Piclop Bill of Materials

My accumulation of parts for the Piclop build is complete, and here's the Bill of Materials that I've come up with.

Item	Source	Price
Raspberry Pi	Adafruit or MCM Electronics	$35-45
Raspberry Pi camera	Adafruit or MCM Electronics	$25-30
8"/200 mm camera cable	Adafruit	$2
NEMA 17 stepper	EMSL	$15-16
16014 ball bearing	Amazon/WJB	$10
line laser module	AixiZ (on eBay)	$8 each
A4988 stepper driver	MakerGeeks	$10
ULN2003A driver IC	Discount Components Warehouse (on eBay)	$7.49 (for 10)
RasPi HAT protoboard	Adafruit	$5

I already had a few things to start with, including the Raspberry Pi; however, it was the old model B and the availability of the new Raspberry Pi 2 was too much temptation, so I've replaced it. It isn't hard to find a place to buy the Pi 2 but it can be difficult to find one that actually has stock, at least until the manufacturing catches up with demand. In the meantime, if you have a Pi of any flavor it should work fine, and the Pi 2 will be a worthwhile upgrade when they're more readily available. You'll also need the Pi camera of course, which luckily has been out for a while and is easy to get. And in order for it to reach the front of the mount, the cable needs to be a little longer; Adafruit makes an assortment, of which the 8"/200 mm seems to be about right. That could change, though, if it turns out the camera needs to be mounted differently; I also ordered a 12"/300 mm just in case.

The turntable doesn't ask much of the stepper motor used to turn it; the big bearing keeps the friction low even for heavy objects, and prevents binding from the weight being off-center. EDIT: the original version of this article listed two motors that are 48 mm tall, and I've since been told that they won't fit in the Ciclop turntable base. That makes the motor selection a lot more difficult. The motor that remains in the BOM is not the one I'm actually using, but one that I've bought in the past to upgrade a 3D printer and can recommend. However, it is 1.8 degrees per step, or 200 steps per revolution. With standard 1/16th microstepping drivers like the A4988, that means 3200 steps per complete revolution. The default setting for FreeLSS is twice that, 6400 steps, which is most easily obtained by switching to a motor with 0.9 degree per step. They're less common, and I have not yet found someone who sells a 0.9 degree per step motor that's less than 48 mm tall. For reference, the motor I'm using for the Piclop is a Wantai 42BYGH610P2, but the supplier I bought it from is out of stock and doesn't appear to be re-ordering.

The big 16014 bearing is a key feature of the Ciclop turntable design and I think it's an excellent idea. They aren't the easiest things to source, however, with prices ranging from $10 to well over $100. The one I listed was amongst the cheapest I found at $10, though shipping doubled that price. It seems to be well-made and works fine but if you can find one locally you might be able to do better on the total cost.

I did some shopping for laser modules before settling on the ones from AixiZ; they're available from many sources, but I was concerned that most of them don't have the ability to focus the laser optics. In normal use they'd be expected to be used over a considerably longer distance than we'll need for the scanner and without focusing I was afraid they'd produce a blurry line. AixiZ seemed to have a good reputation, and later I heard from Uriah Liggett, creator of FreeLSS and ATLAS, that he likes their modules. One thing that I didn't realize at first is that they're somewhat larger, at 12 mm diameter; the original Ciclop holders were made for 8 mm modules and needed to be redesigned to work with these lasers.

The driver board needs two ICs, the A4988 stepper driver (which is actually a tiny circuit board with the IC and a bunch of other components) and a ULN2003A Darlington array to drive the lasers. Both are widely available; most 3D printers use the A4988 to drive their steppers and if you use RAMPS on your printer you may already have a spare (if you don't, I highly recommend buying one!) I got mine from MakerGeeks since I was ordering other things from them anyway, but they're essentially generic items. The ULN2003A is even more generic, so I picked an eBay seller with a good rating and a decent price, albeit for a pack of 10 chips; I figured I might need spares, and the cost of buying just one was going to be several dollars by the time I paid for shipping from a commercial supplier. I'm hoping to assemble the circuit on the Adafruit protoboard HAT, though it will be tight; I haven't yet tried to wire it.

There are three voltage levels needed for the FreeLSS driver circuit: 12 volts for the stepper motor (via the A4988 driver), 5 volts for the Pi, and 3.3 volts for the laser modules. It's easy to get all three from a modern PC power supply, but I didn't want to have that kind of bulk. For testing, I've been using a supply that I salvaged from some old equipment, capable of 3 amps at both 12 and 5 volts, with a regulator on the protoboard to produce 3.3 volts. For the final product I'll either continue with that supply or just bring 12 volts to the board and use separate regulators for the other two, depending on the real estate that's available.

Of course all the parts needed to be printed, and for that I decided to start with a fresh roll of 1.75 mm PLA; I hate running out partway through a project and having to change colors! For this one I picked MakerGeeks 'Dark as Night' black, one of the filaments that they have started to make in-house. The quality has been excellent and the prints are very nice; the only thing I noticed is that it wants to be a lot hotter than any of the other PLA I use, 225° C rather than the 200° I am used to.