<h2>Simple Machines</h2>
<p>We got a circular motion, and need a linear one. The most simple set up for this is known from steam engines:</p>
<p><a href="https://i.sstatic.net/6vWzy.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/6vWzy.png" alt="A crank driving a lever converting circular motion into linear motion" /></a></p>
<p>The downside is, that this is a 90° turn from the motor. But to turn a circular motion by 90° is easy: Gears.</p>
<p>There are many options of gear types that would work to drive the transmission disk in a right angle from the motor:</p>
<ul>
<li>Helical Gears engage in a 90° to one another. McMaster Carr describes them as &quot;For smooth, quiet operation at high speeds under heavy loads, helical gears have curved teeth that engage gradually and stay in contact longer than straight teeth. Because the curved teeth create thrust loads (loads that are parallel to the shaft), helical gear systems often require thrust bearings to prevent wear from misalignment.&quot;</li>
<li>Miter Gears have their teeth mounted on a cone. There are 2 types (normal and spiraled), and McMaster Carr describes them as &quot;Miter gears have straight teeth and a conical profile for transmitting motion at a right angle without changing shaft speed or torque. They're more efficient than spiral miter gears, which means they require less power to do the same work; however, they are noisier when run at high speeds and under heavy loads.&quot;</li>
<li>Very similar are Beveled Gears, but the tooth geometry is simpler. McMaster Carr says: &quot;Similar to miter gears, bevel gears have straight teeth and a conical profile for transmitting motion at a right angle. Unlike miter gears, one of the gears (sometimes called a pinion) is smaller than the other.&quot;</li>
<li>The outside of the disk is connected to a worm gear. The linear motion will be slow but VERY powerful, and the machine can't drive the motor. McMaster Carr says: &quot;Worm gears use screw threads to reduce shaft speed by ratios of 18:1 and greater while transmitting motion at a right angle. Unlike bevel gears, worm gears operate in one direction only; they transmit motion from worm to gear and cannot be reversed.&quot;</li>
</ul>
<h2>Redesigning the original part: the Angled plane in motion</h2>
<p>Your basic idea <strong>works</strong> but your design had two large problems:</p>
<ul>
<li>The alignment feature for the pushrod is way underdesigned</li>
<li>The Pushrod is missing a secondary alignment feature</li>
</ul>
<p>That is easy to solve, and reduced to the working areas, this is what might appear in your construction, approximating the actually very complex surface to an angled face:</p>
<p><a href="https://i.sstatic.net/Hxwio.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Hxwio.png" alt="approximated Redesigned original design of OP" /></a></p>
<p>The rotating angled plane is good to act. To prevent rotation of the green pushrod, I made the retainment lugs <strong>much</strong> beefier and part of the whole shaft, not an addition onto the shaft. That made it a large rectangle, which prevents any rotation in the grey housing part.</p>
<p>Do note that the rendition as a simple ramped cylinder is just a very rough approximation of the actual body you need, which would be the rotational cut of a rotating and sliding cylinder. The required cam track can be quite tricky to design in CAD.</p>
<p>The shaft <strong>also</strong> protrudes through the bottom angled surface in the most forward position, which prevents the shaft from misaligning at that critical point and not hitting the bore it has to get back into. This protrusion can be much shorter than shown, but it is very much aiding in reliability and preventing the misalignment you saw.</p>
<p>As an additional factor, the turning disk might need to be made from two halves that are connected, so it can be put around the shaft and not contain an insert-slot that would result in misalignment. You might need interlocking pegs between the parts of the rotating barrel to force alignment.</p>
<p><a href="https://i.sstatic.net/fOqHu.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/fOqHu.png" alt="The two plane parts turned into a rotating Barrel set together by two parts." /></a></p>
<p>However, there's one problem with the design in itself: the setup has very large contact areas and will induce lots of friction.</p>

CC BY-SA 4.0
2023-12-17T13:57:49.757Z
Am I missing something, or will the driving pin on the green shaft snap off when you rotate the red part? Because in your image, the pin is perpendicular to the green shaft, but the slot in the red part is not perpendicular to the green shaft above and below the shaft.
Fritz
CC BY-SA 4.0
2023-12-17T14:00:46.953Z
To fix that, the cutout in the red shape would need to be some kind of sweep of the green pin along a sinusoidal trajectory around the green shaft, so that the face of the cutout is orthogonal to the shaft all around.
Fritz
CC BY-SA 4.0
2023-12-17T17:55:51.803Z
@Fritz indeed, the cut as depicted lacks space, but is meant as a representation more than the actual,  extremely complex path.
Trish
CC BY-SA 4.0
2023-12-18T08:24:05.467Z
Sounds like you should mention that in your answer then. Right now a reader could understand that the mechanisms in your images would work as they are shown, when in fact they would not.
Fritz
CC BY-SA 4.0
2023-12-15T19:22:18.463Z
2023-12-18T10:46:01.610Z
2023-12-18T10:46:01.610Z
Trish
<p>The following might seem obvious, but it shouldn't be overlooked either.</p>
<p>Unless you have one of those Wire EDM cutting machines, with very precise tolerances<sup>1</sup>, that can seamlessly cut a shape out of blocks of metal that then, seemingly, <em>glide</em> out of the surrounding block, with little to no <em>stiction</em><sup>2</sup>, then your printed surfaces of the screw will have imperfections that may cause the binding. The first step would be to shave, sand and smooth the surfaces. Maybe even treat with another chemical, such as acetone (depending upon your printing material) to smooth the surfaces even further.</p>
<p>However, in addition to that, some lubricant may be in order. Every gear box or mechanism contains a little oil or grease.</p>
<p>So, your original design <em>may</em> still work, with a little help from smoothing and lubricating any mating surfaces. As Trish states, your design has a lot of surface friction, so every bit of polishing of the surfaces will help.</p>
<hr />
<p><sup>1</sup> Approaching <span class="math-container">$\frac{5}{1000}$</span> (i.e. five thousandths) of a millimetre</p>
<p><sup>2</sup> Such as the objects shown at the start of this video: <a href="https://www.youtube.com/watch?v=f9zyenX2PWk" rel="nofollow noreferrer">How these impossibly thin cuts are made</a></p>

CC BY-SA 4.0
2023-12-16T03:33:08.393Z
Yes, it is very rare to see example like this, i saw this once and can not find it too, but as trish said the design itself has problem and you said this need to be very smooth and well cutting so it seem to be sensitive to be made so i switch to gears option (scotch yokes) very common and no sensitive techniques
Ahmed Mohamed Hassan
CC BY-SA 4.0
2023-12-18T12:04:49.123Z
I think you're refering to wire EDM machines, e.g. https://www.youtube.com/watch?v=7OMTDW0vH0Y
towe
CC BY-SA 4.0
2023-12-18T14:50:55.753Z
@towe - Yes, that's it. Many thanks :-) Actually, your link then linked to the video that I had originally seen: [How these impossibly thin cuts are made](https://www.youtube.com/watch?v=f9zyenX2PWk). So, double thanks are in order..!
Greenonline
CC BY-SA 4.0
2023-12-16T02:57:05.413Z
2023-12-18T15:24:52.583Z
2023-12-18T15:24:52.583Z
Greenonline
<p>I need to convert the rotation movement of a motor to a linear movement (it has to be in the same axis of the motor).</p>
<p>I made a 3D model in Tinkercad consisting of two parts:</p>
<ul>
<li><p>the first part will mount on the motor and has a shape like screw inside</p>
<p><a href="https://i.sstatic.net/KyB3n.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/KyB3n.jpg" alt="enter image description here" /></a></p>
<p><a href="https://i.sstatic.net/FR874.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/FR874.jpg" alt="enter image description here" /></a></p>
</li>
<li><p>the second part is a plunger that should move in linear direction when the motor rotate with the first part</p>
<p><a href="https://i.sstatic.net/1jGhG.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/1jGhG.jpg" alt="enter image description here" /></a></p>
<p><a href="https://i.sstatic.net/ZxDLa.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ZxDLa.jpg" alt="enter image description here" /></a></p>
<p><a href="https://i.sstatic.net/CUSRY.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/CUSRY.jpg" alt="enter image description here" /></a></p>
</li>
</ul>
<p>I printed this model but the plunger gets stuck inside the first part and do not move.</p>
<p>So it fails.</p>
<p>I want a simple way to convert the rotary move to linear in the same axis of motor.</p>
<p>I broke part #1 (&quot;the first part&quot;) from behind to see what happened inside. I found it sticks as part #2 jumps above the screw shape.</p>
<p><a href="https://i.sstatic.net/ZkUvK.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/ZkUvK.jpg" alt="enter image description here" /></a></p>
<p>I think this mechanism is hard to be done.</p>
<p>So I switched to scotch yokes mechanism.</p>
<p>Hope it works!!</p>
<p>The vertical gear will pull the horizontal gears to move the articulator in a linear movement.</p>
<p><a href="https://i.sstatic.net/zEL29.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/zEL29.jpg" alt="enter image description here" /></a></p>

CC BY-SA 4.0
2023-12-15T20:32:21.247Z
I'm seeing some close votes for this question, too bad. Although this appears to be a question which could be hosted on SE.Engineering, this *is* related to 3D printing! Note that our 3D printer leadscrews transfer the rotational stepper motion in linear displacement through the lead screw nut. I'm voting not to close this question.
0scar
CC BY-SA 4.0
2023-12-18T21:28:06.223Z
What's the question? How to convert rotational movement to linear movement on the same axis? How to design a model that can be used to convert rotational movement to linear movements on the same axis? I suggest to reflect an actual question in the title. I agree this should not be closed and fits on this site.
Bob Ortiz
<rotation>
Convert rotation movement to a linear movement, in the same axis
Ahmed Mohamed Hassan
# Convert rotation movement to a linear movement, in the same axis

(Asked by: username_0 on 2023-12-14)

I need to convert the rotation movement of a motor to a linear movement (it has to be in the same axis of the motor).

I made a 3D model in Tinkercad consisting of two parts:

* the first part will mount on the motor and has a shape like screw inside

  [![enter image description here](https://i.sstatic.net/KyB3n.jpg)](https://i.sstatic.net/KyB3n.jpg)

  [![enter image description here](https://i.sstatic.net/FR874.jpg)](https://i.sstatic.net/FR874.jpg)
* the second part is a plunger that should move in linear direction when the motor rotate with the first part

  [![enter image description here](https://i.sstatic.net/1jGhG.jpg)](https://i.sstatic.net/1jGhG.jpg)

  [![enter image description here](https://i.sstatic.net/ZxDLa.jpg)](https://i.sstatic.net/ZxDLa.jpg)

  [![enter image description here](https://i.sstatic.net/CUSRY.jpg)](https://i.sstatic.net/CUSRY.jpg)

I printed this model but the plunger gets stuck inside the first part and do not move.

So it fails.

I want a simple way to convert the rotary move to linear in the same axis of motor.

I broke part #1 ("the first part") from behind to see what happened inside. I found it sticks as part #2 jumps above the screw shape.

[![enter image description here](https://i.sstatic.net/ZkUvK.jpg)](https://i.sstatic.net/ZkUvK.jpg)

I think this mechanism is hard to be done.

So I switched to scotch yokes mechanism.

Hope it works!!

The vertical gear will pull the horizontal gears to move the articulator in a linear movement.

[![enter image description here](https://i.sstatic.net/zEL29.jpg)](https://i.sstatic.net/zEL29.jpg)

**Tags:** rotation

> **Comments:**
> **username_1**: I'm seeing some close votes for this question, too bad. Although this appears to be a question which could be hosted on SE.Engineering, this *is* related to 3D printing! Note that our 3D printer leadscrews transfer the rotational stepper motion in linear displacement through the lead screw nut. I'm voting not to close this question.  
> **username_2**: What's the question? How to convert rotational movement to linear movement on the same axis? How to design a model that can be used to convert rotational movement to linear movements on the same axis? I suggest to reflect an actual question in the title. I agree this should not be closed and fits on this site.  

---

## 2 answers

### Answer by username_3 on 2023-12-15. Score: 3 | Accepted answer

## Simple Machines

We got a circular motion, and need a linear one. The most simple set up for this is known from steam engines:

[![A crank driving a lever converting circular motion into linear motion](https://i.sstatic.net/6vWzy.png)](https://i.sstatic.net/6vWzy.png)

The downside is, that this is a 90° turn from the motor. But to turn a circular motion by 90° is easy: Gears.

There are many options of gear types that would work to drive the transmission disk in a right angle from the motor:

* Helical Gears engage in a 90° to one another. McMaster Carr describes them as "For smooth, quiet operation at high speeds under heavy loads, helical gears have curved teeth that engage gradually and stay in contact longer than straight teeth. Because the curved teeth create thrust loads (loads that are parallel to the shaft), helical gear systems often require thrust bearings to prevent wear from misalignment."
* Miter Gears have their teeth mounted on a cone. There are 2 types (normal and spiraled), and McMaster Carr describes them as "Miter gears have straight teeth and a conical profile for transmitting motion at a right angle without changing shaft speed or torque. They're more efficient than spiral miter gears, which means they require less power to do the same work; however, they are noisier when run at high speeds and under heavy loads."
* Very similar are Beveled Gears, but the tooth geometry is simpler. McMaster Carr says: "Similar to miter gears, bevel gears have straight teeth and a conical profile for transmitting motion at a right angle. Unlike miter gears, one of the gears (sometimes called a pinion) is smaller than the other."
* The outside of the disk is connected to a worm gear. The linear motion will be slow but VERY powerful, and the machine can't drive the motor. McMaster Carr says: "Worm gears use screw threads to reduce shaft speed by ratios of 18:1 and greater while transmitting motion at a right angle. Unlike bevel gears, worm gears operate in one direction only; they transmit motion from worm to gear and cannot be reversed."

## Redesigning the original part: the Angled plane in motion

Your basic idea **works** but your design had two large problems:

* The alignment feature for the pushrod is way underdesigned
* The Pushrod is missing a secondary alignment feature

That is easy to solve, and reduced to the working areas, this is what might appear in your construction, approximating the actually very complex surface to an angled face:

[![approximated Redesigned original design of OP](https://i.sstatic.net/Hxwio.png)](https://i.sstatic.net/Hxwio.png)

The rotating angled plane is good to act. To prevent rotation of the green pushrod, I made the retainment lugs **much** beefier and part of the whole shaft, not an addition onto the shaft. That made it a large rectangle, which prevents any rotation in the grey housing part.

Do note that the rendition as a simple ramped cylinder is just a very rough approximation of the actual body you need, which would be the rotational cut of a rotating and sliding cylinder. The required cam track can be quite tricky to design in CAD.

The shaft **also** protrudes through the bottom angled surface in the most forward position, which prevents the shaft from misaligning at that critical point and not hitting the bore it has to get back into. This protrusion can be much shorter than shown, but it is very much aiding in reliability and preventing the misalignment you saw.

As an additional factor, the turning disk might need to be made from two halves that are connected, so it can be put around the shaft and not contain an insert-slot that would result in misalignment. You might need interlocking pegs between the parts of the rotating barrel to force alignment.

[![The two plane parts turned into a rotating Barrel set together by two parts.](https://i.sstatic.net/fOqHu.png)](https://i.sstatic.net/fOqHu.png)

However, there's one problem with the design in itself: the setup has very large contact areas and will induce lots of friction.

> **Comments:**
> **username_4**: Am I missing something, or will the driving pin on the green shaft snap off when you rotate the red part? Because in your image, the pin is perpendicular to the green shaft, but the slot in the red part is not perpendicular to the green shaft above and below the shaft.  
> **username_4**: To fix that, the cutout in the red shape would need to be some kind of sweep of the green pin along a sinusoidal trajectory around the green shaft, so that the face of the cutout is orthogonal to the shaft all around.  
> **username_3**: @username_4 indeed, the cut as depicted lacks space, but is meant as a representation more than the actual,  extremely complex path.  
> **username_4**: Sounds like you should mention that in your answer then. Right now a reader could understand that the mechanisms in your images would work as they are shown, when in fact they would not.  

---

### Answer by username_5 on 2023-12-16. Score: 3

The following might seem obvious, but it shouldn't be overlooked either.

Unless you have one of those Wire EDM cutting machines, with very precise tolerances1, that can seamlessly cut a shape out of blocks of metal that then, seemingly, *glide* out of the surrounding block, with little to no *stiction*2, then your printed surfaces of the screw will have imperfections that may cause the binding. The first step would be to shave, sand and smooth the surfaces. Maybe even treat with another chemical, such as acetone (depending upon your printing material) to smooth the surfaces even further.

However, in addition to that, some lubricant may be in order. Every gear box or mechanism contains a little oil or grease.

So, your original design *may* still work, with a little help from smoothing and lubricating any mating surfaces. As username_3 states, your design has a lot of surface friction, so every bit of polishing of the surfaces will help.

---

1 Approaching $\frac{5}{1000}$ (i.e. five thousandths) of a millimetre

2 Such as the objects shown at the start of this video: [How these impossibly thin cuts are made](https://www.youtube.com/watch?v=f9zyenX2PWk)

> **Comments:**
> **username_0**: Yes, it is very rare to see example like this, i saw this once and can not find it too, but as username_3 said the design itself has problem and you said this need to be very smooth and well cutting so it seem to be sensitive to be made so i switch to gears option (scotch yokes) very common and no sensitive techniques  
> **username_6**: I think you're refering to wire EDM machines, e.g. https://www.youtube.com/watch?v=7OMTDW0vH0Y  
> **username_5**: @username_6 - Yes, that's it. Many thanks :-) Actually, your link then linked to the video that I had originally seen: [How these impossibly thin cuts are made](https://www.youtube.com/watch?v=f9zyenX2PWk). So, double thanks are in order..!  

---

