pic: LIN-101, 3D-printable modular linear actuator

See thread for description. tl;dr is that it’s a 3D printable cheap linear actuator.

LIN-101 is a fairly complicated attempt to make a COTS + 3D printer linear actuator. There are no machined parts on this; a hacksaw, drill press, and 3D printer are all that’s needed. A 1/4"-20 tap would be good too, but moving the pivot further out would allow for the use of a shaft collar instead.
Total cost including all hardware is about $60-80, but that’s assuming you’re buying 100-packs of screws off McMaster (and thus could make 10+ of these for <$30 a pop after the initial investment). This would take ~11 hours to print on an Ultimaker or 2x that on a Makerbot. There are a couple of difficult to print features, but nothing that can’t be cleaned up with a drill bit and a file.

The free speed on a 1:1 Versaplanetary off a 775pro and the 30:40 gear reduction is ~19in/s. Assuming an efficiency of 50%, this can handle a 40lb thrust load at 20 amps. Belts, chains, or some other gears can be used as well. There are two versions of the VP mount piece; one that has slots for tensioning and one with just bare holes.
I’m confident in this being able to sustain at least 40-50lbs thrust force. Side loads are taken up by a 2.5" 3-D printed shell braced against the inside of the tube, and needs to be tested for strength (probably more than 50ft-lbs on that). The sketchiest parts of this are the coil spring pins used to secure the nut inside the 1x1 Versaframe actuator and the cross-screws used to couple the leadscrew to the hex shaft. Both of those need to be load tested and tested to see how hard they are to machine.
A WCP hall effect sensor can be placed on the output to provide zeroing capabilities.

The base length of this is about 1" longer than the AM DART. This means that where the DART is 11" long for a 6" stroke, this is 12" long for a 6" stroke. However, this is fully modular; stroke length can be adjusted by changing out the Versaframe actuator, the leadscrew, and the 4 8-32 threaded rods that tie this together. There could be ways to shorten the base length, but ATM I can’t think of a way to do it without making more machining necessary.

CAD is available here:

The LIN-101/Release folder has finished parts. The .STEP is a generic STEP file, the zip folder is a pack&go, and the .STLs are for direct printing (not recommended).
I printed one of the acme nut holders today and will be tweaking dimensions a bit based on my results.

It’s been literally a week since the Maker Faire Anand and you already made your own copy of the linear actuators you showed me? :rolleyes:

Looks hella sick bro - definitely down to clown with this on the 9299 offseason bot.

Are you planning on releasing CAD for this? Also, are all the COTS parts easily sourceable (e.g. from McMaster) or are there some weird parts in there? I’m especially interested in the lead screw (or is that 3D printed?)

Can we get a cut-away shot? Would like to see the internals.

I don’t know where we would even use this, but if you can come up with a good use for it I’d be down. :smiley:

I had a picture of the Makerfaire one up the whole time I was CADding this! For those curious: https://www.kickstarter.com/projects/deezmaker/maker-muscle-worlds-first-customizable-actuator-fo
That was also really cool, especially the usage of the custom extruion, although I didn’t like their use of the weirdo leadscrew over a normal one. Needs the extra pitch I suppose. It’s not shown on the Kickstarter page, but they had a CIM version at their booth.

CAD is available. I actually posted the link to it at the end of the image description but it looks like most of it got cropped somehow. I just put it back int he first post.
All parts are available from McMaster and Vex/WCP (thunderhex, a few bearings, and gears). The leadscrew is a 3/8"-12 that’s about $4/ft from McMaster. The nut I just found on Ebay, but Fastenal offers them as well.
Interestingly enough, it’s possible to use a regular 3/8" threaded rod and nut over ACME versions at the cost of massive efficiency losses.

Here’s a transparent casing view:

Here’s a cross-section:

CAD is up, so that should answer some questions too.

This is actually really cool.

This is the type of stuff I love seeing in FIRST.

Taking something (seemingly) complex and boiling it down to something approachable.


Maybe it’s not needed, but I feel like the white “cap” part on the end where the tube comes out should extend down further to make it more ridged.

Worth noting to anyone viewing this thread in the from the photo gallery: you have to click the “view entire thread” link under the picture to see the full description with the CAN url. :wink:

EDIT: Any chance you could upload those files in a generic format like a STEP? Inventor appears to be unable to convert any of them. =/

Thank you! I’ve always liked saving money, and having 3d printers at hand has opened up tons of possibilities for me.

You can make the white end cap as long as you need. I chose 2.5" because it’s braced against the tube and lowers print times, but it’s easy to modify for your needs. Testing would be prudent.
There is a .STEP file in grabcad. Check in the “LIN-101 / Release” folder.

Really nice work!

Instead of making the output side bushing any longer, I would fix a sleeve/slider around the inner end of the tubing. Then the bearing length is between the output end and where ever the inner side of the tubing is. So if you have 6" of travel, the bearing length would be 6" or if the actuator was extended, you would still have around 2-3" of bearing length. This would maximize the side load capacity. This would also take the load off the lead screw, lead nut and reduce friction when the assembly is side loaded making it more efficient to drive.

This makes me wish we had a 3D printer that was reliable.

Thank you Kevin! Ultimakers are really good investments in my opinion, so if you can afford one you should jump on it. Given 2451’s resources you could probably CNC mill the whole lot anyway. :stuck_out_tongue:

I see what you’re saying. I was considering doing that but I wanted to reduce part count. Looking back on it and what you’re saying about the leadscrew loading, I think it’s a lot more viable, especially if I can keep both bushings 1" long or less to reduce the base length as well.