Marci's Mount - for Hadley Telescope

I wanted to make a rocker mount for my Hadley, and because I don't have easy access to woodworking tools I decided to make a printed one. My main goal was to make it sturdy, I did not want it to wobble, and that worked out very nicely.

This mount uses two ⌀45 cm disks for the azimuthal motion, the whole design is based on that size and it does unfortunately not work for smaller disks. I may make an adjustable version at some point. The rods are ⌀12mm.

The center of the bearings on Hadley sit at approximately 70 cm from the ground, which makes for very comfortable viewing while sitting down. I recommend aligning the focuser as shown in the pictures, this makes a big difference especially when viewing objects at low altitude.

Features

• The mount was designed with rigidity in mind. The M shape of the mount, combined with the horizontal and diagonal cross bars leave very little wiggle room.
• All files are easily printable, no supports are needed. They should easily fit even on small printers; if you can print Hadley, you can print this mount.
• The mount uses a vinyl disk that sits on top of teflon pads, for very smooth motion.
• It is very lightweight, and can easily disassembled for compact storage or travel.

Instructions

Printing

Print the models in this orientation. Supports should not be necessary.

Note that the bearing interfaces and the back feet are not identical! Make sure you print a left and a right (they are marked). You will need 8 each of the end joint and mid joint.

Print the feet at 100% infill. For the bearing interfaces and the end joint piece I have included modifier files for the heat inserts (the colored circles in the image above), set the infill to 100%. They should be in the right spot automatically when you load them.

The mid joints have a strong curve at the bottom, which for some may be tricky to print. I recommend doing a test before printing a full set. I included a version with custom designed supports. To use them split the object into parts, then print the supports with 1 bottom layer, 1 perimeter, 0 top layers, 0% infill. The supports print fast, use very little material, and should come off easily with a clean result.

The supports should look like this in the slicer.

Install the M4x6 heat set inserts. The three inserts on the side of the bearing interfaces are optional, for attaching e.g. a clamp to add some tension to the bearing, or a holder for eyepieces or other accessories.

Making

Cut the aluminium tubes to size. The four legs need to be cut fairly accurately, there is some room for play but not much; try to get at least within ~5mm.

• front legs, 2x: 655 mm
• back legs, 2x: 642 mm

The length of the other rods is not that critical. For the diagonal cross bars I just used the two longest left overs I had, so approximately 350 mm long. The horizontal cross bars I used are about 100mm for the front one, and 250mm for the back. For the back one, just make sure it sits low enough so that the telescope doesn't bump into it when you point it up.

Assembly

Wooden base

Drill 8mm center holes in the disks. Install 3 feet evenly spaced (see sketch) on the edge of the bottom disk. I made mine adjustable but in hindsight this is overkill; I never used it. Use your own imagination.

In the bottom disk install the center bolt using washers on both sides, and lock it in place with a nut to prevent any wiggle. Install the 3 teflon pads such that they are evenly spaced around the center bolt, and such that they sit right at the edge of the vinyl record. I had to drill out the center hole of the vinyl to fit around the bolt.

On the top disk, install the feet of the mount using wood screws, again evenly spaced along the edge. Make sure left and right are placed correctly, they are marked. Place it on top of the vinyl, put a washer around the center bolt and add a nyloc nut.

Building the Mount

• Install the end joints on each of the cross bars using M4x8 screws. The four legs get 2 mid joints each. Align them in opposite directions of each other such that the head of the adjustment screws face outwards; this will come in handy later. 
• Install the legs into the feet on the base; make sure they are fully inserted, and lock them in place using M4x8 screws. Next add the bearing interfaces on top, check the markings on top for alignment. Insert the rods fully (this can be a bit tricky), and fix them in place with the M4x8 screws
• Add the front horizontal bar with M4x15 screws in the mid joints, but don't tighten them yet. Adjust the position of the bar up and down to set the width between the bearing interfaces. Get it approximately right, then carefully put your Hadley on top. Adjust the position of the crossbar till the outside of the bearing interfaces sit flush with the flanges of the bearings on Hadley, then tighten them. It's possible the back is not fully aligned yet at this stage.
• Repeat this step with the rear horizontal bar to get the bearing interfaces fully aligned.
• Add the diagonal cross bars.
• Adjust as needed till you are satisfied with the alignment, then double check all screws to make sure they are tightened sufficiently. This really helps to add rigidity. There should now be very little play in the system. The midjoints should sit nice and flush when tightened.

• Adjust the tension for the nyloc nut on the center bolt. It should be tight enough that the top disk cannot wobble, but still allow it to rotate freely. Test by trying to turn the mount, using two hands to grab one of the mount interfaces, there should be very little friction.

Clear skies!

This mount has served me very well so far, and I think you will like it a lot as well. I have found that while observing it works great to grab the bearing of Hadley with two hands, and control it like you were using a steering wheel. This causes the least amount of wobble in my experience. Happy viewing!

Bill of Materials