Hadley Telescope Tensioner Assembly

prusaprinters

<p>Adds downward pressure on the bearings to ensure the telescope doesn't rotate under its own weight. Depending on the telescope's balance and the stuff you attach on it, you might find this necessary when viewing objects at high-ish declination. Marked as a remix to link to the main Hadley project.</p><p>Yeah, a single spring pointing downward and attached to a screw would work, but this over-engineered design has the following advantages:</p><ul><li>Takes less vertical space on the mount, which allows mounting other things directly below the bearings (red light, storage, etc.). This was important to me because I have plans for this area.</li><li>Non-permanent (secure hooks to detach and attach the four tensioning springs)</li><li>Looks clean and fits well with the telescope (IMHO)</li></ul><p><strong>Also pictured in the overview photo:</strong></p><ul><li><a href="https://www.printables.com/model/269938-dobsonian-mount-storage-fits-hadley-telescope-moun">Dobsionian Mount Storage (fits Hadley Telescope)</a></li><li><a href="https://www.printables.com/model/254079-hadley-telescope-double-dovetail-finderscope-mount">Hadley Telescope Double Dovetail Finderscope Mount</a></li><li><a href="https://www.printables.com/model/256728-cheshire-collimation-eyepiece-for-reflector-telesc">Cheshire Collimation Eyepiece for Reflector Telescopes</a></li><li><a href="https://www.printables.com/model/241467-simple-rack-and-pinion-focuser-for-hadley-telescop">Simple Rack and Pinion Focuser for Hadley Telescope</a></li></ul><h3>BOM</h3><ul><li><strong>4 x</strong> medium-low strength (eyeball it) extension springs. Mine are 28mm long and the end loops have an inner diameter of ~7mm. The Fusion 360 source file is included so you can tweak dimensions to fit the springs you have.</li><li><strong>4 x</strong> 1.5" flat head wood screws for the posts</li><li><strong>2 x </strong>2" machine screw (same as required in the Hadley build)</li><li><strong>2 x </strong>machine screw nuts (same as required in the Hadley build)</li></ul><h3>Customization Instructions</h3><p>The four parameters you'll most likely need to modify if you don't have similar hardware to mine are:</p><ul><li><code>spring_wire_gauge</code> (the thickness of the spring's wire, for tolerances)</li><li><code>spring_eye_diameter</code> (the ID of the spring's end loop that goes into the plastic part)</li><li><code>wood_screw_hole_diameter</code> (diameter of the threaded part of you wood screws)</li><li><code>wood_screw_head_diameter</code> (diameter of the head of your wood screws)</li></ul><h3>Printing Instructions</h3><p>The springs are embedded in the upper part and hooks at print time which removes the need for some kind of removable cap and ensures the springs are never going to slip out. This means you'll have to program a pause and insert the hardware at the appropriate time.</p><p>Example:</p><figure class="image"><img src="https://media.printables.com/media/prints/273290/rich_content/1f7d3d69-fa26-4788-97fc-3e2d12a554e9/img_1873.jpeg#%7B%22uuid%22%3A%22f0d5d0dd-806d-4f1b-bb68-a57831eb8a59%22%2C%22w%22%3A4032%2C%22h%22%3A3024%7D"></figure><figure class="image"><img src="https://media.printables.com/media/prints/273290/rich_content/3afcc95b-5dc8-4aa6-86c6-3cefc4550449/img_1875.jpeg#%7B%22uuid%22%3A%223213df17-a519-4b04-ba47-86803d13a6af%22%2C%22w%22%3A4032%2C%22h%22%3A3024%7D"></figure><p>For my prints I used Kapton tape to hold the springs in place when necessary. Holding them by hand for a layer or two until they're captive might also work fine. I rarely need to but somehow this time I had to use some glue stick to get good adhesion on the Prusa satin sheet.</p><h4>Actual instructions:</h4><ol><li>Print the inner part and embed two springs at the appropriate time (photo 1).</li><li>Print the left hook and embed the “inner part with two springs” at the appropriate time (photo 2).</li><li>Print the right hook and do the same.</li></ol><p>The provided <i>3mf</i> files already have a pause programmed at the appropriate height, as well as properly mirrored hooks for left and right.</p>