RogueTwo Robots

Re; mounting the hubs.

I went belts and braces... The shaft/hub has a key way so I used that... The hub also comes with grub screws in, the screws are to long as standard by about 3mm so I drilled two dimples about 3mm deep into the shaft (one per grub screw)

Then the end of the shaft has some dodgy American thread in it, I drilled and taped that out to M5, put a bolt and a washer in the end...

Then the wheels slide over the hub and are secured with a circlip. In testing the circlip did pop off.. So the washer under the m5bolt is big enough to stop the wheels sliding of the hub.

That's great thank you.

I'm on my second drill powered pusher and looked at Gimson's and the Banebots stuff but couldn't work out how the hubs and stuff went together, but have been really interested in these. After a rough tot-up with a pair of 775's, 16:1 gearboxes, hubs and wheels I get the cash total to about $165 / £100 plus shipping, does that sound about right?

That's one calculation I forgot to do actually, the speed.
Never really bothered with torque figures much, the arena is a law unto itself and what comes out on top in theory and on paper doesn't always come out top when fighting. That said, theoretically C3 would win in a pushing match. 720 and Drumroll (still calling it Drumroll 2, not 3 ;)) will be faster but smaller wheels = more pushing power plus you've got four of them so I would expect C3 to take it.

I actually intended to drop the wheel size down to 98mm when I first thought about redesigning back in May, but for some reason I completely forgot when I fired up the CAD last week. And belts and braces is what I was going to go for too, same with tapping out the end shaft hole to a metric thread. Thought about doing it to the gearbox mounts too but more likely to screw something up there, plus it's easy enough to get the 10-32 (or whatever silly imperial size) socket cap screws on eBay.

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After a rough tot-up with a pair of 775's, 16:1 gearboxes, hubs and wheels I get the cash total to about $165 / £100 plus shipping, does that sound about right?

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I get it to be just over $180, that was with 98mm wheels. Bear in mind that you also need to order the pinion gears for the motors, and keyways for between the motor shafts and the hubs to stop the wheels from slipping. The hubs do have grub screws but I wouldn't trust them to hold all 100% of the load. Plus they'll wear down over time if they're loosened and tightened. Here's a screenshot of all the parts that you'd need (as far as I can tell - Dave or Alex can enlighten me if I've missed anything crucial):

Attachment 4237

Plus, as you said, shipping etc on top of that which can add $60-odd onto the cost. Worth it in the long run though it seems.

One question though Dave (Moulds - too many Daves on here :P). Have you had to use your spare gearbox yet? I like the idea of having one as a spare but it does push the price up a fair bit. Planning on getting a spare motor anyway but not sure if I could get away with just ordering some of the individual gearbox parts that are more likely to fail rather than going for the whole assembly.

Not used it yet, but did swap it because when i taped the end of the shaft i snaped my M5 tap in it lol... so my spare has a tap stuck in it...

id deffo get a spare motor, and make sure you support the back some how (ive got a tube that supports the motors against eachother in the centre) as overtime they will weaken or could bend due to big impacts- one of mines bent slightly and sits at a slight angle to the gearbox after the big hit with NST- it runs ok but im going to swap it out for a spare before GSL just to make sure its super reliable again. Also- i taped my gearbox mount holes to M5 too... there blind holes, so you cant run the tap to deep to damage anything.

RE; your order;

Nope! if your getting 2x 2wide hubs you'll need a minimum of 4 off wheels... and for the price id get a set of spare "snap rings"... circlips if your english... as they dont cost much and if they ping of at an event there not going to be easy to find lol... also worth getting a set of alen keys from the US... as they come with some dodgy bolts with heads that dont tend to come in your average imperial allen key set.

Tip with the banebots wheels- after a match you'll find they furr up a bit because there a real soft compound- take the robot outside after its rained and do a burnout on some slabs or similar... it gets all the arena dust etc out of the wheels and makes them super grippy again.

Which compound tyre are you going for jamie? Ive got about 12 off the orange 98mm wheels kicking about with the hex hole... so if you go 98mm dont bother buying spares as i bring all mine to the champs and your welcome to use them should urse get smushed... im going to buy a few sets of the blue this year though and see if they last a bit longer.

I went down to our local engineering shop and found these.

Attachment 4238

They are a exact match for the 4 long bolts on the gearbox's. I think they were £4, but at least I will always be able to get my gearbox's apart of I need to. I would have to be left stranded over such a simple thing. I also got a load of circlips from uni before I went so I have quite a few of those spare.

Actually, on this subject, one of the gearbox's was supplied with the wrong mod of gear to go on the motor shaft. I was just going to cut the gear off but where can I find a replacement? I have emailed them twice with no response.

Great bunch of advice there Dave, thanks. I did double up the wheels when I was sussing out what to order for myself, but just forgot yesterday as it was a rushed example. I've used the green and blue Banebots wheels and experienced the fluffing effect. The blue ones definitely last longer but you still have to change them fairly frequently compared to, say, traditional Blue wheels.

Think I'll probably just stick with the 124mm wheels; I did look at the CADs to see how workable it would be to downsize but I'm happy with the current setup. I'll be placing my Banebots order in mid-February (when I get paid) so if you haven't got your 50A shore wheels by then, feel free to stick them in my order to save on shipping.

Update

Took a trip home this weekend and found this nice pile of roboteer's presents waiting for me. Who says Christmas only comes once a year? :proud:

http://i31.photobucket.com/albums/c3...ps9cb6f1ac.jpg

Several tonnes of packaging later, it was broken down into this:

http://i31.photobucket.com/albums/c3...pscdf2bd72.jpg

Sorted out tools-wise for the milling machine now. The yellow box is a set of collets and holder for the endmills as I only realised a moment before placing the order that I couldn't just stick the cutters in the chuck.

The drills are for the drum shaft holes, spade bits ain't going to cut it anymore. The 20mm one is for when I get a new drum made and upsize the shaft but the current drum has 17mm bearings fitted so can't do much there. Also threw some needle roller thrust bearings in there too. Hadn't planned to use them but they were on discount at the same place that I got the collets from so I figured why not.

The aluminium from AW needs cut and milled down to size so hopefully can make a start on that tomorrow and have something a bit more tangible to post :)

Is the ally structure your robot body? If so where did you get it made and stuff?

It's just the cut to size option from alu whorehouse isn't it?

Hows the finish on the cuts Jamie? I'm going to be almost copying that photo part for part in a weeks time lol

Is the new Drumroll going to be ready for the champs Jamie?