I Bought a Pick and Place: I Have No Idea What I'm Doing!

| Comments

These are some of my favorite blogs to write. I bought a thing, and I have no idea how it works. I don’t get to write many of these, because I rarely jump directly into the deep end of the swimming pool.

When I bought a 3D printer, the only relevant was goofing around in a pirated copy of 3D Studio Max for MS-DOS sometime around 1994. When I bought my Shapeoko CNC, I was at least a bit more prepared. I model all my 3D-printed parts using OpenSCAD, and I still get to model my 2D parts for the CNC in OpenSCAD. When I bought an electric unicycle, I was more than a little worried that I’d never figure out how to ride it.

I am almost completely unprepared for the LumenPNP. I have never designed a printed circuit board (PCB). I have never soldered tiny surface mount components. The OpenPNP software looks rather terrifying! At least the LumenPNP looks kind of like someone built my Shapeoko XXL out of 3D printer parts, and all three machines speak G-code!

What is a pick and place machine?!

It is a robot! If you’ve seen a 3D printer or a CNC router, then a pick and place will look familiar to you. They’re all CNC machines, and the biggest difference between the three is the tool that they carry. A 3D printer’s tool extrudes plastic, a CNC router’s tool cuts away material, while a pick and place machine’s tool is a vacuum nozzle that picks up and drops off tiny components.

Why would you want to move components around? We have a tiny board with 21 LEDs that we want to manufacture in bulk. We order PCBs from PCBWay. The PCB has the wiring to connect each LED in the correct order, but someone has to install those 21 LEDs in the correct place.

We can pay PCBWay to do this, and if you buy enough units the price is quite reasonable. I can do it by hand, but this is not a good use of my time. I am way too slow.

We decided to buy a robot kit from Opulo pick the LEDs and place them on the boards for us!

How far along are we?!

The open-source LumenPNP kit arrived a little over a month ago. I had the machine assembled and moving around on its own in less than a week. OpenPNP has control of the machine. The cameras are probably calibrated. My machine can very precisely locate its home position using the camera.

I have a stack of 2x5 panels of our OoberLights Micro PCBs on hand. I have 1,000 LEDs. I just have to put some time into following Opulo’s documentation.

How difficult was the LumenPNP kit to assemble?

Putting the LumenPNP kit together was mostly painless, and the documentation was nearly perfect. I’ve never assembled a genuine Prusa MK3, but I have put together older unofficial Prusa i3 printers. I have also assembled a Shapeoko XXL kit.

The LumenPNP fits somewhere in the middle. 3D printers can be a pain to assemble because they are so compact. The LumenPNP is so spread out that you rarely have to do any contortions to get your hands into position to work on something.

It shares that quality with the giant Shapeoko XXL, but the LumenPNP has the advantage that it weighs almost nothing in comparison. I can easily lift the LumenPNP above my head or carry it around the house with one hand. When I move my Shapeoko, I make sure I have help!

It took me the better part of a week to finish the assembly, but I wasn’t working hard. I’d sit down, usually work my way through one entire section of the build guide, then walk away. If I got a bit frustrated, or if my back bothered me from bending over to reach thing, I would just take a break.

What’s next for us?

Do you mean aside from more procrastination?!

I am certain that there’s more calibration to work on. My backlash compensation suggests that I didn’t get my pixels per millimeter correct in my camera calibration. If I’m interpreting things correctly, my backlash might still be off by 0.1 mm or so.

I don’t think that’s great, but our Neopixel LEDs are about 2 mm across. I expect these chonky boys to get pulled into place when we reflow the solder if they’re only off by 0.1 mm.

Then I have to learn how to make OpenPNP work with our design files. I think I’m expecting that to be more work than assembling the machine, but I am hoping to be surprised!

Why did we buy a pick and place?

We could have had PCBWay do 100% of the work. Why on Earth would we do this part ourselves! This could be a 2,500 word blog of its own, so I will attempt to keep this to a few paragraphs.

The trouble is in the quantities. For me to be able to sell you an OoberLights Micro module for around $10 or $12, we really need the cost per unit to be down under $3. That means we’d have to buy 1,000 units in a single batch. Then the Butter, What?! team has to hope that enough folks will be interested in buying OoberLights modules.

I’d rather have a $1,200 LumenPNP build, $200 in worthless PCBs, and a reels with 21,000 unused Neopixels than have a box with $2,400 in unsold OoberLights Micros. I could get most of my money back from the LEDs, and I bet the pick and place would be easy to sell.

What if we want to make a slightly larger board with one more ring of LEDs? If we are relying on PCBWay to do all the work for us, then we have to buy about 1,000 units of those boards. That is a financial risk.

Having the LumenPNP on hand will allow us to be much more agile. We already have LEDs on hand. We can just spend another $100 on a stack of larger PCBs, pick and place a few panels, and see how it goes. No need to spend $2,000 to $3,000 to see if people are interested in buying the larger panels.

This is awesome.

Final thoughts

We still have a long way to go, but I am super excited! We have a new robot. We have all the things we need to feed it materials to create exciting parts for us. All we have to do is convince me to keep plugging away at it!

I am excited that we didn’t have to spend $2,500 and hope that an order of 1,000 OoberLights Micro boards would arrive in working condition, and I am even more excited that we don’t have to hope and pray that we sell 1,000 boards. I am excited to see how this all works out for us!