Azimuth Bearing for 8" Dob (Parametric)

Originally posted on https://www.thingiverse.com/thing:6898975

I have struggled with the azimuth movement for my 8" dob for a while. I happened to be building a Hadley telescope and had printed Hadley Telescope Azimuth Bearing for it. I found the action to be super smooth and did a quick test on the 8" dob. It was amazing! But it's a little smaller than I want so I built this model to print a bearing as large as I can. I also included a guide for drilling holes.

The model attached to this post is for my 8" dob. The key change to make is the bearing diameter, keeping in mind this is the center of the "V", the race the PTFE tube sits in. I can print up to 255mm x 255mm, so this is what I sized the model to barely fit into. The scad is attached.

Parts needed:

• print 2 each of the bearings
• PTFE tube, 4mm OD
• flat head screws (I had #8 x 1" flat head screws laying around)
• print guide (optional)
• spare filament length (optional)

You can use the spare filament in the PTFE tube to make it easier to assemble.

This is an original model based on the Hadley Telescope Azimuth Bearing design.

Assembly

1. For top and bottom drilled one hole using the guide, place one screw to hold it, then drilled the remaining holes.
2. Attach bearing to top and bottom with screws, making sure screw heads are below level of the printed material
3. Insert PTFE (with filament core) onto one bearing and sandwich with the other.
4. Move bearings around to make sure the PTFE is seated inside the bearing "V".
5. Attach top and bottom using bolt, making sure to keep PTFE in the bearing.
6. Adjust bolt tightness carefully so that there is just a little wiggle and movement of the bearing is smooth.

Customization

In the scad file the variables you can change are at the top. The model does not have a way to change the screw head but the flat head works well. This section simply outlines what you need to change.

Change Bearing Diameter

Change bearing_d, keeping in mind there is a wall on the outside of this that will increase overall diameter by 18.5mm.

Change PTFE Diameter

Change ptfe_d.

Change Bearing Height

Maybe you need more clearance. Change bearing_h.

Change Screw

The screw parameters assume a flat head. But if you wanted to resize it:

• screw_head_d - diameter of the screw head
• screw_head_h - height of just the screw head
• screw_shaft_d - diameter of the screw shaft

Note that screw_shaft_h is calculated based on screw_head_h and bearing_h.