HardWired - Upgrades and general build diary

[plargen]

i use 5mm steel on scruffy but i had to use 2mm steel in the base and ali top plates to keep it in weight

[Max]

Bare in mind that if you go for brushless drive then you've got to make you own gearboxes, and because its brushless you will need a huge reduction, either 2 or 3 stage. To do that you at least need access to a decent pillar drill and be really precise but ideally you need a milling machine to make the gearbox plates. I would guess you are looking at at least £75 for the gearboxes assuming you go for the reduced price gears on technobots.

[Ellis]

5mm steel is usable, but for the weight you're probably better off working with some sort of wear-plate, like Hardox. Same weight as steel but for combat it completely outclasses it. It's hard to find 3.2mm anymore, but 4mm Hardox will prevent pretty much anything from getting into your machine and it'll be worlds tougher than 5mm steel. That said there's the cost to balance, and 5mm steel will do the job, it just may get bent by some of the harder hitters.

As for brushless drive I don't think you're looking at huge cost for the reduction, really. Around the feather drive scale the rpm is pretty versatile. The typical 550 drill motor spins at around 20,000rpm. You can get that and lower with brushless fairly easily.

You won't be able to use completely unmodified innards from a drill gearbox, as it'll most likely shred itself under much more power than the normal 550 size, but if you don't drop in a huge motor and you take the right procedures I can sort of see that working. With an expectancy of short run time, anyway, haha.

An alternative, though it ramps up price a bit, is to mate a brushless to a Banebots gearbox.

Good luck anyway, will be interesting to see brushless drive in action.

[Flag Captured]

Thanks everyone! Sorry I can't reply to everyone just yet (will do when I'm next on!) been and still am quite busy (cheers, Sixth Form) but I've now got the funding required for HardWired II thanks to my 18th being a few days ago, and I'm getting some scrap materials shortly so it'll be well underway!

Still going ahead with the spinner plan, going to run a high torque, moderately high RPM brushless driving a steel bar spinner, then hopefully this brushless drive will go according to plan too... the motors I've been looking at if I remember rightly are similar RPM to a drill motor, and I've got some spare drills about so it's just a case of experimenting with what works and what doesn't... they're only 2/3S I think, so I don't think they're anything amazingly powerful but I'm sure I've figured them out to be powerful enough to give the robot enough of a kick. At the end of the day, I'm hoping the bar spinner's powerful enough to do the talking end, and the drive is just as nippy as possible. Probably not the best way to do things, but I'd just like to try out something a little bit different in terms of the whole setup where I can. Who knows, I might just stumble upon a winning formu- actually, no I won't... but still, it'll be fun I'm sure!

[Flag Captured]

Sorted, ish! Pretty much got my exams out of the way, so now I can get onto more important things, like building robots

Depends on the dimensions of your robot, 5mm steel all round will be quite heavy, maybe you could get your hands on some stronger material and reduce the thickness of the armour.

The machine's only going to be quite small, intending to make it as compact as possible so that I can get it more heavily armoured. Not got the exact dimensions down, but the main box is going to be even smaller than HardWired I was, and that was tiny...
I've been looking at some stronger material, but again the budget means I'm really tied to what I can go for, and these steel offcuts are the cheapest thing I can get for what I'd need... I have considered Hardox or similar, but I can't find it at a decent enough price to make it a viable armour, with starting again from scratch with new (non-homemade and therefore working) ESCs, new transmitter/receiver, motors and all that! Thanks though, I'll definitely look into some tougher material when the inevitable rebuild comes along somewhere down the line!

i use 5mm steel on scruffy but i had to use 2mm steel in the base and ali top plates to keep it in weight

Ah, I see - I've got some aluminium spare from Hardwired I (well, it used to actually be HardWired I) so I'll definitely give that a use in this one. It's only going to be a small one, and hopefully I'll be able to get the bar spinner cleanly in the weight limit too, but I guess I'll see how that one goes! Have you had positive experience with 5mm steel in combat? It seems like it'd be able to stand up to things, but I have no experience of using it myself!

Bare in mind that if you go for brushless drive then you've got to make you own gearboxes, and because its brushless you will need a huge reduction, either 2 or 3 stage. To do that you at least need access to a decent pillar drill and be really precise but ideally you need a milling machine to make the gearbox plates. I would guess you are looking at at least £75 for the gearboxes assuming you go for the reduced price gears on technobots.

Yes, that's one of the downsides of that I suppose... I've been looking at a few different options and I'm going to try and get those made/adapted from something else as cheaply as possible, I've got a few gears to hand at the minute so I'll attempt to get that done, or something along those lines. The motors I'm looking at (http://www.hobbyking.com/hobbyking/s...0KV_2665W.html) appear quite beefy and low-ish RPM so hopefully I won't have to reduce the speed as much, but I don't know. All a bit of a learning curve from here, experimenting and seeing what goes best! Need to do a bit more research on how to figure out amps and watts and all that sort of thing - it's tough being a roboteer when you're electronically illiterate haha!

5mm steel is usable, but for the weight you're probably better off working with some sort of wear-plate, like Hardox. Same weight as steel but for combat it completely outclasses it. It's hard to find 3.2mm anymore, but 4mm Hardox will prevent pretty much anything from getting into your machine and it'll be worlds tougher than 5mm steel. That said there's the cost to balance, and 5mm steel will do the job, it just may get bent by some of the harder hitters.

As for brushless drive I don't think you're looking at huge cost for the reduction, really. Around the feather drive scale the rpm is pretty versatile. The typical 550 drill motor spins at around 20,000rpm. You can get that and lower with brushless fairly easily.

You won't be able to use completely unmodified innards from a drill gearbox, as it'll most likely shred itself under much more power than the normal 550 size, but if you don't drop in a huge motor and you take the right procedures I can sort of see that working. With an expectancy of short run time, anyway, haha.

An alternative, though it ramps up price a bit, is to mate a brushless to a Banebots gearbox.

Good luck anyway, will be interesting to see brushless drive in action.

Ah, brilliant! I have been looking at Hardox but it's a lot more expensive than I thought! Most of the suppliers want you to buy a big sheet of it too, which is a bit of an expensive and scary thought! Thanks though, glad to know it'll at least stand up to stuff - it's not a permanent solution I don't think, I'm wanting to get tougher armour but it's the whole cost thing again - still having to cut corners despite raising my budget to £200!

Also nice to hear too, the motors I've seen are around 8000 RPM at the voltage I'll be running them at (6S) so hopefully I don't need too drastic a reduction... that said, I'm sure something will go wrong along the way! The drill gearbox is a sound idea too, definitely look into giving that a go - might not last as long as you said, but it's a step in the right direction for future incarnations! Definitely look into getting the gears swapped out for metal ones if they're plastic though, because that's a recipe for failure in itself!

Thanks too Hopefully it'll be something different in any case, I think it'll require a lot more work than I'm anticipating to get it running properly but maybe it'll end up being a neat new feature, and it'll mean I don't have to hack my own ESCs to save a bit of money!




And I apologise for the short essay there, catching up on replies a bit!

[Flag Captured]

Also, I've got a provisional parts list together now which are as follows:

Battery: 2x http://hobbyking.com/hobbyking/store..._6S1P_30C.html
Drive: 2x http://www.hobbyking.com/hobbyking/s...0KV_2665W.html
Bar spinner drive: http://hobbyking.com/hobbyking/store..._60_Glow_.html (maybe use another one of the above motors for it)
Transmitter/receiver: http://hobbyking.com/hobbyking/store...y_Mode_1_.html / OrangeRx R620 Spektrum/JR DSM2 Compatible Full Range 6Ch 2.4Ghz Receiver w/Failsafe

Everything else, I already own. Attempting to recycle as much as I can to cut the price down as much as I can!
All the parts here aren't final either, I'm sure that I've made a massive oversight in the electrical side of things, but that's why I'm posting them here, so that I don't make an expensive mistake later on... Also still need to buy power LEDs and power links, fuses etc but I need to learn which LEDs I'll need to buy first, primarily. The rest, I'm fine with but those power LEDs are something that I have no idea about!

[Andy]

That all sounds great, the one thing I don't agree with is the need for brushless drive, but if you pull it off I guess it could perform pretty well.

Also try getting in contact with companies about getting offcuts of hardox, normally is a lot cheaper for what we use it for

[Max]

Sounds good, but I don't see any brushless escs? Also I doubt you need 2 of those batteries, one should be plenty.
I now like the idea of brushless drive but you will want a good reduction ratio to avoid drawing lots of amps, at 6s I think throw motors will do about 8000rpm so a 16:1 reduction is what you are after if using 100mm wheels so perhaps hack a drill gearbox to make a 3:1 first stage using a larger pinion gear and then keep the 6:1 second stage, of you can find te right gears that would be the easiest way I can think of with relatively little machining.

[Flag Captured]

That all sounds great, the one thing I don't agree with is the need for brushless drive, but if you pull it off I guess it could perform pretty well.

Also try getting in contact with companies about getting offcuts of hardox, normally is a lot cheaper for what we use it for

Thanks! It's more a bit of an experiment than anything, I quite like the idea of a brushless drive, but if it turns out hopeless then I'll likely revert to some drill motors and hack some TZ85As or something, as much as I'd rather not because I'm not 100% confident to not mess it up!

I'll have a look round and contact a few of them, see if I can find anything from any of them - thanks for the tips!

Sounds good, but I don't see any brushless escs? Also I doubt you need 2 of those batteries, one should be plenty.
I now like the idea of brushless drive but you will want a good reduction ratio to avoid drawing lots of amps, at 6s I think throw motors will do about 8000rpm so a 16:1 reduction is what you are after if using 100mm wheels so perhaps hack a drill gearbox to make a 3:1 first stage using a larger pinion gear and then keep the 6:1 second stage, of you can find te right gears that would be the easiest way I can think of with relatively little machining.

Ah, yes - I forgot those! Going for some TZ85As, the ones BotBitz use (I think) but unhacked... http://hobbyking.com/hobbyking/store...=turnigy%2085A

Only reason for 2 batteries was to have the motors and drive running on two separate power supplies, but I guess it'd be better to just have the one. Saves up a bit of the budget then for some other parts if they're needed!
Ah, I see - I am worried about the amps because the motor's max amp draw (I think I've worked out) is about 90A, with the max of the ESC being 85A. Or, at least, I think I've worked that out right... May need to upgrade to some other ESCs for the drive though, but a lot of them seem expensive or only go in one direction which isn't much help!
That sounds a good plan too, I've got two old drill gearboxes that I used in HardWired I so hopefully I'll be able to take those out. I'm going to get some new ones too for a sacrificial plywood robot so they'll be good for spares afterwards too! I know someone who may be able to help machine a few gears up, so I'll give that a go! Failing that, I know somewhere that sells smaller gears for RC cars and all that, so I'll see if I can find anything there! Thanks for the help, really appreciate it!

[Max]

I'd like to change my answer for the easiest thing to do for the gearing, I would do as others have done and remove the shaft from the brushless motor, then turn down the end of the shaft to 5mm diameter on a lathe, then press fit one of the 15T pinion gears from Gimson robotics onto the shafts once they are back in. Then also buy some of the 15T planet gears from Gimson to convert the gearbox to 24:1. then turn another part to mate the brushless motor to the drill gearbox to replace the 2nd half of the plastic casing that currently hold the drill motor to the gearbox as this is too small.
If you have access to a lathe, lots of patience, the drill gearboxes and some offcuts of material to make the motor holder then this solution would only cost about £10.
It does mean your robot may be a bit slow as obviously 24:1 is more than the ideal 16:1 but this will help stop you drawing massive currents and you could always use some larger wheels or wrap bike tyre round the wheels. If you want the 16:1 ratio then you can buy MOD0.7 gears to alter the 1st stage gear ratio but I cant figure out how people are able to change the size of the gears in the first stage (to upgrade to 24:1) as I don't think the gears would mesh with the ring gear as they are still on the same axle but are smaller in diameter, does anyone know how this works or even understand what I mean?
hope some of that's helpful,
Max

[Flag Captured]

It's very helpful, thank you! And maybe it would be slower, but wouldn't the 24:1 ratio give it better pushing power? It'd only be a temporary fix anyway, just until I could make some from scratch... I will have a good look into it though, if I can find a solution for the gears too I'll post it here! As for wheels as well, I'm not sure what size I'm going for yet, need to finalise my design yet - just working out what parts to buy at the minute and then building a prototype with some offcuts of MDF I've got laying about!

[Flag Captured]

Quick update, decided on ditching the brushless drive for now and sticking with some hacked TZ85As and Brushed motors. Probably the easiest thing to do at the minute, no point messing about when I'm on a budget and don't really know what I'm doing in the first place...
Still having the brushless bar spinner though! Going have it as close to 4 kilos as possible, but need to figure out what I'll need to mount that all safely. Thinking of a steel box section frame above/below the bar, but I don't know if that'll be strong enough...

[daveimi]

Bet advice I was ever given came from the Might Mouse Team

"...get yourself a pair of Gimson's and a Sabertooth, works right out of the box for 70 odd quid..."

[Flag Captured]

That does sound some very useful advice, thank you! Was looking at the Gimson GR02s, look very good I have to say... I don't suppose it was mentioned which Sabretooth controller as well? Is it the 2X12 ones, because if so I think I may have a drive system sorted (finally!)

[Shakey]

The 2x12 would be nowhere near enough. Most of the speed controllers in use today seem to be like the TZ85's (hacked brusless). There are many options to choose from but the 25A mark seems to be a good place to start looking.