First Project - Shopping List

Hi Guys,

Another newbie question, I've been looking at the forum & have took a stab at the basic kit list for our first project and I was hoping for some feedback before I go spending a couple of hundred quid on all the wrong kit & set the garage on fire! :p


Here is what i'm planning so far....


Motors - Argos Simple Value Cordless Drill http://www.argos.co.uk/v1/static/Pro...er/7112946.htm


ESCs - Bitbots 35a ESC


Battery - Hobbyking - Turnigy 5000mAh 4S 30C Lipo Pack

Radio Tx - SPEKTRUM DX6i DSMX 2.4Ghz
http://www.ebay.co.uk/itm/SPEKTRUM-D...0AAOSwHnFVy2GU


Radio Rx - Lemon RX 6 Channel Receiver FULL DSMX & DSM2
http://www.ebay.co.uk/itm/Lemon-RX-6...wAAOSwv0tVSOyo


Cables / Connectors - 14AWG wiring and XT60 connectors


I was also wondering if anyone can recommend a good source for wheels? (pref UK based), are the cheapest Argos Drills OK? and is there anywhere I can buy pre-made motor mounts that are suitable for the drill motors?


Cheers,


Alex

Hi Alex,

Looks like a good list, everything on there is pretty go-to standard for starting off in feathers, so well done for doing your research beforehand :)

The only advice I would offer is to go for the Botbitz 85A controllers instead of the 30A ones. They are more expensive to begin with, but will leave the door open to make the robot to 4-wheel drive with two extra drills if you ever wanted to do that as an upgrade or a rebuild. It will give you a larger operating margin as well, so there is less of a chance of them being damaged. Just my 2 pence worth.

Featherweight-sized wheels that screw directly onto the drill output shafts are quite hard to come by these days (we used to have a great selection a fair few years ago) so most people tend to make their own. For example, if you get a hold of some 3/8" UNF nuts (this matches the thread on the drill motor shaft) and use a heavy duty soldering iron or blowtorch to heat them up, you can then press/melt them into the bore of something like this: http://www.bearingboys.co.uk/BZMM100...r_Wheel-8698-p

This will give you something with moderate grip that can screw straight on to the motor and be secured in place with the reverse threaded screw from the drill. They will be prone to wear over time so you might find that the nut starts to slip or the wheel starts to wobble a little, so may be worth making a couple of spares.

Pre-made motor mounts are again quite hard to come by now. Robo Challenge used to make some but don't anymore, so again you have to usually go for the home-brew approach. Depending on your tools and skills, there are a couple of options. You can just drills some holes in the baseplate and pass a jubilee clip through them, one at either end of the motor, to strap them down to the chassis. Not the most precise or solid method but keeps them in place and is cheap and cheerful. The other option, which is the method I use and useful if you have bulkheads in your robot, is to cut a 30mm x 25mm rectangle out of the bulkhead material. This allows the double-D shaped collar on the drill gearbox to slot through but prevents the assembly from rotating. You can then use the circular black plate with the two screw holes that came off the drill casing to secure the motor in place by clamping it to the bulkhead. The collar is around 22mm deep so if your bulkhead thickness is less than that, you'll need to make a spacer of some sort. Hope that doesn't sound too much like gobbledygook!

What did you have in mind for chassis materials?

Hi Jamie,

Thanks for the info - I'll deffo get a few of those wheels ordered & I was going to for the 85a ESCs but Ellis said he's got some supply issues with them at the moment, so I'll probably just go with the 30's..... I can always drop them into a Beetleweight in the future should i catch the roboteering bug (sorry - i know that was a crap joke but i couldn't resist).

As for the chassis material.... i'm a bit embarrassed to say that i've not really thought that far ahead yet. In my mind my first goal is just to get all the kit nailed to an old chopping board (currently eyeing up one in the kitchen - which will please the wife no end) and get it to move about the garage floor. Once I've done that I'll sit down with the weeman and we'll knock up some plans, we are not even sure what kinda robot we are going to go for, think a spinner may be the current front runner but we'll see. Off the top of my head i was roughly planning a 3mm Steel (Angle) Chassis but not sure if it's better to use steel plate or thick HDPE armour, or maybe some kinda combo? I was also wondering, is it worth building a prototype using MDF?

Cheers,

Alex

Hi Alex,

With regards to the ESCs, you could always grab ones from Hobbyking. The Turnigy TZ85a, they're pretty much the brushless original ones, which you can then modify/program if you're up to it. (Currently what I'm doing with mines)

From what I've heard/read HDPE can provide more armour for the same weight (or something to that effect), somebody correct me if I'm wrong.

Ah yeah, I remember reading in the other thread that the 85s would be out of stock for a while. Fair enough, 30s will do the job fine.

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As for the chassis material.... i'm a bit embarrassed to say that i've not really thought that far ahead yet.

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Nothing to be embarrassed about there. A lot of people started out by strapping their components down to a bit of wood or chopping board as their first steps. If anything, it's actually better doing it that way as you can get familiar with all the components without having to worry about fitting them into a particular chassis or having to get the wiring really tidy. Just get used to what all the components are, how they talk to each other and have fun with it.

With regards to armour etc, the best thing I've found is to have a steel frame or chassis to form the main part as this gives a strong core, and then add a layer of HDPE as armour on the outside. The HDPE absorbs the impacts from spinners and other robots and dissipates part of it while the steel underneath keeps the shape and holds everything together. You can of course have metal as armour too but it is possible that the metal deforms from a heavy impact from a spinner and locks up a wheel or twists the chassis as the force tends to be transmitted through the chassis rather than just being absorbed and dissipated.

That's not to say that's the only way to do it though, HDPE can be used for chassis parts too. For example, I use 20mm thick sheet as the main bulkheads in my electric axe featherweight. As long as it's not a major load-bearing part or something that will be subjected to large forces, it's fine. You can also use Nylon as well for such things, but it is more expensive and not as easy to work with as HDPE, though it is stronger for things like bulkheads.

All of this you'll learn as you go along, so don't take what I say as gospel. It does of course depend on what tools and skills you have too for working on various materials, but to begin with, just do what you want to do and what's within your means, then go onwards and upwards from there :)