Designing an equatorial wedge for a small telescope

[the_digital_dentist]

It's just two plates, about 6" wide, that are hinged together with a screw to adjust the angle between the plates (similar to this).  The vast majority of designs I have seen use piano hinges and plywood which bothers me, so I'm trying to design something more solid, using 1/4" or 1/2" cast aluminum tooling plate.  I'm thinking of using a ball bearing door hinge, but if someone has a better idea, I'm all ears.  The angle between the plates is set to 90 degrees minus the latitude where the scope is located, about 47 degrees in the Milwaukee area, and needs to be finely adjustable, over a range of maybe 40-70 degrees.  The hinge needs to be free of play, and alignment should be very accurate.  

This is a crude illustration of the wedge showing the range of motion required of the hinge (40-70 degrees).  The blue is the top of the tripod, the green is the base of the telescope, and the purple are aluminum pieces, probably cast tooling plate.

Anyone have a spare ball bearing door hinge laying around for sale or trade?

Anyone have any brilliant ideas to make this as simple and solid as possible?

[the_digital_dentist]

Some of the wedges on this page are the sort of thing I am thinking about.

[the_digital_dentist]

Here is what I have come up with so far...

There will be 4 pillow block bearings with shoulder screws threaded into two rotating blocks.  A long screw to adjust the angle of the telescope mounting plate will pass through the two rotating blocks. The upper block will be threaded, the lower block will have a bearing (red) mounted and locked into it.  Turning the long screw will move the two blocks closer or apart, and they are free to rotate to stay aligned.  Hopefully this will operate with minimal or no play.  Just have to figure out what to do for a hinge...

[Tom Gralewicz]

There are some ball bearing door hinges on the table in the meeting room, a bunch were donated a while back.

Tom Gralewicz

Chronic Maker

(414) 380-1716

milwaukeemakerspace.org

--

---
You received this message because you are subscribed to the Google Groups "milwaukeemakerspace" group.
To unsubscribe from this group and stop receiving emails from it, send an email to milwaukeemakerspace+unsub...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[the_digital_dentist]

Great, I'll check them out!  Thanks!