From The Ground Up (Advice Thread)

I think that joeychevron has a good point there...

I am building a spinner myself as my first robot, and it has turned out to
be EXTREMLY expensive......but it has also been very fun to build, so I
still dont regret the choice of bot.

My advice would be that if you really WANT to build a spinner, then you
SHOULD build a spinner. I think that the whole point of building a robot is
that it´s a fun hobby, and I dont think it would be as rewarding to build a
kind of bot you don´t like. But I am not that experienced in the sport, so
you should probably listen to the other builders instead of me.... :)

:lol: Everyone has a valid point worth listening to!

Expense really isn't a problem, I have the patience of a tibetan monk. (Good comparison?) :lol:

Anyway, I'm definitely buying an angle grinder, I just used a hacksaw to build my workbench legs and it doesn't half ache. :mrgreen:

Well, I have my workshop up and my work bench inserted.
Now all I need is a shopping list for equipment.
If any of you have a list of relevant equipment for building bots, please could you send me a link/picture?
Thank you very much! :mrgreen:

Quote:

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Originally Posted by Roland

Sorry for more questions, and thanks for your answers so far!

What program should I use to design a 3d/2d design of my robot? I know it's early, but it's fun messing about with different looks. (My first will be box shaped anyway).

Thanks. ^_^

-Roland

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If your still looking for some CAD software a highly recommend pro engineer.

Being a total idiot, there's a list in one of the tutorials supplied in this thread. Sorry.
Anyhow, is machine mart a good place to buy equipment from? Is it true they have vat free evenings? I'm in East Sussex, where are the closest events to me?
Which event organiser did the one at the Brighton center a few years back?

Sorry I ask so many questions.

I had a look at cad software and to be honest I'm not going to bother until I get a better computer. This ones pretty old, so muh we'll see. Thanks anyway.

Quote:

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Originally Posted by Roland

Being a total idiot, there's a list in one of the tutorials supplied in this thread. Sorry.
Anyhow, is machine mart a good place to buy equipment from? Is it true they have vat free evenings? I'm in East Sussex, where are the closest events to me?
Which event organiser did the one at the Brighton center a few years back?

Sorry I ask so many questions.

I had a look at cad software and to be honest I'm not going to bother until I get a better computer. This ones pretty old, so muh we'll see. Thanks anyway.

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Machine mart aint bad price wise but everywhere has constantly got deals on so its a case of looking online to see whos doing what at the best price and then finding the closest store to you. or just buy online, sometimes you need to to get the reduced price.

as for cad software, you'll find that you'll need quite a powerful machine to run it. especially if you have loads of parts to your assembly. i have a separate machine with nothing on but my cad software. your best bet for a cheap powerful computer would be to build your own. if you haven't a clue where to start im sure there's a forum for it. although now days complete machines have come right down in price. aldi sell good machines occasionally if your not a badge snob.

I've been reading the Riobotz tutorial posted a little way back in this thread, I've compiled a large amount of notes to look at while I'm designing, but I'm somewhat confused by the offensive/defensive wedge designs, could anyone explain it in a simpler way?
Thanks for the contributions so far, they've all been very helpful. :D

Edit: I forgot to ask, I couldn't find a list with sizes of parts, I was wondering if anyone knew of one I could use, since I don't currently have CAD, and I'm starting with pen and paper, is it worth buying the parts now before I design to work out sizes?

These are about wedges vs spinners: Defensive wedges are lower to stop you from being thrown/spun around allowing you to keep attacking the spinner. Offensive wedges are steeper to cause the spinner to launch itself with its own weapon energy.

Quote:

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Originally Posted by daliad100

These are about wedges vs spinners: Defensive wedges are lower to stop you from being thrown/spun around allowing you to keep attacking the spinner. Offensive wedges are steeper to cause the spinner to launch itself with its own weapon energy.

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Ooh choices choices! :lol:
Thanks for the answer. :)

Sorry to be a bug, but I'm in desperate need with help on the internal dimension question, I want to get designing asap. Soooorry. :uhoh:

Hey Roland,

What parts sizes do you need? I can't guarantee I know sizes for every part you need but I should be able to help out with things like drill motors and such.

Minimally the Robochallenge blue wheels, (I know 100 mm is the diameter, but I don't know the depth) and width depth and height of an average drill motor.
Thanks a buuuunch. :D

Haha, I'm looking at my internals diagram here, and I'm thinking, what is a victor and why is it connected to my drive motors? Euuurgh. I hate being a noob who doesn't know where to find information.

A victor is a speed controller. It is used to take the output from your reciever and turn it into PWM that can be used to control the speed of your motor.

Drill motor dimensions are roughly speaking 50mm diameter (max) and 150mm long (including the shaft) the shaft is about 25mm long with a 3/8 UNF thread for 15mm along it being common.

:rofl: Thanks! I asked my granddad about it and he explained what it was, I also got a helpful lesson on volts, current, RPM and torque. :) Looks like I'm set for the designing stages! Yippeeeee! Thanks everybody so far. :D

The Robo Challenge 100mm diameter blue wheels have a width/depth of approximately 30mm. There is a boss in the centre of the wheel, protruding out one side. This is where the drill motor nuts are pressed/melted in to. The boss is about 25mm in diameter and sticks out past the wheel by about 5mm, making the total width roughly 35mm.

EDIT: Here's a pic:

[attachment=0:2184e0gr]blue_wheel_dimensions.JPG[/attachment:2184e0gr]

Hmm, I'm wondering whether or not the blue wheels are a good idea then, I'm aiming for a tornado-esque design, so I'm wanting as much surface area with the floor as I can get. I do actually have some small tyres at home I scrapped off an old RC monster truck which would fit the bill, but I stupidly didn't keep the plastic drums for templates, how might I go about building a set of wheels? I originally thought I could stick two blue wheels inside a rubber lining, but that might be too expensive and weak.

I hate to answer for him, but I think thats what k_c_r does but with a bicycle tyre outside the blue wheels and that seems to get decent grip. Could always try that with the RC car wheels you have and if that doesn't work you could either go with just blue wheels or the bicycle wheel idea, but maybe better asking Jamie how best to go about it first.

And of course there is the possibility that i'm completely wrong....

yes thats what i usually do, cut a strip of bicycle tyre (free from dumps\rubbish tips) and then screw it into the wheel. if its done right its great, needing little tlc and has great traction

I'll try that then, we have a massive amount of bike tyres in the shed, so that's good. So far I've got a definite list of parts, all I need now is a safety switch which I understand already, and a RC motherboard which I'm slightly baffled by! :D More questions! (no surprise) :?
I have no idea what sort of interface I should be looking for, and what is a BEC? I looked it up but I don't think it's a big english cheese...

The receiver would be your r/c mother board everything is controlled by this.

Note the receiver is about the size of a matchbox.

Don't panic about the channel port / plug markings they're fairly standard for all receivers and pertain to r/c planes.
http://www.modelflying.co.uk/sites/3...500_01_big.jpg

Your ESC [ Electronic Speed Controller/s ] will simply plug into it...the one shown below is a DUAL speed controller it will control 2 motors.

http://www.robotmarketplace.com/prod...rpionxl_lg.jpg

The receiver needs a voltage supply of around 5v.... ( the receiver shown has a Voltage Range: 3.5 - 9.6V )...you could use a small battery pack to supply the receiver.

http://www.sussex-model-centre.co.uk...ry_SPM9520.jpg

OR take a supply from your main batteries....we do this with a BEC [ Battery Eliminator Circuit ]

http://www.offshoreelectrics.com/pro...BEC_medium.jpg

To confuse things even more your ESC... like the Scorpion pictured here ... may have a built in BEC :?

Ok, so if it's built in (Edit:BEC) it's mandatory?
And if I where to buy a seperate battery pack for the receiver, how would I wire it through the safety switch? OR would I then need two, or perhaps none at all for the reciever battery?
Very helpful thanks. :D

Quote:

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Originally Posted by Roland

Ok, so if it's built in (Edit:BEC) it's mandatory?

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NO ..OPTIONAL

Quote:

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Originally Posted by Roland

And if I where to buy a seperate battery pack for the receiver, how would I wire it through the safety switch? OR would I then need two, or perhaps none at all for the reciever battery?
Very helpful thanks. :D

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You want a removable link in one of the main battery supply wires...this acts as a switch

A BEC is not mandatory, but is one less thing to fail. Hence simplicity until is breaks...


It's best you have a switch for a rx, preferably next to the link. Mainly to stop the battery from draining between the arena and the pits, though partly for safety.

Thanks everybody. :) I've been pondering over the design for a while, and I've decided that want a sturdy machine, as small as I can get it, I had a look at ratios and by the size of my wheels the rest of the chassis should come to around 400mm*256mm! My current problem is I can't fit the drill motors onto the wheels, I've thought of two ways to fix it, the first being my preferred of having the motors parallel to the wheels, but slightly down a bit, and attaching it to the axel on the wheels using bevel gears and of course the other which is to simply expand the machine - which I currently don't want to do for a few reasons: the larger it gets the more surface area I have to cover with armour increasing weight; I'll have to put more support onto the frame and the fact that I expand it means I'm going to have a large amount of empty space, which I want to prevent. So which one would have a larger advantage? :O
My design so far is here: EDIT: IT'S SO BIG HOW DO I MAKE IT SMALLER :cry: :lol:
http://img843.imageshack.us/img843/3969/robotb.jpg

A picture that large should probably be linked to or I think just uploading it as an attachment and not inserting it will make it smaller.

If you can get chains/belts you can have the motors diagonally with for example the rear motor powering the left side and the front motor powering the right side.

You could also try making the robot shorter and wider so its 400mm wide and 256mm long so it will weigh about the same but you will fit in four drill motors far easier with no extra gears

Solved the problem earlier but I couldn't edit the post, it's now 470*300*70. I'm all set to go, but I'm not sure on what thickness the steel box section should be, I was thinking 20mm*20mm*2mm but that might be too heavy. Any ideas?
Thanks for the contribution though, I'll keep it in mind.

problem solved. woop.

i believe 1mm thickness would do the trick actually. my old fw frame was mad eof 2mm thick box section and it felt like an overkill.
But thena gain i never fought with that chassie so im not 100% sure.

Oh good. 1mm is what I wanted, the frame was going to come to 7kg which I thought was a slight bit too much, so dropping it to 1mm should reduce that numbrero. :D
I can't find any duel speed controllers anywheeeeeeere. :(
Does anybody know where I should look?

technobots

robot market place

Having look now. :D
I'm confused then, what should I be using for structural walls? If I used 1mm steel I wouldn't be able to weld it, so what would be the best method to attach it all together?
Or should I use a fairly thick aluminium alloy? Euuurgh. I don't know and there's nowhere else but here to ask. ;_;
I feel like a bug. xD

Welding thinner metals is much easier with a mig or tig welder but with good welding skills and thin welding rods you can theoretically weld thin metal with an arc welder.

I remember seing someone clamping a piece of material (copper or aluminium should do the trick) behind the weld to be a heatsink and help prevent blow through. I would suggest you practice on some scrap pieces first though.

If you don't want to weld then bolts and angle plates are probably the next best bet.

Hijacking this thread for a quick question.

I'm in the midst of building my first real FW which is going to be powered by 2 standard drill motors and 1 additional for the weapon.
I'm aiming for it to be compact and was wondering exactly how far from the motors I need to put my 2,4ghz Spectrum RX?
I've seen very tight builds and was curious if there are any significant interference from motors when using 2,4ghz equipment?

I will twist the cables to the battery and the motors but havn't planned on using capacitors on the motors unless i experience interference.
I'm also thinking of shielding the RX with a folded piece of aluminm but not sure if it would help.

The spectrum 2.4ghz eliminates 99.9% of interfearence so not to worry .....

I was wondering why general purpose tufnol wasn't used in featherweight machines, what reasons are there behind that?

Thanks. :)

Sorry for the bump.
Finished the workshop today, got my vice in, drill press and wall grinder, not too shabby!
I can't seem to find any hardox sellers on ebay or commercially, where ought I be looking, or should I just use mild steel?

I'm going to go right out there and say I don't understand motors, I can't find a decent resource to teach me about them either.
All I think I know is that the higher the current on a motor the quicker it runs down a battery. Other than that I know nothing.
Learning process I suppose, so if any of you could give me a quick lesson on working out torque, the benefits for gearboxes on motors and voltage's effect on batteries I'd be in debt to you, if not that if any of you know some resources I could use that would be brilliant. I have looked at the riobotz tutorial extensively but some of it's extremely advanced for me. Even so it has been ridiculously helpful, thanks for posting that!

Thanks again! Sorry for all the trouble. :mrgreen:

for hardox you can get it from jl steel, mtl steel, direct from ssab or from a private seller ie someone on the forum. i've bought some hardox off gary recently, not sure if he still has any though.

http://www.societyofrobots.com/actuators_dcmotors.shtml
http://www.micromo.com/dc-motor-tutorials.aspx


http://architeuthis-dux.org/torquecalc.asp

Wow! You're very quick, thanks a bunch to both of you. :) I'm rather ill today so I'll get reading right away! :mrgreen:

I've been doing some cad work using google sketchup, and my design so far looks like this:

http://img854.imageshack.us/img854/7513/picture1lt.png

It looks rather sparse, simply because I have two problems, assuming I use graupner speed 900s I'm not sure what batteries would be the most efficient to use, plus that and the set up, parallel or series?

My other idea was to attach a belt to the front and back wheels so that if a motor died out the remaining motor would still run both wheels. This came from the idea of having only two motors to save cost and weight but I'm not sure if that would really benefit my rammer design. Any advice would be brilliant. :mrgreen: Sorry I'm such a bug.