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I designed a bigger, stronger, and longer version of the "meArm" robotic arm. Robot arms are fun to watch and more fun to play with. This design gives you the added bonus of building your own robot arm. Using a 3d printer and parts from the hardware store I was able to increase the lifting ability and strength of the original "meArm" kit. I added a few new features to correct issues I had with the original kit.

To view the original "meArm" check out his project at Pocket-Sized-Robot-Arm-meArm-V04 . I purchased his kit from adafruit.com/products/2012 and had fun putting it together and trying it out. I love the design it looks like a robot arm in a factory. The original "meArm" is a good kit but a little weak for any real use. So I fired up SketchUp and warmed up the 3d printer. Time to make it bigger, stronger and longer! I doubled the scale, added bearings to the joints for smother movement, and bigger servos to help move heavier objects. I had some issues to overcome and have more improvements I would like to make but I am well on the way to a successful project.

Download my files from thingiverse.com

Check out my web sight at engineeringwithjazz.com

Special thanks to:

My dad's boss Jimmy without him I could never have made this project. His help with measuring, tolerances, and using his 3d printer made all the difference. Thanks!

And to:

phenoptix for releasing this project as open source. I have learned so much!

Step 1: Parts List

Hardware:

  • 18 ~ 5/8" long M4 screws
  • 1 ~ 3/4" long M4 screw
  • 3 ~ 1-3/4" long M4 screws
  • 22 ~ M4 nuts (I used the ones with nylon inside)
  • 3 ~ Small washers
  • 12 ~ Bearings 624ZZ 13mm OD x 4mm ID amazon.com
  • 12 ~ Small screws for servo horn

3D Printed parts:

  • Base
  • Bace Center Strut
  • Center Beam
  • Center Beam Top
  • Grip Arm
  • Grip
  • Long Arm
  • Servo Arm
  • Short Arm (Two of these)
  • Stand
  • Stand Lid
  • Support Arm
  • Tri Support

Tools:

  • Pilips screwdriver
  • 3d Printer
  • Grinder (to shorten some of the screws)

Electronics


Step 2: ​Assembly of the Stand

After you print the required parts t is time to start assembly. Lets start from the bottom up. Insert the nuts into the bottom of the stand then screw the lid on with the servo hole closest to the servo cutout in the stand. The stand is where I made my first improvements. In the kit the servos have a little wobble in the holders mine are nice and tight with mounting holes to make them even more secure. The second improvement is the nubs on the lid. They help prevent the arm from tilting when something heavy is picked up.

Step 3: ​Assembly of the Base

The base will need a servo horn screwed into the bottom. There is also a center strut that will need 4 nuts press fit into it. The center strut is mounted into the base using four screws. You may need to remove the center strut latter in the build to insert the locking screw into the side servo horn. That is why I made it removable.

Step 4: ​Assembly of the Arm (Elbow)

Now to start on the arm. First lets attach the parts for the elbow. The long arm will need a press fit nut. Then the short arm will require two bearings. The bearings press in and hit a stop. The stop is the side that attaches to the long arm. Insert the screw into the bearing and attach to the nut on the long arm. Attach the servo horn to the servo arm. Then the servo arm will require another nut and will attach to the other end of the short arm.

Step 5: ​Assembly of the Arm (Center Beam)

The center beam is in two parts (Center Beam & Center Beam Top). The top will require four nuts press fit. A servo horn will also need to be screwed onto the Center Beam along with one press fit nut. This is where I made a mistake designing the part in 3d. This servo horn will need to be screwed on upside down from the other two. This will not affect the arm strength in any way. Now connect the two parts using the 1-3/4" screws. I noticed my mistake after I printed the part and adjusted all other parts to fit the mistake. If I were to redesign I would fix this error. You print you learn.

Step 6: ​Assembly of the Arm (Attach Elbow)

Insert a bearing into the middle of the long arm. Then screw to the center beam on the opposite side from the servo horn on the center beam. When complete the servo horn gear holes should both point away from the center beam.

Step 7: ​Assembly of the Arm (Build Shoulder)

This can be a little tricky because the arms look the same but each one is a little bit different. You will need the tri-support, one of the short arms, the support arm, and the gripper arm. The gripper arm is a little thinner on one end. The support arm has both of the bearings holes on the same side. Press fit the two nuts into the tri support. Then attach the support arm to the long end of the tri support using a bearing and screw. Next attach the short arm into the other nut on the tri support. The gripper arm and the tri support will require bearings. Be careful which way you put the gripper arm onto the tri support. If you put it on upside down it will not attach properly to the gripper head. The bearing side on the opposite end should be facing down. Use the 3/4" long screw and place washers in between the two bearings on the tri support and the gripper arm. This will screw onto the center beam in the next step.

Step 8: ​Assembly of the Arm (Attach Shoulder)

Now screw the shoulder onto the center beam. This will attach to the center beam on the same side as the servo horn. If you notice in the photo I have the gripper arm on upside down (See note). So if yours looks like mine in the photo you will need to flip it over. Otherwise move on to the next step.

Step 9: ​Assembly of the Arm (Attach Gripper Head)

The gripper head requires three nuts press fit. Three bearings are also need to be put into the arms and all attached using screws.

Step 10: ​Assembly of the Arm (Attach Arm to Base)

The arm is ready to attach to the base. First attach the support arm to the base. This nut is the one sticking out from the back of the base. Then attach the arm to the center strut on the base using a bearing and screw.

Step 11: ​Assembly of the Arm (Insert Servos)

The servos slide into the holes in the side of the base and with some careful fidgeting of the servo arm into there respective servo horns. This part requires some patience. Then insert the servo into the stand and attach the base.

Step 12: Final Thoughts and Improvements

When assembled the arm is super strong and stiff. All the joints move easy and will not where out. The original had a 7" reach mine is 14". I added some steel legs for ballast and it looks mean. Some people compared it to a evil spider. I do not have a active gripper like the original because I am using a electromagnet. If I would use a gripper I think I would change the design to have more fingers or use the DIY Universal Robot Gripper.

Servo Trouble:

The servos I have pictured are from adafruit.com and have a extra wire for position feedback. I was going to use them for a learning arm (Move it by hand and it would record the movement and play back). But the servos were not strong enough to move the arm when fully extended. So I switched to some high torque ones from polou.com that I put on the parts list. They have not come in yet so I am excited to see how they will do. The trade off is they do not have feedback so no learning arm for me. I think if I removed some of the plastic from the center beam the original servos might work.

Changes I would make if I build another:

  • The base limits total travel so I would remove the front and back sides.
  • Update the radius on all parts so they match (cosmetic)
  • Interchangeable gripper head to hold different grippers
  • Wire management built in to model
  • Stronger legs on the stand
  • LED's just because
  • Reduce weight of all parts by adding holes (triangle shaped)
  • Some kind of cord keeper to prevent the wires from twisting when it rotates
  • I think using stepper motors with gears could add to the weight capacity and give 360 degree rotation at the base. (Might be a bad idea I don't know)
  • Many more small changes I have yet to discover

<p>Hello <a href="https://www.instructables.com/member/Jazzmyn/" rel="nofollow">Jazzmyn</a>,</p><p>Here is a I project completed made on top of your bigger me arm.</p><p>One of the issue that with software test automation is the inability to interact with the physical world.</p><p>This means of you want to automate the test scripts of a POS software the most important business critical test scenarios are not getting executed since it demands interaction between different types of payment cards and card reader.</p><p>So we decided to make a robotic arm that can be controlled from Calabash in order to achieve 100% automation as a proof of concept.</p><p>Few days back we completed the Phase 1 of this robotic arm.</p><p>And it did meet our goals set for Phase 1 successfully.</p><p>Please find more about this project here:</p><p>https://nishabe.wordpress.com/2016/01/25/a-robotic-arm-integrated-with-calabash-2/</p><p>Thank you <a href="https://www.instructables.com/member/phenoptix/" rel="nofollow">phenoptix</a>, for this original version.</p>
<p>Hello Jazzmyn,</p><p>I need your opinion on few things.</p><p>My original meArm is working as expected.</p><p>In ordert to use meArm in my project, I need to make sure mt robotoc arm (meArm in this case) is able to do the below two things:</p><p>1) Move the tip of meArm elbow in a perfectly vertical line</p><p>2) with considerable force.</p><p>The trials with meArm shows that it is not that easy with the current setup.</p><p>Please see this video: </p><p><iframe allowfullscreen="" frameborder="0" height="281" src="//www.youtube.com/embed/q3XiRHwjE_s" width="500"></iframe></p><p>How can I resolve these two issues?</p><p>My current direction of thoughts are:</p><p>1) tweak the structure and 3D print it and</p><p>2) Upgrade the servos to add some more power.</p><p>Whats your thoughts on it?</p><p>Note: I have used the IK library from: https://github.com/yorkhackspace/meArm </p><p>and also did the calibration steps explained here: <a href="http://bitofahack.com/post/1433701488" rel="nofollow">http://bitofahack.com/post/1433701488</a></p>
<p>Great remix. I had to dremel it a bit to fit in my steppers. I have lots of improvements in mind so renaming mine to F.R.E.D :) Thanks for the great design. There is a video of it's first moves up on youtube: (https://www.youtube.com/watch?v=xp_opt2vvFU&amp;feature=youtu.be)</p>
<p>Hi</p><p>I am a new farmer and have a problem to solve maybe by a robot arm.</p><p>Strong men are able to connect the hydraulic couplings between tractor and tools i may connect like hay cutter, hay liner, hay baler etc.</p><p>As i am a pensionist 67 years old, i am weaker in my arms and can not connect the couplings and need to call the neighbour who is costly minimum charge, and i am embarrassed. I am from Norway sorry for my english.</p><p>Are you able to give up some names of companies who make a very flexible robot arm both to work and fastening to the tractor ? Have 3 different tractors. Can be run by electric air or hydraulic but need to be strong in material and power, but most practical would be</p><p>moved by a hand pump as sometime the tractor is 100m from the barn.</p><p>Look very much forward to your reply as this problem need to be solved soon.</p><p>kind regard</p><p>stein Larner stein@legrandecherat.eu</p>
<p>I love the scalability of 3D printers. Awesome project!</p>
Couplings are used to attach 2 axles together , they are wider than the shaft . This can be used to hold the axle connecting two parts (axle instead of bolts and couplings instead of nuts)
<p>You totally beat me in terms of building a meArm first; I haven't even ordered any parts yet (I've been meaning to do that for months, now)... and then you went ahead an engineered your own version? Gosh!</p><p>That's awesome, BTW!</p>
<p>It took me almost as long as you have been thinking about it to design and build one. I also filled the scrap plastic box next to the 3d printer. But it was all worthwhile. I learned so much. Just got my electromagnet working and installed yesterday it is so cool!</p>
Nice . You could also use couplings and axles instead of nuts and bolts both for less friction and avoiding possible damage .
<p>Any specific part suggestions? I googled the term &quot;couplings and axles&quot; but I did not see anything that I think would work. I know what a axle is but not a coupling. A link with a picture would help me have a better idea of what you are recommending. I want to avoid damage! Thanks for the suggestion.</p>
<p>Fantastic build! Surely entered into the remix contest? Thanks so much for making this and making my day! Normally this would make the week but yesterday the #meArm had a couple of seconds on UK TV's Gadget Show.</p>
<p>Congratulations on the TV show. Every second counts! Love your kit and glad to know you like my build. I am about to attach my electromagnet so I am excited as well. Yes I am entered into the remix contest drop by and vote if you have time. Did you notice any loss of fine control when you made your big arm? I am thinking it is a distance from center thing I am fighting.</p>
really cool, id love to build one but, are you planing on doing a v2 with all your extras with it or are you just going to stay with this one.
<p>Yes, or at least some of them. I still have a lot of programming I want to experiment with first. Keep a eye on out you may see more soon.</p>

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Bio: From Arduino to Rube Goldberg follow along as we explore engineering together. With a focus on electronics come see projects based on 3d printing, physics ... More »
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