A lot of medial and industrial appliances are using foot switches to control systems. And too many of sensitive systems don't connect their internal DC/AC lines outside the units.
The issue started when I decided to rebuild this old EMS AirFlow / Ultrasonic Dental Scaling Unit.
As its foot switch was missing. and I noticed two internal switches which turn to ON by pneumatic.
these switches has only one Air input.
One of my friend told me to replace the entire mechanism by electric foot switch which is available in our market!
After a while of studying the unit. I noticed that the designer didn't do that cause he doesn't need to drive any DC current outside the unit, also, I noticed that the available 2 switches don't start simultaneously. which means that I should use a special pedal.
To prevent spreading the sandblast to the clinic atmosphere they designed the unit to start water irrigation after a half push, then when you entirely press the pedal, it will start the AirFlow cleaning.
I tried a lot of scouting in our market with no chance to find such pedal. Also this item seems to be expensive as it was designed to be used in medical section!
That 's why I decided to design my own Foot switch.
Step 1: Materials and Tools: - 1 - Pneumatic Pump.
1- Pneumatic Pump: you have several options:
1-1 Medical blood-pressure-monitoring tool pump which can be collected from medical store.
1-2 Mercedes™ BENZ 115 old model water blower foot pump. Goofy!
1-3 Watch repair shop manual Air blower
1-4 Camera Shutter release Pneumatic
Step 2: Materials and Tools: - 2 - Rubber Tube.
2- Rubber tube:
2-1 The Tube which is used for car carburetor.
2-2 Dental systems internal tubing.
Step 3: Materials and Tools: - 3 - Springs.
3- Different types of springs, or flared tubes or a piece of telescopic antenna.
Step 4: Materials and Tools: - 4 - Sewing String and Flowable Adhesive.
4 - Sewing String and flowable adhesive.
Step 5: Materials and Tools: - 5 - Tools.
5 Tools such:
5-2 Metallic tube cutter.
5-3 Tube flaring tools.
5-4 Handcrafting drill +
N.B Some tools are not listed.
Step 6: Materials and Tools: - 6 - Heat Shrinkable Tubes.
6- Heat shrinkable tubes:
(Industrial tubes used by shops which deal with heating elements).
N.B As written on most of shrinkable tubes i.e. 160/80 shrinks 50% in the diameter, but its length stays as is, after heating.
Step 7: Materials and Tools: - 7 - Heat Gun.
7- Heat Gun
7-1 Industrial Heat Gun,
7-2 Hot air rework station. used for electronic repair.
7-3 Hair Blower with head adapter ” this one is very slow”
1- using this tool and other sharp tools should be done under parent supervision.
2- And be careful to let the heated items to cool-down before retouching.
Step 8: Instructions: - 1 - Protect One End of the Rubber Tube From Accidental Closure.
1- Protect one end of the tube from accidental closure:
After you selected the adequate rubber tube which connects the foot switch to the unit and it should fit to the entry of the pump:
1-1 Tightly, Put about 2cm long with adequate diameter of spring into the one end of the rubber tube.
N.B adjust the beginning of the spring to protect it not to entirely go and hide into the rubber tube.
1-2 Or use a prefabricated flared tube for the same purpose.
1-3 You can make your own flared tube using a piece of old telescopic antenna with adequate diameter with the cutting and flaring tools (more details can be found in the internet).
Step 9: Instructions: - 2 - Adapt the Pump to the Tube.
2- Adapt the pump to the tube.
Step 10: Instructions: - 3 - Fix the Pump With the Rubber Tube.
3 - Make about 20 turns of good sewing thread on the neck of the pump, then use a small drop of adhesive on the produced fixing ring.
Step 11: Instructions: - 4 - Make Another Ring on the Beginning of the Tube.
4 - It’s better to make another ring from the thread on the beginning of the tube near the pump.
Then test the foot switch in place before going for shrink.
Step 12: Instructions: - 5 - Go Shrink.
5- Use the adequate heat shrinkable tube diameter and the Heat Gun to fix everything together and to hide the entire neck of the pump (Cosmetic – durability).
Note that I fixed the nut not to loose by adding extra ring of string to the other end of the rubber tube, see the illustrations.
As I mentioned before the shrinkable tube will shrink to the written value (usually to 50% of the diameter). and it's better to test a small piece of shrink before application in place.
Now the pump can be used by hand, but if we need to convert it to a pedal pump then follow the next steps.
N.B By the way there is a lot of videos which teach you how to use heat shrink tube with heat gun. also I embedded a video in www.youtube.com for the whole procedure.
But I suggest you to read until you reach the last page then go for the video.
Step 13: Instructions: - 6 - Making the Plastic Base of the Pump
6 - Making Plastic Base (Pedal):
Keep the pump attached to the appliance or close the other end of the rubber tube to hold pressure inside the pump.
Now we are going to make a bed of the pedal into the base:
press 3rd the way on the pump and there is several ways to take the impression, then to fabricate the plastic base using manual saw, or LASER cutting machines, I will show that by the illustrations.