Chriske

Any steel ball is ok, I'd use a somewhat bigger ball. See to it that the ball is fixed(not glued) in the centre of the device. Make a shallow pit in the bottom preventing the ball rolling around at the bottom. As long as you insert lots of grease in the device. It'll do the job for years to come. Don't use that thick grease that will stiffen up when it gets colder. Did you already drew the device, how will it look like..?

The red is a safety ring fixed onto the axis, to keep it from flying away during storm. The blue cover is also fixed to the axis to keep water out of the unit. It needs to be lowered of course.

Keep it simple, cheap and sturdy at the same time. You most likely have all the component in house. Print a tube with a hole(grey) At the bottom of the tube place a small piece of brass or other material. In the centre of that piece of metal drill a very shallow hole. In that hole place a small ball, you need to crush an old (broke) ball bearing. Fill that compartment with grease. Put axis with a (very)flat bottom on top of that little ball and your done. No ball bearing at hand : drill a hole and tap - M8 or so- put a fitting bolt with a pointy end upward in that (grey)main unit.

Hold on, I make quick drawing...

I'd go for PLA.

Woow, nice one..! A few days back we had a halo around the sun, was very nice.

Found it.. That's about 30 years old if I'm not mistaken.

Seeing this nice scope I remember a very long time ago I made small telescope 4" or so. Grinded the mirror out of the bottom of a bottle of Genever.(Gin) That brand genever had square shaped bottles, so very difficult to figure that bottom into a parabola...😳 I'll try and find that little thing and post a picture. I do remember now, while observing and emptying that bottle we had to issues, the balance of the scope kept on changing very slowly + images got blurry all the time.

First parts, needs a bit cleaning-up before assembling, there's a small burr at the bottom of each part.

You could use the encoder disk out of an old computer mouse or completely other approach, Hall sensors..?

Does it need to be that accurate to use an encoder..?

Now that HST is finished and 'floating' around it's time to continue building on Falcon9/Dragon. Plans were already made. Fairing parts are already printed. As I said before it will be a fast build. Michel(my colleague model builder) will take care of the Falcon's LUT. One Falcon will hang somewhere on the ceiling and a second Falcon, only first stage + intersection will be standing on the ground landing-feet wide open, covered in soot. Once more Turbosquid will guide us to find out what external parts hang around Falcon9. Although these are good drawings, we don't know how accurate they are.

Urania...😉

Done..!! Most probably these are the last pictures. We're very happy with the result.

Today my son Steven and I started restoring my observatory. It hasn't been used for several years. All my observations these last years were done from other locations. Reason for this restoration : my son wants to get started in astronomy. And he want to do it all, observing, taking pictures, even making his own scope. The mirrors we were grinding were on hold for a few months due to Corona. But now we're back in business. Total length of my observatory is about 10m, observatory itself is 5m long and 3.5m wide. The roll-off roof is very easy to handle. All the wood on the left is gone now and will be replaced next week. Also some pruning needs to be done...you surely might have noticed...😁

I know Neal, but doing that, I lose my hobby. Now I'm having fun, making these things at my own pace. You're not the first pointing that out to me btw...😉 Thanks for the kind words btw

You're all welcome to visit our public observatory. Beside the things I showed you during these builds there's lots to see here. We do have a 400mm RC + a few smaller scopes, a planetarium --> room for 40 people in comfortable (rotating) chairs. During shows people can rotate the backs of the chairs backward. Auditorium + 3 different large rooms for the 16 courses that start(each year) mid September. I do the course 'Telescope making advanced'. And together with another Urania member(Michel, that other mission specialist..😁) I started building models like this HST. Last year I printed 4 SaturnV rockets, HST almost finished now. Next we will build two Falcon9 rockets. One version is a 'ready to be launched(with Fairing) version, and the second will be only the first stage that just has landed, well covered in soot of course Meanwhile on one of my printers I'm busy printing all the parts for an even bigger SaturnV rocket. This time it'll be 4.1 meter high. Crawler, Launch-platform, and LUT included. Goal for this SaturnV was open door mid Sept. But due Corona this project is postponed and a new deadline to finish that project is open-door 2021.

This the one Neil...😉

As I said before Neil, That is the only item in this project I did not draw myself. Downloaded it from the net. Don't remember which site, GrabCad or Thingiverse. At the same scale (1:7) these guys are 25.5 cm high. In fact mine should be a bit larger, I'm 1.94m..😁

View from another angle while working on HST today. SaturnV in the right corner is the one I made before, it is 2m high

One of the last things that will be mounted are these three little guys. They are needed as last balance control of HST. Two mission specialist (Michel/Chris) and the third (Marc) is the guy taking care of the finances to build this HST

Another picture taken in the entrance of our planetarium during work today. in the background you see backlit pictures taken by HST. All these pictures are stacked 4 meters high 6 rows side by side. It's really awesome to look at. Our manager is very proud..!

While hanging there still to do these very last items : Frontcover Backcover Pointers Astronauts Wiring