Drilling out a rotary switch for N1 + SPD REF, how not to….

[milezee]

from my blog at milezee737.wordpress.com:

So I wanted to add rotary encoders to the rotary switches for N1 set and Speed Ref. I don't know why, its a rarely used function if N1 hasn't been set by the FMC. And who doesn't use the FMC for a departure except in action films?

Anyway. It involved drilling a small hole down the shaft of the rotary switch in order to add a rotary encoder on to the same shaft of the rotary switch. Here is an example.

So here are my tips on how not to do this.

Disassemble the rotary switch first.

When you open up the rotary switch, the bearings will fly out. Don't lose them (like I did). When you pull out the spring, this will fly across the room too, don't lose this either (like I did).

Cut down the shaft of the switch to the desired height using a small hacksaw, don't chop it with snips (like I did) it will have a ragged edge.

Drill through the removed base first, don't try and drill through the shaft and base with out first disassembling the switch (like I did).

Use a vice, or at least grip the parts with pliers when drilling. Don't hold the parts by hand while drilling so that if you let go they suddenly start spinning around wildly on the end of the dill almost breaking your fingertips (like I did).

Drill in short sections. Let the plastic cool down in between. Don't try and drill through the shaft in one go, melting the plastic so that when you stop drilling it fuses with the drill bit and can't be removed (like I did), or bending the drill bit (like I did).

I'm trying to sum up the courage to do the second switch now, incorporating what I've learnt from doing the first.
Happy cockpit building.

http://milezee737.files.wordpress.com/2014/01/wp_20140110_0041.jpg

[archen]

Some tips for you.

When opening the rotary so that inside a plastic bag that can collect the balls and spring.

When drilling it is very important that the plastic don't get too hot. When drilling you need to keep a good speed so the chips don't get to small. The heat is removed with the chips so if you drill to slow it will also get overheated. It's also very important that the chips evacuation is good. That means when the cutting length is longer than the drills cut length it selfs you need to clear the chips by pecking. The chips have no where to go when you are drilling deeper that the cut length of the drill. Peck 1mm at time and clear chips every time. This is why your drill ended up in the rotary. Once the chips have nowhere to go it's heated up within seconds.

Also if you can get access to a lathe that is much more easier to get the hole in center.




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[archen]

Double post

[Sean]

Some more tips for you...

Open browser of your choice.

Type in address box:

http://www.archensimparts.com/

Select N1 & SPD rotaries -----> Add to basket.

Click Checkout.

Follow on screen instructions.

Wait a few days.


BINGO!

[milezee]

Some more tips for you...

Open browser of your choice.

Type in address box:

http://www.archensimparts.com/

Select N1 & SPD rotaries -----> Add to basket.

Click Checkout.

Follow on screen instructions.

Wait a few days.


BINGO!

I wish.
Built by the master.
I'm on a budget
My post was tounge in cheek, to make the veterans smile.

[archen]

How was your second try?


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[Sean]

It certainly made me smile. Took me back a few years when I started building. It was episodes like that that was the decider for me. I just didn't have the expertise (or patience).

[milezee]

Second try was much better and cleaner.
I squeezed in some time this morning (I have an 18 month old daughter).
No lost springs + bearings. No broken finger. No melted or bent drill bits ;-)

Got to figure out a good (read no fuss and cheap) way to mount the encoder now.
Also off to prosim forum now to figure out why my encoder seems really jittery.
Its an alps encoder, middle pin to ground, the other 2 pins to pin 1 + 2 on a pokeys56. I configure the pin to pulse up on and pulse down on in prosim but it doesn move the values smothly or in a consistent direction. Not sure what I'm doing wrong at this point if anyone wants to chime in.