RogueTwo Robots

[Mouldy]

yeah.. your ones exploded because you didn't pre-load them and had them fitted terribly... mine are fine.

[overkill]

Those bearings have excellent specs, with higher radial load capacity than a 20mm ID tapered roller bearing - you definitely exceeded Mouldy's design there . If you ever need an upgrade, look at this:



Specifications: http://medias.schaeffler.com/medias/...PP*SL045004-PP

2.7 times the dynamic load capacity and still only 42mm; I am looking at these for when I design a drum to replace the beaters in my current bots.

[Mouldy]

Yeah there nice... when i chose my bearings i was most worried about side loading's (such as the big hit my drum tool from NST) - lasted pretty well from that worse case impact.

[overkill]

Same problem over here - I just can't find the perfect bearing that takes huge loads from every direction, so I plan to float the drum on its axle and have really large diameter bronze thrust washers on each end so that side impacts are taken up by the drum itself and not the bearing.

[Ellis]

I used £4.50 ebay-sourced 20x42x15 taper rollers in Rango and they're as-new lol.

[overkill]

I've had mixed success with cheap no-name bearings; sometimes they are just as good as an expensive one, occasionally they fail before the event.

[GlenR]

Needle rollers are pretty good as long as you run them on precision ground shaft.

The problem is the thrust needle bearings that tend to go with them are total ass, they break very easily. I replaced them with plastic washers called oilmids or some such and they were much more durable. Efficiency still goes out the window when turning with a setup like that however.. Not that big of a problem with a drum though me thinks!

That drum is looking proper nasty too

[craig_colliass]

Though I have never had a drum spinner I can testify to the durability of taper roller bearings on fighting robots.
I calculate Saint has been in over 250 fights in it's life and in that time after all the flips and hits that robot has endured. The bearings on the big wheels are perfectly fine. the exact same system is now fitted to Gabriel.
But like anything they have to be fitted correctly. I'm sure Dave, myself or many others can advise.

[RogueTwoRobots]

Those bearings have excellent specs, with higher radial load capacity than a 20mm ID tapered roller bearing - you definitely exceeded Mouldy's design there

Is it bad that I didn't even look at the tech specs? I just saw the dimensions and thought 'yeah they seem about right'
Just assumed they were decent since they were £20 a pop!

[RogueTwoRobots]

Update

Just back in from a 12-hour workshop session. I now have the back of a 70-year-old. Was back home yesterday but didn't manage to get a huge amount done, made up for it today though.

First up in Drumroll's ever continuing quest to become 720, front skids, needed to allow the drum teeth to clear the floor. Last year the bottom ones were ali and the top ones HDPE. This year I've just gone for Nylon for both, mostly as I had a block of spare material that was able to provide six skids (two spares) and it's pretty good for that sort of job. Last year's ones weren't hugely consistent - the bolt holes varied slightly in each - so I made a small drilling template this time and it was a huge improvement:



And the bottom ones fixed in place:



Still to mill a small chamfer into them but I'm hoping, time permitting, that I can incorporate the curvy front ends again this year so I'll wait until that's done (or not) before cutting the chamfer.
The drum teeth are pretty close to the ground but still a millimetre or two higher than I'd like, but I didn't want to skim them down any further as I'm expecting a bit of wear in them when I'm testing the robot's drive outside on the concrete and that may shave a little off slightly.

So that was Friday's endeavours. Today was an armour day. Knew it was going to take an absolute age but it needed done. Been deliberating between a couple of options for armour depending on weight, and since weight was looking good, I went for my first option, which is a 3mm steel angle frame with HDPE bolted on. Haven't cut the HDPE yet but here's where things stand with the frame. Cutting and shaping the first piece:



The sum of the angles involved comes to around 720°



The angle steel was welded to the steel plates that you can see fitted to the front and rear of the ali chassis. The welds were then cleaned up with a grinding/flap disc. The final shape is mostly there but I still need to hit them with the flap disc tomorrow just to clean them up fully. Would have done it today but time was getting on and the neighbours were probably sick of hearing the angle grinder all day:



Once complete, I weighed each section separately, and they were both around 620g each, much lighter than I was expecting. So with everything thrown on the scales again, here's where it's at:



There's still the HDPE to add to that, which is 8mm thick but I'll be layering it up to 16mm, as well as the usual collection of fixings. Should be comfortably underweight as I've still got the back-up of milling some weight out of the bulkheads, but may add a few supporting brackets etc to the innards where needed, mostly to stop any of the components from working their way into the belt transmission!

HDPE should be done tomorrow, post-chocolate. Had set a Sunday evening deadline for getting Drumroll done, allowing me to focus on Reaver and maybe Onyx, but it'll likely be Monday now before it's done, so that all but eliminates the possibility of cobbling Onyx back together for whiteboards (which is maybe a good thing if Shiny is going to be lurking in them!)