Berzerker - undercutting bar spinner - 2010

[Metal Demons]

OK...a lot of hassle later, including a burglary - here goes the build thread! Sadly the brushless drumbot project got wrecked by having a toolbox holding most of the metal parts for the damn thing - including the very nicely machined drum done by Kenny (ALK Engineering) - stolen by some burglars. Thankfully insurance paid out - that and I feel better off at the moment - so it's time to go ahead! Here's the start of the build thread (requested by Dave):



Basically - T shaped spinning bar undercutter powered by two brushless motors, swinging a bar up to 800mm long (the bar in the above CAD renders is 700mm). The weapon drive is by a 90 degree twisted timing belt - by rule of thumb the belt should be long enough not to jump, especially with wider pulleys and flanges.

The rest of the bot is pretty straightforward - a couple of rock crawler motors run through 16:1 planetary gearboxes to the wheels, which should move it about nicely, RC helicopter gyro to stabilise it against the spinup torque of the weapon, and a whole bunch of batteries; I'm leaning in the direction of a small lipo pack to run the drives with A123s on the weapon for the insane 70c burst current they can deliver (that, and they're a lot cheaper than the huge lipo packs I'd need to run the weapon).

Most of the chassis will be heat bent grade 5 Ti of various thicknesses; work on that will start after the New Year

[grant_ploughbot]

Sorry to hear your drun and other parts were stolen - but this new design does sound pretty awesome
Good luck with it!

[calumco]

no way really sorry to hear that, after all that work on it and the drum aswell

but the new robot is lookin just as good

good luck with it

[Metal Demons]

Just ordered a section of S7 tool steel bar stock which will become the weapon bar...

[Mouldy]

Should be nasty with 3 times the energy of 360 .. But why are you using S7? Its pretty soft.

[Metal Demons]

Should be nasty with 3 times the energy of 360 .. But why are you using S7? Its pretty soft.

Only going to harden to 54hrc, true... does the job though, far, far cheaper than more exotic steels. I'd rather get the thing working asap with a simple pocketed bar weapon, and upgrade later at some point with a Ti bar/Ali or Mg stiffener/counterweighted single tooth in a harder steel... but I can't be arsed to FEA impact analyse everything to see if it will work (especially as my software is crap) right before term starts again. : S7 just has such a high impact strength compared to a lot of steels that it's a lot easier to get away with.

[swanaldo]

Nick.....i am probably the most foul mouthed person you will ever meet but i do refrain from using bad language on this forum.

Can you please do the same.

[Metal Demons]

Sorry mate, won't happen again

Got the Ti and all (3mm and 6.25mm, grade 5) and will be getting the chassis heat bent on a press brake soonish...

Got a nice block of 7075 to be machined into the weapon mount also. Soon as I get some parts actually finished, oh yes there will be photos

[Metal Demons]

OKAY, time to resurrect this! Finals rather took over my life this spring/summer, and I've been on holiday for a week afterwards, but now it's time to get down to actually building something

First lot of parts came off the waterjet today, so here goes a shot of the internal layout - brushless escs and a couple more little batteries excluded as those bolt to the sides of the frame (which STILL NEEDS TO BE WELDED UP but that'll be done next week or so). You'll be able to see how this section all fits in if you take a peek at some of the renderings in my first post.



Yeah, the gearboxes haven't been assembled and bolted down because I've lost my tin of grease and they'll have to come off anyway when putting the frame on...

Hmm, I wonder what's under that front strip? :twisted:


After all, big spinning things need power...

Oh, and here's the beginnings of a little 3lb robot - yeah, another spinner! It's going to have a little Scorpion motor running a horizontal blade off a timing belt drive, you'll probably be able to work out how it'll look pretty easily...

[Mouldy]

Looking Really good! Welcome to the stupid world of overpowered brushless spinners lol Be interesting to see how bad the voltage sags on the a123's with the castle link software.