Looking for KFC225 autopilot red disconnect button

[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.

 

[Rich Grise]

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.

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?

The switch manufacturer is probably one of the well known names...

Any info would be much appreciated.

One of these links might have some useful info:
http://www.google.com/search?q=pushbutton+switch

Good Luck!
Rich

 

[Peter]

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?

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.

 

[Brian Whatcott]

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:
http://www.google.com/search?q=pushbutton+switch

Good Luck!
Rich

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

 

[Rich Grise]

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?

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 http://www.csgnetwork.com/screwinfo.html ,
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

 

[Peter]

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.

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.

 

[Rich Grise]

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.

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.

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.

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

 

[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.

 

[Peter]

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.

I've just got one sent to me by a very kind person - thank you all!