Bot Building Questions!

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bot_bandit
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Bot Building Questions!

Post by bot_bandit » Sat Jul 09, 2016 1:44 pm

I am currently in the process of designing and building my first antweight robot. A simple servo flipper for my first one! Pretty much all the parts are on the way, however I plan to have a 3D printed body (planning to ask our very own Shakey for this one :wink: ) which I don't want to start designing until all the parts are here. Hobbyking are currently out of stock of the batteries I ordered so I am not sure when this bot will be done by. A brief description of the idea is a 3D printed frame with polycarbonate panels: similar in concept to Anticide. Possibly to have the top chassis of the bot screw on to a base to allow access to all inside electronics and/or a removable panel (ie screw not glue) near the battery for even easier access. This leads to my first question: how are 3D printers at printing small screw threads? If the answer is bad, what methods do you guys use for attaching screws to 3D printed bots (ie can you print a regular hole and drill a screw in without causing cracking?) or is there a better way to connect things you want to be able to take apart? Also what tools are best to use for cutting polycarbonate? My next question is about ON/OFF switches. Basically, does anyone use them? A switch (perhaps accessible under the flipper?) seems more convenient that having to disconnect the battery each time. Another question to go along with this is how long does a battery charge generally last (im using the 7.4V Turnigy lipo which seems pretty standard). If it's only a couple of matches and the battery has to be disconnected often anyway I'll rethink the design a little to make it easy access and hence I obviously wouldn't really need a switch. My next questions are about the LEDs, I'd like to add some to the bot. Rory briefly explained this to me when I ordered the NanoTwo however I was wondering if anyone could provide a little more in depth, ie perhaps a photo of how you connected them? This leads to my final question which is whether there is a good place online to buy a few LEDs, a small length of wires, screws and resistors without having to pay about £5 postage for about a £2 order. Thanks for your time and hope this made sense! :) Any further advice on design is also very welcome.
Last edited by bot_bandit on Thu Aug 04, 2016 5:14 pm, edited 2 times in total.
Luke H - Team Bandit

AntRoboteer
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Re: First time questions. Switches, LEDs and 3D printing

Post by AntRoboteer » Sat Jul 09, 2016 3:40 pm

OK, so here are the answers as I see them:

1) 3D printers aren't great at threads. We just put holes which are slightly smaller than the threaded end of the screw and then drill the screw in after it has printed. Never had any cracking providing that the screw holes are encased inside a square section and are bulked out around the edges.

2) We use scissors to cut 1.5mm polycarbonate and under; they're absolutely fine

3) We do use ON/OFF switches and while they come at a weight premium sometimes if you buy the wrong sized switches, they are very convenient indeed. Definitely worth having.

4) Our batteries often take 15 mins or so to charge but this can vary depending on battery capacity + charger

5) Rory will know best about the LEDs as I don't really add any right now.

Hope that helps! :D

bot_bandit
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Re: First time questions. Switches, LEDs and 3D printing

Post by bot_bandit » Sat Jul 09, 2016 4:42 pm

Thanks, I know that was a rather long and rambling set of questions! You've pretty much addressed all the queries I had. :) Just wondering how long a battery lasts before it had to be charged again though?
Luke H - Team Bandit

AntRoboteer
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Re: First time questions. Switches, LEDs and 3D printing

Post by AntRoboteer » Sat Jul 09, 2016 4:57 pm

Depends on the mAh rating of the battery and the configuration of the bot in question. With 180mAh batteries we get around 20-30 minutes of useful power from our robots and they range from 4WD pushers to flippers, walkers and 4 bar lifter/axe robots and this remains pretty much the same for every robot we've used but depending on your config, this time may be higher or lower (generally dependent on the complexity of the weapons).

bot_bandit
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Re: First time questions. Switches, LEDs and 3D printing

Post by bot_bandit » Sat Jul 09, 2016 5:53 pm

Thanks again for your answer! :)
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Shakey
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Re: First time questions. Switches, LEDs and 3D printing

Post by Shakey » Sat Jul 09, 2016 10:00 pm

I stick to 180mah 2S LiPos (Turnigy Nanotech) and even in my higher powered robots I can get at least 10 minutes running out of them.

3D printers are bad at threads. I use M2 screws to hold everything onto a 3D printed chassis that doesn't get bolted on with a seperate metal nut. "1) 3D printers aren't great at threads. We just put holes which are slightly smaller than the threaded end of the screw and then drill the screw in after it has printed. Never had any cracking providing that the screw holes are encased inside a square section and are bulked out around the edges." Good advice right here!

LED's I just order off of ebay, can get a pack of 20 for £2 with free postage if you hunt around a bit. You just need to wire the LED using the +ve and -ve of the receiver with a resistor in line somewhere. The order doesn't matter as long as the LED is the right way around.

Yeah I just use scissors for 1.5mm polycarb, I wouldn't go thicker as it becomes a pain to work with and 1.5mm is enough.

I always use switches in my bots and you can pick up some nice small ones in maplins like the ones in the link in my signature (seems a waste of postage for one switch though :P ).

One thing on 3D printing is don't skimp out on bulking the chassis, your armour is only as good as what you bolt it to. I print in ABS for it's nice material strength that has a density of 1g/cm^3 so you can put a lot of plastic into the chassis without worrying about weight.
Nuts And Bots - For all your components and ready built antweights!

Alex Shakespeare - Team Shakey / Nuts And Bots / Team Nuts:
AWS 44, 45, 49, 51 & 55 Winner - Far too many robots!

bot_bandit
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Re: First time questions. Switches, LEDs and 3D printing

Post by bot_bandit » Sun Jul 10, 2016 6:24 am

Shakey wrote:
One thing on 3D printing is don't skimp out on bulking the chassis, your armour is only as good as what you bolt it to. I print in ABS for it's nice material strength that has a density of 1g/cm^3 so you can put a lot of plastic into the chassis without worrying about weight.
Thanks again for great advice. You guys are so kind! About what thickness of plastic do you recommend going up to?
I'd love to get the 3D printing from you so perhaps I can get a switch from you then too! :P
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Hogi
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Re: First time questions. Switches, LEDs and 3D printing

Post by Hogi » Sun Jul 10, 2016 8:17 am

Maplin do a great micro switch for just a couple of quid. Welcome to antweights by the way and good luck with you're first build. :)
Daniel Jackson.

Team Hectic.

Many antweights

Super antweights: territorial.

Fleaweights: fleadom fighter, gaztons.

Featherweights: hectic (under construction)

bot_bandit
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Location: North Yorkshire

Re: First time questions. Switches, LEDs and 3D printing

Post by bot_bandit » Thu Aug 04, 2016 4:15 pm

I'm back with some more questions for you guys! Just wondering how you go about cutting metal? Was thinking about getting a 1mm titanium sheet for some armour plating and was wondering how it can be cut? as I have limited tools! thanks
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Fenrir
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Re: Bot Building Questions!

Post by Fenrir » Thu Aug 04, 2016 6:07 pm

I've ordered some titanium for myself for a similar purpose. 1mm Aluminium I've had success cutting with scissors and straightening out with a hammer as it tends to curl a little, if you wanted that as an option too.

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