Newtonian Mirror Cell for reflecting telescopes

prusaprinters

<p>A mirror cell for a six-inch Newtonian. &nbsp;It may be rescaled or adapted to metric - the user just needs to identify which hex-bolts will fit after scaling. &nbsp;Note the depicted backplate is not included, it needs serious revision to be tenable. &nbsp;That's from a shelved design for which I made one wobbly but working prototype. &nbsp;But the cell itself is perfect for the job!<br><br><strong>If you do plan on re-scaling, you can find CAD files for any and all screws on McMaster-Carr's site.</strong></p><p><strong>Print directions</strong><br>This part will hold a two-to-five pound hunk of glass. &nbsp;It needs to be sturdy. &nbsp;3-5 perimeters depending on your nozzle size, and a cubic infill of 30% to 50% depending on how brave you're feeling. &nbsp;The rest can be printed solid.</p><p><br><strong>Bill of Materials as Scaled:</strong></p><ul><li>3x ¼-20 bolt, <i>long. </i>3+ inches give or take.</li><li>3x heavy-ish springs which will slide over these bolts. &nbsp;A $5 assortment with sufficient ID should have plenty.</li><li>1x parabolic mirror, ¼ wave surface error or better</li><li>3x thru-threaded knob, ¼-20. &nbsp;Nyloc/vibration dampening ideal.</li><li>6x ¼" washer</li><li>3x nylon screws (M4, M5, #10, #8, any size that'll fit in the side holes) and matching nuts</li><li>M4 or #8 bolts and nuts, x6 each bolts and 6 or 12 each nuts</li><li>A plan to make a newtonian. &nbsp;This is just one small but critical and challenging piece of one.</li><li>The rest of a newtonian telescope, which you should source elsewhere.</li><li>A backplate for a mirror cell. &nbsp;This piece is far more simple.</li></ul><p><strong>Assembly</strong></p><p>Use the primary cell as a marking/drilling guide for your back-plate, ideally plywood.</p><p>Pull the 3 large bolts through the cell so the hexes embed. &nbsp;This may need some force or heat-setting. &nbsp;Then run a washer, spring, and washer over the bolts. &nbsp;Hold the cell face-down now, with the springs upwards. &nbsp;Pull the back-plate down over the bolts, and secure it with the three knobs. &nbsp;This may be challenging - it took a bit of elbow grease for me to put the anti-vibration knobs on, but it was worth it. &nbsp;The telescope maintains collimation perfectly.</p><p>&nbsp;</p><p>The washers are optional, but help tremendously to reduce long-term creep in this print. &nbsp;I'm not sure how big an issue that is or isn't, because my prototype uses them!</p><p><img src="https://media.printables.com/media/prints/226270/rich_content/e0f5be06-d530-445c-bbf8-270c4c582547/unknow14n.png#%7B%22uuid%22%3A%2213960c3e-fd4b-4dc5-9741-461129a90bf7%22%2C%22w%22%3A873%2C%22h%22%3A669%7D"></p><p>Flip it back, insert the three feet into the slots. &nbsp;Then gently place the primary in. &nbsp;Take extreme care from here on to not touch the primary with the screws. &nbsp;The coating is very fragile.<br><br>Hex nuts go inside the clips, bolts through those. &nbsp;Nuts also through the underside of the cell. &nbsp;You may need a heat tool to insert the nuts from underneath. &nbsp;You may forgo the nuts in the clips, if desired.</p><p>The clips should be only tight enough to retain the mirror - you should be able to slide a piece of paper between them and the mirror / freely spin the mirror. &nbsp;The same goes for the side-bolts, which should just keep the mirror from bouncing around.</p><p>You now have a sturdy, collimate-able primary cell for a six inch newtonian.</p><p>&nbsp;</p><p>See below for details on the assembled cell.<img src="https://media.printables.com/media/prints/226270/rich_content/f0474365-cd0c-48b1-b4ee-f9fd0de7c437/u125nknown.png#%7B%22uuid%22%3A%22c4954933-94e6-40d3-9987-dc54e88b3448%22%2C%22w%22%3A1281%2C%22h%22%3A747%7D"><img src="https://media.printables.com/media/prints/226270/rich_content/296d53ae-0c22-4fd4-bf7a-76c9b9e8f99c/unkno53wn.png#%7B%22uuid%22%3A%2256b19ea1-54cc-44ca-a12a-1ce53f09e41c%22%2C%22w%22%3A665%2C%22h%22%3A710%7D"></p><p>&nbsp;</p><h3><strong>FAQ</strong><br>&nbsp;</h3><p><strong>What if I use metric/ can't find imperial screws or vice versa?</strong><br>Metric or whatever standard works fine - this is thread agnostic, we only care about clearance and the width of a hex-nut. &nbsp;Print a little section of this (your slicer should let you do this!), go to a hardware store, find what screws/nuts fit.</p><p><strong>Can you provide the backplate?</strong><br>The backplate would take some revision to be workable. &nbsp;If enough support rolls in from <i>Hadley,</i> I can support my other projects some more. &nbsp;But for now, this is as-is - and this plus my focuser is already enough to make building a larger newtonian significantly easier.</p><p><strong>Does this scale up or down?</strong><br>Yes, but so do the screw-holes and engineering challenges. &nbsp;Also note that beyond eight to ten inches, mirror support becomes much more complicated. &nbsp;The square-cube law also comes into play, and I doubt even a monolithic print such as this would adequately hold up.</p><p><strong>Modifications, etc:</strong><br>You can find other telescope parts, improvements, alternates in my collection <a href=" https://www.printables.com/social/134622-maff/collections/189408"><strong>here</strong></a>. &nbsp;Support these files as well!</p><p><strong>How can I support this?</strong><br>Tips are always appreciated, as is support on <a href=" https://www.printables.com/social/134622-maff/collections/189408"><strong>Printables</strong></a>. &nbsp;I'm also (barely) on <a href="https://www.patreon.com/posts/initial-release-67659789"><strong>Patreon</strong></a><strong>, </strong>where I host shelved projects I don't have time to provide support/documentation. &nbsp;Designing, testing and improving takes a lot of time, parts, and filament - and support gets me more of all three.<br>&nbsp;</p><h4><br><img src="https://media.printables.com/media/prints/226270/rich_content/a6981d9a-cfe3-491f-8ade-461ed3172563/image0-144.jpg#%7B%22uuid%22%3A%2282de297f-12ff-4cd8-93a4-563df936340a%22%2C%22w%22%3A820%2C%22h%22%3A1180%7D"><br><br><br>Support</h4><p><a href="https://www.patreon.com/Kissner"><strong>Patreon</strong></a></p>