MeArm V0.4 - Pocket Sized Robot Arm

by phenoptix, published

MeArm V0.4 - Pocket Sized Robot Arm by phenoptix Jun 11, 2014


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The MeArm is a low cost robot arm. It is designed to be light weight and inexpensive - to be the perfect introduction to robotics. You can cut, print or even whittle (carve from wood) a MeArm and they've also available on our website at mearm.com

The current version is the v1.0 and is available from mearm.com with the files available here
This version has a number of improvements over the v0.3 and now has support for the Arduino and Raspberry Pi.
This version is currently available with fixings and servos at mearm.com in the UK
The Hackaday Store in the USA.
For more distributors worldwide please see our distributors page!
Find out more and follow on hackaday projects

MeArm is a trademark of MeArm Limited UK. Use of the MeArm designs is allowed but not use of the MeArm trademark.


The v0.4 is a tweaked step up from the v0.3.
Full build instructions at instructables!

Parts list differs slightly from v0.3 and has been recently revised (previous v0.4 counts in brackets). We think this is now the optimal loadout, most tolerant to the differences in the thickness of acrylics as supplied by perspex.
Nut x 10
6mm x 9 (was 11)
8mm x 12 (was 13)
10mm x 3
12mm x 7 (was 6)
20mm x 4

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Good job.The design could include the inclusion of cables.

Does anyone have an idea as to how to control the arm with a rasepi?

There are "cleaner" vectors files available here:
Converted into SVG file format
Removed rasters to lower printing cost
Organized into two files to be printable on P1-sized acrylic sheets. (or plywood)
Used the color coding required by Ponoko
Added an M3 wrench for convenience

I have two quick questions as I plan to print this for a robotics project I have to do in school. I need help from either @phenoptix or anyone else who has the answers. My first question is how thick of a piece of plexiglass should I laser cut this on? My second question is will this robot go below 90 degrees, below level with which it rotates? My third question is at fully extended in up and down position how tall does it come out to be? Thank you for anyone who can answer!

@StefanL38 I'd like to try and take something positive from your comments. What I'll say is I shared the exact files I use to laser cut these. Your interpreter has messed them up. There's also a pdf you can trace with about 30 seconds effort and a .cdr.
Before you comment on what to give open source why not try and share something yourself, so far you've shared nothing but negativity.

The DXF-File is a bit crappy. Wholes are not exact circular somehow squares with rounded edges.
rounded edges are build from several secants instead of a part of a circle.

Why the heck did you make it so complicated??
If I want to use a CAD-CAM-Software (like ESTLCAM) to create milling GCode it does not work exactly becauses circles arent exact circles etc. Don't give OpenSource a poor quality image!

@andrewKI you can conclude thickness through measuring parts where the main-plane fit in an angle of 90 degrees and after fitting both parts build a straigt line. 3mm I think.

Is it still 200mm x 300mm? And i do not find any information about thickness.

Is possible to 3d print the parts?

Just uploaded the .cdr for the v0.4. Not had a chance to look at it but should be fine!

I have access to a laser cutter to cut the parts for this arm but I am told I need a coreldraw (.cdr) file and not a .dxf file.

Does anybody know how to convert MeArmV0.4.dxf to a .cdr file?



Open a new file in Coreldraw when you're at the computer with the laser. Make sure the size of the project is the same as the size of laser bed or at least the size of the stock material you are cutting. Just drag and drop the DXF into that file, and it will as you for units. Automatic usually works fine, but you may have to set it to mm.

That's it.

What is the dimension for the acrylic sheet if I have it laser cut ?

The old dimensions are 200mm x 300mm. The newest file should fit on an 8.5"x11" piece of acrylic. Make sure dimensions are imported correctly before you start cutting.

Does anyone have a list of nuts and bolts I need? v0.4 Fixings metric system, Thanks

I had the .dfx file converted to .eps to so I could use Ponoko to get the parts made. I'm not 100% sure if the dimensions are still correct. Would anyone who has successfully built the #meArm be willing to take a look at my .eps file to verify everything is correct? Also, if it is right it might be nice if Phenoptix could include the .eps in the Thing Files. Thanks!

@rob......do you have the eps file as the dxf file will not load into Ponoko.......line colours maybe. Anyway I don't have any way of editing dxf so teh eps would be great.


I get a kit, but I would make some "enhancements".
now I've downloaded the dxf, but when I open it in AI it's about 10 times too small.
couldn't you upload one with the correct size?

Have reuploaded the file with a 300 x 200mm bounding box. It should allow you to scale to the correct size.

Any chance of moving it the components to one side a bit so it fits in US A-sized 8.5x11 formats? 11" is 279mm, instead of 300, so your current picture is close, (and the 8.5" direction is wider than 200, so that's fine.)

I uploaded a new V0.4 dxf that is re-nested to fit on an 8 1/2" x 11" sheet.


Thrust bearing base for MeArm V0.4

I've assembled the kit and will (laser)cut tomorrow some additional parts to

  • stabilize the servo and to
  • change the screw moving the jaws (the screw should come from the bottom). the holes of the two elements must be 'exchanged'.

v0.3 had a 25 mm square for reference. Is the square in the upper-left also meant to be used for reference? What size should I scale it to?

The one in the upper left is more for making sure the cutter starts where I want it too! I'll do a version with the reference now, but most parts are the same size as the v0.3 so you might be able to scale to those for the time being

Oh great - yeah it would be helpful to have with the reference. Thank you! I'm not super great at Illustrator, and I had a hard time confirming that the shapes were the same size as v0.3.

Sorry for the delay in sorting, added a 300 x 200mm bounding box for easy scaling.

Is it possible with this design to "blow up" the pattern 2-4x the size and use larger steppers/dcmotors? which would be more beneficial stepper or dcmotors?

You could increase the size of the pattern, but there's quite a decent amount more work involved in terms of getting motors to fit. The pattern is designed for hobby micro-size servos. By switching to steppers or DC motors, you would have to figure out new mounting plates. Certain servos have the advantage of position control, which you will need to control each of the arm joints. Using DC motors will likely get you better power, but you may have to install potentiometers or some other method or closing the position feedback loop.

Are there any source files available? Would like to do some modifications

The dxf is pretty much the source. I design on a flat sheet. Can check with Jack Howard who uses a cad model, would that be more suitable?

Nah, its fine. Will probably redraw the parts I want to modify in openscad :)

@tomvdb - did you make any progress in remodelling in openSCAD ? I have built a 0.4 from a phenoptix kit, and (like you) would like to print my own, maybe with some mods. I have tried working from the 0.4 dxf, but I'm now thinking that it might be better to just re-model for 3D printing. Maybe we could share the work and get it done quicker/better with two on it ?

Any progress?
I also want to print it.
Ir says you can print it in the description

There's a set of stl files over here http://www.thingiverse.com/thing:616239 if that helps!

MeArm 0.4 Printable (.stl)

Yes that helps. Thanks!