Ambika encoder - it's all about the size

Assembling my Ambika, I today received my encoder from Reichelt (Rotary encoder w/ switch, 24 steps, 25mm shaft, STEC12E08), noticing that this part only has a 15mm shaft (compared to the pots with 25mm shafts).

Is that a problem or will the shaft be long enough to reach to the front panel of the enclosure?

If not, can I use any other encoder, or is the number of steps important?

if in doubt a dip of hot glue will work wonders…

… and glue what to what? The knob onto the shaft?

Yups. Or if you are more pro like me, cover the shaft first with something the glue doesn’t stick to. Olive Oil works great :wink:

ok, thanks, I’ll try that.

I have here the right one. Contact me . Costs 5€ inc shipping.


FYI, this is the replacement at mouser for the discontinued encoder. Sadly its 30mm. I should get them in the mail shortly and report…

@tubeohm It would be great if I can get one of those.

@fcd72’s method works somehow, but the inner structure of my knobs is slippery like teflon and the hot glue does not stick that well on it. For a temporary fix its works quite well, but feels not durable enough.

Mouser’s stock keeps getting Run on…

You can use the PEC12R series (Haven’t verified the new “R” part). I think the stated shaft lengths are measured different for total length, can’t be sure, I haven’t ordered any of the new 12R’s since mouser got stock. For the 11R series I use 20mm on my shruthi and I think for the 12R series it would be 25mm.

If its only 30mm for the one encoder, just cut 5mm of it off with a hot knife (melting through) or a Dremel like tool.

Thanks for the ideas.
Actually I had a longer one with a round metal shaft and a different step size, but it’s unclear to me, if the step size does matter (I think it’s has 30 detents / 15 steps).

I’ll go with the right sized one, getting it from tubeOhm.

Resurrecting an old thread - I’ve finally bought an Ambika case by Adrian and encountered the same problem: Alps encoder from Reichelt already fitted, shaft too short.

The only proper one I can find (Bourns PEC12R 25mm) is available at Mouser. 20 Euro shipping, not worth it unless I buy more parts. Alps encoders are gone, Farnell has neither Alps nor Bourns, Panasonic won’t fit if I read specs correctly. Even if I find a proper encoder resoldering might be tricky as others reported before.

> a dip of hot glue will work wonders….

What about cutting 5 mm length of shaft from some pot and glueing it on top of encoder’s shaft, then putting the knob on. Will it work, has anyone tried that?

The glue option will work as long as your knob also grabs at least a mm or so of the original shaft. Otherwise it will snap sooner or later.

@shiftr - thanks.

My caliper says the knob will grab 2 mm of the original shaft. The worry is: will it break the moment I’ll pull the knob off to open the case? Then glue it again, this time forever… etc.?

There are many threads on the same topic here, another one added today. My simple question is about real experiences on effort/cost effective solution that someone tried and could recommend.

Just replace the bloody encoder? - however difficult resoldering or getting that Bourns might be - or is there a “dip of hot glue” trick that’s gonna last?


you can unsolder the encoder with a little practice and patience.

Hold your iron to the encoder pins and apply a huge mass of solder. Then you have a large “blob”/ball of molten solder on the PCB that has a thermal mass large enough to stay molten for a few seconds. Try to maneuver this molten blob around to cover as many pins of the encoder as possible. You will want to cover e.g. all pins on the left side first. Then apply some pressure to the encoder to tilt it so that the pins with the molten solder will lift out of the board a few mm.
Then you move the molten blob to the pins on the other side and put pressure on the encoder in the opposite direction so that the other pins lift out as well. Effectively you always keep more then half of the pins molten and tilt the encoder, then change sides and repeat.
You will have to repeat this procedure roughly 3-5times.

Once its out, take some solder wick and remove the big blob and clear the holes in the pcb, so that you can stuff a new encoder in.

@ TheSlowGrowth - sound advice, thanks!

Hi Mouser had some good ones made of metal
Mouser Part No:652-PEC11R-4220F-S12
PN: PEC11R-4220F-S0012


you can use a heat gun to get it out. Just blast it on the solder side until you can pull it out

You should shield un-related parts of the board when using that brute-force approach with the heat gun…

I’ve tried my own idea:

> What about cutting 5 mm length of shaft from some pot and glueing it on top of encoder’s shaft, then putting the knob on. Will it work, has anyone tried that?

It works… well, probably until I try disassembling. But my Ambika is finally inside the case and looks great, thanks for all suggestions.

PS. An afterthought:

My poor performance record of successfully desoldering components - big or SMT - tells me:
if you’ve got proper tools and experience - piece of cake, if you’ve got neither - avoid.

Soldering is easier than desoldering. There must be some catch here: going down the mountain happens to be more difficult (and dangerous) than climbing one… :slight_smile: