HardWired II

I was going to go for some planetary ones, probably more robust drill/GR02 style ones with adjustments so they can take beefier motors! I need them to be as compact as possible so I've got space for the disc and all the stuff to go along with!

If you find a 36:1 planetary GB with a 5mm motor pinion, I would be really interested.

I've had a change of plan yet again, going for actual drill gearboxes with a 375w brushless replacing the drill motor, should have plenty enough power whilst not turning the gearbox into dust... It's much easier as far as a direct bolt-in goes though, and the motors themselves are about a tenner which is excellent for me and my silly low budget for a rebuild!

Does anyone know a good place to buy small pieces of 3-4mm hardox? I need a bit just big enough for HardWired's lid so I can weld it on, just to replace the stainless steel and help give it a little bit more structural strength after I cut the base off! That, and I'm going to need a couple of hardox angles onto the main frame to allow a HDPE base to be bolted on. Welding it's really my only option because I don't think my B&Q budget cordless drill's going to have much fun with two layers of 3.2mm hardox...

On the update side of things, I've had a chat with a few people and getting some parts made - specifically the gearboxes which will be great to get done. Plan at the minute is a set of 100mm-ish colsons with 36:1 planetary gearboxes (drills, essentially) and one of these (http://www.hobbyking.co.uk/hobbyking...er_2400kv.html) to replace the standard motor. Should save some space/weight and be pretty powerful too. I'll run them on 3S, may go for two packs and wire them together all weird like and run the weapon motor on 6S, like a couple of machines do. Slight refinement from the previous parts list, quite a bit cheaper and means I've got enough room for everything plus shock mounting, so I'm happy with that now!

Also nearly finished with Uni work too, so expect some cardboard/mdf mock-ups of it with the disc on by the end of the week!

Looking forward to seeing this progress mate it sounds pretty impressive. With the hardox, it might be worth doing an internet search for companies near to you and inquiring about offcuts, you never know you might get lucky.

I'll be interested to see how your drive system works out, might be a future upgrade for Hatchet if it works well, Generic chinese inrunners FTW.

For Hardox give Pegasus Profiles or JL Steel a try.

Cheers! Going to have a good look when I can, get some progress made. Speaking of which...

Actual work has been done on HardWired 2!
Cad work, but I've got somewhere with it nonetheless!

http://i1355.photobucket.com/albums/...pse1b00311.jpg
http://i1355.photobucket.com/albums/...psb31671b6.png

140mm-ish OD, huge hole in the middle is for a 47mm OD roller bearing, but also have done a design that's been adjusted to take smaller and/or simpler ones because I don't have a great load of engineering expertise so the simpler the better! (He says, designing a single toothed spinner). Takes a 20mm dead shaft too, with the bearing being in the disc. The bulkheads are going to be bolted to the hardox chassis extensively, but a bit extra strength doesn't harm!

Centre of gravity somehow is spot-on, and it's been designed with 10mm hardox in mind as material, but I'm definitely considering upping that to 20. Rough calculations of weight come out at about 800/900g (with the bearing holders bolted on) which is admittedly a little on the light side but it'll probably help with spinup time. Failing that again, can double it to put it much closer to 2kg.

Still a bit of tweaking to do, but it's progress! Soon as I hear word back as to whether I've made it into the world champs, I'll get it all cut and whatnot.

Nice!

Put a heavy fillet where the base of the tooth joins the outer circumeference of the disk and also put a small (1-2mm) fillet on the tip of the tooth. They will absolutely break off/round off otherwise.

Definitely pad out the weight to 2kg if you can. 140mm OD at 900g Probably wont do much but nibble harmlessly on the opposition :P

How are you planning to machine the disk center for a bearing? And what keeps the disk attached to said bearing? Machining the hardox out will be very difficult.

What Glen said. I traced the design and ran some stress analysis with some mods:

The original shape with 20mm thickness:

http://www.nswrfc.org/Nick/HW1_003.jpg

As expected, the base of the tooth has plenty of stress and there is also some stress building up around the largest hole behind the tooth.

A modified shape with a small radius:

http://www.nswrfc.org/Nick/HW2_003.jpg

The small radius (about 5mm) doesn't do much to reduce stress. I made the two balancing holes a more equal size, which definitely reduces stress in that area.

The same thing with a large radius:

http://www.nswrfc.org/Nick/HW3_003.jpg

The large radius definitely helps! Another stress reducing change would be to reduce the hight of the tooth. I imaging you want to spin the disk pretty fast, so the tooth will never use all of that bite depth.

Great, thanks for the input! Thanks for those pictures too Nick, definitely helps to see the effects that has - what program's that one too you've used? Seems extremely useful for ensuring things won't dissolve upon impact haha. Will definitely up it to 20mm then as well Glen - not sure I'd like to just be scratching the paintwork given what I could be up against haha :p

I uploaded these at 4am and in my tiredness I appear to have forgotten about the bearings... I had planned to bolt on essentially hardox washers (with 4x8mm bolts straight through the disc) to keep the bearings in then loctite the bearing onto the disc itself maybe? I'll try and cad on what I mean, but on one side there'd be a small hardox disc of about maybe 70mm diameter, 3mm thick and on the other side I'd have an aluminium pulley again (of roughly the same size) bolted on. Not sure how many other ways there are to do it with a dead shaft if I'm honest, though I may be missing something there...

Also, as for the tooth depth, I don't think I will use all of it but I'm trying to get the machine to be pretty fast and drive into stuff at speed, try and get some nice engagements where possible! Though, I could certainly drop the tooth size and then scale the whole thing up a little to add more weight... Might have a go at making one like that to see how it might work out! How much bite is preferable for this sort of thing? I seem to have 20mm in my head as a 'good' figure but part of me's thinking now that's a ridiculously huge amount...