Hadley Adapted FuseBridge 1.25" Focuser

prusaprinters

<p><strong>UPDATES:</strong></p><p>Added version with mounting screw holes countersink so knob does not collide with screw head for those using full sized screw heads.</p><p>&nbsp;</p><p>This focuser is based on the Crayford design, where a smooth pinion is rolled along a smooth drawtube, and the friction between them allows you to focus the eyepiece.</p><p>This focuser uses standardized hardware that is affordable and very common in hardware supply stores. The cheapest way to construct this focuser would be ordering the appropriate hardware from Aliexpress. .&nbsp;</p><figure class="image image-style-align-left"><img src="https://media.printables.com/media/prints/299484/rich_content/6d7ef10f-c793-4cfa-a7e5-ef31232f4a6a/technical-build-list.png#%7B%22uuid%22%3A%22a070030c-a3f5-4be6-a9d3-05226511240c%22%2C%22w%22%3A493%2C%22h%22%3A615%7D"></figure><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>A hardware list from Mc-Master Carr is included so you can verify specifications before getting hardware from cheaper sources.&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>The drawtube itself is made of extruded Polycarbonate, if the length of the tube is cut to 68mm long the focuser travel will be 1.5". Of course you can select a different length for your application. I recommend scuffing the outside of the drawtube with 350 or finer grit to minimize reflections and improve motion.</p><p>&nbsp;</p><p>See photos for assembly.</p><p>&nbsp;</p><figure class="image image-style-align-left image_resized" style="width:57.09%;"><img src="https://media.printables.com/media/prints/299484/rich_content/8680d600-802c-4931-b354-d90cc298428d/screenshot-2022-10-20-172615.png#%7B%22uuid%22%3A%2233efc1d0-6457-4da5-9cd7-e12d526ea777%22%2C%22w%22%3A891%2C%22h%22%3A690%7D"></figure><p>You will only need 4 3D Printed components for this focuser:</p><p>1 Main Body-Hadley-focuser</p><p>2 Turn Knob Fixed</p><p>1 Drawtube Bottom and top Ring</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>&nbsp;</p><p>Hardware Components:</p><p>2 Bronze bearings</p><p>4 3x8x3 bearings</p><p>8 M3 washers/ 4 M3 nuts</p><p>3 M4 Nylon screws</p><p>1 M4x80mm Dowel pin, Stainless steel</p><p>1 1.25"ID x 1.5" OD PC tube, your desired length</p><p>2 M3 Grub screws</p><p>4 M4 8mm screws</p><figure class="image image-style-align-right image_resized" style="width:41.24%;"><img src="https://media.printables.com/media/prints/299484/rich_content/89059b4b-d873-4abb-a2cf-4bedc27b4cce/bearing-assy-x4.png#%7B%22uuid%22%3A%22e94c7ad4-7e36-4582-9c9d-1ec027007c75%22%2C%22w%22%3A853%2C%22h%22%3A511%7D"></figure><p>Note: assemble the 4 bearing screws shown to the right with a M3 nut in the slots.</p><p>&nbsp;</p><p>&nbsp;</p><p>Shaft, Knobs, and Bearing assembly</p><figure class="image"><img src="https://media.printables.com/media/prints/299484/rich_content/b5e486ea-a008-4217-8a0d-5b00d9810acf/screenshot-2022-10-20-172905.png#%7B%22uuid%22%3A%221dc9cef9-2731-4db7-b959-d771c8e2429a%22%2C%22w%22%3A1065%2C%22h%22%3A565%7D"></figure><p>2 Nylon screws provide tension against the shaft.</p><figure class="image"><img src="https://media.printables.com/media/prints/299484/rich_content/0135d551-7fa3-447d-97ae-146e24ba2c3c/screenshot-2022-10-20-172553.png#%7B%22uuid%22%3A%228d19e1e1-8dea-47a2-9afb-9d730c44187f%22%2C%22w%22%3A755%2C%22h%22%3A563%7D"></figure><p>Attach the Focuser as you would a regular Hadley Helical Focuser.</p><figure class="image"><img src="https://media.printables.com/media/prints/299484/rich_content/5f97e065-23b4-494b-9921-b33ac5543ea7/screenshot-2022-10-20-175148.png#%7B%22uuid%22%3A%22168aaf06-4990-4047-90a1-a13b6e06ea7f%22%2C%22w%22%3A768%2C%22h%22%3A753%7D"></figure><p>&nbsp;</p><p>For those of you not using low profile thin head bolts there is a STL model with a countersink so the heads of the bolts don't collide with the focuser knob.</p><figure class="image image_resized" style="width:68.24%;"><img src="https://media.printables.com/media/prints/299484/rich_content/877a6555-c808-4644-ab8e-7cd73d1a3859/image.png#%7B%22uuid%22%3A%225cd7a4a8-4ef3-4a13-8a5b-a8178852c979%22%2C%22w%22%3A671%2C%22h%22%3A393%7D"></figure>