[Question] Ideas on where to build my robot.

[Shakey]

You wouldn't want to gear them down more, they're already on the slow end of drive.

If we take a 2wd bot and a 4wd bot as an example (Most the principles of a 4wd bot apply to tracks). When a 2wd bot turns the wheels just turn and follow the arc of the turn. When a 4wd bot turns the wheels slip sideways as they aren't lined up with the arc, this produces a high turning load as the motors now no longer have to turn the robot but also slide the wheels across the floor to some extent.

So while 2 drill motors will happily move and turn a 2wd bot a 4wd bot is a much bigger challenge and is likely to burn them out. Tracks add to this by having the turning load of 4wd with the extra tension and friction of tracks leading to a very quick death to motors. This is why most drill motored robots that are 4wd use 4 motors as they need more power.

You can do 2 motors for one side off of one esc, a TZ85 will be perfectly happy with 2 drill motors.

One thing with tracks, it's fine if you want to go that route but be warned they offer a lot of extra challenge and unreliability for no considerable gain other than looking cool. :P

[R9000]

Wow, thanks for all the info! Yeah that makes a lot of sense now, considering the centre of rotation is now in between all four wheels, and the tracks will scrape along the floor. I think since I'm going 4WD now, I'll still go with the tracks. I like a challenge, and hopefully if they get too unreliable I can just switch them out for wheels and maintain really decent pushing power.
Again, thanks for all the sage wisdom, I really appreciate it.

[daveimi]

A 2wd drill powered robot will physically push 13.6kg without any problems. They key to out-pushing someone is getting under them and lifting their drive off the floor. Tracks are a world of pain.

[R9000]

They key to out-pushing someone is getting under them and lifting their drive off the floor.

That should be happening too with my robot. :P So are you saying tracks aren't worth it at all? Like I said, I can always switch to wheels retrospectively.

[R9000]

You can do 2 motors for one side off of one esc, a TZ85 will be perfectly happy with 2 drill motors.

I've been looking into the TZ85s today, but the only ones I can find are for brushless motors, and to my knowledge drill motors are brushed. Were you suggesting I mod them to be brushed, or are there brushed TZ85s I haven't seen? I'm also unsure on the current draw from 18v drill motors - could I use an ESC with lower current rating? I checked out Ranglebox, 85A ESCs are sold out but 30A ESCs are in stock.
Here Rapidrory suggested the motors need around 60A, but the thread ended with Giles going for making his own ESCs. I'm not opposed to this, but while I'm not clueless on PWMs, I don't think I have the experience to build a reliable ESC at this point.

[PJ-27]

TZs are brushless ESCs that are commonly 'hacked' to become brushed ESCs.

Ranglebox re-sell the pre-hacked versions, or you can hack them yourself (there's plenty of info on this forum).

[R9000]

Ah yeah, I've found the thread. Thanks!

[daveimi]

By all means build tracks, I meant what I said in a friendly and easy going way For a first build sticking to tried and tested stuff is usually a big help till you find your feet. It sounds crazy but in a way there aren't many positives for tracks other than looking cool and being a bit different. It's added complication and they're really hard to get right. A lot of the basics of robot building use tried and tested methods, and the advice is usually to stick to the tried and tested methods to get the basics and use that as a base to build upon.

[R9000]

Alright, I appreciate the advice, and I'm sure you're 100% correct. At this point, I've already ordered the tracks and sprockets yesterday, but I can always change them out if things get too complicated. Had I not already ordered, I'd probably follow your advice here. I understand what both you and Shakey said, and I don't want to come across as me just ignoring it, especially having no experience. But as it stands I'll give it a try, then I've only got myself to blame if it doesn't work out. Either way, hopefully it'll be an interesting and educational experiment.

[firefly]

Im not the most experienced roboteer either but wouldn't metal tracks have no traction on the metal floors some arenas have? Biteforce (Battlebot champ 2015) I think got round this by putting magnets in the tracks. Feel free to say im completely wrong

[Andy]

It'll probably be rubber tracks that he is using

[firefly]

It'll probably be rubber tracks that he is using

Nope, he said he was going to use Heng Long tracks which are metal

[Andy]

ah, in that case i am not sure either lol

[daveimi]

The tracks are metal segments with rubber studs bolted to the segments.

[firefly]

Ok cool, I see