Tt3d its science, if you take notes.

It has been about a year since my last attempt at building a functional touch slider that works with custom Project Diva controllers but its back! It was a combination of seeing a 18×24″ piece of single sided copper clad FR4 in my amazon recommended bar, not wanting to invest $1000 into developing a hobbyweight Combat Robot, and a new copper sensor layout idea that I saw on a datasheet.

I knew from my last “attempt” that a lot had to change. The three main things were to significantly shorted the traces from sensor pad to MPR121, less gap between sensor pads, and to zig-zag the sensors allowing for better contact on multiple pads while also increasing overall width. With these criteria in mind, I went to Inventor and whipped up a few sketches of different patterns and imported to CorelDraw.


After filling in the bits that needed filling in, I set the whole file to inverse color and I was ready for the laser cutter. For anyone following along at home, this is the image to use if you want to attempt your own. If you have CorelDraw, I can give you the native file to import instead of using the JPEG below.

For anyone not familiar with making a PCB with a laser cutter, it is done by spraying the entire board with paint, and etching away the negative of your copper layout. After a little cleaning with rubbing alcohol, the whole board is etched in ferric chloride. For anyone following along at home, my laser settings on an Epilog 40W laser were speed 5% and power 10%. My next attempt will probably be 12-15% to remove a little more on those thin traces between the contacts, two were bridged after etching.

I got some base code to work off of from Reddit user u/Fatso666 and modified it to work with all four sensors. Did a little cleanup and it’s working! I unplugged the middle four arrows for the time being to plug into the Arduino that is hiding underneath the controller and taped a box behind to hold up the slider but everything registers without issue. I will still be working to revise the code to operate smoother and more efficient. I may try to possibly add code for tracking LEDs up top just like the real cabinet but I don’t want to get ahead of myself just yet.

This project all started when Tom Cohen gave me a 1:9.4 scale Higgs Farm Rocket kit and I knew I had to make it just a little bit better. I designed the trailers basic shape in CAD using photographs of it as reference. The frame is welded from 1/2″ steel tubing and the tower arm is made from steel rods welded to shape. I used a linear actuator from Actuonix to raise and lower the tower. The rocket rides on a 10x10mm maker beam and micro rail buttons which are basically just nylon 2-56 pan head screws. The wheels and covers are 3D printed from HIPS plastic with rubber tires from my local hobby store. Finishing the build is a 1:10 scale RC Suzuki Jimny which does a decent job of pulling the trailer weighing three times as much.

The mini trailer at MDRAs Red Glare 2018 was well received with many people asking if the tower really lifts and taking videos of it doing so. The Higgs Rocket was launched on an E-30 composite motor which scooted a lot faster than I thought it would. Luckily a fellow rocketeer picked it up from the other side of the ditch saving me a long recovery walk.

As many people who have sold on Craigslist before know, the majority of messages you will receive are less than legitimate. Unfortunately for those who are new to online selling, the red flags which are clear to many will go undetected to the less experienced. I received one such message and decided to enter the eye of the storm. I responded to one of these scammers and pretended to be someone interested in the offer made in the name of science.

This is what I will call the first contact. In this message the scammer will ask if the bike is still available. It was at this point that something was off as MOTORCYCLE and SALE were capitalized which seemed a bit strange. I responded letting him know it was available and received a second message soon after. At this point I knew it was a scam as I had a very detailed Craigslist post with price and condition including all the service I had performed on it in the past year. The scammer clearly had not read the post and likely got my phone number from an automated bot. Because I knew what he was going to tell me next I gave him a price almost an order of magnitude over the listed price, a whopping $13,500.

He agrees. His next message is the meat of the scam and I will explain how it works. The scammer will send a fake check to you for a larger amount than the price you just gave. In my case I was sent a check for $16,550. The reasoning for the additional money is because you are responsible to pay the shippers in cash for your own bike to be stolen. Sometimes the scammer will also tell you that any money left over from the shipping costs is yours to keep. The result is you lose your bike and transport costs to the shippers which gets delivered right to the scammer.

Keep in mind that I said fake check. You will be mailed a check that looks very real and even passes the security features listed on the back of the check. The checks are often from real accounts so your bank will put the listed amount in your account and you will believe that you actually received the money. Reality sets in a week to a month later when the fraudulent check is discovered and the funds are removed and you find yourself in a possible lawsuit for passing a counterfeit check. Due to this very real possibility, I covered up the company name and all numbers on the check.

So where does this leave me? I still have my bike and when the scammer asks for the address for bike pickup, I will be giving the address of the local police department. Will this stop the scammer? Not a chance as even if I were to find this one and get him arrested on felony charges for sending counterfeit checks through the USPS, the vast quantity of similar internet cretins will just fill in the void. The lesson to take away from this is that dealing in person with buyers and only accepting cash are major factors in preventing a situation like this. There are more variations of this scam and other types entirely such as the VIN check scam or a potential buyer going for a test ride and stealing the bike right there. Be cautious, look for the red flags, and if something seems too good to be true, it probably is.