Boring Brick

[mrsam]

Had a chance today to sit down and draw up some design ideas for Hatchet 2 and also priced up the majority if parts that i'll need and overall it's not too bad if you consider i have almost a year to build it. The new look chassis design i have is radical to say the least and makes Hatchet 1 look a bit boring in comparison, i'll be keeping that under wraps though until i start building. Here's a list of the specs i'm currently considering..

4mm Aluminium Baseplate
20mm Hdpe bulkheads with 8-10mm Hdpe bent and wrapped around the whole body in a single piece
15mm nylon axe bulkheads with bushings/bearings to really free the axe up
5s 2650mah 65 - 130c Turnigy nano tech lipo, don't believe the rating for a second but it's a good price
Tz85 drive speed controllers
12v drill motors for the drive, still not ready to fork out for gimsons although i'll see what money is like.
Same axe as before but much more powerful, 5 - 6:1 reduction instead of 3.5:1 and 8mm chain rather than 6, couple that with the higher voltage and the switch to lipo and i think i'll have an awesome weapon.
80mm wheels this time rather than 100 as i feel they were a little exposed this year.

Let me know what you think

[mrsam]

I'm thinking about some 18v drills but a dual battery set up might be a good idea, the 30 amp electronize i'm using for the axe is 24v max and a 6s lipo fully charged is around 25ish, i know that No Toy runs that set up but his axe runs on a bigger ratio with smaller gear motors so maybe it's easier on the ESC that way, besides the way that Hatchet's axe ran on the current ratio on just 16.8v Nimh proves that it has the power already so if i increase the ratio slightly and up the voltage to 5s i reckon it'll have more than enough power without being over the top.

[Flag Captured]

Well, you've got the weight (and space, if you buy the right ones) for a dual battery setup, maybe 4/5s drive, 6s axe? The only worry would be overvolting the drills too much, they're not the most reliable things in the world as far as I remember... If you've got 18v drill motors though, go nuts!

[mrsam]

If i can get Hatchet running by then i'll definitely try my best to get up there, it's not much more than an hour on the train so it's possible. I've watched the gladiator battle back and that 18v battery made the axe look really powerful so at least a 5s lipo will be going in, if not 6s, it depends what this version can handle.

[Flag Captured]

It does! Really compliments the whole look! Well, if that really was what caused the motor to go kaput, you're the only person to have caused terminal damage to HardWired this year! The motor still ran somehow but I think it was running at stall mostly. I was just feathering it but I was still technically mobile I guess!

And I definitely will be going to Barnsley, it's literally 15 minutes away haha - hope you can make it up too! We definitely need that 1V1! Hopefully I'll have sussed HardWired's traction issues by then so we'll be able to have a proper old scrap!

[mrsam]

Yeah the scoop looks awesome, definitely a keeper! that grub screw was probably one of the ones that got left on my bench which were undersized so i didn't use them, that's about the most damage Hatchet did to a robot aha. I really hope i can make it to Barnsley with Hatchet as you said you were going to go i want that 1 on 1 with Hardwired!

[Flag Captured]

Just have the chassis made out of 7mm Hardox, that'll protect it!

Seriously though, it's a very solid machine and with some upgrades it'll be very strong. In any case, it looks rather mean with that scoop - I can't believe it actually fit, and I'm rather glad I brought it down for you now haha! Just need to fit a 5S LiPo, check up/replace your drive motors and improve the transmission on the axe and that'll be quite a formidable opponent!

Also, regarding your wheels... Remember how I said a motor went? I shook it to see if there was any loose parts of the magnets or whatever and there was a small m4 grub screw in there. How that happened, I have no idea, but I guess that solves two mysteries of the champs! I'd guess it was when I did the wheel change on mine, probably managed to pick it up on that little bit of grease that ended up on the gears...

[mrsam]

Quick video of Hatchet post champs, filmed this yesterday but it's taken forever to upload http://s921.photobucket.com/user/mrs...3ca13.mp4.html

[mrsam]

Yeah that would be great Nick, since the Binky fight having some kind of protection for the motor seems a must, it got too close to taking it out

[overkill]

Not that you needed it this time, but I can post some photos on battle-hardening those scooter motors so they are a bit more shockproof.

[mrsam]

The wheels would screw onto the shaft tight as usual but then as soon as the robot was in the arena they would just spin on the shaft and not tighten up, not really sure why but it may be because the grub screws went early on and i didn't have spares. In terms of grip what had actually happened was that the tread had worn down so much that the screws holding it on were proud above the rubber hence no grip, but i only discovered this once i got it back for a proper strip down. As for the base material i'm still undecided, the 10mm Hdpe baseplate that was made at the event has held up brilliantly but i still think 10mm for a baseplate is too thick.

Edit: also just noticed your bit about the axe motor Matt, the current motor is more than powerful enough, if you think about it it's a 24v motor which i was running at 16.8v and it still had enough power to swing Hatchet's axe enough to break the chain on the axe several times. It definitely needs to be protected though and that is something that ill address in the next one, just some Hdpe bent around it with a heat gun would probably be adequate.

[Flag Captured]

The wheels are acting up? How do they act up? The only thing I can see is lack of grip by the compound of the tyre used.
That seems also the issue with the wheels of Hardwired. I'm going to look into that, as several other machines use the same tyre.

The wheels appeared to not quite have enough grip on the floor, but I think that might have been a clearance issue, they did slip on the shafts after some damage though, I have a feeling there's a locking screw gone loose on it somewhere, but I didn't have too close a look at the wheels...

I think the biggest problem with HardWired's wheels is purely that they spun so fast that there was no way they could get grip. I put it in he arena with Massacre's bar taped above the wheels and run it on low speed, with a lower charge on the battery and it seems to solve some of the problems. The biggest thing I found was wear though, mine wore out after only 2/3 fights, but that's most likely because of the fast spinning.

Hatchets problems appeared to stem from the baseplate issue and it beaching itself I think but I could be wrong!

[maddox10]

Same base of hubs as the ones used in Defector. Shouldn't slip on the shafts.
Maybe adding a setscrew grabbing the shaft could help.

[overkill]

The threads on the wheel hubs looked pretty stripped to me; I saw the wheels just spinning on the gearbox shafts at times.

Perhaps rather than a 5mm baseplate, some vertical ali plates or L sections would be better - it seemed that the bot was flexing after impacts and then the frame was scraping on the floor.

If you use threaded inserts (a good idea IMHO), make them as deep as possible to prevent pull-out.

[maddox10]

After rereading the large post.

Is it an option to use alineas next time? Makes it a tad more easy to read.

On the ali baseplate. 5mm ali = 12mm HDPE in weight. 5 mm Ali bends, 10mm HDPE flexes.

Upgrade to LiPo, easy weight, saves money, and is the new standard. LiFePo4 is fine too, and has the advantage of being allowed to be recharged in the robot.

The wheels are acting up? How do they act up? The only thing I can see is lack of grip by the compound of the tyre used.
That seems also the issue with the wheels of Hardwired. I'm going to look into that, as several other machines use the same tyre.

The scoop. It was ment to be active, that's why there are axles in there. Making it heavier than needed. Nothing an anglegrinder and a welder can't solve tough. For a passive scoop you want one solid back/mounting plate.

More axes... if I find the time...