# Press and release a button to rotate an object?

## Summary:

need ideas for how this can be done (sketch attached)

## Main Question or Discussion Point

I'm going to hire a ME to do this but I first want to know whether it is at all doable, exactly what is needed here and what design specifically has to be requested.
Here's a sketch of the desired device:

Proportionally and size-wise it shoud be similar to a pen. Rotation should be around 10 degrees, not much.
The red object is the button, the green is the housing and blue is the rotating part.
I vaguely remember having a toy like this as a kid where the plastic top of the stick would rotate when a button on the stick was pressed.

I think it should be done with a tiny spiral shaped spring (like in old dial telephones or cranked music boxes) for the rotating part to be squeezed and rotate the rotating blue piece and when the button is released have the spring rotate the blue piece back. Since the button is so far from the rotating part I'm not sure a lever under the button + a single gear attached to the tiny spring would suffice.

Any ideas are welcome.

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BvU
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anorlunda
Mentor
I see the sketch OK.

BvU
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The image host is Imgur. It's the default image provider for many sites, even Reddit and StackExchange. I'm not going to have a cookies discussion, just putting this out there.

BvU
Homework Helper
Imgur is keeping this available for the forum for eternity, you think ?

fresh_42
Mentor
2018 Award
I took the imgur image and copied it in the post.

For all who are interested: copy image on imgur and release via Ctrl+V here does the job.

BvU
Imgur is keeping this available for the forum for eternity, you think ?
In fact yes, Imgur keeps images idenfinitely unlike other hosts, that's why Reddit and StackExchange uses it instead of hosting themselves.
Are we seriously talking about Imgur? Everyone who uses message boards should know about Imgur by now.
Cookies and Imgur have zero to do with my question.

DaveC426913
Gold Member
How many times must it operate before needing to be reset?

Just a few? A spring will work.

Multiple 360 degree rotations, 10 degrees at a time? The mechanical press of the button may be enough to move the machinery to trigger a rotation.

anorlunda
Mentor
DaveC426913
Gold Member
Here is a super simple mechanism that has all the moving parts in one place.

I haven't detailed the escapement here.

A push of the button engages the 36 tooth gear and turns it one tooth. When the button is released the other stop prevents the gear from slipping back.

Below is an example of an escapement to illustrate how the tooth angles facilitate one-way ratcheting.

It does not need to be this complex. For example, it doesn't need the rocker pivot. Bendy plastic arms like in my illo above will suffice.

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Thanks all. Sorry that I wasn't clear enough in my OP. I need the press to engage a rotation, and the release of the button to cause rotation back to the original angle. The rotation can't keep incrementing after each press and not rotate back upon button release. That's where the need for spring comes.

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DaveC426913
Gold Member
Oh. That's way easy. Just levers. All you're doing is converting a motion by 90 degrees, and at a 1:1 ratio, to-boot.

The only spring you'll need is in the button itself, to ... er ... de-depress it.
All your levers will be slaved to it, so when it pops back out, it will also de-rotate the head.

What do you need our help with?

All you're doing is converting a motion by 90 degrees, and at a 1:1 ratio, to-boot.
Not really, the blue part is rotational motion if you pay attention to the arrows.

DaveC426913
Gold Member
Not really, the blue part is rotational motion if you pay attention to the arrows.
I paid attention to the arrows...

It doesn't matter. It's joined with a connection that can move and pivot freely - like two links of a chain - except their outer ends are embedded in your moving parts.

If you push one end, the other end will move, constrained by what it's attached to.

Anything like this:

Rotational or pivotal movement of either end doesn't matter. You're pushing/pulling only.

The rim of the head will be pushed laterally, the rim constrained by its own central pivot.

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DaveC426913
Gold Member

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DaveC426913
Gold Member

These are simply schematics, to show you where attachment points are, and how components will move, but I assure you it will do the job.

Did you want me to flesh it out a little?

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DaveC426913
Gold Member
A couple of clarifying questions:
1. You already answered the question of what full angle is required: "about" ten degrees, so clearly not critical.
2. What degree of error tolerance for that rotation is required? Does it matter whether the rotation is virtually identical each time? i.e. Is it OK if it's 9-ish one time and 11-ish the next time?
3. What forces will be in-play? Will the act of rotation meet resistance (whether due to opposing forces or merely inertia of a massive component mounted on it)?
4. What degree of "grip" is required? Is it all right if, in either position, there is a little play?
5. What conditions need it operate under? Upside down?
6. What degree of robustness is required for the complete device? Does this need to survive a backpacking trip?
There are lots of other questions that will come into play in the design, such as
• materials (plastic? steel?)
• cost?
• reliability (see #6)
• mass (probably not an important factor in such a small device).
Finally: your idea of overall size is "a pen" - I assume you mean like a ballpoint pen - so about 7".

I don't know how accurate your 3D sketch is meant to be, but - assuming you grip it at the bottom with your thumb on the button, that makes the "handle" only about 1.5" tall - barely enough for 3 fingers. It also makes the button about 1/4" wide.

I'm sure you'll refine that, but these are details that might factor in the the mechanism. We should know where you're going with it.

Tom.G
An even simpler approach, lets see if I can do a word-picture.

• The top rotational part has an axle going down to the pushbutton.
• The bottom of the axle is bent at a right angle so the pushbutton can rotate the axle.
• There is a link, pivoted at both ends, that connects the pushbutton to the bent end of axle.
• There is a compression coil spring under the head of the pushbutton.

Consider the letter "L" with the top rotating piece mounted on the top of the "L".
The pushbutton has a pivoted link from it to the leg of the "L"

The pivoted link is needed to transfer the radial pushbutton motion to the off-center leg of the "L".

Hmm, depending on the quantity, durability, and needed force, the pushbutton and link could use a hinge and be molded from one piece of plastic... perhaps with some snap or slotted attachment to the leg of the "L" for easy assembly.

Perhaps @DaveC426913 could do a nice drawing. (not my strong point!)

Cheers,
Tom

View attachment 251283

These are simply schematics, to show you where attachment points are, and how components will move, but I assure you it will do the job.

Did you want me to flesh it out a little?
Thank you for the detailed responses and diagrams.
I understand the design up to the point the joint attaches to the inside rim of the red head. I don't get how that would cause rotation. I can think of few ways but none seem a good approach due to complexity so I would love to hear what you had in mind instead.
Thanks again.

A couple of clarifying questions:
1. You already answered the question of what full angle is required: "about" ten degrees, so clearly not critical.
2. What degree of error tolerance for that rotation is required? Does it matter whether the rotation is virtually identical each time? i.e. Is it OK if it's 9-ish one time and 11-ish the next time?
3. What forces will be in-play? Will the act of rotation meet resistance (whether due to opposing forces or merely inertia of a massive component mounted on it)?
4. What degree of "grip" is required? Is it all right if, in either position, there is a little play?
5. What conditions need it operate under? Upside down?
6. What degree of robustness is required for the complete device? Does this need to survive a backpacking trip?
There are lots of other questions that will come into play in the design, such as
• materials (plastic? steel?)
• cost?
• reliability (see #6)
• mass (probably not an important factor in such a small device).
Finally: your idea of overall size is "a pen" - I assume you mean like a ballpoint pen - so about 7".

I don't know how accurate your 3D sketch is meant to be, but - assuming you grip it at the bottom with your thumb on the button, that makes the "handle" only about 1.5" tall - barely enough for 3 fingers. It also makes the button about 1/4" wide.

I'm sure you'll refine that, but these are details that might factor in the the mechanism. We should know where you're going with it.
The sketch is just a skech, proportions are not correct. But you are right regarding the diameter being that of a ballpoint pen.

2) I fear the rotation inaccuracies may accumulate over time. If however, the spring will cause the rotation to go back to original, then it's not an issue. I'd expect an accuracy of +-0.25 degrees easily achievable with properly injection molded or powder bed 3d printed plastic or aluminum pieces.

3) The component is just 5 grams and notin contact with anything else. We can have a tiny bearing to ease the rotating.

4) Do you mean backlash? I wouldn't want any (<+-0.01 degrees) play by pure gravity/room air

5) Yes it could also be used upside down

6) No, to be used indoors.

Mass is probably not an issue. I'd prefer everything to be ABS plastic except the inside mechanism which can be other plastic or aluminum/steel if needed.

Thanks.

An even simpler approach, lets see if I can do a word-picture.

• The top rotational part has an axle going down to the pushbutton.
• The bottom of the axle is bent at a right angle so the pushbutton can rotate the axle.
• There is a link, pivoted at both ends, that connects the pushbutton to the bent end of axle.
• There is a compression coil spring under the head of the pushbutton.

Consider the letter "L" with the top rotating piece mounted on the top of the "L".
The pushbutton has a pivoted link from it to the leg of the "L"

The pivoted link is needed to transfer the radial pushbutton motion to the off-center leg of the "L".

Hmm, depending on the quantity, durability, and needed force, the pushbutton and link could use a hinge and be molded from one piece of plastic... perhaps with some snap or slotted attachment to the leg of the "L" for easy assembly.

Perhaps @DaveC426913 could do a nice drawing. (not my strong point!)

Cheers,
Tom
Hi, Thanks.

Terribly sorry but I'm not sure I understand this part:
• The bottom of the axle is bent at a right angle so the pushbutton can rotate the axle.
• There is a link, pivoted at both ends, that connects the pushbutton to the bent end of axle.

I'll make an illustration for you to verify if I understand your idea.

DaveC426913
Gold Member
An even simpler approach, lets see if I can do a word-picture.

• The top rotational part has an axle going down to the pushbutton.
• The bottom of the axle is bent at a right angle so the pushbutton can rotate the axle.
• There is a link, pivoted at both ends, that connects the pushbutton to the bent end of axle.
• There is a compression coil spring under the head of the pushbutton.

Consider the letter "L" with the top rotating piece mounted on the top of the "L".
The pushbutton has a pivoted link from it to the leg of the "L"
That's WAY simpler than my contraption.

Although:
You transfer movement by torsion. I chose transferring movement by translation because I felt it would transfer the movement more faithfully along the length of the shaft.

DaveC426913
Gold Member
Hi, Thanks.

Terribly sorry but I'm not sure I understand this part:
• The bottom of the axle is bent at a right angle so the pushbutton can rotate the axle.
• There is a link, pivoted at both ends, that connects the pushbutton to the bent end of axle.

I'll make an illustration for you to verify if I understand your idea.
You could have an arm on the axle, or just a gear.

#### Attachments

• 43.4 KB Views: 34
DaveC426913
Gold Member
Indeed. The rack and pinion system Tom G thought of will work nicely.

A rotation of 10 degrees, for a pen that is about 8mm in diameter, is less than 1mm.
That's easily within the press range of any store-bought push-button.

Tom.G
You could have an arm on the axle, or just a gear.
Yeah, I considered a gear but rejected that because because keeping them engaged requires there be almost Zero wobble, or play, in the pushbutton.

A variation, perhaps suitable if the product is metal instead of plastic, would be put a spring-pin (dowel-pin) thru the axle to replace the pinion. You can end up with a similiar linkage approach used in the popup stopper in a bathroom sink. That linkage implements "Pull up the handle and the stopper moves down to plug the drain."

Aww heck, words don't work. Guess I'm forced to draw the darn thing.

EDIT:
ARRRGH Can't attach a file! Ever since PFs supposed 'upgrade'!!! The only button that appears is DELETE.
Oops, the attachment did show up, at the bottom of this post. It just didn't show in the Preview.
/EDIT:

I'll try some text graphics using [ code=text ].

Code:
Sheet metal
|                     _______
|                    |         |
|    i i             |        |
-------\/--------------|       |       Pushbutton
------------------------|       |
i i             |        |
i i             |______|
i i
i i
i i   Pin thru both
i i
___i_i____
/           \
/    Axle   \
\              /
\________/
i i
i i
I give up on a drawing. I hope you can make sense of the mess that PF made of it.

Cheers,
Tom

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