Rango - Build diary

[Max]

Will there be anything holding together/spaced apart the 2 aluminium bulkheads? Or is it just the back plate and the base?
Looks very solid and precision made though.

[Ellis]

The inner bulkheads are spaced/held together by the 10mm alu motor mount plate (which is slotted into them, you can see the slots), and the 20mm weapon shaft is also structural; it sits 5mm into the bulkheads and has an m10 bolt in either end clamping the whole lot. The hardox wedge is welded solid and will also play a structural roll, hopefully completely locking up the front.

I wish I hadn't needed to use HDPE for this machine, I fear it'll be the root of many problems, but I had to start building with the design I had, and that design still used HDPE. :P

The back is by far the weakest area. It'll be a matter of luck and driving dictating the fate of the bot.

[RogueTwoRobots]

Randy is looking good Ellis
Judging by the slimline profile it might even fit underneath Massacre's blade!

[harry hills]

It doesn't :3

[Ellis]

It doesn't :3

It might after a fight or two though. :P

Jeroen came online and greeted me with some pictures of the machining progress on bits for Rango. I can't really describe how chuffed I am. Give this guy a medal.

First-

-these are the drive shafts that transfer power from the right angle gears to the drive. The gears have keyways, as do the pulleys, and I bought some 3*3 keystock. I am completely doing away with setscrews for Rango in the hope it'll make the drive a tad less unreliable. The shafts are 10mm titanium to try and save some grams.

Second-

-one side of the drum is done, as is the OD. The threaded holes are what clamp the discs to the drum (5x m8 bolts) and the two holes right on the edge of the drum are for pins, intended to take the big stresses. The bolts would probably do the job alone, but this design means the bulk of the energy is stored in the drum, not the discs, so energy has to be transferred through to the tooth tips. The pins will be bits of 10/8mm ti, the drum is 7075T6.

Also visible here is the weapon shaft. The original was going to be 20mm silversteel (I may still use this if I have the weight) but this one, in more 7075, saves some very welcome weight. I had Jeroen make it, as no amount of adjustment will stop my minilathe from cutting a slight taper, which across 4" is a bit more apparent than I'd like.

Lastly,

The half assembled setup. The discs are Creusabro 8000 (cut alongside Harry's weapon bar(s)). For a sense of scale, the drum is 86mm in diameter, the tooth tip covers a 120mm circle.

Once again, Jeroen is the guy behind the machines. I can't wait to get these parts, and I can't wait for the day I might be able to make them myself. For now, that medal really needs to happen.

[overkill]

I would be very wary about using titanium for pins - I tried saving weight with some very expensive Ti bolts and every one of them sheared, where the steel bolts never did. Those steel disks look fantastic, keen to see how they rip into the opposition!

[Max]

The drum looks awesome! Out of interst is this going to be invertible? I assume so but can't imagine how without it running with the drum on the ground!

Also are you using timing pulleys with the timing belts for the wheels or just plain pulleys?

[Ellis]

Hey Nick, that's a bit worrying! I'd want a refund, haha. Will bear it in mind.

Max, it isn't very invertable, if that makes sense. The back wheels run on the ground when inverted (and the drum just slides) but there is so little weight over them I doubt it'll do anything. If I have any weight left I'll stick some magnets in the top panel back there in the hope it might give enough grip to prevent being counted out.

All of the belts/pulleys on the drive are toothed.

[mrsam]

Looking good that drum reminds me so much of k2

[overkill]

With all those M8 bolts around the drum, I can't see you having any problems with the disks shifting much. BTW: if you are having weight issues, why not bore out the drum a bit more? The weight near the centre of rotation will be adding very little to the KE of the weapon. That might give you back enough weight to add the hold-down magnets.