Maximum rep rate for a standard microswitch.

[amdx]

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

Mikek

 

[Cursitor Doom]

On Sun, 15 Sep 2019 18:45:05 -0500, amdx wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

Mikek

Why not use a hall-effect instead? Or laser and photo-diode with a small
mirror stuck to the side of the quill? I don't see a microswitch as being
suitable for this application.



--
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protocols constitutes acceptance of this condition.

 

[amdx]

On 9/15/2019 6:50 PM, Phil Allison wrote:

amdx wrote:

----------------

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?


** Try using a reed switch with a small permanent magnet, magnet rotating switch fixed.

Many cassette decks used such an arrangement as a tape movement sensor.


... Phil

That's sounds good, if I can find my reed switches. We had a hurricane
11 months ago and all my supplies got reshuffled. Pain in the ass
committing the position of everything back into a new memory.

Mikek

 

[Phil Allison]

amdx wrote:

----------------

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

** Try using a reed switch with a small permanent magnet, magnet rotating switch fixed.

Many cassette decks used such an arrangement as a tape movement sensor.


.... Phil

 

[amdx]

On 9/15/2019 8:01 PM, jlarkin@highlandsniptechnology.com wrote:

On Sun, 15 Sep 2019 18:45:05 -0500, amdx <nojunk@knology.net> wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

6 Hz should be OK at 50% duty cycle.

Are you debouncing the closure?

Not yet, I'm hoping there is a bit of debounce caused by the
electro/mechanics of the counter. It draws 3/4 amp at 12 volts, I can do
plenty of fast wire touches without it counting,it does give a nice
counter EMF. It won't count until the voltage reaches 6.2 volts.
I'll put in a search tomorrow for my reed switches.

Mikek

 

[amdx]

On 9/15/2019 6:54 PM, Cursitor Doom wrote:

On Sun, 15 Sep 2019 18:45:05 -0500, amdx wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

Mikek

Why not use a hall-effect instead? Or laser and photo-diode with a small
mirror stuck to the side of the quill? I don't see a microswitch as being
suitable for this application.

I have a Root Veeder counter all it needs is a pulse, I wanted the
project to be counting the turns on a coil, not developing a circuit to
make a pulse to drive the counter.
Just trying to keep it simple, until I buy a lathe.
Mikek

 

On Sun, 15 Sep 2019 18:45:05 -0500, amdx <nojunk@knology.net> wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

6 Hz should be OK at 50% duty cycle.

Are you debouncing the closure?

 

[Phil Allison]

jla...@highlandsniptechnology.com wrote:
-------------------------------------------

6 Hz should be OK at 50% duty cycle.

** Bet JL has never tried it.

I know a reed switch will easily do the job far better.

But I'm not a "designer" . ...



..... Phil

 

[whit3rd]

On Sunday, September 15, 2019 at 6:16:34 PM UTC-7, amdx wrote:

... I'm hoping there is a bit of debounce caused by the
electro/mechanics of the counter. It draws 3/4 amp at 12 volts, I can do
plenty of fast wire touches without it counting,it does give a nice
counter EMF. It won't count until the voltage reaches 6.2 volts.
I'll put in a search tomorrow for my reed switches.

Reed switches won't play nice with 3/4 amp, though.
A one-shot for debounce, into a solid state counter
like this
<https://www.digikey.com/product-detail/en/red-lion-controls/SCUB1000/RLC1000-ND/15288>
might be the easiest, and would probably work with the microswitch. It only
needs a button cell for power.

 

[Phil Allison]

whit3rd wrote:
---------------

Reed switches won't play nice with 3/4 amp,

** Nonsense, 12V at 750ma is a piece of cake.

Small ones are typically rated at 1 amp and 200V for millions of cycles at up to 100Hz.

Larger types are rated at 250V and 5 amps.



..... Phil

 

[Joe Chisolm]

On Sun, 15 Sep 2019 18:45:05 -0500, amdx wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

Mikek

counter with Hall sensor and a little magnet
17 bucks

https://www.amazon.com/DIGITEN-Digital-Counter-Proximity-Switch/dp/
B016U4IZ6K

--
Chisolm
Texas-American

 

[Phil Allison]

Whoey Louie wrote:

------------------

Reed switches won't play nice with 3/4 amp,


** Nonsense, 12V at 750ma is a piece of cake.

Small ones are typically rated at 1 amp and 200V for millions
of cycles at up to 100Hz.

Larger types are rated at 250V and 5 amps.


.... Phil

-------------------------

Whether you can mount a magnet on the drill press and
whether it has enough time over the switch to make it
work might be a question though.

** If the OP can mount a suitable cam he can also mount a small magnet.

Now: The OP's drill turns at up to 300rpm or 166mS per rev.

Operate time for a reed switch is about 2.5mS or 1.5% of a rev.

Betcha it will work just fine.



.... Phil

 

[Whoey Louie]

On Sunday, September 15, 2019 at 10:51:57 PM UTC-4, Phil Allison wrote:

whit3rd wrote:
---------------


Reed switches won't play nice with 3/4 amp,


** Nonsense, 12V at 750ma is a piece of cake.

Small ones are typically rated at 1 amp and 200V for millions of cycles at up to 100Hz.

Larger types are rated at 250V and 5 amps.



.... Phil

Whether you can mount a magnet on the drill press and whether it has enough time over the switch to make it work might be a question though.

 

[Sylvia Else]

On 16/09/2019 9:45 am, amdx wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
 It doesn't work. Unreliable counting.
 My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

                                 Mikek

How are you doing the counting?

Sylvia.

 

[Michael Terrell]

On Sunday, September 15, 2019 at 7:45:07 PM UTC-4, amdx wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

Mikek

Use something made for the job. These come in different counts per turn, and are rated up to 5000 RPM. They run on DC and can be used to count turns, show direction or show the shaft position.

Encoder-360P-R-Incremental-Rotary-Encoder-360p-r-AB-phase-encoder-6mm-Shaft

https://www.ebay.com/itm/121841623742

 

Dana ponedjeljak, 16. rujna 2019. u 01:45:07 UTC+2, korisnik amdx napisao je:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

Mikek

You can use an inductive sensor instead of a mechanical switch. Inductive sensor has approximately few kHz switching frequency.

 

[Phil Allison]

Michael Terrell wrote:

Use something made for the job. These come in different counts per turn, and are rated up to 5000 RPM. They run on DC and can be used to count turns, show direction or show the shaft position.

** Nice unit but overkill.

The op only wants to count turns cos he is winding inductors.

His mechanical counter is fine, it just needs a one cycle per rev switch to drive it.


..... Phil

 

[Steve Wilson]

amdx <nojunk@knology.net> wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

Mikek

Reflective strip of tape and an optical proximity sensor.

 

[Phil Allison]

amdx wrote:
------------

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

** The reference I found suggests 1 cycle per second is the norm used in mechanical life testing of such switches. 6Hz seems very high.

But as I posted earlier, reed relays can do it very easily.


..... Phil

 

[Jasen Betts]

On 2019-09-16, amdx <nojunk@knology.net> wrote:

On 9/15/2019 6:54 PM, Cursitor Doom wrote:
On Sun, 15 Sep 2019 18:45:05 -0500, amdx wrote:

I wanted to make a turns counter for my drill press.
I have it set for 330 RPMs or about 6 cycles per second.
It doesn't work. Unreliable counting.
My high point is (switch closure time) about 1/12 of the rotation, I
wonder if I did a 50/50 duty cycle if it would be better.

Or, is expecting the switch to operate at 6Hz just to fast for a
standard microswitch?

Mikek

Why not use a hall-effect instead? Or laser and photo-diode with a small
mirror stuck to the side of the quill? I don't see a microswitch as being
suitable for this application.



I have a Root Veeder counter all it needs is a pulse, I wanted the
project to be counting the turns on a coil, not developing a circuit to
make a pulse to drive the counter.

I had a small electomechanical counter that was fine with the sub 10ms
pulses that I got from a half-wave rectifier,

It must be that your microswitch is too slow. perhaps you can arrange
for the counter's drive current to pass through some moving part of the
drill.

> Just trying to keep it simple, until I buy a lathe.

With a lathe would you use the lead screw as a counter, or do you have
some other strategy in mind?

--
When I tried casting out nines I made a hash of it.