Thread: Ensign Wedgeley Crusher (FW Sportsman)

24th-25th January (days 7-8 )
The two sources of panic for this week (alongside the general “there’s still essentially a whole robot to build aaaaagh” panic) were:

1. The OrangeRx receiver seemingly throwing some kind of wobbly. I initially thought the FeatherTwo had died, which would’ve been game-over at this point. I posted about this on the forum and reached a state of “this will probably be OK” thanks to everyone else’s reassurances.
2. Fuses. I ordered a bolt-down fuse from RS, and after a long boring series of mixups by RS I eventually determined that I would not receive it in time. A lack of fuse would’ve meant a failed tech check and long, sad journey home. Fortunately, VW used to use bolt down strip fuses, and my local autoparts shop had a few 80A ones in stock. I don’t think the guy behind the counter quite knew what to make of my joyous celebration at the sight of 3 strip fuses….

With that final component in place, I was finally able to sort out the wiring. At this point I should say, I made absolutely zero consideration of the harness layout inside the robot when sizing the box at the back. It was just “approx size of a battery + a bit”. I’m used to working with 20 or maybe 18 awg wire which takes up no space. 12 and 14 awg does not bend nearly as much. It didn’t help that I forgot quite how big SB50 connectors are (that's what I used for the link).
In the end it all JUST fit in, but there wasn’t much space to spare and some of the wiring was curved rather more than I’d have liked. I used ring terminals and M5 bolts glued into the base to keep everything secure.

It was a late addition to strap the battery on to the lid of the electrics compartment; that was basically the only way to fit it in, but in retrospect I like the outcome because it adds some “poke-yoke” safety to the setup - basically to remove the lid, you have to disconnect the battery, so you can’t forget to unplug it when opening up and leave something live by accident.
Note the extremely shoddy addition of safety lights from the drills; these are only legal because the lid doesn’t fit properly, so they shine out of the gap at the back:



Next job was to plug some actual motors into everything and see if they turned the right way.
SUCCESS! The drive worked.
DISASTER! The worm motor for the weapon didn’t do anything.
A quick spot of fault-finding revealed that the relay was switching, the power supply to the switch was fine, and the motor still worked when plugged into something else. That narrowed it down to the connections in the relay. I took a wild guess at how I thought the switch was meant to work, soldered a bit of wire in place, and struck gold! We now had a fully functioning electrical system.

26th January (day 9)
This was crunch time - the day before Robodojo. We were staying nearby overnight so had to travel up this evening. At this point we had no components for the weapon system other than the motor, so there was still plenty to do.

First job for me was to cut and drill out the mounts for the motor. This went slightly better than last time, as I only drilled *most* of the holes in the wrong place. I need to work on my measuring and marking skills. Untidy as it was, with some extra clearance it all fitted together, and gratifyingly both were wrong in the same way so at least the two piece matched up.

Meanwhile, Becky and Simon were cutting and fixing the remaining HDPE sections, and making the front prong that forms the lower jaw of the weapon. This was originally meant to be made of steel but we decided given the time available that HDPE was all we could manage in the time available.

The final fiddly job was to make the two bosses that fit the weapon gearmotor shafts. These came from more bits that I rescued from the scrap bin at work - I just had to drill out an 8mm hole down the centre, then drill and tap three M5 holes in each (one as a set screw to fit the D shaft of the motor, two to attach the upper jaw.

Having gotten all that sorted, all that remained was the aforementioned upper jaw. At this point it was probably getting on for 7 PM, so again fabricating it out of steel was not on the cards, as was cutting up stud to make metal teeth. The original plan of an extra wide jaw went out of the window, and I just cut two HDPE jaws on the bandsaw, with a largely aesthetic pattern of teeth.
Still, shortly after 7:30 PM on Saturday, nearly 13 hours full before tech checks started, we had something resembling a completed robot:
DSC_0579.jpg

Quite a lot of wonky bits and some bits that straight up didn’t fit properly, but it was finished and it operated! Note I didn't say "worked", as that would imply it was effective in some way. I think the cradle was the only thing I was truly happy with...

All that remained was to go home, eat dinner, pack and still get to the pub before last orders, which we just managed (it was a close thing thanks to an accident on the M1 and some bad advice from google maps).