Come Here And Say That Again - build dairy

[RogueTwoRobots]

Robo Challenge arena is 3.6m x 4.8m if I remember rightly.

[mark_m]

Wedge has arrived

The wedge has arrived, the bends look good but its also heavier than expected. Sigh. The '3mm' Hardox (That I was expecting to be around 3.2mm) is actually 3.4mm. I've looked at the different wheel options and I think I can loose enough weight there for this and the motor mistake, fingers crossed...

2017-08-16 14.50.32.jpg2017-08-16 15.00.28.jpg

[mark_m]

build update

mixed progress this week, looking back lots has got done but its not gone that well and its going to be very tight for weight and time. I had a terribly unproductive weekend, making a bunch of mistakes, but the last couple of evenings have gone fairly well.

The closed cell polyethylene foam for the wheels arrived. The density feels about right to me. fairly stiff but with some give and should save 2kg:
2017-08-17 11.27.40.jpg
The lighter batteries also came, they save ~500g:
2017-08-17 19.13.08.jpg
I find it amazing that such small batteries can put out so many amps now. Hopefully these can perform to spec. With this change and the foam tyres, I think I'm about on track to be in weight. fingers crossed.

I've now countersunk the hardox wedge:
2017-08-20 10.37.34.jpg2017-08-19 20.46.32.jpg

machined the foam:
2017-08-22 23.55.13.jpg
made a lightweight plastic hub:
2017-08-22 23.57.57.jpg
trimmed the tread from the kart tyre:
2017-08-22 23.55.28.jpg
then stretched the tyre over the foam:
2017-08-23 00.04.32.jpg
The wheel's overly complicated but is lightweight and I think will do the job. I expect large chunks will get taken out by any spinners it meets but I think that's probably inevitable with big exposed wheels.

I've also machined the thick wall aluminium tube axle to take the wheel bearings and eclips:
2017-08-23 00.06.21.jpg
It doesn't feel substantial enough for such exposed wheels, but I'm hoping the fact the wheels are foam will limit how much force the axle actually sees.

Another little thing I'm trying that I thinks fairly new (which I originally wanted to use on Deadlock): a dual removable link with push button quick release pin:
2017-08-23 00.06.56.jpg
The sprung balls are locked out unless the button is pushed, so the link is locked in.

I've also machined the mounts for the wedge rubber
2017-08-23 00.07.24.jpg

and machined more dense foam to mount the batteries:
2017-08-23 00.08.16.jpg
I rushed this machining, taking much more aggressive cuts than the wheel foam (and forgot to use conventional milling, as that seems to work better on foam), so the finish is really rough but it should do the job.

The mounting brackets have now arrived, so I tried making a little 3d printed jig to help bend them. it worked perfectly for the first bend but then started cracking and yielding and subsequent bends weren't as good. I need to come up with a better way as I've got another 50 to bend...
2017-08-22 16.52.57.jpg

Here's how CHASTA is right now:
2017-08-23 00.28.59.jpg
So, getting there. Progress needs to speed up a little if I'm going to be done in time though.

[Andy]

Very nice work Mark, look forward to seeing it