Introduction: Pick and Place Machine

I have a small electronics design and manufacturing business and originally built my circuit boards by hand. As the volume grew I had two options: have someone else make the boards, or, become more efficient and keep making them myself. The volume was too small to interest assembly houses so I figured out how to become more efficient.

My original board manufacturing consisted of using a compressed air-powered dispenser to put solder paste on a board. I then used a vacuum attachment to pick up the surface mount components and place them on the board.

My first improvement consisted of getting stencils so that I could apply the solder paste to a board with a single swipe of a squeegee, however I continued to place the components by hand.

When I was touring board manufacturers, I saw their pick and place machines. These were huge things, roughly the size of a small van, and cost 100's of thousands of dollars. Surely there was something smaller for the prototyping market. I searched for desktop pick and place machines and found this:

Sparkfun CHMT36VA

I have been a Sparkfun customer for many years and trusted their comments on the machine. I looked for additional reviews and instructional videos and found quite a few. I didn't see anything that dissuaded me from trying this machine. I emailed Charmhigh to get the current price and payment instructions. A week after I sent the payment, a DHL truck showed up with a forklift and placed a crate on the floor of my garage.

This Instructable describes my experience setting up and using the Charmhigh CHMT36VA desktop pick and place machine.

Step 1: Unboxing

Here are the obligatory unboxing pictures.

The machine is well padded and secured by fitted foam. The cardboard box contains cables, parts, and some paperwork. The parts box contains the nozzles, allen wrenches, grease, camera alignment tool, IC tray mounting hardware, spare o rings, and a spare pull pin and pull pin solenoid.

In order to get the machine to my basement shop, I had to remove the parts reel assembly so it would fit through the doors and down the stairs. In the course of removing the reel assembly I discovered some sharp edges on the metal plates on the ends. I disassembled it and filed and sanded all the edges of the two metal plates. I added a coat of beeswax to the plates before I put them back together.

Step 2: Setup

The day before the machine arrived I got an email from Kim Liu at Charmhigh. This included links to videos in YouTube. These videos, and some from Jerry Walker, prepared me to set up the machine. I had already downloaded the manual and studied it before buying, and I reviewed it again as I set up the machine.

Other than removing cable ties and foam packing from the machine, there is little to do to prepare it. Two cables connect to a computer, a laptop in my case. Software is provided on a USB memory stick. I didn't have any trouble connecting, loading software and running diagnostics.

Charmhigh recommends placing the machine on a sturdy surface. I placed mine on an old oak dining table that I had modified with piano casters. The casters allow me to get to all sides of the machine if I need to, and roll it against the wall to save space. The casters also help to absorb some of the motion of the table when the machine is running.

Next I loaded my reels. There is a video that shows how. For my first board I needed only 4 reels and an IC tray for the CPU.

I didn't have an IC tray to mount with the included hardware. Instead, I designed one and 3D printed it. The bed of the machine has a pattern of M5 threaded holes and I designed the tray so I could easily fasten it to the bed.

The PCB clamp slides along some rods and springs hold the PCB in place. For small boards, it's a good idea to place a spare board at the right side to ensure that the PCB clamp remains square. Otherwise, the right spring will push against the clamp and cant it at an angle. (See 3rd picture.)

With the hardware and supplies all set to go, the machine needs to be programmed. You have to define the layout of the board, the location and size of the reeled parts to be mounted, and the location and size of parts in the IC tray, if any. There is also a feature that lets you populate multiple boards, which is referred to as a batch.

There are 2 ways to do the programming. One method starts with an extract file from your board design software. The Jerry Walker videos show in depth how to do this. With only eight parts per board, I chose to set up the program manually. The Charmhigh videos show how to do this.

Step 3: Running

Once the programming is done, you load the file and run it. There is a single-step option that allows you to go through the file a part at a time to verify the program is correct. You also discover that there are a lot of details to placing a part:

  1. Move the pull pin to the desired part
  2. Lower the pin and pull the tape forward
  3. Position the nozzle over the freshly exposed part
  4. Pick up the part
  5. Move the part over the up-facing camera to find the center and orientation
  6. Rotate the part as needed
  7. Move to the board position
  8. Place it on the board
  9. And repeat.

Compared to placing parts by hand, the machine is quite fast, and accurate. It's mesmerizing to watch.

Step 4: Some Observations

I'm quite pleased with the design and construction of the machine. All the parts are machined well and cleanly. The gears for the belts have three set screws. The main bed or frame is a solid piece of aluminum 10mm (0.4") thick. The stepper motors are beefy NEMA 23's that barely get warm after running all day.

I needed to do very little tuning or adjusting to run my first board. I did run into a few things that took a little research or were not explained in the manual:

Take-Up Reels Tension

While running a job I noticed that some parts were not being placed and the job stopped. The cover tape was not being pulled off after the tape was advanced by the pull pin. This was fixed by tightening the set screws a little on the take-up reels. After loading reels and fastening the cover tape leader to the take-up reels, it's a good idea to manually turn the take-up reel shaft to be sure the reel is tight enough to pull the cover tape back. The machine needs to be off to turn the shaft by hand. The diagnostics panel also has an option for activating the take-up reels.

Stuck Pull Pin

After running a few boards successfully, the machine stopped again because it couldn't pick up parts due to the tape not advancing. I went to the diagnostics screen and discovered the pull pin was not coming down every time I activated it. I contacted Kim Liu at Charmhigh and she suggested replacing the pin with one of the spares, because it might be bent. She sent a picture showing how to remove the solenoid. (See 1st picture.)

I unfastened the two screws, lowered the solenoid and pulled out the pin. Be careful of the spring when you do this as the spring is very delicate and likes to run away and hide! I checked the pin and it didn't seem to be any more bent than the spares. I did notice, however, that when I inserted it into the spare solenoid and pushed it up and down, it would sometimes catch. Close examination of the pins showed a sharp edge on the shoulder near the tip of the pin. See the second picture and the blue mark. I used a marker to color the edge and then used some fine sandpaper to polish it. The removed mark provides evidence of your work and ensures that you've sanded evenly all around the pin. Once I replaced the polished pin in the solenoid, it moved up and down without catching. I reassembled everything and the machine runs fine.

Customer Service

Customer service is excellent. Any questions I had before and after the sale were answered promptly, usually within a few hours.

Step 5: Resources

The Charmhigh web site is here.

In addition to the list of tutorial videos sent by Charmhigh I found the ones from Jerry Walker helpful. He has a series of seven and they go into detail about extracting and modifying a file from your design software. Definitely worth it if you have a boards with a lot of parts that you don't want to set up manually.

Additional videos and reviews can be found by searching on chmt36va and a very similar machine chmt48.