Controller now integrated inside feeder. Can be used/flashed over usb serial. Also contains rs485 for connecting multiple feeders into same bus(spring pins not visible). 2 motor drivers, 4 buttons and 1 rgb led on top.
It seems that there are lot of interest and expectations about small desktop pnp machines.
I published brdmaker into hackaday to get some feedback and positive drive into my personal project. Also i hoped that it would provide some spark of fuel for others imagination who work with similar projects. Both of those goals are reached over expectations.
Why i started this project?
Decision to start this project was born when i had need to manufacture small patches of pcb boards.
Collecting and sending part kits to overseas for assembly is just too hard way to go.
I wanted to pnp machine that would assemble 100 boards a day, each having few hundreds of parts, meaning that machine does have to be super fast but pretty fast anyway. Also meaning that machine has to be able operate reliably without interruptions.
Also i need to use latest parts that requires machine to be very accurate enough to be able to place those reliably.
It was clear that existing DIY pnp machines without feeders would not survive. I thought that i would need commercial machine.
I did some research and was a bit disappointed that there were not so many machines under 15k price range having double vision, feeders and required accuracy.
When reading interviews found out that CV is very difficult task and all machines are having troubles with it. None on the machines is having support for all of the packages. Also software need be updated often when manufacturer is fixing issues. Updates and support are usually available only to latest machines, so when you machine gets ears you might find yourself with non working machine and only support you get from manufacturer is a phone number of their salesman.
So if the firmware and software would be opensource i could patch the code when needed. Also i would like to experiment new coming manufacturing techniques. But do there exist any commercial machine with opensource software? I could not find any.
Then i found awesome OpenPnp software project. It was having all the needed features and ability add more if needed. Only the proper hardware was missing.
So this is what brdMaker is going to be: fast, accurate, reliable, based on open source software.
First 3 of those never comes for free, so brdMaker probably never find the way to every makers desk, but maybe for somebody who has need to get things done seriously
There is very good support for vacuum sensing in OpenPnp. I finally managed to draw board for the sensor. Sensor(MPS20N0040D-D) sticks directly into vacuum channel. There is op-amp on board as well as 2 HALS for Z height sensing. Going to use SmoothieBoard temperature inputs for the vacuum sensor input.
Hal sensors arrived from TI. They have great sample service provided by Digikey.
I ordered drv5053's that are very basic linear output Hal sensors. After trying different location for detection i ended up to place sensors under the gear driven by the worm gear. After multiple trials i ended up to place 4 of those between every 90 degrees. Magnet was "stick" shape moving on radius between the sensors. Problem was that neodymium magnet was definitely too strong, it was saturating the HAL sensor when getting close. Also setup was very sensitive to many environmental changes. I decided to change setup so that magnet would be less powerful and circular shape having poles on round sides. Also sensors would work in differential mode, 2 sensors in x axle and 2 in y axle. Position angle would be calculated from x,y vectors. Lets continue when magnets arrive.
An an alternative i decided to try to detect holes in in the tape. I placed LTE-302 or something similar and led very close to pickup hole and in correct height to detect the hole location. Also i added another pair 6mm away because smaller parts are placed with 2mm spacing. Photodiode output is fed into analog input so it is quite easy to locate different places of holes by software, begin of hole, end of hole, etc. Did some test when feeding real tape with motor and setup was working very fine. Now it is possible to detect end of tape and stuck tape conditions. Those sensors are probably not working with transparent tape, let's see. Magnetic position sensing is maybe the only way to go with those. Also there is now pcb's on bottom side too. top pcb will be just dummy board acting as a cover and reel holder. Thru plated holes of pcb will act as an bearing for gear axle, tin+copper, steel pair should work well as an bearing.
So the feeder will be 18mm thick 4 layer pcb where 2 axis robot and controller is embedded in the middle insulator layer. Very traditional design..
I know that there are many people out there who would like to experiment with automatic pick and placing.
Photo is from very early openpnp tests. Elektor readers recognize the machine from more than decade ago.
I posted this to show that making working pick and placing machine does not have to be complicated. Only two quickly printed custom parts, if you have some frame like this available.
When you get your feet wet, you start to realize where you want to swim.
It is obvious that up looking camera needs proper lighting to detect alignment of different components.
i did pyramid shaped light(4 pcbs) that each side has 24 pieces of ws2812b, total 96 leds that each can be controlled by color and intensity. Next task is to add support for those into SmoothieBoard.
Plan is to have own bitstream file for every lighting profile. Profiles can be changed by custom G-Codes.
Great that there are so many new people following this project.
There are numerous changes in feeder design.
I decided to leave the concept of placing tape into gear manually. Now tape is inserted and removed always with the motor. Also added small part under the pickup location to push the tape upward. As you some tapes are thicker than another and tape cannot be loose at pickup location.
Also tape now returns from back. Tape has to bend some amount to travel the route and requires some force for pending. Luckily the feeder is very powerful because of transmission, but i think still fast enough.
Cover of the feeder will be controller PCB.
Also started to think how feeders are connected to machine. Plan is to add "back plane" pcb, that will be electric gateway as well as mechanical locators for the feeders. Every feeder has four 4 mm "banana" plugs that will plug into back plane. Those "bananas" are heavy enough to mechanically locate feeders into their place. So there is no need for separate locator pins and connectors.2 pins will provide power and 2 act as an bus (i2c or rs485). Every reader has it's own address an there will be jumpers or dips for setting it.
Some changes are still needed. Pickup location is for example now too "far".
Just drop message if you tips or comments.
Thanks for your support!!
Gear now uses 1.2mm x 20mm nails. Just flat head is cut off with side cutters. With correct size of hole, pins are easy to push in into correct depth. Little screw locking is applied into hole beforehand. Ordered some HAL sensors from TI. When arrives, try to experiment position sensing with those.
Smoothieboiard arrived. Also added separate 3.5A stepper drivers for x & y axles.
Works very well with openpnp after some configuration wonders (creek alphapeths etc).
Also doing now 32 microstepping with full power. Steppers run very Smoothly.
Some calibration is still needed, but generally looks promising.
On clip brdMaker is jogging(0.1mm) on 0.4mm pitch bga pins. Those "big" pads are 0402 what are actually not so big at all.
0.4mm bga is very close to the "state of the art" in pcb technology. Hopefully brdmaker will be placing those soon.
Printed prototype now feeds and peels. Some work is still needed to redefine tape route. Original plan was to guide it downwards, now i would like to guide it backward, under the reel.
Also sensors for position tracking are needed and of course controller.
Current state of design with side opened to see ultra simple interior.
Hit "follow" if want to see more "work in progress" posts.