Tashic's Robots

https://www.youtube.com/watch?v=w53VoBPa844

http://s1355.photobucket.com/user/Th...37810.jpg.html

Very brittle indeed. I do recall Sam changed it to HDPE after that, and had no problems afterwards with the strength... so take that how you will!

The base of Hatchet is now 10mm HDPE rather than 10mm Polycarb. Its been clobbered by so many robots, even direct hits from Battleaxe, and its still fine. Go with HDPE.

On the other hand if you won't be fighting in full combat events with this then polycarb will be fine. And you can make spares for bits likely to suffer if it's cheap and sourced close to home. Polycarb shatters, but only in high speed impacts.

I went on the assumption it was a spinner-proof design! Yeah, non-spinner events should put up with polycarbonate well enough and if you can get replacements easily it may be cheaper. What's the weight density like of Polycarb and HDPE, are they around the same?

Because if so, it's always possible you could build with what's to hand and then remake the same parts in HDPE in the future if you choose to go to a full combat event, that's possible I suppose!

HDPE is lighter so that works out well. About 0.95g/cm3, vs polycarb's 1.21g/cm3.

Yesterday I sent an email to direct plastics to see if sending to italy is possible, I'm now waiting a respones.

Only if that fails I will use polycarb, and not only I can get that near home, but they can also cut the parts for me.

But I hope to get the HDPE instead.

Bit late but still, Polycarb isn't the best material to use as you can see from Hatchet, to put it into perspective that was a 10mm thick piece that shattered into 3 pieces from just landing on top of a spinner at about half it's throttle. If it's all you can get hold of and you don't plan on using it in spinner combat it will be fine but hdpe is the better option both for impact resistance and weight. Also with regards to the axe motor I'd recommend running it slightly higher, I ran Hatchet's at 16.8v and that swung a 1.5kg axe with a fair bit of force so it depends on how heavy yours is, if it's on the lighter side then you might need the extra speed you'd get from a voltage increase, lastly if you're planning to use chain and sprockets stay away from the 6mm stuff and go for the 8mm, Hatchet broke a chain in almost every fight and it gets a bit annoying having to replace/fix chains all of the time.

Hi, I might found a way of getting the HDPE, for now I got 2 new drills to add to the ones in Black Wood, now I need to know what capacity the battery needs to be, since a friend of mine is ordering from hobby king.
Is this one fine?:http://www.hobbyking.com/hobbyking/s...case_pack.html
later is going to be the weapon motor.

A lot of feathers do with just 2000 to 3000mah packs.

5000mah will be more than you need. Bulls it runs on one and can do 2 fights easily on them while using the big s900's.
With that 20c rating you'll be able to safely pull a 100a without damaging your Lipo and a pair of drill motors won't draw that much.

If you've got the weight to use that one comfortably go for it, or look for another with an higher C rating. Should you add a scooter motor for an axe or upgrade your drives it will help to be able to draw even more amps.

I ran HW2 on an almost identical pack (just a higher C rate, everything else was the same) and I barely even had to charge it after each fight, and that has two Speed 900 style motors in it. My driving style hardly involves me going easy on the throttle either!

It depends on how you are for weight and size really as Niels said, if you have plenty of weight left over that couldn't reasonably used for added armour or anything, go for it - it's much handier to have that bigger capacity than have to be worrying with a low capacity pack. And if you take part in any events that are in the style of this year's Gladiator tournament at the UK FW Champs, you'll be at a much bigger advantage than usual too!

On HDPE, I can supply the stuff easely enough. But P&P is an additional cost from Belgium. PM me about sizes and cost.

Hi all!
I will pm you when I solved some other things.
Meanwhile what material should I make the base?
I'm thinking of steel, but what thickness?

A full steel baseplate is heavy. Thinner than 2mm is just waiting to be crumbled like a tin can.

Best case is to use 3.2mm Hardox, still the weight of steel, but way stronger.
A sheet of 200*200*3.2mm weights 1 kg. An avarage feather is 300*400mm, resulting in 3 kg baseplate.

Did some testing these last few days, by making this platform:
Attachment 5078Attachment 5079
the motor holders are made out of 3mm steel, if it turns out to be too heavy, I might make them out of HDPE.
The wheels are made using slices of go-kart tyres which I screwed them to the wheels:
Attachment 5080Attachment 5081
The go-kart rubber is very grippy! When I try to push the robot, the wheels don't slide but they turn the motors.
The problem is that leaving them this wide, the wheels aren't perfectly round, but they flex with the weight.

Also the scooter motor had arrived, and I will do some tests on that later.

Updates:

Started the build by getting the base and making the axe mechanism:
Attachment 5117Attachment 5118Attachment 5119Attachment 5120

Right now it weights 8,5kg including the axe, the gear ratio for it is 5:1, having on the handle 55 teeth and on the motor 11.
The base is 2,5mm steel and the dimentions are 315mm X 370mm not counting the slots for the wheels.

This is what (hopefully) it's going to look:
Attachment 5121

I decided to make a lower body (kind of looks like K2 now), to save weight, and the scooter motor is closer to the center:
Attachment 5122

I will think of a cover for it later.

Thats a real nice drivetrain there. Will be interesting to see the robot finished.

So, some time ago I found a place to get the HDPE from italy, and 2 days ago I ordered some sheets.
I thought that the parcel would arrive next week, but after school I found them in the living room:

Attachment 5166
Wow they look chunkier than I thought!!:eek:

They are two 20mm black sheets and two 10mm white (they only sell the 20mm sheets in black).
I only really need one of each but I wanted some more to use them when needed.
So hopefully I will make some progress these days.

One more thing, what insert do you use and how you "insert" them in the HDPE?

Edit:
Little bit of progress, I made the supports for the axe out of wood, after I made some modifications to the very cheap jigsaw:
Attachment 5167Attachment 5168Attachment 5169
I also need to shorten the chain, like a lot! Which means some spares.

Also about the inserts, are these good?:
Attachment 5170

Or I need ones without the lip?

Nice progress mate. Look forward to seeing the finished robot. Might want a bigger shaft on the axe though? What size is the current one?

Thanks, the shaft is 1cm diameter.

Yeah you probably want a bit more on that. Maybe try for 20mm if you can manage it? I don't own an axe bot myself but I seem to recall Hatchet's shaft being 15-20mm...

Onyx's shaft is 12mm silver steel and it has gradually bent over time. Not to the point of making the axe inoperable, but enough to make it a pain to take apart/get back together. We're talking about a 1 year period and a lot of axe hits though, so it's not an instant problem, but I'd say 15mm would be a more comfortable size.

Hatchet axe has a 20mm shaft , and the handle double layer steel tube with the bigger tube 1" heavy gauge steampipe.

I agree with people's comments about the shaft I'd definitely increase the diameter just to be safe, Hatchet's is just as Mario said and is really strong and really well made but it's overkill for overkills sake.

Depending on how powerful your axe is you may have issues with the 6mm chain snapping like I did last year, the 8mm stuff is much stronger and handles the new Hatchet's set up no problem despite it being much more powerful, may be a worthwhile upgrade to be on the safe side.

Robot looks great though I can't wait to see it going, are you planning on coming to any UK events with it?

Thanks, shouldn't be difficult to upgrade the shaft.

And yes I plan to bring it someday to the UK, Sam.

More progress:

Progress has been very slow, because school manages to be stressful even if we don't do anything most of the time:
Attachment 5229
The axe head is (of course) not final, it's just a piece of HDPE that looked like an axe after I made the parts.
Attachment 5230
The bulkheads and the motor are fixed to the base, today I made the front pannel.

Also a question, what you use to cut HDPE?
I used a rubbish, el cheapo jigsaw, that has a very wobbly blade, so I made some modifications that made a very small difference.
This is the cut on the front plate:
Attachment 5231
It was actually worse than this, the blade tended to turn to the right.

I use different means to cut it. Jigsaw, disk saw, even an anglegrinder (melts the stuff, not clean nor good to welded it.)

I've used an angle grinder to cut to cut it before, works okay but it does tend to melt it a little bit and it's really messy. Personally i use a chop saw with a wood ripping blade, nice clean, accurate cuts but if that's not within your means a grinder will work fine.

Also just a thought, you might want to shorten the axe shaft quite a bit, it's make it less likely to bend and you'll get a faster weapon because your axe head will be closer to the pivot point.

A bit more progress:

The front HDPE pannel is bolted to the supports and the base, and I fitted the chain and did a selfrighting test:

https://www.youtube.com/watch?v=_UfS7IHn-10

Also did a test on a small metal container, and this is the result:

Attachment 5269Attachment 5270

Will see how it will perform with an axe head.

And yes, I will shorten the axe.

Small update:

front and back has been cut and bolted:
Attachment 5378Attachment 5379Attachment 5380

Now for the sides and then start with the steel! (And very likely weight shaving)

That looks awesome man, sort of got a whiff of Hatchet about it but 4wd and sleeker. It's actually eerily similar to how the new Hatchet was going to be, can't wait to see it going.

Little drive test:
https://www.youtube.com/watch?v=npOWzjtGlWA

Servos and microswitches with 2 12 cell NiCd packs, one for each side.

Continued the build, by adding front and side armour:
http://www.fightingrobots.co.uk/atta...tid=5480&stc=1http://www.fightingrobots.co.uk/atta...tid=5481&stc=1
I still need to add bolts.

Now the problem is that at this stage I'm 1kg short of the weight limit, and I still need a top cover and electronics.
So when you fing that your robot is overweight, or is going to be over weight, what do you do?
Also how people make their drill motor mounts and how much they weight?

Moar progress, about time...

http://www.fightingrobots.co.uk/atta...tid=5618&stc=1http://www.fightingrobots.co.uk/atta...tid=5619&stc=1

Other than the obvious top cover (10mm HDPE), I replaced the base with 3mm aluminium, and the mounts are now 10mm HDPE too, so now I have 2Kg for the electronics and battery, plus other things to remove for the axe, but that's for later.

Tz85's from hobbyking, and I'm thinking of a 5s 4000mAh lipo battery, 4s is probably not enough to self right.
I'll then need to build a box for said battery and ESCs.

As the motors are rated only for 12V, can I just reduce the travel on my TX to save them?

You're a really talented builder. That's fucking ace!

You can definitely rate limit your radio to reduce motor heating but with 12V motors running on 14.8V, its probably not necessary. A 4AH battery seems way too large for a non-spinner; it doesn't hurt to have extra capacity but you can save weight & money with a smaller pack. Without knowing much about your bot, I'd guess a 2.5AH pack is probably enough.

The battery is going to be 5s, so 18.5V, and apparently I keep overestimating how much capacity the robot needs.

Also Harry, the robot isn't precisely built, pretty much everything is wonky and not straight if you look carefully, but it's still functional and I like it overall ;).