# Controlled solenoid stroke length

#### maurodelazeri

Joined Oct 21, 2020
35
Let me create a scenario to better illustrate the problem I have 1500 pens that I want to individually actuate upwards with 3 different distances, ex: 10mm/15mm/20mm I thought I could use solenoids to do this, but I'm not sure if this is the best option and how accurate the solenoid will be, another point is that speed is very important to me, that's why I'm initially not considering servos for example.
Any input is much appreciated thanks!

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#### shortbus

Joined Sep 30, 2009
8,817
Solenoids for the most part work in a stop to stop way. By stop I mean the solid end of the movement. It is hard to control solenoids to an accurate, intermediate place of movement.

Maybe explaining more of what your trying to do will give ideas for you.

#### AlbertHall

Joined Jun 4, 2014
11,506
Do you want to activate only one pen at a time, or multiples?
And if multiple pens would they all be the same height?

#### maurodelazeri

Joined Oct 21, 2020
35
To have an idea, this image illustrate how the "pens" will be place - side by side

The tricky part is that not every "pen" needs to be activated at the same time and the distance of the stroke needs to be controlled to vary (10mm / 15mm /20 mm) these numbers do not need to be 100% accurate, they can have a 10% tolerance for example.

ex: at a certain time I want to activate the first pen from left to right, then the second and then the third and others I might want to active these same three at the same time.

In terms of force, its around 5N, so, not so much, but the speed is important, that's why, like I mentioned before I didn't think servos fit this problem well, but I might be wrong thought, I don't know how I can measure the speed of a servo in compassion with a solenoid, but I think ll be a lot...

any input is appreciated

#### AlbertHall

Joined Jun 4, 2014
11,506
If you are activating more than one at the same time would they need to able to have different strokes - for instance pen 1 10mm and pen 2 20mm.

#### maurodelazeri

Joined Oct 21, 2020
35
If you are activating more than one at the same time would they need to able to have different strokes - for instance pen 1 10mm and pen 2 20mm.
The idea is to use an individual solenoid for each "pen"and this solenoid be able to do this 3 different strokes, so if I want I ll be able to activate 1 and 2 with 20mm at the same time for example

I'm planning to manage each solenoid using a Siemens micro controller with the number of output ports I need, in this project I think 3000

At first I thought it was a trivial problem, but, going deeper, I realized that it is not

#### ElectricSpidey

Joined Dec 2, 2017
1,814
Sounds like a tough nut.

Maybe some sort of cam, turned by solenoid strokes.

IE:

1 stroke = 10mm
2 strokes = 15mm
3 strokes = 20mm

I doubt if you could ever control the length of a solenoid stroke purely electronically, without being some custom device.

#### maurodelazeri

Joined Oct 21, 2020
35
Sounds like a tough nut.

Maybe some sort of cam, turned by solenoid strokes.

IE:

1 stroke = 10mm
2 strokes = 15mm
3 strokes = 20mm

I doubt if you could ever control the length of a solenoid stroke purely electronically, without being some custom device.
yupp...

one possible solution I thought (mechanic solution)

The main solenoid is in the vertical and can reach 20mm, the solenoids in the horizontal limit the movement to 10mm and 15mm when active, if not active, the movement will be full 20mm

that makes sense? I would rather to have it controlled electronically but, I'm not finding a solution

#### crutschow

Joined Mar 14, 2008
27,756
So what speed of operation do you want?

Joined Jul 18, 2013
23,642
Just don't use AC versions of solenoids!
You will get burn out in short order!
Max.

#### ElectricSpidey

Joined Dec 2, 2017
1,814
"that makes sense? "

Makes perfect sense, the trick is to make it work reliably.

#### AlbertHall

Joined Jun 4, 2014
11,506
yupp...

one possible solution I thought (mechanic solution)

View attachment 220207The main solenoid is in the vertical and can reach 20mm, the solenoids in the horizontal limit the movement to 10mm and 15mm when active, if not active, the movement will be full 20mm

that makes sense? I would rather to have it controlled electronically but, I'm not finding a solution
If you're going to use three solenoide it might be easier to use three separate solenoids for each key and to have them limited to different strokes.

#### andrewmm

Joined Feb 25, 2011
1,757
would be 1000 times simpler if you could re define the problem to only need two positions,
the cost and complexity of such a solution would be much less ,

#### maurodelazeri

Joined Oct 21, 2020
35
would be 1000 times simpler if you could re define the problem to only need two positions,
the cost and complexity of such a solution would be much less ,
why would it be simpler with two?

#### maurodelazeri

Joined Oct 21, 2020
35
If you're going to use three solenoide it might be easier to use three separate solenoids for each key and to have them limited to different strokes.
right, I think that is the path I ll go

#### andrewmm

Joined Feb 25, 2011
1,757
why would it be simpler with two?
two as in up or down,
then you could just use a normal solonoid,

Or maybe I'm miss understanding .

#### maurodelazeri

Joined Oct 21, 2020
35
two as in up or down,
then you could just use a normal solonoid,

Or maybe I'm miss understanding .
I need upwards movements, the down movement you are saying is just the off state of the solenoid

#### djsfantasi

Joined Apr 11, 2010
7,842
The problem with using three solenoids is space. Can you fit multiple solenoids between neighboring pens?

Have you considered a stepper motor driving a rack gear? The rack would be attached to the pen.

#### maurodelazeri

Joined Oct 21, 2020
35
The problem with using three solenoids is space. Can you fit multiple solenoids between neighboring pens?

Have you considered a stepper motor driving a rack gear? The rack would be attached to the pen.
View attachment 220237
yup, you are right, there is a bit of a challenge in terms of space... stepper motors and servo motors are an option, but the problem is speed, it is much slower compared to a solenoid

#### djsfantasi

Joined Apr 11, 2010
7,842
How much slower? Stepper motors are used in Laser Show Projections. They gotta be pretty fast.