Parametric Mini Hex Knobs

Purpose

Some projects in the house, garage, and yard need adjustments often, for instance the position of a lamp. Nobody tends to walk around the house with a cordless driver and socket set (well, I do, but that's beside the point), so it's nice to have knobs for a variety of situations.

I saw M3 universal hex screw and nut knob by HD_Creator, and immediately wanted to print it, though I didn't have an immediate need and my M3 screws don't even have hex heads! I just liked it.

Changes for the Remix

I did have a couple of wish list items. One, I often use ¼ inch - 20 bolts, Q20 for short, for household projects, so I needed additional sizes. I've been learning OnShape, and am starting to use their implementation of variables, to change sizes, but it is just not the same as the ease of changing values with OpenSCAD. So that is what I used for this remix.

The change to the new software also helps fix my other wish items. The second is a chance to change the height. I know I can scale just the z-axis only, in the slicer, but I wanted a little extra control, as follows.

• Total height - how long/tall you want the knob to be
• Support height - you need at least a little material from the nut to the end of the knob, or the nut will just break through.
• Additional height - the total, minus the support height, is whatever's left over. It will cover up the nut, plus have enough for your fingers to grab. Calculated automatically.

Finally, I wanted to have options for the diameter of the shaft and for the fit of the nut/hex head. The bolt shaft is easy, not critical. The diameter of the hexagon for the nut deserves more thinking. I do some projects, little jigs and such, where the fit is loose enough that when I take off the knob, the nut falls out. This is fine, for me. I do some other things where I want a more permanent fit; I put the knob together with a nut and bolt, and crank it down with a cordless nut driver. These will never come out, and this is cool too. Your preferences may vary.

Dial in the Perfect Fit

Pro Tip: you'll need to experiment a couple of times, for each new size of screw. Change the total height to 4mm or so, the support height to about 1mm. (See the very short, all white example, in the photo). Only print one item, using a brim for the smaller sizes like M3, M4. This will print very fast, and still allow testing the fit of the hex head easily. When you are happy with the fit, change the total height and support height back to the proper values. Then print however many copies you like.

Print Details

I used PETG, with a small bit of stringing, but, thanks to help from Prusa Support, great bed adhesion. PLA should be fine.

Layers: 0.2mm

Perimeters: 4

Infill: 20%

What to Download