Attaching Knobs to Rotary Encoders

[lonelyoutpost]

Hi

I want to attach plastic knobs to the rotary encoders on one of my panels. I can easily drill a hole in the knob of the correct diameter but how can I stop the knob rotating freely? With other rotary switches that have a plastic handle I have drilled a hole and used a little grub screw but the rotary encoder shafts are metal, D-style shafts and will be almost impossible to drill. Any ideas?

Thanks,

Matt

[Geremy Britton]

Sometimes the holes on the bottom of the knobs is D shaped so they fit in without the use of grub screws, more authentically however, there is a grub screw which clamps the knob to the D shaped rotary.

[lonelyoutpost]

Thanks. That's the conclusion I arrived at. It's not going to be easy but I'll give it a go.

[Geremy Britton]

If it's not working too well for you, try adding some superglue!

[tomahawk66]

Hello Matt,

I regularly drill M2/M3/M4 holes laterally through the D-style steel shafts of my rotary encoders and rotary switches, in order to construct my special switches, like those pictured below: push-pull switch with dual concentric rotary encoders and push-pull switch with rotary encoder and concentric rotary switch (Such switches are used on my Fokker 100 AFCAS, and my MD-11 MCP):

http://www.mycockpit.org/forums/attachment.php?attachmentid=11389&stc=1

Earlier, I would clamp these in a small vice and drill into the metal with a hand-held DeWalt drill, starting with an M1.5 hole and enlarging it to M2/M3/M4 step-wise, as desired. I have also then successfully tapped screw threads into the holes. The critical issues are clamping the workpiece and ensuring that you go through the flat surface perpendicularly:

http://www.mycockpit.org/forums/attachment.php?attachmentid=11390&stc=1

http://www.mycockpit.org/forums/attachment.php?attachmentid=11392&stc=1

I had varying success with achieving perpendicularity of the hole, and to better ensure this I switched to using my mini-milling machine, as shown:

http://www.mycockpit.org/forums/attachment.php?attachmentid=11391&stc=1

The detailed procedure includes first marking the location of the hole with a scriber and centre-punch, then drilling a pilot-hole with a centre-drill. The hole is then enlarged step-wise to the desired target diameter with regular twist-drills.

Hope this helps you!

Regards,

Chakko.

[lonelyoutpost]

Wow! Thanks Chakko. Not just a reply but a tutorial! This is really very helpful. Thanks for taking the time to provide the pictures. It's certainly given me a bit more confidence to go home and try this for myself. I didn't think it was possible but now I know it is.

Cheers,

Matt

[lonelyoutpost]

BTW I'm very impressed with your dual concentric push-pull switches. You really are an artist and an inspiration. Thanks for sharing!

[tomahawk66]

Thank you, Matt.
I should emphasize that first marking out the location of your proposed hole with a scriber, and then deepening that indentation with a centre-punch, is an essential pre-requisite to drilling. Especially if you are attempting this with a hand drill! Otherwise your twist-drill-bit is bound to wander when it hits the metal surface.
Regards,
Chakko.

[lonelyoutpost]

Thanks again, Chakko. I have already ordered a scriber, centre-punch and a better vice as per your instructions. Thanks for the good advice.
Best wishes,
Matt

[lonelyoutpost]

Quick Update - I did it! Much easier than I though it would be. Thanks to Chakko for the great advice.

Matt

http://www.mycockpit.org/forums/attachment.php?attachmentid=11403&stc=1