If by stroke length you mean the length the razor cuts to its ending position (before retracting back up), then it is 1 inch.

That might be doable with a solenoid.
Do you know what force is required?

 

That might be doable with a solenoid.
Do you know what force is required?

No I do not. It is a cigar cutter. I think as long as it is not cutting slow, it will not require much force.

 

The motor turns 180 then stops briefly and either reverses 180 or continues 180. This
is going to require another timer.

Is the motor geared to 30 RPM? If not, how do you expect it to rotate only 180° in 1 second. An ungeared motor will spin at 1000s of RPMs. In one second it will spin many times around.

With a hobby servo, you command it to move to a position. There is no need for a timer. Implied is that a servo does not spin

The motor I am looking at is geared it rotates at 200 rpm

Ok. You mention a servo. RPM is not relevant when talking about servos.

A continuous rotating servo might work better

A continuous servo either spins in either direction or stops. Pulse width less than or greater than 1500 mS turns in either direction. A pulse width of 1500 mS stops.

Pretty accurate. The motor is fixed to a cam which drives a down a blade. Like a cam and follower system. It is a cutting mechanism. The motor is driving the cutting motion.

A servo can easily be positioned accurately at any number of degrees, from 0 to 180.

Gearing down a motor to a specific speed and position is not easy.

BTW, with a servo, you wouldn’t need a cam

But with all the talk of servos, your picture shows a normal DC motor with a gear train.

 

By far, the easiest thing to do is use a switch that is activated by the cam just after the cut is finished and the blade is retracted. That switch would then stop the motor. The push button overrides the switch to start the motor going again, getting it past the other switch to perform the next cut.

 

By far, the easiest thing to do is use a switch that is activated by the cam just after the cut is finished and the blade is retracted. That switch would then stop the motor. The push button overrides the switch to start the motor going again, getting it past the other switch to perform the next cut.

Good point.
I like Crutschow’s idea of a solenoid. It would simplify the whole thing by taking the rotational issue out of the picture.

 

By far, the easiest thing to do is use a switch that is activated by the cam just after the cut is finished and the blade is retracted. That switch would then stop the motor. The push button overrides the switch to start the motor going again, getting it past the other switch to perform the next cut.

Probably a normally closed reed switch that is connected in series to the battery would work. When the cam finishes a 180 degree turn it pushes against it. I like your idea, but do you think it’s smarter then a solenoid?

 

Probably a normally closed reed switch that is connected in series to the battery would work. When the cam finishes a 180 degree turn it pushes against it. I like your idea, but do you think it’s smarter then a solenoid?

That might be doable with a solenoid.
Do you know what force is required?

Not sure the solenoid will work. It needs to fit in a tight space (as shown in the photo) and will need 1” stroke which not many small solenoids offer.

 

I am unsure the solenoid will work. 1 inch is an oddly large stroke, not to mention the solenoid would have to be small and compact. The idea from Bob is a smart one. It could be used to turn the motor off, but I don’t see the advantage in that over the motor’s timed ON method we already made with the timer circuit because the motor will not automatically retract. Based on my knowledge of gear motors, they simply stop. They do not reverse rotation and go back to their starting position.

 

If you want to stay with the DC motor use a 30rpm motor which provides 1/2 rotation in 1 second.

 

If you want to stay with the DC motor use a 30rpm motor which provides 1/2 rotation in 1 second.

That will be to slow. It needs to be fast to cut the cigar.

 

That will be to slow. It needs to be fast to cut the cigar.

It moves 180 degrees in 1 second. That's what you said was needed in post #40 correct?

 

It moves 180 degrees in 1 second. That's what you said was needed in post #40 correct?

It doesn’t have to be one second. It can be .25 seconds or any amount of time that will cut the cigar fast and move only 180 degrees.

 

Crutschow's post #27 contains a circuit I built. I am now attempting to convert the 1 second ON Output of the timer circuit to a Microservo 180 deg. rotation. In other words, I am attempting to forget about the 1 second DC Motor ON period, and replacing it with a Microservo that simply spins 180 degrees. I built the following circuit that uses a transistor to rotate a servo to a position:

The problem is this:
In my circuit I want to use only one push button switch. The issue with the circuit above's implementation is that one button sends the servo about 180 degrees in one direction and the other button returns it back 180 degrees. So, when I build this circuit with my one button, the first click rotates it 180 degrees. But, for every button push after that, the servo just vibrates a little, indicating that it is already at its desired angular position.

Please advise me on how I may implement this 'Servo Tester Circuit' into my single button idea.
Again, I want the servo to rotate 180 degrees for every time I push the button.
Note: The direction of the 180 degree rotation does not matter because it is driving a cam. The only requirement is that it rotates 180 degrees each button push.
Thank you.

 

Getting more complicated using a single switch. Do you mean a quick press of the button or press and hold as in the circuit posted?

 

I’m on the road, so I can’t draw a schematic but…
A solution is to replace the buttons with PNP or P-channel transistors. You’ll need to separate the buttons and pin 7 positive source. Add the resistor value from the positive connection to each of the resistors individual resistor to get the resistor value for the pushbutton.
Then, I’d drive/ connect the base/ gate of each transistor (button) to a flip-flop.
A flip-flop has two outputs: Q & Q-bar. These are complimentary. When either is high, the otheris low. These outputs and the transistor buttons will cause you servo to move back and forth.

 

Getting more complicated using a single switch. Do you mean a quick press of the button or press and hold as in the circuit posted?

Any quick press button. Doesn’t matter if it’s momentary or not, as long as it does the job with one quick push

 

I’m on the road, so I can’t draw a schematic but…
A solution is to replace the buttons with PNP or P-channel transistors. You’ll need to separate the buttons and pin 7 positive source. Add the resistor value from the positive connection to each of the resistors individual resistor to get the resistor value for the pushbutton.
Then, I’d drive/ connect the base/ gate of each transistor (button) to a flip-flop.
A flip-flop has two outputs: Q & Q-bar. These are complimentary. When either is high, the otheris low. These outputs and the transistor buttons will cause you servo to move back and forth.

Understood. These concepts are new to me, so I will wait on that circuit schematic. I only have 2N2222 transistors and IRF 540 Mosfets, so it would be convenient if you could use one of those.

 

The timed dx motor actually seems to be working just fine. I am using a 22 microFarad capacitor and a 3.3 kiloOhm resistor and it spins about 180 degrees every button push. I don’t believe there’s a need for the microservo.

 

Built the circuit with a perfboard.
My first time soldering this summer.
The circuit is not acting correctly, like it did in the breadboard.

The original breadboard circuit worked correctly like this:
1) Push Button is pushed
2) LED (representing the heating element) ON for about 8 seconds
3) LED OFF
4) Motor Spins for short time

Right now, the LED is on when I power on the board (before I even touch button) and stays on indefinitely.
The motor never spins when the button is pushed.

I have triple checked my perfboard soldering connections, and cannot find a mistake.
Please let me know if you guys see any issues.

 

I suggest some more practicing soldering. There is a lot of solder, excess component leads and wires. I guarantee you that somewhere on that board, there is an unwanted connection. But without a schematic and better pictures (flip one side so the components on the top and the connections on the bottom are aligned between the two pictures.