Rotary to linear drive

by mgg942, published

Rotary to linear drive by mgg942 Oct 29, 2015

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98847Views 16029Downloads Found in Engineering


This is a reworked update of Things 614962 and 652717.
The geometry has been corrected to give a more truly linear output, and some fixing points have been enlarged for greater robustness.
A complete set of stl file have been uploaded here.
The model is based on mechanism 329 from 507movements.com.
Designed in Moi and made in PLA on an Ultimaker 1.

An animation created in Blender is available here: https://youtu.be/T4Nh_J__8oU
A video of the printed model is available here: https://youtu.be/Cy_rkiBq3vw
Note the flexing!

Print Settings






0.2 mm layers




Please check orientation prior to printing.
I used PLA and recommend it over ABS for this application.
I recommend 1.2mm walls and 40% fill.
For the larger prints I used a brim.
I used support for one item only - the smaller gear. This was a disadvantage of the improved geometry. In the earlier version I cheated a bit on the geometry to make the gear easier to print but when I (recently) created an animation of the older version I was a bit shocked by how much adverse effect the cheat had on the linearity of the output. Hence the redesign.


Generally I design holes in which something rotates to a nominal dimension such as 6mm diameter or 8mm diameter and the male parts about 0.3mm of 0.4mm under nominal.
Post printing I use hand reamers to bring the holes to the correct size and roundness.

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How do you put this together? Thanks for all the work put into this.

I used 3mm x 10mm long button head cap screws.

Think I know what I'm gonna use this for ( ͡° ͜ʖ ͡°)

I was searching thatttt thankkkk yoouuuuuu :))

Comments deleted.

Do you have the SW Drawing of this project. I need dimensions of all parts of this project. Can you help me? I must finish the my assignment in a week.

By "SW Drawing" do you mean Solidworks Files?
I designed this in Moment of Inspiration (Moi).NOT Solidworks.
And why exactly do require the design files?

I am an university student.(Mechatronics Eng.). I will make it as the project of period. Thank you for your helping. Yeah I mean Solidworks Files.

Suggest that you try using OnShape to create the files that you are after.

My brother, ı need only the dimension of the all parts. Please help me. My purpose is only making a project for my lesson. And I must draw it on SolidWorks Program.

İf you want to send the dimension files my e-mail address is [email protected] THANK YOU FOUR YOUR ALL EFFORT.

I don't have files which shows dimensions. That's not necessary for my work flow.
I'll send a .stp file to your email address - I hope that will be enough for you.

Annoying people asking for the files... always for the same, avoid to do work for university/college.

Never seen this idea before, genius.

Is there a specific ratio that gives you this quality?

Agree - whoever first thought up this mechanism is (or was) one smart cookie.

Reckon that a 2:1 ratio is mandatory.

I believe this type of machine is due to 16th century polymath Gerolamo Cardano. Yes, the 2:1 is mandatory. If the ratio is p:q for integers p and q then you will "draw" hypocycloid with p cusps. You could turn this into a mechanical spirograph very easily.

Can you upload Solidworks or STEP part-files for this. Having trouble importing the STLs into Solidworks. Thanks in advance.

Great design, elegant and simple. Does it work the other way around? I need to transform linear movement into rotatory, do you think this would work?

In answer to your question - no, I'm afraid not really,
The problem is that when the 'piston' is fully back, and when it is fully forward, everything is in-line.
If you look at the first photo which shows the piston not quite fully extended you can imagine the slight rotation to make it fully extended and then the piston rod would be exactly in-line with the centre of the small gear so there would be no leverage to rotate the small gear.
When not fully out (nor fully back) then, yes, it can be operated in reverse.
If you can overcome that problem....

what is distance between pushed and non pushed? Thank you

If I've understood you correctly, the answer is 70mm.

great, thank you :)

Rotary to perfectly linear - geometry rules.

Printed... almost assembled... what screws to use?!

Sorry for not specifying.
I use M3 button head cap screws.

Great build !

Would be nice for a paste extruder (with calibration for non linearity)

Amazing! congrats on getting it featured!

My printer isn't calibrated well enough to print it but I must try it someday. The link of 507 website alone is worth getting it featured :)

Yeah. That site is a great source of ideas.

very inpresive! I did not know what it did before I saw the vid

Thanks - and not surprised!