Hatchet 2

I couldn't be bothered to trawl back through to find the original thread for hatchet so here's a brand new spiffy one for you. Decided i may as well build a new hatchet and at least try and get it to the champs this year if it gets picked, with that in mind i've taken a good month or so of design time trying to keep what was good and discard the rest. The only real thing that i've kept the same is the axe and scoop set up, the shape is roughly the same with a few improvements (nicer looking bulkheads, better weight distribution/wheel placement and a slightly bigger chassis). the new body is now 20mm thick Hdpe with a 10mm base seeing as i got a really good deal on some offcuts that i just couldn't say no to. I don't want to overload you all with information at this point so here's a couple of teaser pics to make the reading worthwhile.
http://i921.photobucket.com/albums/a...25211307_n.jpghttp://i921.photobucket.com/albums/a...68693854_n.jpghttp://i921.photobucket.com/albums/a...30645616_n.jpgand yes.......it's white now... big whoop you want a fight about it?

Cut all of the panels out for the new Hatchet this morning, i still have to do the baseplate but i've had enough of getting covered in swarf for today. I quite like it in white although i'm not sure i'll keep the pointy bits at the top of the bulkheads. http://i921.photobucket.com/albums/a...91574115_n.jpghttp://i921.photobucket.com/albums/a...18484030_n.jpghttp://i921.photobucket.com/albums/a...10780775_n.jpg

Where did you find chopping boards that thick lol :)

Looks good

Cheers David, it's not chopping boards it's proper hdpe from direct plastics. Chopping boards tend to be ldpe which shatters when it gets impacted.

Cut out the baseplate for Hatchet today, by hand...which sucked, it's 10mm Hdpe this year instead of the 10mm Polycarb which, well let's say it didn't work and leave it at that shall we? (Mr mangle come at me bro). If you noticed the gaping ground cleance around the sides and front it's supposed to be like that..honest, the front part will be covered by the scoop and around the sides i'm hoping that if one side gets lifted up the wheel stays on the ground, that's the plan anyway. Also ditching the chain and sprockets for T10 timing pulleys and belts, the theory being that the belts are stronger and less stretchy/likely to jump off, i'm hoping by using such a large tooth pitch that there isn't a whole lot of slip. http://i921.photobucket.com/albums/a...19221826_n.jpghttp://i921.photobucket.com/albums/a...70980006_n.jpghttp://i921.photobucket.com/albums/a...63820699_n.jpghttp://i921.photobucket.com/albums/a...30880922_n.jpg

I was only kidding about the chopping board, and this is really impressive, I keep checking back to see if you've done any more. Electric axes are the most interesting robots to me as the pneumatic stuff goes over my head so it's nice seeing lecky stuff as it's within reach lol.

Ah okay lol wasn't sure, cheers too, it's certainly not the most advanced robot around but it should be a massive improvement on last years Hatchet. I like to think I've ironed out most of the flaws and should end up with a machine that is at least slightly competitive.

What are the full specs of the axe? Length, head weight, motor, ratio etc?

Would be interesting to see what it's like in comparison to others

Alex still has the original but from memory the axe was around 400mm and weighed around 1.5kg, the head is 6mm Hardox 450. As for the power specs it's going to be run by a 300w scooter motor at 6s on a 3.3:1 reduction. Last year it was a 3.5:1 reduction on 16.8v NIMH so it should pack a much bigger punch this time around.

Did you find it hard to get a timing pulley setup that worked with your existing motor output and axe drive shaft and stuff? Oh...sorry for being a pain...which esc are you using for the scooter motor?

No need to apologise, you learn by asking. The big pulley I got from Harry at the champs last year, it needs modding to make it fit a 20mm shaft but that won't take too long. The pulley for the scooter motor i'm getting from http://www.beltingonline.com/ and I'll get them to bore out the centre hole to 8mm to fit the output shaft of the motor. I'll be using the same 30a Electronize I used for the axe last year, although I have a 60a victor as a spare.

Got the drill motors for the drive yesterday and set about hacking them into usable drive motors, I'll include the link for anybody who wants it because they were a great little find. They're bosch psr 18v drills which are usually around £60 brand new and i got them for £12.50 each, granted there's no battery included but if you're only after the motor and gearbox it's no problem. A couple of things i've discovered about them, firstly they don't have all metal gears which although annoying isn't too much of a problem, they are really compact..like stupidly compact and the output shaft is tiny which means it's very unlikely to bend. The motors are 600 sized Johnsons rather than your standard cheapo chinese 550 which considering the price is even better, also the build quality seems pretty solid, better than standard drills anyway. Some bad points though, the GB and motor are not attached yet the holes to mount the motors are there, it's like they forgot to put the screws in.....weird right? Also the chucks are on TIGHT, after some advice and a fair bit of head scratching i figured out a pretty fool proof way of removing them, you take the gearbox apart and get a round piece of steel in some pliers and wedge that in between the pins on the carrier plate, then you put a fairly big allen key in the chuck and twist the two in opposite directions, takes a fair bit of force but it does get the chucks off. Wow i just wrote a whole essay on my drive motors, anyway for any that are interested here's the link http://www.ebay.co.uk/itm/331196477100

And some pictures
http://i921.photobucket.com/albums/a...75937265_n.jpghttp://i921.photobucket.com/albums/a...91962400_n.jpghttp://i921.photobucket.com/albums/a...ps7f6c0fe9.jpghttp://i921.photobucket.com/albums/a...37866124_n.jpg

Those look pretty good for drive! I'll be interested to see how they run.

Starting bolting the body together today, i forgot how much tapping into Hdpe sucks. I managed to duff up on of the holes for one side panel so i'll have to remake that. Other than that everything is straight and the whole chassis just seems so much stronger this time around, I've also brought a piece of 5mm 6082 Alu to brace the rear corners with seeing as how the 3mm cheese grade i used last year held up so well. If all goes to plan i should have a completed chassis by early next week.

http://i921.photobucket.com/albums/a...30646152_n.jpghttp://i921.photobucket.com/albums/a...76973929_n.jpghttp://i921.photobucket.com/albums/a...05953867_n.jpghttp://i921.photobucket.com/albums/a...79374803_n.jpg

That looks really neat and tidy, almost machined. I have aspergers with duff motor skills so shake like hell doing anything like this, being that neat is only something i can dream of.

I've got a big pull down circular saw that I use to cut hdpe, means I can get it neat and fairly accurate. If you ever need any bits cutting drop me a PM, as long as you supply the material and pay postage I'm more than happy to do it.

More progress on Hatchet, managed to get most of the body bolted together before i ran out of bolts (well that was silly wasn't it). I've also managed to somehow lose any kind of countersink bit so until the new one turns up they all just kind of stick out. Other than that though it's going together really well, i might actually have a working robot well before Whitwick which will be it's first outing.

http://i921.photobucket.com/albums/a...37394117_n.jpghttp://i921.photobucket.com/albums/a...10388969_n.jpghttp://i921.photobucket.com/albums/a...84966815_n.jpghttp://i921.photobucket.com/albums/a...16766039_n.jpg

Updates!

It's been a productive week or so for me, after finding out that Hatchet is in the World Champs i decided to throw myself into finishing it so i have plenty of time for testing, but first i needed to buy the old robot back from Alex...so that's what i did. Ian was kind enough to drop it down on his way to Robochallenge and i quickly set about removing anything of use, this included the axe, scoop, 3 30a Electronize and a Park BEC. I then decided to leave the old girl alone and focus on the new one, i ordered a crap load of parts, 2 2200mah lipo's ( 5 and 6s), 2 new 8mm sprockets (8 and 40 tooth), some heavy duty 8mm chain, a brand new 300w scooter motor and an Imax B6 charger. With my bank account feeling the full force of a robot induced craze i set about working on the actual robot, as i'm still waiting for a few bits and pieces to come i haven't got as far as i had hoped but Hey 3 months is loads of time right......? The drives have been mounted, one bulkhead has been cut to accommodate the axe motor and all holes are thoroughly counter sunk. If you managed to sit through all of that well done you.....here's some pics for your trouble.

http://i921.photobucket.com/albums/a...71988906_n.jpghttp://i921.photobucket.com/albums/a...93411307_n.jpghttp://i921.photobucket.com/albums/a...69218642_n.jpghttp://i921.photobucket.com/albums/a...64481732_n.jpghttp://i921.photobucket.com/albums/a...34737369_n.jpghttp://i921.photobucket.com/albums/a...80712389_n.jpg

Huge amount of progress today, got the scooter motor and axe set up mounted and finished off the electronics. The electronize for the drive may be going in favor of some borrowed Tz85's from Hardwired 2 (thank you Matt). I did manage a little axe test at 5s and a couple of things became apparent, the weapon is much more powerful than last year causing the machine to jump violently when it fires, the sprocket on them motor however has a habit of coming off, there's a grub screw holding it on and it keeps letting go. To hopefully fix this i've ground a flat on the shaft and used massive amounts of Loctite to hopefully keep the screw in place.

http://i921.photobucket.com/albums/a...86568034_n.jpghttp://i921.photobucket.com/albums/a...93659928_n.jpghttp://i921.photobucket.com/albums/a...28545160_n.jpg

If the grub screw still fails, try drilling & tapping the hole for a larger screw - the bigger the better! Also use a fine pitched thread as they are harder to work loose.

Similar to Nick said, however I tend to drill a through hole and then get a bolt with a straight shank to push through with a nut on the other side. It takes a lot of the stress out of the shaft that tapping puts in.

ready to kick ass and chew bubble gum...

And I'm all out of gum

On a side note Hatchet broke itself, the troublesome grub screw that I thought I had fixed decided it would carry on turning on the shaft regardless of how tight it was and has just cut a massive gouge all the way round. I'm working on trying to have the sprocket welded on but that may have to wait a while, the axe is out of commission for now though.

That's a shame, weld the pinion on and it'll sort it.

Or upgrade to a Magmotor. That would also work...

You're really pushing that Magmotor aha, I've ordered a 350w scooter motor instead of 300 for a bit more power though, a welded on pinion should hold.

Keyway?

The new motor shaft is threaded with a flat, would cutting a keyway in the sprocket and then tightening a nut on the end of the shaft to stop it slipping off hold do you think?

Weld the end and be done with it :)

Did you get one of those geared 350w motors? I recall that style of shaft on them. They have a lot of power but be careful as they are low inductance motors.

No it's not one of the geared ones just the normal mahoosive motor, I think I will just weld the pinion on if I can get it done, seems the least hassle.

Hatchet's all up and running again after the whole *grubscrew eating the motor shaft* thing, had the sprocket welded onto a new motor (350w this time instead of 300) and that seems to have sorted it. Managed a little video, just to clear it up the axe doesn't actually hit the floor because it's travel is stopped by the front bulkhead about 5mm from the ground. https://www.facebook.com/video.php?v=346043228929766

Can't see that, can you upload it to youtube?

Seconded

Can't get the video link to upload it seeing as it was uploaded by someone else, I'll get another video some point this week.

For those who couldn't view the other video http://vid921.photobucket.com/albums...pszuyjpzbj.mp4

That's 6s with a 350w motor, the chain is a bit too tight ATM but it'll slacken off.

Looks like my upgrades to the old chassis are surviving well enough, hehe

That axe has got quite a bit more kick, both for that extra 50W and the 6S power. You can really give things a proper thump this time round!

It's got some pretty big gouges in it and the motor protection you put on is a different shape now, it's definitely got more kick this time around but It could do with a tail or something to stop it hopping around so much.

Haven't updated this in a while, Hatchet is about 90% done as it currently stands. Since my last post it's had barrel nuts put into the chassis in every bolt hole to reduce the risk of stripped threads/bolts being pulled out, the wheel guards have been put on, the rear Aluminium bracing has been attached and all of the wiring has been redone to make it simpler and neater. The Deans connectors have gone in favor of Xt60's and the Electronize for firing the axe has been replaced with a Victor 885, this has made the axe response much faster and it is now a much more effective weapon. If anything though the weapon has too much power for it's own good, the force from the axe has actually pulled the motor forward by twisting the mounting bracket, the chain was a little too tight and that probably didn't help but now it's slackened off a bit the problem hopefully won't get any worse. Not much left to do now, just needs a set of drive esc's (borrowing some tz85's), a lid, a cradle and the LED strip needs wiring in ( you can see the wires it needs attaching to in one of the pictures).

If you managed to sit and read all of that well done, here is you reward......

http://i921.photobucket.com/albums/a...psac4b6zir.jpghttp://i921.photobucket.com/albums/a...pssuerc3j3.jpghttp://i921.photobucket.com/albums/a...pslrzwnp0z.jpghttp://i921.photobucket.com/albums/a...pscgrqzlf7.jpghttp://vid921.photobucket.com/albums...psqdsaqkni.mp4

I fancy one of these new style Black n Decker work mates that double up as an ironing board...

Short update nothing too major, finally got round to some of the little jobs i've been putting off on Hatchet. The LED strip has been installed, looks rather nice against the white hdpe, padded out the lipo bay and velcro'd the shit out of anything that needed it.

Also managed a little bit of testing at 6s, it's pretty damn scary. Rather than type out what happened, why don't i just show you eh?

Short clip of the axe pounding an old bucket
https://www.facebook.com/video.php?v...50101088258859

And it's first ever self righting test, all i can say...is what the actual hell
https://www.facebook.com/video.php?v...34219223308485

http://i921.photobucket.com/albums/a...psshrnttqr.jpg

axe looks insanely quick