Reliable Slide Switches?

[Doug White]

I have a couple small magnetic-base gooseneck work lights mounted on my
milling machine. They were designed for 20W 12V MR-16 halogen bulbs,
but those get really HOT. After scorching myself a couple times bumping
into them, I switched to LED replacements that draw about 1/5th the
power of the halogens.

They have C&K garden variety 6A 125V slide switches mounted on the back
end. After relatively infrequent use (I only run the mill a couple days
a month), the switch on one became intermittent. I installed an
identical switch & it's been fine.

Just recently, the switch on the 2nd light has started exhibiting the
exact same symptoms. I don't want to keep replacing these things. They
are pop-riveted in place (no easy way to get at a nut inside), and
swapping them out every few years is annoying. I always thought C&K
made decent switches, and of the options on Digikey, they are the most
expensive.

Are there other brands I should consider trying, or do people think I
just got ones from a bad batch?

The only other thing I can think of is that the LED bulbs may have a
funny startup surge that is cooking the contacts. I didn't do a post-
mortem on the first one, but the contacts should be loafing at the
reduced load they are seeing.

Suggestions welcome.

Thanks!

Doug White

[MOP CAP]

This does not supprise me. Switches designed for switching a faire
amount of power do not work very well on low power or "dry" circuits.
Your LED's are essentally such a circuit. You probably cannot find
a slide switch that is designed for "dry" circuits. Even if you did the
next person that comes along might
replace the LED's with the original halogen bulbs and burn out the
switch. No solution just info.
CP

[Phil Allison]

MOP CAP wrote:

>
>
> This does not supprise me. Switches designed for switching a faire
> amount of power do not work very well on low power or "dry" circuits.
> Your LED's are essentally such a circuit.
>

** That is utterly wrong !!!!!!!!

The circuit is still 12V and the load is several watts - so NOTHING like "dry switching".

> You probably cannot find
> a slide switch that is designed for "dry" circuits.
>

** Also completely wrong - most slide switches are just fine for the job.

So called "dry switching" applies to signals like audio and video where the level is in the millivolt range and perfect contact must be made with no signal at the time of switching.


The OP's hunch is likely close to the fact and he only needs to DO a post mortem to find out.


.... Phil

[whit3rd]

On Wednesday, November 23, 2016 at 8:03:45 AM UTC-8, Doug White wrote:
> I have a couple small magnetic-base gooseneck work lights mounted on my
> milling machine. They were designed for 20W 12V MR-16 halogen bulbs,

> but... I switched to LED replacements

> They have C&K garden variety 6A 125V slide switches...
>the switch on one became intermittent....

> Just recently, the switch on the 2nd light has started exhibiting the
> exact same symptoms.

If you can detach the power supply, try running the switch with a 120V
incandescent lamp as its load (60W to 100W bulb). It's possible some
small amount of oil or dirt is coating the switch, and 100 mA isn't enough
current to burn it off. The polymers in a switch, or grease that makes it slide,
can outgas or seep into the metal/metal contact area with distressing results.
That switch is supposed to handle higher voltages and currents, and might
be self-cleaning if given a chance.

[Allodoxaphobia]

On Wed, 23 Nov 2016 16:03:42 GMT, Doug White wrote:
>
> Are there other brands I should consider trying, or do people
> think I just got ones from a bad batch?

I've always felt that "Reliable Slide Switch" was an oxymoron.

[Doug White]

Allodoxaphobia <knock_you...@example.net> wrote in
news:slrno3dudp.2g4q.k...@vps.jonz.net:

Perhaps, but I'd be surprised if I have more than a few hundred cycles on
these things. That's rediculous.

Doug White

[Doug White]

whit3rd <whi...@gmail.com> wrote in
news:e121ecb5-d453-4ffc...@googlegroups.com:

I've tried cycling them to wipe off any thin flim or corrosion. It
feels more like a mechnical problem than anything else. If I flip it &
it doesn't light, I can often get it working by backing up the switch
just a hair & wiggling it. Getting it working at one point during the
day is no guarantee that it will work the next tiem I try it an hour
later.

The particular switch (C&K S102031SS03Q) has a plastic body, which
surprised me. I may try at least seeing if I can find an old fashioned
one with a metal housing.

I'd love to find one with threaded holes in the mounting ears. That
would be a lot easier to work with.

Doug White

[whit3rd]

On Thursday, November 24, 2016 at 8:56:16 AM UTC-8, Doug White wrote:
> whit3rd <whi...@gmail.com> wrote in
> news:e121ecb5-d453-4ffc...@googlegroups.com:
>
> > On Wednesday, November 23, 2016 at 8:03:45 AM UTC-8, Doug White wrote:

> >> They have C&K garden variety 6A 125V slide switches...
> >>the switch on one became intermittent....
> >> Just recently, the switch on the 2nd light has started exhibiting the
> >> exact same symptoms.
> >
> > If you can detach the power supply, try running the switch with a 120V
> > incandescent lamp as its load (60W to 100W bulb).

> I've tried cycling them to wipe off any thin flim or corrosion. It
> feels more like a mechnical problem than anything else.

It IS a mechanical problem, if the film on the metal is too tenacious to be
dislodged by sliding. You haven't any control over the contact pressure,
but you CAN increase the electrical stress, and carbonize the insulator as you
run the switch over it (creating a hot spark).

[Ron D.]

You can get slide switches with threaded holes. This is typically used in a ceiling fan.

[Doug White]

"Ron D." <Ron.D...@gmail.com> wrote in
news:9e8aa000-5afd-4988...@googlegroups.com:

> You can get slide switches with threaded holes. This is typically
> used in a ceiling fan.

I haven't found any with threads with the required 1.125" hole spacing.

I have found both a Switchcraft and a CW switch that use the old style
folded metal & phenolic PCB construction, but no threaded holes. Both
are rated for 3A (vs 6A for the plastic C&K), which should still be OK,
even for the original 20W 12V AC halogen bulb. With the LED replacement
bulb, it should be loafing.

Both the Switchcraft and the CW cost about half what the C&K do. They
are all so cheap that I will probably just order a couple of each. I
will try the C&K again on the theory that I may have gotten ones from a
bad batch. I'll also take the flaky one apart & see if I can figure out
what the failure mechanism is. if one of the replacements dies
prematurely, I will install a Switchcraft.

I'll report back when I have the replacements in hand & do an autopsy on
the bad one.

Doug White

[Jon Elson]

Yes, I'm with you. I have seen some very special switches that had a slider
or rocker that operated a microswitch with a cam-like mechanism. These were
probably for aerospace reliability level applications, and prices
accordingly.

The typical slide switches have really mediocre contacts with thin plating,
and once the springy contact fingers had worn down, you'd get poor contact,
base metal on base metal.

Jon

[Jeff Layman]

On 27/11/16 03:22, Doug White wrote:
> "Ron D." <Ron.D...@gmail.com> wrote in
> news:9e8aa000-5afd-4988...@googlegroups.com:
>
>> You can get slide switches with threaded holes. This is typically
>> used in a ceiling fan.
>
> I haven't found any with threads with the required 1.125" hole spacing.

Maybe some ideas to consider if all else fails:
1. Is there enough thickness to cut a thread in the mounting hole with a
fine-pitch screw tap? The data sheet shows it to be 0.052" (1.32mm).
2. Consider glueing a nut onto the switch with epoxy, although from the
data sheet there is very little space between the hole and the body of
the switch for a nut.
3. If you can get to the power lead to the lamp, consider fitting a
separate, more reliable switch in the lead, and just leave the slide
switch in the "on" position (or even solder a short circuit across it).

--

Jeff

[Ron D.]

Check out http://ceilingfanparts.com/images/pullchainsw.htm (RVSS6) You may have to verify that they are threaded. It's been a while since I ordered that part. The switchcraft 46206 series doesn't have threads.

You can also use two of these speed nuts:
http://www.marshallshardware.com/products/productList.aspx?uid=2-411-246-228

Too bad this place doesn't give dimensions. Here's https://www.mcmaster.com/#speed-nuts/=1584m2a a place that does.

[Tim R]

Just a random thought.

I had a small single bulb floor lamp I used over a music stand. The switch was inline with the cord, not a slide switch but a thumb wheel type.

I put a CFL in it. I got arcing when switching and the switch didn't always work. I had to go back to an incandescent. My take was that the electronics in the CFL were too much for a maybe marginal switch. These run at a power factor less than 0.6. Anyway it worked fine with an incandescent.

And yet, now I have an LED in it and that also works fine.

[Doug White]

Doug White <gwh...@alum.mit.edu> wrote in
news:XnsA6CCE394CADA1...@69.16.179.42:

Haven't had a chance to tear apart the old switch, but one of the CW
brand switches Digikey sells has threaded holes (although it's VERY hard
to tell from the data sheet), so that will make replacing it easier in
the future. Also, it's a DPDT, so I can tie the contacts in parallel.
That ought to extend the life at least a bit.

In the meantime, I tried to fix a dead rechargeable stick vacuum this
morning, and the proprietary 3 position slide switch is toast. I
suspect it got cooked from my daughter's hair clogging the beater brush
& stalling the motor. It seemed like every time I went to use it the
brush was seized up and I had to spend a half an hour pulling hair out.
She's got her own place now, so that should be less of an issue in the
future...

Doug White

[Doug White]

Doug White <gwh...@alum.mit.edu> wrote in

news:XnsA6EA927AC720B...@69.16.179.43:

I took apart the original switch that died. The construction inside is
very different from the typical ones with a phenolic board. The C&K is
molded plastic, and the contacts are to the side of the switch slider,
rather than underneath. The contacts didn't look pitted or worn, but
there was some green corrosion. The design looks like it should provide
a good wiping action, but the force is supplied by a wimpy little coil
spring. I suspect that the corrosion built up to the point where the
feeble wiping force couldn't reliably break through the crud. I had
tried sliding it back & forth to scrub the contacts, but that didn't do
it. I don't know if the spring is too weak to start with, or maybe took
a compression set over time.

The DPDT CW brand switch with the threaded holes installed very nicely,
and with the contacts doubled up, it should last a long time. Not
having to mess with pop rivets means it will be trivial to replace if I
ever need to.

Thanks for all the input & discussion.

Doug White

[w9gb]

Switchcraft / Conxall does mfg. Slide Switches with "Tapped Flanges" (available special order #2).
http://www.switchcraft.com/Category.aspx?Parent=654

Switchcraft 46200 Series Slide Switches, 2 Position, 1 Pole, 2 Pole : Spec Sheet
http://www.switchcraft.com/Specification.aspx?Parent=429
Standard Slide switch (larger then 1.20"). 46200 Series are 2 Position, 1 Pole, 2 Pole

SPECIAL ORDER FEATURES

1. .344 inch (8.74 mm) high knobs are standard; other heights available.
2. #6-32 and #4-40 tapped flanges for mounting available).
3. P.C. terminals.
4. Series 46000R switches are CSA marked on special order only.

[Doug White]

w9gb <gregor...@gmail.com> wrote in
news:b0d2860b-bfe9-48d7...@googlegroups.com:

> Switchcraft / Conxall does mfg. Slide Switches with "Tapped Flanges"
> (available special order #2).
> http://www.switchcraft.com/Category.aspx?Parent=654
>
> Switchcraft 46200 Series Slide Switches, 2 Position, 1 Pole, 2 Pole :
> Spec Sheet http://www.switchcraft.com/Specification.aspx?Parent=429
> Standard Slide switch (larger then 1.20"). 46200 Series are 2
> Position, 1 Pole, 2 Pole

The CW switches with the threaded holes I bought are very similar to
Switchcaft's design, and have the same contact ratings. The big advantage
of the CW's is that Digikey stocks them...

Doug White

[mog...@hotmail.com]

I keep thinking that touch-button (semiconductor), not push-button (mechanically actuated) is what you want. Touch button means there's no mechanically actuated "turn on" or "turn off" parts to get worn out.

Touch button just stays there motionless when you touch it and maybe lights-up or whatever, but it starts what you want without its own motion which could cause its own wear and tear. Buttons without wear and tear mechanical motion are offered by companies like "ideal", "little fuse", "keymatech", etc ...