Although [Simon Boak] had no use for an automatic paper tape punch, this was one of those intrusive project thoughts that had to be put to rest. With not a lot of DIY projects to look at, the first step was to prototype a punch mechanism that would work reliably. This involved the machining of a block of aluminium with holes at the right locations for the punch (HSS rods) to push through and create holes into the paper without distortions. Next was to automate this process.
To drive the punches, 12V solenoids were selected, but using leverage to not require the solenoids to provide all the force directly. On the electronics side this then left designing a PCB with the solenoid drivers and an Arduino Nano-style board as the brains, all of which including the Arduino source can be found on GitHub. Much like with commercial tape punch machines, this unit receives the data stream via the serial port (and optional parallel port), with the pattern punched into the 1″ paper tape.
One issue was finding blank paper tape, for which [Simon] cut up rolls of thermal paper using a 3D-printed rig with appropriately installed sharp blades. This paper tape seems to work quite well so far, albeit with the compromise that due to the current drawn by each solenoid (~1.7A) only one solenoid gets activated at any time. This makes it slower than commercial punch machines.
Thanks to [Tim] for the tip.
The retro computer community needed something like this. While DIY paper tape readers are pretty common, punches being a much harder problem are not. Well done.
The paper (and mylar) tape itself is getting somewhat scarce and expensive. I’ve built tape readers by adding new electronics to industrial mechs, and I’ve built a few readers from scratch, but this project would be beyond me. I hope that someone picks it up and builds up a kit to sell.
It’s mentioned that this punch is slowed down somewhat because the solenoids don’t fire at once. My two commercial DSI punches work up to 300 baud with, not surprisingly, big-a transformers, a bridge or two, and big capacitors. They don’t make ’em like they used to, because no one could afford it!
There are some mylar based wide format inkjet papers out there that would probably work much better for this because receipt paper, even if they have reduced PFAs, usually still have it in the coating.
At least this is what my label supplier told me last week. Almost all of the new commercial stuff you find still has the bad chemicals, but it has an encapsulation layer above it to keep it from shedding in your pockets.
Funny you mention the BIG-A transformers… There is a real reason why a lot of retro kit has BIG-A transformers and huge linear supplies with giant capacitors and heatsinks. The current draw on a lot of this stuff is/was quite large. Giant unregulated power supplies that could supply 10’s of amps are not uncommon in a lot of older gear in this category! Over the years, they gradually became switchers, but still massive and heavy!
I think that some praise should be given to the quality of the build. The details such as the wiring, and how the enclosure is built including the fascinating mechanics, are a true feast for the eyes. The Step model on git really allows to appreciate the work done.
I am probably older than you and used to work for AT&T Telegraph in Atlanta, Georgia. I had significant experience with paper tape readers and punches and your project is very impressive. Beautiful work!
blank tape is getting very hard to find these days. original punch paper had a lubricant infused to not wear down the punch block so fast. it is also very strong and smooth.
Would Tyvek house wrap work?
dang, he really beat everyone to the punch
Not clear to me from the web posting…
Where do the index holes come from? Is there a dedicated punch/solenoid for this?
That’s right – punch #4 is a smaller one for the index holes
I can only see the pictures and hear the sound, but from the sound it does not seem to be quite up to the speed of the classics.
I know how the old stuff sounds from curiousmarc’s channel on YT
her’s a classic puncher: https://youtu.be/yzulZaJbdUU?t=649
That video also has images from the service manual on how some parts work and it’s interesting to see.
It seems to pre-set a whole line of holes to be punched and then punch the character in one go from what I gather.
Lots of bit of paper flying all over the place in the video.
I would build it like a rotary press, with a big flywheel to run the punches and the solenoids just to enable/disable individual punches. The flywheel could be synchronized to the paper feed (for which I would use a Geneva wheel and feed dogs, like a sewing machine).