Wanted: non-flimsy rotary encoders - Page 1
Forum section: electronics / projects

author: pastaclub
author_rank: Regular Contributor
timestamp: April 12, 2024, 09:56:04 am
content: I’m looking for rotary encoders which are sturdy enough so that the shaft doesn’t wobble around when you just slightly touch it. (I mean those simple 3-pin A,B quadrature ones with 24 positions and no detents, typically 12x12mm footprint, snap-in PCB mounted, as they are used for example in digital oscilloscopes).The problem is (as seen on the bottom side) that the tolerance of the hole around the shaft is very generous and with a 25mm long shaft plus knob, you can move the knob to the side by more than 1mm while it should ideally just rotate around the Z axis.I tried Bourns, ALPS Alpine and Song Huei - they are all flimsy (while their potentiometers are not).Any part recommendations?I would be fine with a PCB-mounted version with metal shaft (i.e. one that is mounted on the bottom side of the PCB, with the shaft and pins facing upwards through the PCB, and a nut is installed on the top side) but it seems that only potentiometers, not encoders are available in such packages.…and it should still be affordable, since it’s not for a spacecraft and I need many of those.

author: tooki
author_rank: Super Contributor
timestamp: April 12, 2024, 10:07:01 am
content: Can you add shaft stabilization through the mechanical design of your enclosure? For example, by providing a bushing the shaft passes through?I could even imagine designing a bushing that screws onto the threads of a rotary encoder.Or you can do what many products do and stabilize the knob rather than the shaft.And finally, the likely most common approach: keep your shafts as short as possible by mounting the encoder as close to the front panel as possible.

author: pastaclub
author_rank: Regular Contributor
timestamp: April 12, 2024, 11:23:03 am
content: Having a tight tolerance hole in the front panel sounds like the easiest remedy. I’d have to try that. I’m just worried that (with many encoders on the PCB) it will become difficult to install the front panel.Do you have examples of stabilized knobs?

author: xvr
author_rank: Frequent Contributor
timestamp: April 12, 2024, 01:00:18 pm
content: > I would be fine with a PCB-mounted version with metal shaft (i.e. one that is mounted on the bottom side of the PCB, with the shaft and pins facing upwards through the PCB, and a nut is installed on the top side) but it seems that only potentiometers, not encoders are available in such packages.This one?https://www.digikey.ie/en/products/detail/bourns-inc/PEC11R-4220K-S0024/6164059

author: tooki
author_rank: Super Contributor
timestamp: April 12, 2024, 07:23:36 pm
content: Quote from: xvr on April 12, 2024, 01:00:18 pmNo, that’s an ordinary one mounted on thetopside of the PCB, but OP said one that mounts to thebottomside. They mean a reverse-mount unit, which does exist for potentiometers.

author: tooki
author_rank: Super Contributor
timestamp: April 12, 2024, 07:24:11 pm
content: Quote from: pastaclub on April 12, 2024, 11:23:03 amNot handy, but if I remember, I’ll take a photo of an example at work.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: April 12, 2024, 08:02:02 pm
content: Quote from: pastaclub on April 12, 2024, 11:23:03 amOne option would be to use an available encoder with a nut-mount, but choose a 'longer than usual' shaft bushing.That has to reduce the shaft slop, and secures the bushing, so does not rely on the PCB for stiffness.This example ?https://www.lcsc.com/product-detail/span-style-background-color-ff0-Rotary-span-Encoders_ALPSALPINE-EC12E2460802_C470685.html