Rotary to linear drive

by mgg942 Oct 29, 2015
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Do you make mechanism designs because I need a a design of mine made

Haha, love the comments about a machine for in_the_dark_stuff... but from a technical point of view, weight over the end of the piston when fully forward will probably break the support :-)

My girlfriend is gonna love this!

I just build one and attached to a power drill. Of course it destructed but not before going like the clappers. A fun build and works well providing you don't overpower it.

Would have made a good video!

is there any chance this will print correctly if scaled at 60% and printed at 50% speed?

Well, - there's a question!
As far as printing at 60% scale is concerned I can see two problems.

  1. The column which is part of the small gear will become weak.
  2. The fixing holes will become too small for 3mm screws.

As far as printing at 50% speed - I think that would be fine.

Good luck,

i won't know how many people made pervert things with it ^^


I just finished printing and assembling it. Question: how do you get the handle_inner to stay in the handle? It looks like they should just press together, but it's not a tight fit. Did you glue them? Same question for the handle to the driver?


Yes, Stu, they are meant to be press fits.
If I were you I'd scale up the handle a tiny bit and reprint as there doesn't appear to be a good glue for PLA.
Once that looks a good fit with the driver, then scale up the handle-inner a tiny bit to suit the handle.
I'd assemble the handle, handle inner and sleeve before pressing the handle into the driver.
Good luck,

I came up with an easier solution... See attached files. :-)

Mind you don't heat up the parts when operating under power - PLA doesn't have much heat tolerance.

Hello everyone.
I'm completely new to this and I wanted to print this model. I'm located in Canada but also have a mailing address in the U.S.
I tried to print it on Shapeways but each piece was about 20 bucks each. anyone know a good place to print those? I don't have a 3D printer yet


Sorry, can't help, Raul.
I live in Australia.

Dear mgg942 ~
My name is Owen. I'm college students and Taiwanese. Recently , i design a project in our course.
I have a part of my project which need "push" act. I found your design is really fit to my project.
Would you can let me put your design on my project? I'll modify some place rather than copy all of it.
When i done my project, i can share it to you on E-mail~
Thank you :))

Best Wish

                                                  Email: 4a527902@stust.edu.tw
                                                  Owen Chen

Hi, Owen,
Yes - please go ahead.
I look forward to hearing from you again when you have completed your project.

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 omerkayan51@gmail.com 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.

whats worse is they dont know how to use the stl files to get the dimensions, even with SW,

I know this was over a year ago but reading this really annoyed me !

and just designing the parts himself in solidworks is only the work of an afternoon, from my experience. the lazyness of some people despite paying for the classes they're trying to avoid the work of.

Never seen this idea before, genius.

Is there a specific ratio that gives you this quality?

James Watt was forced to use this linkage in his steam engine when he first conceived it because he didn't have the rights the the standard crank used for most steam and gas engines. Eventually he got the rights and his engines then had normal cranks.

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!