Portable Arduino Workbench Part 1

Having multiple projects in flight means that I soon get disorganised and the picture of my desk shows just what can happen. Not only this desk, I've a cabin which ends up in a similar state and a wood workshop to, though that is tidier, power tools and mess ends badly. I'm also getting older and my eyesight is getting poorer, so things get mislaid and in the confusion, temporarily get lost. The reason my desk is covered, is because I carry bits of a project indoors, then outdoors, then take them somewhere else, all the time loosing things, or having to try carrying multiple bits, one finger for each.

To address this, a few weeks ago I decided to build a simple carry case for a project or two, with built in power, breadboards and meters which wasn't expensive, and that would fulfil 90% of a projects requirements, and of course, easily portable from place to place.

Part 1 just covers the box. I built two to start with, both very similar designs, but with a different lid design. There is nothing clever about this box, the design is 20x23cm internal, glued together and then a hinge, clasp, handle and feet added. If a wider box is required the 25cm external width can be extended to the required size, 25cm was chosen by me as it would fit on a desk easily.

The list of supplies is to build the wooden box, some of the offcuts can be reused but its suggested that a similar amount of plywood is purchased to fit out the internals and to experiment with different layouts.

9mm plywood 25cm wide by 122cm long

1 strap handle, less than 25cm long

8 rubber feet (only four required if the box isn't going to be stackable)

piano hinge, about 20cm wide

clasp

Short 1cm screws for fittings

2cm screws for fixing the sides together if needed

wood glue

The ply cutting sheet is in the attached pdf.

The cutting list and an example board layout is as follows. I've used 9mm ply but if you have a different thickness that isn't an issue as all the joints are external butt joints. This is a rough box build not cabinet making.

2 x 25cm x 20cm for base and lid

2 x 10cm x 25cm for hinge side

1 x 25cm x 2 cm for rear lid

1 x 25 cm x 18cm for rear base

2 x 20cm x 20cm for sides (these will each be cut into two to make the lid profile)

If you have access to a table saw these are easy to cut up and some wood stores will cut these up for you if you ask, usually for a small charge. They are unlikely to cut the lid profile though, that you will probably need to do yourself.

Have a piece of sand paper on hand and lightly sand off any cut edges to prevent splinters, sometimes the cut is clean, but its no fun picking bits of sharp wood out of your fingers. Ultimately I intend to varnish these boxes which will help prevent further splinters.

I've done two lid profiles. Being a project box, the idea is that all the project stays inside the box, so the lid will hold the assembled electronics, breadboard etc, and the base will hold the power supply, meters etc as well as the loose components. As the breadboard needs to be easily accessible, the lid profile has to facilitate easy access.

My first profile was a straight diagonal. I'd already decided that the edge of the lid would be 2cm, so it was just a case of cutting a straight line across the side pieces from 2cm down to 10cm down and job done. This is easiest to do but does mean that the sides can encroach on the access to the breadboards. The second lid profile is curved, with a low front which then curves up to the rear. I actually like this profile better but it takes more cutting effort. The curved profile was measured by drawing a centre line across the side panel and then using a can to give the curves.

The straight diagonal can be marked on the wood and cut straight across, either with a hand saw or a power saw.

The curved shape can be cut with a fret or coping saw, but I was able to cut it with a power band saw. For the curved line, printing it out on paper and transferring the profile to the wood with pencil before cutting works well.

The box goes together as two separate pieces, lid and base, so mark all the components as to where they are going to fit, base or lid, left or right, front or back and do a trial assembly. If you have clamps this is much easier.

For my first box, I used both wood glue and screws. First drilling screw holes in the edge, then applying the glue to an edge, and finally fixing them together with screws. This worked very well but a bit fiddly.

Having found that the glue was very strong in my case, the second box was glued and clamped which was much easier to do and appears to be just as strong.

Now you have two halves of the box, they need to be joined together with the piano hinge. Cut a length of hinge with screw holes evenly spaced at each end and fold the hinge flat against the box joint between the two 10cm panels and use short 1cm screws to fix. Marking the screw holes with a sharp point beforehand will make putting the screws in easier.

At the other side of the box, the clasp has to be fitted. Fit the hook on the short 2cm lid section first, using short 1cm screws, and then with the loop of the clasp over hook, pull the top and bottom of box together and mark where the centre of the screw holes lies. Release the loop and put a hole about 1mm under this position to put the screw in and fix the clasp there. This ensures that when the clasp is closed it will have a small amount of tension to hold the lid down.

On the base, measure an equal distance in from the four corners so that the rubber feet you have chosen just touch the edges of the box and screw the feet on.

On the lid fit the strap handle across the centre of the box lid from side to side, centring it up across the length.so that it will carry easily.

Fit four more rubber feet to the lid, measuring an extra 'foot' width in from the front and rear so that when two boxes are stacked, the feet overlap. These extra feet will ensure that the lid sits evenly when open.

I've already fitted an IEC socket/fuse/switch to one of the boxes for its internal power supply and will be adding more in part 2.

The box/carry case aspect of this could be used for anything, but these pictures show a trial fitting of the basic PSU, mains and 12V battery supplies, and where the project is going next. Part 2 will be adding extra features to start making it useful as an Arduino/Raspberry Pi workbench, adding the PSU, power switches, sockets etc.