pass", but there is just something about the two P's that seems right.
On occasional late nights we receive a visit from the neighborhood opossum. Therefore it seemed fitting to name the observatory in his/her honor. Hopefully we'll catch our friend in action soon and can add a photo. Pending determination of gender, we are going to name it either Astro or Stella.
The Possum Pass observatory is currently under construction. The latest construction pictures follow.
Construction pictures from prior days.
As last weekend, we only had a chance to work on the observatory on Sunday. We also got a few minor things done during the week, such as installing latches to hold up the flip-down panel and painting the fascia boards on the shed-side roof. We were hoping to get some of the shed-side roof done, but we laid out the metal panels and trim and were not 100% sure on a few details. It was late in the day and we were tired, and it seemed like a good excuse to call it a day until we have a chance to consult our metal roofing vendor.
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Here's a picture of the flip-down wall. After a lot of thought and measurement, we figured out how to get the siding done on the flip-down south wall. Overall, it looks pretty good. All four pieces of siding line up pretty well, and after a little caulk and paint it should look great. We only trashed one sheet in the process, so overall not too bad I suppose... |
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Here's the fully-sided flip-down panel in action. And I thought it was
heavy with just the 2x4 framing... Had we to do it over again we might have framed it a little lighter, but the HardiPanel requires studs 18" on center. So perhaps there is not much to be done in the weight department. We can probably raise and lower it by hand, but for convenience we may use a simple counterweight system. We'll see... |
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Here's how the flip-down wall is held up. Two simple gravity latches (common on fence gates), one on each end, hold the wall securely in place. The advantage of this sort of system is that the panel can be closed by one person from the outside- just flip it up and the latches will catch (though one needs to be adjusted a bit to latch properly without a little help). |
We only worked Saturday afternoon and Sunday morning, but we managed to get the shed-side roof installed. Since one of the roof trim pieces needs to be replaced due to a minor manufacturing defect, we could only install trim on two of the four sides for the lower roof.
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This is what the roof looked like prior to installing the metal roof.
Installing a metal roof is relatively easy- just screw the metal sheets into
the perlins (the 2x4 boards running from lower right to upper left).
There are little washers on the screws that make it watertight. Cutting the panels was the hardest part. The trim came in 10' lengths and had to be cut to size. The panels are 3' wide and can be ordered to length (9'8" in this case), so we only had to cut one panel since the third panel only needed to be 8" wide. |
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Here is an early-Saturday-evening shot of the roof panels all screwed down to the perlins. We had not yet screwed the panels together. |
| Sunday we screwed the panels together and installed the gable trim, visible here along the leftmost edge. |
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Last weekend it rained, so we didn't get any work done. However, our new roof seems to be properly sealed, so at least we got to test that out.
This weekend we had hoped to get the doors on, as well as finish the roof trim on the shed-side roof. We ended up agonizing over how to do the hinges for the doors, how to build the doors, etc., so we really didn't do anything tangible until Sunday.
| Here's how far we got- about a door and a half. There are still some details to finish on the shed-side door (at left in picture) such as a latch, etc.), but it's pretty close. On the right side you can see the approach we took on getting the doors installed- basically we cut the plywood, attached the wood boards for the left side only, attached the hinges, attached the door to the building, and checked for fit. It was dark when we were attaching the observatory-side door (at right in picture), so we just got it up to cover the doorway (no more plastic sheeting stapled in the doorway- woohoo!). |
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As much of a pain as it is to make doors and get them aligned properly, I now understand the market for pre-hung doors (doors where you buy the door already attached to a frame and just install the entire frame in your doorway). We initially were going to use a pre-hung door, but since we wanted a shorter, non-standard height (to prevent the shed from being higher than it already is), that wasn't really an option.
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Here's the trim on the mostly-finished door. Note the beautiful 45-degree cuts on the trim. Tip if you try this at home: caulk and wood putty are your friends. Use them. We will be caulking and priming this coming weekend (I hope). |
| The door consists of half-inch plywood with 2x4s around the edges on the back, with 1x4 trim on the front. Note the hinges are attached only with two screws right now. Apparently the most common way to attach shed doors is to put the hinges on the outside. However, we wanted a little bit more security, and since opening inward (like most standard outside doors in houses) would take up too much space, we opted for hinges on the inside of the door frame (with non-removable pins of course). Unfortunately the hinges had to be set pretty far towards the outside to allow the door to open all the way. We'll probably drill additional holes to further secure the hinges. |
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We were really hoping to have more tangible progress this weekend, but many of the things we got done are not really "visible". Some things we did:
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Here are the completed doors. We still need to paint them and then install latches, but the door stops, thresholds, etc. are finished and the joints caulked. Basically we are ready to prime and paint them. |
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The roll-off roof will sit on two 14' stainless steel rails (1 1/4" x 1 1/4" angle
iron x 1/8" thick) which I ordered and picked up last week. You can
see a smaller piece we used for prototyping at lower right (the gray thing
with the white price tag on it). Basically, there will be a rail
sitting on the
east and west walls and a wheel assembly (one shown at right) will hold
four wheels in place on each rail. The rest of the roof will be built
connected to these wheel assemblies. (This will make much more sense
once I have a picture of the completed roof.) The wheels have
V-notches in them that keep them lined up on the track. Early tests
are encouraging. The metal rails will rest on the east and west observatory walls and stick out over the lower roof. We will machine some small aluminum blocks that match the slope of the lower roof and will hold the rails at the same height as the east and west walls on the observatory side. That holds the rails level, so we should just be able to roll the roof right across the rails. Sounds easy, right? :-) |
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At this point, our optimistic view is that it will take about three solid weekends worth of work to get the roll-off roof working and get the observatory in a fairly functional state. There will then be quite a bit of "finish" work left like painting, etc., but the observatory should at least be functional. We have other plans for the next two weekends, but we'll get back on it the weekend after. So hopefully by mid-October we'll be in a functional state. Keep your fingers crossed...
After two weeks "off" (well, I did put primer on one door last weekend), we got back to it. Unfortunately, we were pretty much rained out on Saturday the 25th, so we really only had the 26th to make any progress.
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The big news is that we got the basic frame up for the roll-off roof.
Were you unsure how the "wheel assemblies" unveiled in our last installment
would work? Well, at left you see how this whole roll-off roof thing
is supposed to work. The 14-foot steel rails sit on top of the walls
running along the left and right sides of the picture at left. The
wheel assemblies ride along them, and the long 2x4 boards running along the
top and bottom of the picture at left connect the wheel assemblies together
and form the base of the roll-off roof. The rest of the roof framing
(that will hopefully be done next weekend) really only serves to strengthen
the basic structure at left in place, and provide sufficient structure to
hold the metal roof.
What's that thin white thing running horizontally between the left and right walls you ask? One little snag we ran into was that the flip-down panel on the south wall (the wall you can see the most of in the picture at left) does not attach to the walls with the steel rails on them, and the wall at right has decided to bow outwards and make the tops of the walls out-of-square. We thought this might happen when we did the flip-down panel, so we need to arrange some sort of bracing to prevent this. We temporarily used some ratcheting tie-downs to pull the wall back to square so we continue working on the roof. |
| The basic roof structure rolls fairly easily. At right you can see the roof in the fully open position. The roof overhang (not yet built) will hang about 9" over into the observatory side (the right part of the picture), but overall the roof rolls off far enough that it will obscure very little of the sky. |
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Here's the roof sticking out over the shed side. (The plywood is from the temporary roof over the observatory...we just slid it off onto the shed while we worked on the rolling roof.) The steel rail goes nearly to the end of the shed roof, and is temporarily supported by wood blocks that are cut to match the slope of the roof. We are hoping the roof will be sufficiently balanced to allow it to hang over edge of the shed roof a little bit (note the overhang visible along the leftmost edge). |
| And in our closing shot, you can see the temporary roof (plywood laying across 2x4's with tarps on top) re-installed on top of the rolling roof base structure. Also note the two doors are primed. |
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We were really hoping to have more tangible progress this weekend, but many of the things we got done are not really "visible". Some things we did:
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Here are the completed doors. We still need to paint them and then install latches, but the door stops, thresholds, etc. are finished and the joints caulked. Basically we are ready to prime and paint them. |
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The roll-off roof will sit on two 14' stainless steel rails (1 1/4" x 1 1/4" angle
iron x 1/8" thick) which I ordered and picked up last week. You can
see a smaller piece we used for prototyping at lower right (the gray thing
with the white price tag on it). Basically, there will be a rail
sitting on the
east and west walls and a wheel assembly (one shown at right) will hold
four wheels in place on each rail. The rest of the roof will be built
connected to these wheel assemblies. (This will make much more sense
once I have a picture of the completed roof.) The wheels have
V-notches in them that keep them lined up on the track. Early tests
are encouraging. The metal rails will rest on the east and west observatory walls and stick out over the lower roof. We will machine some small aluminum blocks that match the slope of the lower roof and will hold the rails at the same height as the east and west walls on the observatory side. That holds the rails level, so we should just be able to roll the roof right across the rails. Sounds easy, right? :-) |
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At this point, our optimistic view is that it will take about three solid weekends worth of work to get the roll-off roof working and get the observatory in a fairly functional state. There will then be quite a bit of "finish" work left like painting, etc., but the observatory should at least be functional. We have other plans for the next two weekends, but we'll get back on it the weekend after. So hopefully by mid-October we'll be in a functional state. Keep your fingers crossed...
We pretty much got rained out on Saturday again, but on Sunday we finished the shed-side roof trim (finally got around to it) and framed the roll-off roof. Check it out...
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Before shed-side roof trim...
After shed-side roof trim...
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Surprisingly, installing this trim was a huge pain. The issue was that
this is not really a "regular" sort of roof arrangement. Basically we
have the wall of the observatory side (which is very short) meeting the
sloped roof of the shed side, plus two small sections that stick out from
the rest of the building (visible near the left edge of the photos) that
need different trim. Anyway, after pulling our hair out and wearing our hands out with the tin snips, we finally got it working. Along the way we broke a cast metal clamp and a pair of needle-nosed pliers trying to bend the trim to make it fit better. Our advice: don't bother unless you have the proper equipment. Had we to do it over again we probably would have ordered a custom-bent piece of trim. But in the end it came out okay, and besides, it's on the roof...who cares what it looks like as long as it is watertight... |
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The roof framing, visible at right, went surprisingly fast. We gave up
trying to use a circular saw to do the angled cuts- it was faster and easier
with a hand saw and a miter box, and the cuts came out much better than when
we did the lower roof for the shed. With the basic structure in place
from last weekend, the framing only took an hour or two, plus yet another
trip to Home Depot to get some different construction connectors. You may have noticed that we only installed one fascia board out of four (the one at the back of the frame in the picture at left). We did this so we could think about how to handle the gap between the rolling roof and the top of the observatory wall (it it much more visible the picture above). We just didn't want the fascia to be in the way when we addressed this issue, so we left the others off just to be safe. Besides, it was getting a bit late as you can see... |
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The two burning questions you are bound to have at this point are how far
does the roof roll off, and how hard is it to roll. As you can see, it
rolls almost completely clear of the observatory space. At best it
will only cover about a foot, perhaps more if we don't think it will be
supported well enough. The 9.5 foot observatory roof has to roll off
over the shed roof, which is less than 7 feet wide. So far it looks
like there won't be any problems having the observatory roof stick out a
couple of feet beyond the shed roof. As far as weight goes, the structure is easier to roll than we thought. After we covered the roof back up with plywood, I (Chris) rolled it back and forth a few times and was able to do so with only a moderate effort. Hopefully the weight of the frame plus plywood will be close to the final weight so we can avoid having to use some sort of winch, pulley system, garage door opener, etc. to open and close the thing. |
We finally got the metal roof installed on the roll-off roof. It's amazing to see it actually finished and working. A not having to put plywood and tarps over the building at night is a really nice bonus. We also got quite a bit of painting done.
| On Saturday we spent a lot of time waiting for paint to dry. Since the roof trim covers the fascia, we needed to paint the fascia before we could put the roof on (since the lower piece of roof trim goes under the metal sheets). While waiting for the fascia to dry, I put the Takahashi FSQ-106 (a 4" refractor, my wide-field 'scope) on the mount, rolled the roof off, and dropped down the south wall just to see what it would be like. I'm happy to report that 8' x 8' is quite comfortable... |
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Now on to the roofing. We had to cut two panels to make it fit correctly. Cutting these panels with tin snips is not a fun task. However, we didn't think it was worth the cost of renting special equipment, so we just suffered through it. It is probably quite a bit harder than it looks. Remember, when you cut it, the cut piece does not move out of the way. So you have to pull it, tear it, or bend it out of the way every inch and a half or so. Imagine cutting a 9' 8" panel of roofing like this. Twice. It took us a good forty-five minutes or so. Fortunately the ragged edge left by this crude cutting method is nicely covered up by roof trim. I'm sure some roofing installer out there is cringing at the thought of this brute-force method. Either that or laughing really hard... |
| Just one more panel to go! |
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We finished it up Sunday evening. My (Chris') back is still aching from bending over and screwing in all five zillion screws. But it looks great! Now let's just hope it is water-tight. :-) The lower roof appears to be in good shape, so we should be okay. Of course during the first rainstorm I'll be camped out in the observatory just to be sure... |
| And the obligatory "entire shed" shot, taken Monday morning. Note the painted fascia and roof trim on the observatory, and the painted doors and green trim around the doors. Yes, the doors *are* painted, it's just that the color matches the house and the house color is rather similar to the primer color used on HardiPanel siding. Hey, off-white is a beautiful thing. Really... |
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The real icing on the cake was I got to use the observatory Saturday night. I didn't do anything fancy, just set everything up and played around with it for an hour or so before the clouds came in around 11 p.m. I took some quick images of M57 (the Ring nebula in Lyra), one of my favorite objects. I didn't bother to keep them since I was really only testing my polar alignment, but it was nice to actually remember why we've gone to the time, effort, and expense of building this shed-on-steroids.
Speaking of polar alignment, it will be a bit tricky since I cannot see Polaris due to the north roof. I knew this during the design phase, so it's not too big of a deal (you don't have to be able to see Polaris to polar align you know). Anyway, I polar aligned everything before we started on the construction, and it has retained its alignment pretty well. I'll probably end up getting TPoint or some other telescope-modeling software anyway, and that will help get me get it dialed in exactly anyway.
Wish us luck! - Chris 10/11/04
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Last Updated: October 11, 2004
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