Looking for KFC225 autopilot red disconnect button
May 20, 2005 8 Replies
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Rich Grise
If you _know_ it's not metric, it's probably 4-40 or 6-32. These are standard thread sizes in that size of stuff. I've seen those buttons before, so I'm pretty confident about that. Are you in a metric-only country?
One of these links might have some useful info:
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Good Luck! Rich
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Peter
Hi,
Someone has lost the red "disconnect" button onmy KFC225 autopilot.
Honeywell want a lot of money for a whole new switch. Would anyone know who makes this switch? It looks like a standard pushbutton switch, with a button about 9mm diameter.
I could make a new button easily enough if I knew the thread used in the centre of the button (the button has a male screw on it). It certainly isn't metric.
The switch manufacturer is probably one of the well known names...
Any info would be much appreciated.
Peter.
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Brian Whatcott
Hmmm....I must be out of sorts. A person needs a button with a male thread. He could make it himself if he knew the size. The makers price is too high. He wants someone like Rich to tell him the thread size. Have I got the facts right so far?
So the hardware store has some screws at 5 cents each or so for him to try. Let's say he might buy 5 different sizes. That's a quarter. Is that getting too costly, already?
Brian (sour-grapes) Whatcott, Altus, OK
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Rich Grise
No, it's just that in the UK, inch parts (apparently) are kind of few and far between. Didn't they used to refer to them as "English" vs metric? Ironic, ain't it? :-)
The existing shaft on the switch has a male threaded stud. The button (or knob) needs a female thread. But I'd think that even in UK, there's _somebody_ _somewhere_ who has a 4-40 nut or a
6-32 nut on hand, just to check. As Peter said, if he knows the thread size, he can make a button. According to
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, A #4 screw is about .112" OD, which is mumble-mumble millimeters - whaddaya, multiply by 25.4? And #6 is .138". The -40 or -32 is just number of threads per inch, which divided by 25.4 is number of threads per millimeter. With a magnifier and decent scale, it's trivially easy to measure them. He could theoretically even get the right sized tap, and just drill and tap a piece of plastic. What would international mail be on a 2-ounce, $3.00 tap?
For that matter, he could make a little form, add some mold release, and pour some epoxy into it and make a knob in place.
Cheers! Rich
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Peter
I am in the UK, but the autopilot is a Honeywell one, made in the USA. The switch could be Grayhill, for example, or one of the other well known old U.S. names. It isn't a dirt cheap sort; probably $2 rather than $0.2.
I may have found a button - will be back if nothing turns up. Thank you all!
Peter.
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Peter
Rich Grise wrote
It certainly isn't 4-40 (which I assume is 4-40 UNC, same as commonly used on D-connector male screwlocks) as that is too big. The thread OD is slightly less than 3mm.
Sure I could get some screws...
BTW the price of the whole switch was quoted at US$72... but this is AVIATION :) Naturally, it would come with a batch number and an 8130-3 form with a nice rubber stamp on it.
Peter.
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Rich Grise
Oh, dear. That's a tiny little bugger. I was thinking of the ones I'd seen many years ago, in the US military. For what it's worth, the next smaller common sizes are 3-48 and 2-56, but I imagine you've looked them up by now.
Yeah, for that price, at least in my case, it's worth doing a little bit of sculpture or what-not. Do they have "Sculpey" over there? It behaves a lot like modeling clay (which I believe the Brits call "plasticine"), but when you mold it to the shape you want, you can bake it and it hardens to the consistency of bulk HDPE, or a little harder.
I'm also a little surprised that by this time somebody hasn't come up with a knob from their junque box and dropped it in an envelope yet.
Good Luck! Rich
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BobG
I bet they have one at SkyCraft Parts and Surplus in Winter Park Florida. email me a good closeup picture of the unit or the switch.
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Peter
I've just got one sent to me by a very kind person - thank you all!
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