Parameterized hex nut holders for inside of fiberglass or cardboard tubes

prusaprinters

<p>When rebuilding a vintage telescope, I needed some interior hex nut holders to use when bolting some fairly heavy items to the outside of the tube. &nbsp;Only some small washers had been used in the original design, and the resulting high stress had actually caused the tube to develop radiating cracks.</p><p>These nut holders are contoured to the inside diameter of the tube and provide considerable load spreading while still keeping a low profile inside the tube. &nbsp;They are also useful in sport rocketry for anchoring rail button screws in fiberglass or even cardboard airframe tubes.</p><p>The dimensions of the nut holders are completely parameterized in the OnShape CAD file: <a href="https://cad.onshape.com/documents/d2c89c20ba8568edb15e9121/w/4595fab9ea90c9dc62ccb8c8/e/a073ebe5538b02b0213fb42d">https://cad.onshape.com/documents/d2c89c20ba8568edb15e9121/w/4595fab9ea90c9dc62ccb8c8/e/a073ebe5538b02b0213fb42d</a></p><p>You'll most likely need to customize the parameters for your own needs. &nbsp;Have a look at the Feature Studio in the OnShape workspace to see how to do it. &nbsp;All of the example .stl files are for a tube with a 9.375 ID that was used in an 8"/200mm aperture telescope.</p><p>The “hexdiam” parameter is the distance measured between two parallel sides of the hex nut, with a little allowance for clearance. &nbsp;You can play with this by a few thousandths to adjust the press fit.</p><p>A tilt parameter is also provided - many old tube-mount scope accessories had mounting brackets with noticeable toe-in on the mounting bolts.</p><p>These were printed in black PETG with 0.25 layer height and 100% infill. &nbsp;Once they were mounted inside the telescope tube, they were painted over with Black 3.0 to kill the plastic shine.</p>