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Monday, August 21st, 2023 [UTA assembly]
The UTA, Mirror box +trunnions, and Rocker have arrived via USPS. The trusses, wheel barrow handles, Nexus DSC have yet to arrive.
I dry sanded the cage rings and spacers down to 220 grit, with a progression of 120-150-220 grit. After dry sanding, I assembled and epoxied the cage together using 24” bar clamps. The entire assembly was situated atop 2x4’s on the figuring table, as shown at right. This was allowed to set for 48 hours.
Next, I epoxied the upper truss blocks to the lower ring, and clamped them for an additional 48 hours. The picture is shown below. I used popsicle sticks to prevent marring of the wood.
Saturday, December 2nd 2023 [Testing top coats]
Over the summer, I divided a single ¾” thick 3”x 9” of Baltic Birch plywood into two sections using blue masking tape to test tung oil and Helmsman Spar Urethane (Polyurethane) as finish coats. I followed a strict regime with the tung oil. I put on 3 coats of the Helmsman Spar Urethane. This sample was allowed to cure for 3 months and this is the result, seen at right.
The tung oil side is rich and has depth, while the Helmsman side lacks depth and looks relatively flat. It’s evident that the Tung Oil mixture would work better as a clear finish to highlight the figure of the Baltic Birch.
At this juncture, I’ve decided to experiment with dye. I purchased TransTint Dye in the Perfect Red color. To test this, I’ve set up another Baltic Birch Sample of 3”x9”, again divided with blue tape, but this time into 4 sections. One section contains the red dye without a tung oil base. This is the 2nd from left. The far left has a tung oil base, and I stopped after 3 coats of the dye on both red samples. This can be seen at left.
Based on the results, I’ve decided to purchase orange dewaxed shellac flakes, and make a cut using denatured alcohol. I will spray this on as a seal coat so the dye goes on evenly. I’ve chosen orange flakes to move the red towards a warmer color.
The cut is 8 drops of red dye with 1 tablespoon of denatured alcohol.
Friday December 8th, 2023 [Mirror box assembly]
I spent an hour calibrating my miter saw to make square cuts, and made my own square jigs to help pull and keep the mirror box square during assembly. The jigs are oddly shaped to give multiple clamping surfaces for the clamps. Pictures shown below.
Saturday December 9th, 2023 [Mirror box assembly]
Andrea helped me glue up the mirror box today. We started with a dry run, clamping up the mirror box without epoxy, to familiarize ourselves with the process and how it should go together. I used eight 36” bar clamps to clamp the sides, and eight hand clamps to clamp the jigs. I had to use small 8” bar clamps on the corner jigs I made to force two of the mirror box corners into square. Those jigs came in very handy today. They also provide an excellent visual aid if the box is out of square (gaps in between the jig surface and box surface). Picture shown at right and below of a dry run using the corner jigs I made.
When Andrea and I glued everything up, we put a bar clamp on the top and bottom on each side of the mirror box, for a total of eight bar clamps. After clamping, we noticed gaps between the mating surfaces of the jigs and the mirror sides. This indicated to me that the mirror box was out of square. Loosening the clamps a few turns helped get everything squared up. One corner still was a bit stubborn and would not completely square up. Adding a small 8” bar clamp to the jig resulted in a tactile POP, and it was square after that. The picture of the 8” bar clamp on the jig is shown at right.
Picture of the clamp up are shown below.
Sunday, December 10th 2023 [Start of Rocker Box Assembly]
Per the manual, dry sanded the inside of the rocker box with a 80/120 progression. Dry fit- looks good for clamping tomorrow. Pictures shown below.
Monday December 11th, 2023 [Rocker Box dry fit and glue-up]
Dry fit of the rocker sides/panels. All looks good- clamped everything up while dry to practice getting a better square. I was able to obtain a perfect square using the provided 90 degree gussets and my speed square. Once I felt confident in getting square- went ahead and epoxied the finger joints and clamped everything up. Did not tighten the clamps more than a few turns. Pictures below.
Tuesday December 12th, 2023 [Mirror box gussets]
The rocker box is still clamped up- will allow a further 24 hours to cure.
Glued in the gussets for the mirror box using West Systems 105 epoxy mixed in with 205 hardener. I added 404 Silica so it has gap filling properties. I laid the mirror box on its side to glue two gussets in since my clamps don’t reach far enough. See picture below.
Wednesday December 13th, 2023 [Rocker box bottom panel / Mirror box gussets]
Glued the last two gussets in the mirror box using the same 105/205 epoxy mixed in with 404 Silcia. Picture at right.
The rocker box was unclamped, and the process of installing the bottom panel was initiated. The first step was to mark drill lines on the bottom of the rocker panel for drilling the pilot holes for the #6 x 1.25 screws. A 9/64” bit was used. I used an adjustable square to draw my lines 5/16” in from the edge on the front and back where the sides are single thick, and ½” in from the edge on the sides where the sides are double thick.
The screws are 1 ¼” from the corners. On the sides, the screws are spaced apart 7 ¼”. On the front and back, they are spaced apart by 7 5/8”.
Then the pilot holes were sanded flush as to ensure the bottom panel seats flush against the rocker box. Next, the bottom panel was clamped to the rocker box with a slight overlap on all sides- the overlap was checked with an adjustable square to ensure even overlap on all sides.
The bottom panel was then clamped to the rocker box. A bit of 3/64” was used to drill the pilot holes into the rocker sides using the already drilled pilot holes in the bottom panel as a guide. Opposite corners were drilled first, and a screw hand screwed into those corners before the rest of the holes were drilled. All holes were then countersunk.
The bottom panel was then removed, and epoxy was applied on rocker box bottom, with the top facing down. Extra epoxy was used on the front where there is a gap of approximately 1/32” to 1/16” because of the sides not being pressed down against the floor when the rocker was glued on Monday December 11th, 2023. When the bottom panel was re-installed and all the screws driven. A visual check confirms the gap is indeed filled in on the front. Success. Pictures below.
Friday December 14th, 2023 [Groundboard]
Glued up the 3 groundboard feets. Leftover 105/205 epoxy was used, and thinned with Xylene Xylol when epoxy reached ambient temperature (leftover epoxy is stored in the freezer). This worked to make the epoxy less vicious, making it possible to brush on.
A plank of wood was also cut on the table saw, in preparation for flush cutting the mirror and rocker boxes tomorrow. The wood plank provides a flat surface for the router.
Pictures below.
Saturday, December 16th 2023 [Mirror + Rocker box]
Flush cut the edges of the mirror box with a 1 ½” cut length flush bit. The blue/green masking tape used to protect against rail impressions from the flush bit kept gumming up the bit, so my 3rd cut and on was made without the masking tape in place.
The flush cuts were made from left to right, so that the bit, which spins in a clockwise direction, works against the wood. A wood plank of ~6” x 36” at ¾” thick was used to provide a smooth surface for the router, owning to the bumpy texture of the still-epoxied finger joints. A notch of about 1” was made at the edge of the plank, so that the edge of the plank can be flush with the edge of the mirror/rocker box and still be parallel with the surface.
The rocker bottom was flush cut first. I found that it was best to sand the opposite corner of the flush cut start, so that the router can continue it’s flush cut uninterrupted by surface roughness.
After the flush cuts were complete, all surfaces, including the finger jointed edges, were sanded with the ROS using 80 grit sandpaper. Leftover epoxy from the freezer was set out and allowed to acclimate to room temperature, using the wall heater to accelerate the thawing process. All visible gaps in the finger joints were filled in with this leftover epoxy.
Sunday, December 17th 2023 [Building the spray booth]
Purchased four 2”x4”x8’ and ripped them to 1”x2”x8’. Each 2”x4”x8’ yielded four 1”x2”x8’. After ripping, the spray booth was built in about 3-4 hours. The dimensions are: 82” high, 78” deep, and 48” wide. Picture shown at right. The booth will be wrapped in painter’s plastic at a later date when the telescope components are sanded down and ready for its finish.
Monday, December 18th 2023 [Final finishing sanding]
The gap filling that was performed on Saturday, December 16th was sanded down on the rocker and mirror box today.
The rocker box had more gaps that needed to be filled- filled those in today. See figure 11.3.
The mirror box was sanded down to it’s final finishing stage with a progression of 80-120-180-240 grit. The inside of the mirror box was left at its rough 80 grit finish.
The rocker box remains glued up- will sand that down maybe tomorrow night.
The three feet for the groundboard was unclamped and the edges sanded on the oscillating sander. Picture below.
Tuesday, December 19th 2023 [Final sand rocker box + mirror cell plate work]
Sanded the rocker box down to 240 grit with the ROS. Gaps look good- all filled in and sanded smooth. One of the bearing sides was a bit rough and took a bit to get smooth, and final sanding shows maybe it needs some more gap filling tomorrow.
Next, sanded the mirror plate down to 240 grit but decided not to sand the hole insides. Dry fit all the cell parts, and see what the design looks like. Decided to get rid of the travel dowels, as they are not needed. The closed-back cell design gives me pause so I drew in some possible candidates for additional holes to increase ventilation
Wednesday, December 20th 2023 [Mirror Cell plate modification]
This morning I worked on deciding on a cut-out pattern for the mirror cell plate, to increase airflow and ventilation. After about an hour, I decided on the pattern seen in the pictures. The Transformer-like look is entirely unintentional.
Masked the bottom with blue masking tape to prevent tear-out. Cut out all the holes with a 2” hole saw attached to my electric drill. Waited ~5 min between hole cutouts to allow the hole saw to cool down.
Once the holes were cut out, I used my Bosch jigsaw @ setting 0 to cut out the connecting lines between the circles.
Then, cleaned up the cuts on the oscillating sander- this took about an hour.
Then, rounded off the corners with a ¼” roundover bit, on the routing table. Sanded the interior of the holes using a 80-120-180-220 grit progression. The veneer was sanded to 220 using the same aforementioned grit progression.
Thursday, December 21st 2023 [Mirror/rocker box roundover + truss poles]
Rounded off the finger joint corners on both the mirror and rocker boxes with a 1/8 roundover bit, as well as the outside exposed edges. The inside edges cannot be rounded over with the router because of the sides. Did that by hand with a sander with 120 grit sandpaper.
After rounding over, all corners were sanded to 240 grit starting with 120grit.
After sanding all corners, I set the boxes aside and started on the trusses. Wooden plugs were epoxied to the ends of each truss tube (to provide a surface for the truss plate screws). After epoxying, the truss tubes were set on the floor with the plugs facing down. This cured overnight.
Friday, December 22nd 2023 [Mirror box boundary layer fans + truss poles]
Last night when browsing the classifieds on Cloudy Nights, I came across an ad for a 18” New Moon Telescopes f/4.99. This scope had a stereo-cabinet style fan contraption to cool the boundary layer. See picture at right. Upon seeing this, I realized that I have two of the T9 AC infinity airplates, to cool my computer cabinet.
So, I decided to remove one T9 airplate from my computer cabinet, and used that to make measurements on my mirror box. I first assembled the cell and put the mirror in, to check for clearance. All looked good.
The mirror surface sits about 4.5” from the back edge of the mirror box. The bottom of the fans sit about ¼” from the bottom edge of the airplate, so I subtracted ½” and situated the bottom of the airplate 4” from the mirror box edge.
Checking fit, to make sure the lines line up with the airplate. It is 15 5/8” in length and 5 ¼” in width. (double check this)
After the cut- checking clearance against the mirror. Looks good. I do wish I set the airplate about ¾” closer to the mirror box edge, so that the fans blow on both the edge and the surface of the mirror. As it is now, it will do the job.
Rounded over the ground board with a ¼ roundover bit on the router table. Sanded down to 220 grit with a 80/120/220 grit progression.
After sanding down to 220, the feet were epoxied on.
Then, drilled a hole of 5/64” at 1” from the plugged end on all of the truss poles. The hole in the aluminum, NOT the wood, was then enlarged with a 3/16” bit so that the screws start easier. I did this for all 8 poles. Then I assembled one pair of trusses using the fastner plates, cam levers, finish washers, washers, and screws. I then tested this by securing it against the mounting blocks on the UTA only to realize that I drilled the hole ½” too far in on the pole. They are to be drilled ½” from the plugged end, not 1”. This mistake was made because I was tired. At this juncture, I decided to call it a night and shelve the truss segment until the following day.
Sunday, December 24th 2023 [upper truss poles + lower mounting brackets + DRY FIT]
First thing this morning, I addressed the mistake I made on the truss poles. I used a straightedge to draw a line across the face of the wood plug, to make it easier to locate the correct place to drill the new hole ½” in from the plugged end, on the opposite side of the old hole. A 5/64 drill bit was used, and again a 3/16 bit was used to enlarge the hole to allow easy starting of the screw.
Did this for all eight trusses, and assembled four pairs of trusses. Checked fit against the UTA- looks good.
After assembling the four pair of trusses, I started the process of mounting the lower truss brackets. This first required epoxying t-nuts to the mirror box, in recessed holes that were pre-drilled. Leftover west systems 105/205 epoxy was used. A couple dabs on each t-nut was used. A hole of ¼” size was drilled through a piece of scrap wood and the truss head bolt threaded through the hole in the scrap wood into the t-nut to pull it tight. The scrap wood is to prevent marring of the mirror box.
Then the lower truss brackets were installed onto the four pair of trusses I assembled. The brackets are made by Nate of Aurora Precsion. This brackets are angle-independent and are tremendously easy in use- positively locating the UTA with ease.
A dry fit of the telescope was attempted, as to determine the exact location of the focuser board and the telrad base board. Initially, I had hoped to locate the focuser board in the 0° position on the driver side of the telescope, but the design of the UTA prevents this- the wood spacer is in the way. It was decided that the focuser board will be in the 10° position, with the telrad base board in the ~50° position, on a Baltic birch board that will be cut from the scrap leftover from the boundary layer fan installation (Friday December 23rd log entry)
Wednesday, December 27th 2023 [Dry fit to check balance]
Dry fit all the major components, with the telrad, krydex, focuser, etc etc all mounted up. Balance looks good to me- maybe it will be a touch back heavy when all is said and done.
Next, is to make a base board that is to serve as the base for the Telrad on the UTA. I decided to use the BB wood that was cut from the mirror box.
I squared up the scrap wood cut from the mirror box on the router table on the long length, using a 1/16” shim on the left side of the fence. I made 3 passes to get the edge straight and true, and then cut the opposing long length on the table saw so that both edges are parallel with respect to one another. Then I cut both short ends using the miter saw. I accidentally cut it too short, between 1/32” and 1/16”. So, I wrapped blue masking tape around the short end, to create a channel. I then poured epoxy in this channel. This set for 24 hours before I removed the blue masking tape. Picture at right.
Thursday, December 28th 2023 [Filterslide + UTA]
Sanded down the epoxy on the telrad base board, down to about 1/16”. This fits snugly in the UTA. Picture is shown at right, after sanding and test fitting.
Worked on getting the focuser filterslide glued up with the light baffle stops, and mounting it in the correct place on the UTA. The holes in the UTA were drilled with a 1/8 bit. The piles in the BB started to split when driving with a screw despite pre-drilling with the 1/8 bit. So I applied West Systems 105/205 epoxy in the crevice, and clamped overnight, as shown on right.
While the filterslide was mounted on the UTA, I marked where the cage ring edges were on the filterslide sides, and drew a line connecting the top of the filterslide to the bottom of the filterslide. This line represents the cage ring edge. The flat edge of the light baffle, which is the back of the light baffle, will be flush with this line with the smoothed rounded over front of the light baffle forward of the line. The light baffles were epoxied on with West Systems 105/205 as shown at right.
Friday, December 29th 2023 [Telrad base final install + filterslide repair]
In the morning light, I dry fit the telrad base to determine the exact location. Picture at right.
Once location was determined, a mark was drawn at both ends of the telrad base, and the telrad base center-marked on both ends. (2 1/8” in from the edge- 4 ¼” total width). A vertical line was drawn on both the top and bottom ring, and marked at the half way point. At this halfway point, a line of 6” was drawn perpendicular to the vertical line. This provided a reference point for the telrad base. The screw holes were marked 1 ¼” from both sides of the vertical line on the perpendicular line. The holes were countersunk first to prevent hexagonal tearout, and then drilled through with a 1/8” bit.
The board was then fitted into the cage, taking care to make sure the center mark lined up with the vertical lines on the rings, and the middle of the telrad sides lining up with the perpendicular line. Then, I clamped down the telrad base with a bar clamp while I drilled the holes into the telrad base using the previously drilled holes in the rings as a guide, with a 1/8” bit.
The screws were then dipped in leftover West Systems 105/205 epoxy before being driven into the telrad base. Pictures below.
Then I worked on the filterslide, which was broken and in need of repair. The filterslide is fixed now. The problem was actually three-fold;
1. The shims were too wide, and binded the filterslide every time the shim rode under the wood railing.
2. Shims too low- not high enough to reach gear wheel
3. Set screw too low
So what I did was I took all the shims off, and put them on wax paper so I wouldn't lose their adhesive properties, and got a steel straightedge, and cut a third off of each strip using a sharp razor, including the 4th strip you sent me. Then I put the strips back on, and set it so that the shims would not ride under the wood roof.
The other problem is the filterslide itself may not be perfectly flat, or the filterslide wood underside is not perfectly flat. As a result, the set screw that slots itself into each small 1mm hole next to each filter port, was set low enough that it would press and drag against the filterslide surface. You can see the "race tracks" on the bottommost of the filterslide in the pictures below. So I got an allen wrench, and made incremental adjustments until the drag was reduced enough that it would not bind up the filterslide plate, while still slotting itself into the 1mm holes next to each filter hole.
See pictures below. In the last picture, you can see I cut the shim width so they would not ride under the wood
Summer 2024:
It took the spring and entire summer to coat all the parts with 3 coats of a mixture containing orange dewaxed shellac flakes + everclear alcohol. This was followed by a few coats of denatured alcohol mixed with Bright Red trans tint to give the scope the red color it has now. This was followed by 16 coats of wiped on Waterlox finish, which took the majority of summer to cure.
July 2nd 2025: Light baffle + lid modification
I've been building a light baffle into the mirror box to cut down on stray light AND to address the terrible, terrible, terrible mirror lid design. It's terrible. Really no other way to put it. The square lid, even with velcro strips on each of the four sides, still scratches the hell out of the mirror box. Constructed a light baffle 1/16" smaller than the ID of the mirror box, and epoxied that in. Then the mirror lid was cut down into a circle from a square. Much, much, much better. It is a work in progress at the moment but it's light years better now. The 17.5", when you look into the mirror box, is starting to look a lot like Steve's 24" now.
At this point, the telescope is finished- see "Final scope" section.
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