Fixing the entry gate
How I fixed my father’s entry gate with 3D printing
About a year ago, my father came to me asking for my help. This does not happen often – more like not at all. So, I was very interested in what he needed my help with.
He lives with my mother in a family house, and ever since they moved in (nearly 30 years ago), they have had the same remotely controlled entrance gate. The gate gets stuck from time to time, but Dad can disassemble it and fix it quickly. The gate is 30 years old, so it's more about mechanics than electricity ... Good old times, right?
Once again, it got stuck, so Dad disassembled it to find out what had happened. The three rubber components that had served there for almost 30 years disintegrated on the spot. My father contacted RIB, an Italian company, to send him the spare parts. However, they said they couldn’t because this mechanism is ancient and they no longer make spare parts for it. He would have to replace the entire gate with a new mechanism, which could cost a few thousand euros.
He started thinking and wondered if I could do something about it with my 3D printers. He doesn't know much about 3D printing, so he sent me what he had left of the components. I said I would try to replicate it.
At the time, I was still a newbie in 3D printing and 3D modelling, but it seemed like an interesting project.
What my father gave me was really just a few pieces of rubber, not a one-in-one piece. I started studying the dimensions, measuring them, and thinking about how to create the gears in Fusion 360.
From the way my dad talked on the phone, I didn’t think he held out much hope that it could work out, but replacing the gate just because of such a small, cheap piece would hurt even me.
I searched the internet and found some tutorials on how to make gears. From this tutorial, I probably learned the most and based my work on it; I installed a gear extension in Fusion 360.
I was slightly terrified when I discovered how many attributes can be set on the gear setup. First, I tried to set something randomly and then tuned it further.
I printed out each new setting (only a few millimetres high) and tested how well it fit into those rubber pieces and how well it rotated around them. A few iterations later, I came up with the right combination – or at least I hoped I did.
Then it was easy; I extruded the gear to the right height and added a few details that I saw from the rubber particles, such as the cut at the bottom of the gear.
Because of the lower cut, I printed it with supports. Otherwise, it would not work. Or it would work, but a lot of extra modelling, and I'm lazy.
My father needed a total of three gears for the mechanism in the gate. I printed them in PLA, put them next to the crumbled rubbers, took a picture, and sent it to my father, telling him that I was probably done. It took 'only' all Saturday morning.
My father immediately called me back, and his tone had changed. Suddenly, it looked promising. He said he would come the next day and see if they would fit and if the mechanism would spin.
He arrived, and we put the gears on the poles of the engine he brought with him. They fit perfectly. My father rolled his eyes at me as best he could; he was a little shocked that it worked.
But this was not the end. I don't know much, but I wouldn't put a gear with a small infill and in PLA into the gate engine; it wouldn't end well. I got a little of the PC Blend filament; I was terrified to see if it would work and what I would destroy along the way. PC blend is the next level. I put a big piece of glue on the sheet, heated the printer to practically the maximum, and covered the printer so that nothing would blow on it.
PC Blend tends to peel off the sheet, but what stays is very hard to remove without glue as a separator layer. The print turned out to be a little bit peeled off, but not much, so it was probably ok.
I also checked if the gear had shrunk too much, but it turned out well. By the way, I printed it with almost 100% infill.
Here are the three Graces from PC Blend. They've been working happily at my parents' gate for a year now, and there have been no problems. When the rubber falls apart in the other gates that my parents have, I'm ready to save the day.
