Specs:  

Mirror Cell:  The mirror cell was the first part of construction.  It was made from 1" steel tubing for the rungs, and 1 1/4" x 1/8" thick plain steel for the side rails. First, I measured and cut all the parts with a hacksaw, and cleaned everything up with a file. I then drilled and tapped all the required holes. This is an important step, because once assembled, it will not fit into a drill press easily. I had a friend weld the frame together using an arc welder. It required fairly low heat, and the job came out well. I built a jig on a square piece of plywood slightly larger than the frame and tacked the frame in place with nails as supports, carefully ensuring that every thing was in its proper place and squared. Once everything was tack-welded together, it was welded all the way around adjoining pieces. To the left is a picture before the holes were drilled and everything was welded.

After the holes were drilled, and the frame was welded together I made the other parts. Since the cell is an 18 point flotation design I needed 3 support bars (1 per collimation bolt) and six triangles. The concept here is that each of the 18 points supports an equal area of the mirror. Note: New concepts in support have recently emerged which deform the mirror less. Visit http://www.eecg.toronto.edu/~lewis/plop/ for details.  The three collimation bolts pass through the frame (which is tapped for the bolts), and connect to the support bars. Attached to each side of the support bars is a triangle. Sturdy foam pads are attached to the corners of the triangles, and the mirror rests on these pads. The cell components are kept aligned by using a piece of Kydex cut into the shape of a circle, which is secured to the underside of the triangles with double-sided tape. There are three 1" wooden dowels covered with black foam to pad the mirror in case it moves about while being transported. They can be seen at the top and opposite sides on the bottom part of the cell in the picture below. There are two bolts split down the middle with a hacksaw to connect the sling to. I used a strip of 2" wide bronze.  The telescope holds excellent collimation through the night, and great images at the eyepiece.  The picture to the right shows the cell without the sling attached, and also without the triangles.

Secondary Cage:  The secondary cage is made of two rings, 4 aluminum struts with threaded inserts, a focuser board, focuser, spider, secondary holder, secondary mirror, and attached to the cage is an 8X50 finder scope. These parts (except for the wooden parts) can be seen to the left.

The rings are made from 5/8" baltic birch. They are 21" ID and 24 1/2" OD. The struts are 1 1/4" thin-walled aluminum tubing fitted with inserts, and are bolted to the rings. The black liner is Kydex. The focuser is a JMI DX3 focusser. I am extremely happy with this focuser, and highly recommend them to any telescope maker. I am using a 3.1" (minor axis) secondary mirror mounted on a holder/spider from Astrosystems. I have been happy with the work that Astrosystems does as well.

The kydex was purchased from a local supplier in a 4' x 8' sheet. This stuff is shiny on one side, and dull on the other. I cut a piece a little longer than the ID circumference of the assembly, and a little taller than the height of the cage. I then used double-sided tape to attach it to the inside of the cage. Finally, the ends were trimmed with a utility knife. Here you can see it installed on the secondary cage.

Mirror Box:  The mirror box is made from 5/8" baltic birch. Outside dimensions are 23 1/2" width on a side, and the box is 20" tall (deep). This is a little deeper than the Kriege specs, if you're using the book as a guide. However, the mirror has a slightly longish focal length of 103+ inches, and to keep with 6' trusses which I already purchased, I increased the depth of the mirror box during design. The box is reinforced with gussets & corner braces along the inside corners, and is very strong. The mirror cell is bolted with 5/8" bolts along the bottom of the box. The bottom of the cell is flush with the bottom of the mirror box, while the collimation bolts protrude about an inch. To the left is a view from the side. Notice how the bottom corner is rounded to allow a lower profile rocker box.

The picture to the left shows a top view without the thin hardwood cover. You can see the reinforcements of the corners, and the mirror cell without the sling or triangles on the bottom.

The altitude bearings were made from two pieces of 3/4" baltic birch. I routed out the circles, glued them together, routed out the inside cuts, and finally cut the remaining circle in half. This leaves me with two half circles that will be covered on the outside diameter with ebony star, and bolted to the mirror box. The picture to the left shows the altitude bearings roughed out and glued together.

Truss Connectors:  I used 6' of 1 1/4" OD thin walled aluminum tubing for the truss tubes. They are light, dimensionally strong, and aesthetically appealing. The fun part comes in attaching them with a method that is repeatable, dimensionally stable, easy, fast. I chose to use maple split blocks on the mirror box, and a sort of seat & wedge device on the secondary cage.

The split blocks are the devices that attach the truss tubes to the mirror box. This idea comes straight from The Dobsonian Telescope book. First of all I cut 16 maple blocks about3 1/4" x 3 1/2" x 1" about 3/4" thick and glued two together to get a thick piece of material to work with. A 1 1/4" diameter hole was then bored using a forstner bit to a depth of about 2 3/4" into the block for the poles to slide into. On the back side of the block, a 1" wide area was routed out to a depth of 1/4" perpendicular to the bore from the part of the block furthest away from the bore, until the cut finally exposed a part of the bored hole. Then, the block was cut to allow the middle 1" to be flexible from the rest of the block. This allows the pole to be inserted, and the center tongue to be depressed against the pole. To the left is a (terrible) photo of the blocks in rough cut, bored, routed, and middle portion cut to allow the required movement.

Finished Product:  Here are some pics of the completed telescope. The project took too long, too much money, and was too hard... but well worth it! If you want to see some of my initial visual impressions through the scope, check out my Observations page.