Ergonomic Armrest with Tool Holder

Give your hand a helping hand with this ergonomic armrest! You can use it for any activity that requires your hand to stay in the same place/position for extended periods of time and you can use the tool holder to design and use any tools that will keep the object you are working on at your reach at all times.

The armrest is fully printable and no additional parts are needed.*

I have printed all the parts with 4 perimeters and 25% infill. 0,15 mm layer height. All the files are saved in the correct printing orientation and the files are sorted so you can print them one by one in order as they appear in the instructions below. I printed all the parts in PLA.

All of the parts can be printed without supports, although I would recommend using minimal supports for the corner bends in the top and bottom armrest files for a nicer fit. Just support the part that your slicer recognizes as a collapsing overhang.

Before jumping to the assembly, please note there is a BOM .pdf available. Whether you intend to use the tool holder or not, you need to print it and install it as it is crucial for structural support to the armrest. The tool holder (or rather the tool holder adaptor) is M12x1.5 thread. Thread faces are offset by 0,1 mm so you should be able to print any kind of accessory without modifying your M12x1.5 male thread that should be used to connect the tool to this holder.

*In case the table clamp slides all over your desk, you can use a few rubber bands to provide better friction. See the end of the Description section.

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ASSEMBLY

The entire assembly should be pretty clear from BOM itself, but there are a few things to look out for. Here you can see the entire process, divide into 4 main “imaginary” sub-assemblies. Please note that you can print the armrest subassembly in two parts (top and bottom) and as a single part. The intent of two parts is to add a bit more colour, but I will also update this part in the future with a design for a TPU top.

Table clamp assembly

Use the table clamp, clamp bolt and clamp bolt cap.

Thread the bolt into the clamp and press on the cap once the ball joint emerges fully from the thread.

Main lever assembly

Prepare the height adjustment bracket, main lever, pivot bracket and two M14x1,5 nuts. The clamping surface between the parts allows for a 15° angle adjustment. Ensure that the surfaces marked with a red line on the assembled parts' photo are parallel. 

Armrest assembly

If you opted for printing the single part armrest, you can skip this first step. If you have printed the armrest in two parts, ensure that the slots on both halves are oriented as in the photo. below. Note the small notch on the armrest top (white part) that serves as the pin lock. This notch needs to come to the opposite of the larger diameter on the armrest bottom (blue part) slot. Just note - one is up, the other one is down. Check the next few images if you need a better understanding of how this needs to be oriented.

There are tabs on the bottom part that are possibly not optimized. If they should break, you can use some glue to keep both halves together. However, the parts should stay together just fine using friction and arm weight alone - so the glue, in case the tabs break, is only required if you are going to store your armrest upside down.**

After assembling the armrest, you need to connect the armrest pin with the tool holder. Pull the pin through the holder hole (see image below for orientation).

Push the pin head into the armrest slot and slide it to the opposite side. You need to hear the notch click - this is why it was important to orient the top and bottom part correctly. Rotate the holder so it falls into the armrest slot - this will ensure your tool rotates together with your arm.

Armrest lever assembly

Finally, you need to insert the armrest pin into the armrest lever and fasten the lever to the pivot bracket (main lever assembly).

You can use a flathead screwdriver or a 5 cent coin to fasten the pivot pin into the pivot bracket. Screw it all the way in.

Final assembly

All there is left to do now is to connect everything. Connect the armrest to the clamp using the hex pin.

As mentioned before, you can adjust the height of the armrest by rotating the main lever by 15°. Ensure you also correct the armrest lever angle by the same increment (unless you need some kind of a slope for your arm). Once you are done using the armrest, if it is in your way - simply pull out the hex pin, turn everything upside down and store it neatly below your desk. That way, you can get it out of your way without storing it in a separate place or having to reset your height setting.

** If your armrest tabs do break and you intend to store it this way, you can glue the armrest subassembly halves together.

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FINAL INFORMATION

As you will experience, there is some noticeable torsion in case you use the armrest when the levers are fully extended. Even though the armrest is not intended for this kind of use (it is better to adjust the clamp position), I will probably update the design some time in the future for this kind of use as well.

When you are tightening the clamp, do not overtighten it. You can estimate how much is too much if you cannot slide the height adjustment bracket tabs into the table clamp tabs.