PLA Spring Motor Demonstrator

by gzumwalt, published

PLA Spring Motor Demonstrator by gzumwalt Jul 21, 2014


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A spring motor demonstrator printed entirely in PLA, spring and all, requiring no batteries, power supply, electric or drill motors to operate.

And what is it good for? For starters, it can be an interesting study for burgeoning mechanical engineering students of torque versus velocity, as well as spring forces that can be obtained by printing a PLA spring using various infill settings, height and thicknesses. And next, well, read on...

Video is here: https://www.youtube.com/watch?v=e4j5zX3Sbnw&list=UUv_zm49u-RjnCJVwhUO-ecA.

A rolling chassis version is here: http://www.thingiverse.com/thing:430050.

And a wheelie pulling dragster is here: http://www.thingiverse.com/thing:452248.

Use safety glasses when operating the PLA Spring Motor Demonstrator. While I've operated the mechanism well over a hundred times without a failure, I always recommend erring on the side of caution as the spring could snap and send pieces flying where they shouldn't be flying, and that's never a good thing.

Designed using Sketchup 8, and printed in PLA on a Makerbot Replicator 2 using Makerware


Use safety glasses when operating the PLA Spring Motor Demonstrator. While I've operated the mechanism well over a hundred times without a failure, I always recommend erring on the side of caution as the spring could snap and send pieces flying where they shouldn't be flying, and that's never a good thing.

UPDATE: Try "Spring New.stl" as opposed to "Spring.stl". Some have had problems with the original, hopefully the new one will solve those problems.
Carefully study "Assembly.skp". Note that the .skp file should be used as an assembly diagram and not be used to print parts as the parts in the .skp file may not be the final parts as found in the .stl files.

Print all PLA parts from the .stl files, print 3 of "Gear Idler.stl". Print "Knob.stl" and "Spring.stl" with Makerware "Standard" settings modified for 100% infill, the remaining parts using Makerware "Standard" settings with the default infill.

Test fit and trim, file, sand, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on the colors you chose and your printer settings, more or less trimming, filing and/or sanding will be required. The idler gears must spin freely on their respective shafts, and the main gear must spin freely on the hub of "Spring.stl" (prior to pawl installation). Also, "Knob.stl" must spin freely in the frame, while also remaining a tight fit in "Spring.stl".

Assemble as per "Assembly.skp".

Lubricate moving surfaces with light machine oil.

Comment if questions.

Hope you like it!

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Hey Can I get solidworks files for this mechanism, cause I want to use this in one my project.

I will try to make this project this week

I hope you do, and if you have any problems with it, please feel free to comment and I'll do my best to respond. I've built 37 of these for a number of people. Just make sure you print the gears on a raft, or be ready for some intricate filing.

Best of luck!


What a pain in the bum to put together !

What a cool toy !

Is it possible to regulate the speed?

It's not working for me. I can turn the knob, but it won't unwind. I tried printing in ABS and plastic.

It doesn't work. I tried it several times but the motor won't rotate. I also sanded all shafts as recommed.
Whats you secret?

Start by assembling the base, "Side Left.stl" and "Side Right.stl". Then, assemble "Knob.stl", "Spring New.stl", "Pawl.stl" and "Gear Main.stl" into the assembled base. At this point, you should be able to wind "Knob.stl" clockwise, release it, and it should rapidly unwind the spring turning "Gear Main.stl" in the process. If not, I would guess the holes In "Left.stl" and "Right.stl" into which "Knob.stl" and "Spring.stl" are too small.

If the spring assembly is working, then add one "Gear Idler.stl" to the shaft on "Spring.stl" and make sure it spins freely. If not, slightly enlarge the hole in "Gear Idler.stl" until it does. Follow the exact same procedure, with the two "Gear Idler.stl" gears that are placed on the shaft of "Side Right.stl".

If you get this far, it should work with a lubrication using light machine oil on all moving contacting surfaces.

Hope this helps!

Hi, I set the spring print settings to those you sent me and it printed fantastically! many thanks for your help and a most enjoyable print!
The finnished result is now showing in your made section. Kind regards Jules

The honor is yours!

Many thanks for your efforts to print and assemble this thing. I am always inspired by those who attempt, and even more by those who succeed, in printing, assembling and making operational the challenging things I design. My goal in publishing these designs was to re-introduce the skills, patience and talents required to do so to the up and coming engineers, and obviously, you qualify!

Many thanks for your efforts, and I'm inspired by your success!

Absolutely great work!

Hi, thanks for getting back to me! the printhead moves about at high speed with intermittent filament feed so I think it is a g code problem as the BQ Prusa i3 I am using prints every thing else fine! Regards Jules

"Spring New.stl" printed fine using Cura, Ultimaker 2 Extended, and versions / settings as previously described.

If you still need assistance, don't hesitate to let me know how I can help, as I want you to succeed in your print!

Many apologies for the difficulties you are experiencing.

You are welcome.

I'm printing the spring now via Cura 15.04.3 at .1mm layer height, .8 mm shell thickness, .6mm bottom/top thickness and 100% infill on an Ultimaker 2 Extended with a .4mm nozzle. So far so good. I'll let you know how it finishes.

And if you need any further assistance, don't hesitate to comment and I'll do my best to assist.

Hello there, I have almost completed a very enjoyable print and all is looking very good indeed! However I cannot get the spring to print any sense, I am using Cura 15.02.1 and all files have run through Meshmixer and printed fantastically but for some reason Version 1 and 2 springs will not print. I am printing flat with shaft up at 100% infill! I had left this part till last as it will take 2hrs and 10mins. wondering if you can help in any way?
Regards Jules

I'm using Cura 15.04.3 and the file loads and appears fine, but I can't attempt to print it as the printers are all busy.

When you say you can't get it to print, what does it do and/or not do?

I wonder if I could create a wind-up toy with this design...

Check out the car, dragster and helicopter toys I published.

Yes, you can.

Some hints born of experience:
First: it works! Mine goes longer than the vid example!
Second: Do not lubricate using oil. Lubricate with graphite powder (used in locks). Oil clogs the gears and causes drag.
Third: Don't skimp on 100% fill for spring (otherwise not enough torque) or knob (it breaks off) or frame (ends snap off)
Fourth: Sand all axles - they are too large circumference, gears must spin freely.
Great design - thanks!
PS: Makerbot Rep 2 blue PLA

Congratulations and thanks for you comments regarding improvements.

Great work indeed!

dose not work with m3d software

I printed with ABS on a KNP3D at .1mm and it was GREAT! No finishing work required to put it together, and it works very well. Great Job!

Thanks! Glad you liked it!

Post a picture if possible.

Opened the Files in netfabb and both the Spring and the New Spring seem to be inside out.

Yes, that's an artifact of a Sketchup 8 operation I no longer use. Makerware does not have a problem printing it, it just looks darker than normal on the build plate display.

I have major issues with this design. I love the idea, but it did not work out as planned. The right piece with 30% infill had its rod and the tall connecter part on it break off. Also, the rod was way to wide for the gears, and they would not slide on much less turn. I do hope this gets fixed.

Sorry for the problems you have experienced with this design.

Are you printing in PLA or ABS?


After a long time of frustration, sanding down the interlocking frame and rod parts seemed to work. Also, I had to apply silicone lubricant. Maybe you could make the rod slightly thinner on the right part? Anyway, great design! I am looking forward to seeing more in the future.

PLA on a printrbot simple.

which CAD software do you use with your Mac?

Greets from Germany


I used Sketchup 8 for this thing, but am now using Sketchup Make 2015.

Greetings to you from Oklahoma!

How many rotations per minute does the spring motor do with a 1:1 gear ratio? Anyone know?

My knob stripped out the the square hole in the spring. Any thoughts? Everything printed well on a Printrbot Simple sliced with Cura, printed with Repetier

Sorry for the difficulties.

To remove the piece of the knob from the spring? Use a flat punch.

Did you print the knob with 100% infill? If not, try that. If so, reinforce the joint with thin amounts of cyanoacrylate but make sure it dries before inserting it in the spring.

The spring is what failed. I'm reprinting it with solid fill, I'll try reinforcing it.

I have a MakerBot Replicator 5th Generation.

I've printed the left and right bases over and over again (5 or 6 times). Every time it either jams or breaks as soon as you put the entire assembly together. The tall part that the gears sit on is always EXTREMELY brittle, just one touch makes it break. Also, every other part of the base has holes and gaps.

Any Ideas? I'm getting terribly frustrated.

I'm very sorry that you are having difficulties with this print and I'll do my best to help.

Unfortunately, I'm not understanding what problem you are experiencing. Are you saying after the base components are printed they break easy, as when touched? Also, are you using Makerware and if so, what version? Also, what settings are you using (I used .2mm layer height, 10% infill, 2 shells)?

Again, I'm very sorry you are having difficulties with this print.

Sorry for the late response.

I am using MakerBot Desktop. I am printing at .1mm layer height, 4 shells, and 25% infill, 215 C, and some other minor options.
We've tried printing it with 2-4 shells, 180-230 C, 15-25% and others.
I'll try to upload some pictures soon. Here's a copy of my current Custom Profile: http://pastebin.com/EXRjbAk5

The print, and others are mostly turning out with problems with the roof. It is not complete, leaving holes in the top. The holes appear at random, and you can see down to the middle shells and the floor. This can appear in the middle of a flat section or in between layers on the top, where again, you can almost see through the object. I've tried printing with greater roof and floor heights, but no luck. The axle for the gears on the base, half prints on one side, making it hollow, even with 4 shells, making it extremely brittle, even bendy before it breaks.

These are not mine, but here are some examples:
The bottom right edge: http://reprap.org/mediawiki/images/thumb/9/9d/PTPG-FNT-FG01.jpg/391px-PTPG-FNT-FG01.jpg
Number 4: http://airwolf3d.com/wp-content/uploads/2012/11/3D-printed-part-slicing-tutorial-IMG_4478IMG_448404.jpg

Of all the things I've ever designed and built, you've got me stumped on this one.

I don't have a Gen5 printer, so I cannot evaluate the problems you are having. However, it does appear your slicer is not compensating for the full width of the part across the print axis, and therefore leaves the holes you are experiencing which appear to always occur at the edges. Unfortunately, I do not have an answer for that. I've printed 17 of these things at .2mm layer height, 2 shells, 10% infill for all parts except for the knob and spring, without the problems you are encoutering, on a on a Makerbot Replicator 2 using Makerware

Can anyone else here with a Gen5 printer help thefridayjoe?

@typo148 I am also having problems with the pawl. Its missing a couple facets.

Try "Pawl New.stl" and let me know if that fixes it.

Thanks, and sorry for the problems.

pawl is non-manifold. It wont slice with slic3r.

also used the website slic3r suggested, had it repair the code and now it works fine! https://netfabb.azurewebsites.net/

Try "Pawl New.stl" and let me know if that fixes it.

Thanks, and sorry for the problems.

Now turn that into a clock.... ;)

I think I'll need to design a bigger spring...

Wow, skeinforge sliced that spring in the least efficient way possible.. At first I thought I had a jam because I was only looking at the part and didn't see any infill being output.. then I looked at the gear and saw it wasn't extruding. Most of it is travel along the spiral, but the infill is far and few inbetween..

What did you slice it with? Maybe I finally have to get around to trying Slic3r..

The rest of the parts came out great (still have to do the knob after this). Can't wait until it's finished!

Try "Spring New.stl" and see if that helps.

Let me know please, I would like to eliminate any problems you are having!


I use Makerware and have had no problems. But I will look at the spring closer and let you know.

Very sorry for the problem!

We'll make sure you succeed!

Comments deleted.

Good Job !!!

Next step is to combine with escapment system to create a mechanical watch !!!

Thanks very much!

Work in process...

Awesome. Printed it and it worked just like in the video. Great model!

Thanks, and congratulations!

You have THE BEST machines and projects I have found in thingiverse! Thank you!

Thank you so very much for your kind words, I'm very glad you like them!

You too have made my day!

Your wonderful machines always make me smile. Thank you!

Thank you so very much for your kind words!
Your comment made my day!

do you know if this works with abs?

It should, however, you made need to file, trim, sand, etc. more to make the parts fit.
If you try it and have problems, let me know and I'll try to help fix it.

Thanks! Glad you liked it!