Rigid Robotics Build Diary - Flat Damon

[lowndsy]

Flat Damon had a slight delay because it turns out angle grinding plastic throws molten globs of nastiness all around the room and in your face. I did one side but gave up before I went blind.

It took a surprisingly long time to find safety goggles in Stoke, but now I have them I'll be able to permanently mount both motors tonight, then measure up to order the belt and pulleys. I might even permanently stick the chassis together and start adding the bracing (PP chopping board) to make it super rigid.

[Tim The Plumber]

LOL!!

You can just use a hacksaw or something.

[RogueTwoRobots]

Get yourself a jigsaw, hacksaw or standard wood saw. You'll have more success and less molten plastic globules everywhere!

[lowndsy]

Where would be the fun in that? Seriously though, I do have most of those tools, but the snake attachment on my mini angle grinder grinder is the only way to reach certain angles. The rest was done with a jumbo wood saw.

Anyhow, all cutting done now, no injuries.

[lowndsy]

Bit of progress, Flat Damon is now a rolling chassis and I am halfway through cutting up countless strips of PP for the bracing. I also found a huge sheet of plastic that would be perfect for one of the armour layers, but it is cable tied to the side of my building advertising some new flats.

I need to start thinking about speed controllers to get Flat Damon actually moving. I had my eye on a dual controller on amazon that looked perfect, but delivery would have taken ages and I'd have expected more people to be using them if they were that good.

The obvious solution would have been a couple of BotBitz 30As off Ranglebox but they're out of stock. Anyone got any suggestions? Still on a budget so I can't drop £150 on escs just yet. I'll go with NIMH on the batteries for now to avoid, erm, explosions.

[Ellis]

Bit of progress, Flat Damon is now a rolling chassis and I am halfway through cutting up countless strips of PP for the bracing. I also found a huge sheet of plastic that would be perfect for one of the armour layers, but it is cable tied to the side of my building advertising some new flats.

I need to start thinking about speed controllers to get Flat Damon actually moving. I had my eye on a dual controller on amazon that looked perfect, but delivery would have taken ages and I'd have expected more people to be using them if they were that good.

The obvious solution would have been a couple of BotBitz 30As off Ranglebox but they're out of stock. Anyone got any suggestions? Still on a budget so I can't drop £150 on escs just yet. I'll go with NIMH on the batteries for now to avoid, erm, explosions.

I've sent you a pm.

[lowndsy]

Right. Escs might be sorted so while I wait on them I am ready to mount the armour.

I have a lot of mass behind it so I am still deciding whether to go for the normal hdpe or stiffer polypropylene.

When I mount with bolts and rivets I'm going to add some adhesive too. I have some polyurethanes, but could silicon help absorb shocks or would it be too thin to matter?

[maddox10]

HDPE is impossible to glue. Polypropylene almost impossible.

Silicone glue as shock absorber, if used as glue, not thick enough. If used as shockmounting, not useable as glue.

[lowndsy]

Ah, I won't bother then! I have some 3m sticky tape that is holding HDPE quite nicely while I drill - I'll just use that and a sheet of rubber

[lowndsy]

Been a bit quiet while I settled into my new job and got parts ordered.

I went for HDPE after I saw the price of UHMWPE, so that arrives today. All the interior bracing is done and the frame is super rigid. I read that the bot has to survive been thrown across the room but I didn't want to scratch the paint on my walls so I slung the chassis across Tescos carpark instead. It went > 50 yards and bounced all over the tarmac with no damage so I think it'll be fine. I tried to record it but I accidentally threw my phone 50 yards too. It also survived, but I didn't want to try that again. The chassis and drill motors weigh in at 3.5 kg so it'll be pretty solid with all the HDPE bolted to it. From a thread last week it sounds like Flat Damon will be MASSIVE compared to other bots, but I quite like that!

The connection from my motor to the wheel was looking lovely but despite being a little bit over engineered with pillow bearings and long axles I wasn't sure how it would stand up to serious action. It really just needs a big metal plate and lots of bolts. I'm not really equipped for metalworking so I picked up Matts S900 drivetrain from the for sale forum. I might transplant it over, or try to copy it and save the bits for bot number 2. The only way to make space for the larger motors will be the angle grinder again. They should arrive today as well so it'll be a busy weekend of screwing and bolting. The motors put me over budget on this build, but not massively so.

I ordered a cheapo esc for testing. It is a dual unit which I really like the idea of - not sure why. I imagine I'll swap it out for a more standard solutions like the Botbitz ones before Flat Damon gets in a scrap, but the community seems to be a bit busy getting ready for the next RW series atm so I can wait.

All that is left is batteries, wiring and maybe new wheels to suit the new motors.

[lowndsy]

OK, unless someone tells me otherwise, here is my battery choice. 14.8V 4S, 2200mah. Not the most Amp hours, but it fits in the space in my chassis and I can always have a spare on charge.

https://www.wirelessmadness.com/over...attery-ol-2568

I would consider an Optipower with the FRA discount, but quite frankly I can't understand their website or find any products on it.

[cjsowry]

I'm just ahead of you with my first build. got mine moving the other week, a very surreal moment. I'm using a 4s lipo too, despite the norm being 5s. It shifts surprisingly well and the 12v motors don't get hot till after a good 10/15 minutes play time! Regarding esc I'm using hobbywing quicrun duel something. Cheap enough from China via ebay, about £20. Was looking at raglebox and the 85amp one, good esc's but too pricey at the moment with building on a tight budget.
Got any more pictures of your bot to show??

[maddox10]

4S ain't that abnormal for a feather.
Hannibalito and Kashei are both running on 4S.
Valkiri 2 ran on 4S

[lowndsy]

Ha! I bought that same hobbywing esc for my MFA drill motors. Mine only has one 3 pin input from the receiver though - how did you wire yours up?

That was before I got some used s900 motors - I'm not sure if that esc / battery combo work for these bigger motors yet. The motors are in pretty beat up condition anyway so I need to have a think about which ones I use.

Anyone know the best way to connect the battery terminals back on to a motor? quite a few of them have sheared off at the base, just held on by silicon. Do I have to disassemble the motor and pull the plastic off the back or can I just sort of dig into it and solder?

[cjsowry]

Using the same bullet connectors that came with the esc to the motor. Soldered some xt60 connectors to the battery. Via a removable link and some splitters to power the two drive esc's and a third weapon esc. The receiver but just plugs in, my hobbywing quicrun 's have built in BEC so it powers the receiver direct off the esc.

All this is untested in combat, but driving around outside everything works well. Just waiting on a sprocket so I can finish my lifter. Been two weeks now, time for a snotty email me thinks.

When I get home i can upload a video to show you. Might make more sense than my ramblings.