Sourcing Components

This page is to collect useful links and so on to make it easier to source components.

Parts list and part export

The SketchUp file holds most of the information about the design. There's a ruby export script (in the cad directory) that you can install as a plugin. It will generate the parts list (CAD/parts_list.md) with one part per line. The start of each part identifies what it is:

• Assembly: generally composed of a number of named parts, included in one of the other categories
• Part: a component that you need to purchase (or, in a couple of cases, make).
• Fixing: nuts & bolts
• Panel: a laser-cut piece - these were originally laser cut from 3mm polycarbonate, though PMMA is OK.

The exporter will also export DXF files for all the "panel" parts to allow easy laser cutting. If there are any parts you're not sure of, check them out in the sketchup file; it's easiest to find things in the "outliner" (as of the September 2017 version, you access it with Window > Default Tray > Outliner).

The "delrin plates" were machined from plastic (Delrin), and the feet were machined from rubber (though we've successfully 3D printed them). NB the delrin parts show up as panels, but they are not laser cut. The delrin parts can be approximated by stacking several sheets of laser cut plastic though.

Beams and fixings

OpenBeam can be bought from quite a few places - for example Technobots. They probably also sell the M3 screws, nuts, motors, and bearings. NB the screws are listed in the bill of materials twice - once on their own, and once as part of the "screw with nut" assembly. That means that you need only order the number of screws listed - you don't need to add in the "screw with nut" number as well.

Parts list, annotated

• 1x Assembly - Heater Elements

This is the only "Assembly" that isn't listed elsewhere as "Parts", panels or fixings. Ceramic heaters are removed from a fan heater that runs off a car cigarette lighter socket (there are loads of clones on ebay and amazon).

• 2x Part - 60mm Fan

This should be 15mm thick to fit nicely. Can be ordered from RS/Farnell/Mouser etc. or pinched from electronic junk.

• 1x Part - Arduino DUE
• 1x Part - Arduino Metro
• 1x Part - Arduino Shield

Only one Arduino is needed in the electronics module at the back - but there are 2 in the parts list. If you use servo motors with encoders, you might need to add another microcontroller to deal with that (this was mounted between the motors, on top of the device).

• 2x Part - DC MotorWith Encoder
• 2x Part - Servo Motor

DC Servomotors are a good alternative to steppers if you need smooth motion and can afford the higher price. Originally we used a arduino stepper motor shield but latterly converted to DC motors with encoders - using this driver and these motors

• 1x Part - DFROBOT USB Touch Screen

I think this is optional (?)

• 1x Part - Choc Bloc

Buy from your favourite electronics shop!

• 2x Part - DS18B20 Temperature Sensor

Actually 4 or 5 of these are good. You may want to get the waterproof ones if you will use high humidity. There are lots of people selling them on eBay/similar, just search the model number. They're really neat because they can all be on a single one wire bus. You can autodiscover them (todo: link to script)

• 2x Part - Fan Blades

Fan blades are part of the fan and not needed separately

• 1x Part - Flap Servo
• 1x Part - Servo Horn

A small servo motor - check the sketchup file for dimensions

• 2x Part - Back Foot

• 2x Part - Front Foot These were machined from rubber, though they could be 3D printed. Rubber is good for stability and vibration damping.

• 1x Part - HDMI Flat 90

• 1x Part - HDMI Plug

The "flat 90" is used to bring the Raspberry Pi HDMI port out of the box - otherwise you have to plug an HDMI cable into the bottom of the assembly, which is inconvenient. Pay attention to the picture when you order it though - because the HDMI connector is not reversible, there are right- and left-handed versions of this and you need to make sure you get the right one... The plug is part of the Raspberry Pi assembly and doesn't need to be purchased.

• 1x Part - Header 1x15
• 1x Part - Header 1x15#1
• 1x Part - Header 2x3

The above headers are actually part of an Arduino and not something you need to buy!

• 1x Part - Humidity Tube
• 1x Part - Inlet Tube Horizontal
• 1x Part - Inlet Tube Vertical
• 1x Part - Outlet Tube Horizontal
• 1x Part - Outlet Tube Vertical
• 4x Part - Tube Coupler
• 2x Part - Tube Elbow
• 1x Part - Small Fogger

See the Sketchup file for details: any tubing about the right size should do, the original used a 90 degree fitting designed for water cooling systems for PCs. The fogger is easily found for around £10 on eBay - search for "ultrasonic fogger". Many of them have "atmospheric" LEDs on them, the one pictured doesn't, but either should still work.

• 2x Part - M8 Lead Screw
• 2x Part - Shaft Coupler

Depending on the shaft coupler you use, the shaft is 265-275mm long. If you want to use a 5mm-5mm coupler, you can turn down one end to 5mm on a lathe if you have one.

• 1x Part - Motor Driver

This will depend on whether you use stepper motors or servos - a "CNC Shield" (eBay) is probably a good first attempt if you're using steppers.

• 2x Part - Nema 17 stepper motor

Buy this from your favourite robot shop!

• 2x Part - OpenBeam Bearing Mount
• 2x Part - 608 skate bearing

The bearing and bearing mount can be bought in a single package from Technobots or other OpenBeam retailers.

• 1x Part - PSU

The original was a Seasonic SS-250SU

• 1x Part - Raspberry Pi Camera
• 1x Part - Raspberry Pi Model B
• 1x Part - Relay Board
• 1x Part - USB OTG Cable

Other Stuff

You'll probably want a load cell to measure force. These are often pricey (£1-200) but Active Robots sell uncalibrated, much cheaper ones. Rob used this load cell (only ~£10). There's a range of max loads on there if you search the store. We used it with this ADC (available at Maplin and others)