FootMouse With a Trackball V1.0
by javierde22 in Circuits > Computers
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FootMouse With a Trackball V1.0
Given the problems I have found in being able to use the mouse with my foot, I have decided to make a design that is printable so that it can be reproduced and used by anyone who has this need.
Contact on https://www.occitans.com/foot_mouse/
Supplies
Resources
Given the problems I have encountered in using the mouse with my foot, I have decided to make a design that is printable so that it can be reproduced and used by anyone who has this need.
Most of the components can be printed but some will have to be obtained via the web. These are the following links.
1 Logitech ERGO M575 Trackball mouse, which we will use as a base.
https://www.amazon.es/dp/B07W4DHQJ9?psc=1&ref=ppx_yo2ov_dt_b_product_details
1 Rubber ball. This is one of the most important parts of the design, very important is that the diameter must be 29mm (although the website says 30mm) and the type of rubber must be the hardness supplied by this manufacturer (Shore A 46 HA). At the time the project started, they were only one color.
https://www.amazon.es/gp/product/B0BXLHP1FX/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&th=1
Colored beads. It is also very important that they are the same size and hardness, otherwise the trackball system will not work. Dimensions 6x9mm with 4mm hole.
https://www.amazon.es/gp/product/B0CJLMFYKY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
6 switches with 7x7mm spring (without locking)
3 Ball bearings of 10mm diameter (very important that they are of this diameter)
https://www.amazon.es/dp/B0BPSQ25KG?psc=1&ref=ppx_yo2ov_dt_b_product_details
4 M5x80mm countersunk screws. Since they cost me a lot to get, I attached the link.
https://www.amazon.es/dp/B07B2YV1H1?psc=1&ref=ppx_yo2ov_dt_b_product_details
6 M5x30 stainless steel countersunk screws
2 M5x20mm allen head screws
4 M5x30mm allen head screws
1 M5x60mm allen head screw
1 M4x60mm allen head screw
1 M4x50mm allen head screw
7 M4x30mm allen head screws
1 M3x50mm allen head screw
1 M3x30mm allen head screw
1 M3x40mm allen head screw
1 M3x45mm or M3x50mm allen head screw
12 stainless steel washers for M5 screw
13 M5 self-locking stainless steel nuts
9 M4 self-locking stainless steel nuts
2 Stainless steel washers for M3 screw.
4 M3 self-locking stainless steel nuts
1m of flexible cable 0.25mm2 approx.
60cm of heat shrink tubing 2mm in diameter.
At the end of the document I attach some alternative links.
Print All Parts
Print all parts
The plastic I used for this design is black PETG from SUNLU, although it probably works just as well with other types of plastics.
I recommend using it at 218 degrees.
I attach the configuration that I use with the ultimaker Method X printer and with Ender 3 pro (using 0.6mm nozzles)
I am attaching the necessary documents to print all the parts, and some extras that are not necessary in principle but in case we want to modify the design so that it fits better.
The parts that start with “extra_” are variations of the configuration and in principle we should not print them, if we see that the configuration does not fit our requirements then we can use them to adapt the design.
As an alternative link we can go to the thingiverse website https://www.thingiverse.com/thing:6727823
My recommendation for printing the pieces is the following:
NAME Sole.STL If we want to use the mouse with the left foot, we must flip this piece or use the extra_sole_left.STL piece FILL 35% SUPPORT 40% ORIENTATION 
NAME Ball_case.STL FILL 35% SUPPORT 0% (try to do it without supports since it is the most delicate mechanical part regarding operation) ORIENTATION 
NAME Ball_base.STL FILL 35% SUPPORT 0% ORIENTATION 
NAME Spacer1mm.STL FILL 100% SUPPORT 0% ORIENTATION 
NAME Ball_top_cover.STL FILL 100% SUPPORT 0% (try at 0% and if not, increase to 20%). It is very important that the part where the ball goes (the center) is very smooth on the inside. ORIENTATION 
NAME Plate_sole.STL FILL 35% SUPPORT 20% ORIENTATION 
NAME Plate2.STL FILL 100% (It is important for mechanical rigidity) SUPPORT 30% ORIENTATION 
NAME Plate3.STL FILL 35% SUPPORT 50% ORIENTATION Although this piece may not seem to be the best orientation, we put it this way to achieve the best definition in the battery holder.
NAME Sole_reinforcement.STL FILL 100% SUPPORT 0% ORIENTATION 
NAME Toes_spacer.STL FILL 100% SUPPORT 0% ORIENTATION 
NAME Toes_plane.STL If we want to use the mouse with the left foot, we must flip this piece or use the piece extra_toes_plane_left.STL FILL 35% SUPPORT 20% ORIENTATION 
NAME Big_toe.STL If we want to use the mouse with the left foot we must volley this piece or use the extra_big_toe_left.STL piece FILL 35% SUPPORT 50% ORIENTATION In this case, we propose this distribution so that the best printed part is the one that has contact with the big toe.
In this case, we propose this distribution so that the best printed part is the one that has contact with the big toe.
NAME Big_toe_spacer7mm.STL FILL 100% SUPPORT 0% ORIENTATION 
NAME Top_big_toe.STL If we want to use the mouse with the left foot, we must flip this piece or use the piece extra_top_big_toe_left.STL FILL 100% SUPPORT 0% ORIENTATION 
NAME Heel_stop43.STL FILL 100% SUPPORT 30% ORIENTATION 
NAME Heel_shoe.STL FILL 35% SUPPORT 0% ORIENTATION 
NAME heel_bottom.STL FILL 100% SUPPORT 0% ORIENTATION
NAME Battery_case.STL FILL 100% SUPPORT 30% ORIENTATION
NAME Back_case.STL FILL 100% SUPPORT 35% ORINTATION 
Assembly1
Model assembly
Since the printing plastic does not have a very good friction performance, the “beads” have been added at various points of the model.
We started the project by disassembling the trackball and the electronics.
The screws are located under the rubbers, we must first remove the rubbers and then the screws.
When assembling and disassembling the mouse electronics, we must be careful when disassembling the electronic connection straps. On the control board connectors, we must first pull the black part of the connector and when the connector is on top, remove the strap. To keep it, do it in the opposite direction. When placing the straps, keep in mind that the copper part goes on the white part of the connector, as seen in the photo.
Be careful not to fray the tips (as shown in the photo) and make this connection as few times as possible since they are very delicate.
With the ball connector, we will have to pull the white tab upwards, and then we can take out the connecting strap. In this case the copper part should go towards the black part (bottom) as seen in the photo. To place the strap, we must do the reverse procedure. We must be very careful when putting it inside so that it does not fray and check that it has entered well to the bottom.
Assembly2
Then we assemble the base of the mouse
We mount the longest connecting strap on the base of the trackball since it has to go through the whole assembly.
The most critical point is the rubber ball that pulls the trackpad.
Here it is very important that the hole where the bead and the bearing are inserted is very well printed and there is no point that rubs against the bearing ball. The hole where the ball goes is also very important that it is very smooth. If necessary, use very fine sandpaper. The three bearing balls must come out the same and must turn smoothly by hand, otherwise the rubber ball will not work in the mechanism.
To ensure the ball fits into the system, a 1mm spacer has been added to the bottom. The spacer at the top only needs to be installed if the ball protrudes too much from the top (in our design, we did not mount the top spacer). We must ensure that the rubber ball protrudes as little as possible from the hole to prevent the electronics bearings from being forced when pressing the ball with the foot.
The objective is for the rubber ball to roll correctly supported by the 3 bearing balls and to protrude as little as possible from the assembly.
We must assemble the assembly with the following arrangement
Once the lower assembly is assembled, we also add the beads to the upper assembly so that the moving parts have less wear and friction. The big toe and toe pushers also have beads.
Assembly3
We must place the nuts on the screws that support the toe pushers. To keep them in the correct position, tighten the side screws until the nut is in the correct place. Then remove the screws to be able to mount the pushers later.
We assemble the big toe assembly.
We have to assemble the spacer so that it is comfortable for our foot. In my case it is a 7mm spacer but an extra design with other measurements has been added.
We solder the cables of the two switches that we will use as the right button and the left button.
We must use the two legs that we marked (normally open contact)
We must check the buttons placed, so that the one we wire to the control board takes longer to act when we press it, to ensure correct operation. In our design they are the following:
In case of printing the mouse for left-handed people, the right side is used for the big toe and the switch that we must use is the second one.
The rest of the buttons act as a spring so that it has enough force to overcome the weight and friction.
We place the buttons in their position, taking into account that those that are wired will be the ones we have marked previously. If you use the mouse with your right foot, you will place the buttons on the left side, and if you use it with your left foot, you will place them on the right side.
Then we proceed to assemble the rest of the components
We must solder the cables in the lower connectors as indicated in the photo. It has no polarity. The connection on the left corresponds to the left button of the mouse, which in our case will be activated by pressing down with the thumb, in the photo the buttons are marked in blue, and the connection on the right is the right button, which in our case we will activate by moving the thumb upwards.
Once the cables are soldered, we connect the white strap of the electronics on the lower plate to the upper plate.
Assembly4
Once this part is finished, we put the nuts in the holes and secure it with the screws so that the nuts stay in place. Later we will have to remove the screws to put the plate but in this way we secure the nuts in the correct position. We must also put the nuts on the battery cover since they cannot be put on later.
We put the separator between the big toe and the other toes screwed into the sole, and we assemble the whole assembly, without the finger push buttons, as shown in the photo.
Above all, connect the strap that connects the trackball with the main electronics of the plate since it will not be accessible later.
For the moment it is better not to fully tighten the assembly screws and finish tightening everything when it is finished.
Then we put the push buttons on the big toe and the rest of the toes. The rest of the toes will not be used to click the buttons, as we have already mentioned this part does not have to assemble the switches.
We put the side screws that secure them and test the mobility. These should not be tightened too much because then it creates too much friction and the system does not work.
Now we will proceed to assemble the back cover. First we must remove the screws that we have previously put in place to be able to place the cover.
We have to take the plastics from the original trackball, power button, LED and reset button.
We must cut the plastic from the LED leaving only the square that goes over the LEDs.
It is better to mount the power button on the board on the electronic board because it has to match the switch.
We put in all the screws of the assembly, and put in the cover and the battery..
We tighten all the screws and test the mobility of the entire assembly.
Now we need to assemble the heel assembly to have the entire assembly finished. The rear piece of the heel of the foot will depend on the size of our foot. The lower piece of the heel is screwed to the heel and has been made in two pieces so that it can be replaced in case of wear. Two holes have also been added to be able to put beads that give more resistance to the friction of the set.
Once the whole set is assembled, we put the pendrive in the computer and turn on the mouse switch. This has a low battery consumption so I recommend leaving it always on.
To left click, we have to press down with our big toe. To right click we raise the big toe up. The right key has not been used because we find it very difficult to click with the right side of the foot, but by putting the switches it could be used. (My recommendation is not to use it).
Software: Axes Inversion
Axes inversion
The mouse on the x axis (from right to left) must work in the same direction as the normal mouse, but on the Y axis (from top to bottom) it works inverted, this is due to a design flaw. If it is inverted to the opposite it means that we have assembled the base of the trackball incorrectly.
If we do not get used to the Y axis being inverted we can install a program that inverts this axis so that when running the application it works correctly.
I have tested this version on windows10 64bits
To do this we must first download and install the driver for the mouse from the creator's website.
https://github.com/a1xd/rawaccel/releases
https://github.com/a1xd/rawaccel/releases/download/v1.6.1/RawAccel_v1.6.1.zip
Then we must install the program to invert the mouse
https://github.com/oleg-st/InvertMouse/releases
https://github.com/oleg-st/InvertMouse/releases/download/1.0.5/InvertMouse.zip
When we download the latter, we copy the folder to C:
(c:\InvertMouse)
We start the application and configure it as it appears in the image and press the start button.
Every time we want to invert the mouse we must start the application and run the start button.
If we want it to run every time we start Windows we have to enter the key in the registry, either manually or by running the attached files.
If we want it to run only on our user, the key is the following.
If we want it to run on all users, the key is the following.
We download the file and double-click it to add it to the Windows registry.
If we do not want to add it automatically, we can add the key manually. To add it manually, we search for regedit to open the registry.
We go to the corresponding folder and add a new chain key. Here we add the path to the executable.
Once these steps are finished, we restart Windows and when it starts, the application will automatically open, but we must also press the start button.
If we want the start button to start, we have to edit the file c:\InvertMouse\Options.json, right-click on it and open it with WordPad or choose another application and choose WordPad. 
we edit the line
“Running”: false, and we change the false to true “Running”: true, (be careful not to change the structure or the double quotes.
We restart the computer again and it will work.
Sensitive Adjust
We only have to lower the speed of the double click since with the foot it is more difficult to click twice in a row.
In Windows 10 we look for the control panel and enter Mouse. Within the mouse in the Button properties we can adjust the speed of the double click. My recommendation is to lower it two points.
Alternative Links
Alternative links
Below we expand the links to be able to buy the parts in different countries.
Trackball
Ball links although I can't guarantee that they work for this application
Kits buttons
For the buttons we can buy this kit. But be careful, these are with a lock so we will have to carefully disassemble them and break the locking tab.
https://www.amazon.es/gp/product/B01N67ICEC/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1
I can't guarantee that these work