Making the upper tube assemblies (UTA's) This took me about four hours total to this stage. Two to make the rings, one to cut glue and steam the balsa liner and one to glue and align the tubes. To this stage the spiders haven't been fitted and the focuser board isn't installed.

There are several steps to this point

Cut out the six rings, three for each tube. In this case 3/8" (9mm) MDF ring ID=10 1/4" and OD=12 1/4"

I've used a router circle cutting jig from Shaka Scientific Limited  It is great and I'd recommend it to any telescope maker. I also use a DeWalt DW621 plunge router, another great buy.

The centre ring of both UTA's need three holes drilled at 120 degrees apart to allow mounting of the Protostar spiders, it is best to do this before gluing the tubes together as you need to make sure your drilling straight. The holes go from the outside to the inside of the ring through the thin 3/8" edges so take care. Having to make a new ring will really annoy you. I used a hand drill as it's slow and easy to control.

Cut two lots of nine (18) pieces of  1/8" x 4" (3mm x 100mm) balsa 14" (350mm) long

Glue two sets of nine pieces together edge on. (one for each tube)

Leave to dry overnight. Trim edges true if needed removing the barest minimum. If your do this ensure that the long edges of the sheet is the same width exactly. (both ends are going to meet remember) Do any sanding now as it's impossible when it's assembled.

Steam the balsa into a tube. This is easier than it looks it will fold into the right diameter easily. Place it inside the rings (it will be oversized at the moment) and pin it as close to the correct diameter as possible then let it dry for a few hours.

Cut the balsa to fit snugly inside the rings. Take only small cuts off. The last cut leave about 1/8" more than you think you will need as you can push it into make a very tight inside the rings. Make six spacers 7 1/4" long to allow proper placement of the centre rings. These fit between the lower and centre rings and are construction aids only. Get the rings positions in the correct locations. Everything should be snug enough to stay together without pins if you've got the right fit. If you cut off to much just cut the whole sheet back and glue on another panel then try again tomorrow.

Mark the position of the rings for a glue line. Take the rings off and apply the glue.

Roll up the balsa with glue in place and then place rings over the top.

Place some 1/2" packers under the lower ring to create the pivot for the tube.

Use the spacers to correctly locate the centre ring. This not only gets the distance right but ensures everything is square as well.

Locate the top ring flush with the top of the balsa.