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I was asked to make a Dobson base for a friend who just puchased a 2nd hand 200*1000 newtonian tube.
I was asked to make a Dobson base for a friend who just puchased a 2nd hand 200*1000 newtonian tube.
Here are the pictures and explanations!
You will need around 2m x 60cm of melamine board to make such a base. It can be done using just a jigSaw, a screwdriver and a drill, but having a friend with a full machine shop will help!
First you will need to make the altitude bearings.
First you will need to make the altitude bearings.
I used some lefover pine board that I had lying around. But you can make them out of 2 layers of melamine glued together in order to get some thickness.
Make them as round and equal as possible.
I used a lathe, but you can use a router with a jig, or a jigSaw. spend time sanding them!
Then I make the "U" that holds the telescope altitude bearings.
Then I make the "U" that holds the telescope altitude bearings.
Once you have made the altitude bearings and have them attached to the scope "rings", you can measure their spacing. This will give you the width of the U.
The balance point of the tube will give you the minimal height.
You will then cut 3 pieces of wood, the "middle" of the U to the with of the tube holding circles + some margin. And the 2 sides which will hold the altitude bearings. You can see me prepping and cutting these sides which needs to be identical (I do that using a trim bit on the router, but you can also do it cutting both parts with the jig saw at the same time)
Next I will prep the base. 2 identical disks which need to be large enough to hold the "U". Use a large compas to draw and cut them (they do not HAVE to be identical, but it's nicer).
Next I will prep the base. 2 identical disks which need to be large enough to hold the "U". Use a large compas to draw and cut them (they do not HAVE to be identical, but it's nicer).
Next step is to attach the "U". I mark it's spot, drill some holes for the screws and then glue+screw the U
Next step is to attach the "U". I mark it's spot, drill some holes for the screws and then glue+screw the U
Let us check if we messed up! Nope, all good!
Let us check if we messed up! Nope, all good!
TO help in azimuth, I place 3 roller-blading bearings on the base. I use the router to make cross holes to recess the bearings at 120° angle
TO help in azimuth, I place 3 roller-blading bearings on the base. I use the router to make cross holes to recess the bearings at 120° angle
I add 3 feet to the base which I cut using a round saw on a drill
I add 3 feet to the base which I cut using a round saw on a drill
Final assembly! Put a M8 center screw with a wing nut for tentionning. Add 4 plastic surfaces on the altitude bearing contact points to ease the movement, and we are good to go!
Final assembly! Put a M8 center screw with a wing nut for tentionning. Add 4 plastic surfaces on the altitude bearing contact points to ease the movement, and we are good to go!
Took around 1h30mn... not bad!
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