Little help requested with a new bot - receiver, material sourcing etc. thanks.

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JoeHLloyd
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Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by JoeHLloyd » Tue Jan 14, 2020 10:57 pm

Hi everyone, I guess you must be sick and tired of answering these questions, but I have had a good old scour of the forum and interwebs so if the information is out there I've missed it I'm afraid. Apologies, but I have tried. Your generous help is greatly appreciated.

I'm looking at making my second antweight (first was Briestroyer, front-flipper, 3D printed PLA, fought at AWS 60 as my first event, was super happy with the performance at 2W:2L, and really enjoyed meeting everyone in the community) and naturally I want to make a spinner too (even though I think the flipper design will actually be more competitive, I still, like most of us, want to experience the rush of being on the correct side of a scary robot). I've decided to run with a cheese theme for all my future bots, and this one is called Harmesan.

Questions I'm struggling to answer:
1.Weapon: where can I get a g5 titanium disc cut? It looks like maybe Fractory is a possibility?

2.Armour: where is a trustworthy place to source titanium sheet that is actually the grade it claims to be? I'm a little sceptical about ebay bargains from China. And there are more legit looking options in the US but I figured there has to be something UK-based, right? In addition, is there a good place to have it cut to match CAD files? Lasered or waterjet? I guess I could do it by hand with a set of serious tin snips but I would prefer to keep as much as possible CAD.

3.Receiver: this one is overwhelming. There are just so many, and I don't really know what I should be judging them on. My background is in rc cars so soldering the connections direct to the board is something new for me. I'm most interested in one that's very small that will play with the BBB ESC and a weapon ESC. I'm also interested in any good receiver/dual ESC combos that can also run a brushless ESC. Otherwise I was going to use the BBB ESC with a separate receiver.

I got a DYS 1806 motor, and I'll use N20 30:1 gearmotors for drive, 2s 180mah lipos. I think I can probably figure out the wiring from Andy Hibberd's old wiring post on the Q&A. The transmitter I have is a Taranis X9D plus, and I'm going to get a DSM module for it so I can ditch the Blade that Briestroyer is currently paired with.

Any help is massively appreciated.

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jes
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by jes » Wed Jan 15, 2020 11:51 am

I don't know anything about sourcing titanium so can't help you there. I have bought small amounts of brass, aluminium, and stainless steel off eBay and haven't had any problems, but I am also not generally picky about the grade and wouldn't know how to check it anyway.

Regarding receivers:
JoeHLloyd wrote:
Tue Jan 14, 2020 10:57 pm
I'm most interested in one that's very small that will play with the BBB ESC and a weapon ESC.
All receivers should be compatible with all ESCs AFAIK so you shouldn't have to worry about compatibility there. They just output a standardised PWM signal that is the same for every receiver and every ESC/servo. https://en.wikipedia.org/wiki/Servo_control - but if you get an ESC that does not have a "battery eliminator circuit" then you'll need to find some other way to supply 5v to the receiver.

The part you have to worry about is compatibility between the receiver and transmitter, in the sense that they need to be speaking the same protocol and paired with one another. But given your experience with RC cars I'd assume you understand what's compatible there better than I do.

I'm using the BBB dual ESC in my current antweight build and it seems to work perfectly well. There's even a switch on the ESC to allow you to choose between directly driving the ESCs or mixing a throttle signal and a steering signal into the drive for the ESCs.
JoeHLloyd wrote:
Tue Jan 14, 2020 10:57 pm
soldering the connections direct to the board is something new for me
This isn't as scary as it sounds. Once your iron is hot you can desolder a wire almost as quickly as you can unplug a JST connector so it's really not permanent. And FWIW, I ended up with a receiver (a "FlySki FS-iA6") that already had pins soldered in all the holes, and rather than go to the trouble of desoldering them all, I just cut the pins down so they were flush with the top of the receiver and then soldered wires onto the stubs of the pins.

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LimaHotel
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by LimaHotel » Wed Jan 15, 2020 1:14 pm

jes wrote:
Wed Jan 15, 2020 11:51 am
you'll need to find some other way to supply 5v to the receiver.
Not necessarily. Many recievers (for example the dsm2 feather lemon rx that I use) are rated to 2s. Check your reciever, but generally it's still a better idea to run the rx through a bec as it'll be less noisy. (as in the power won't be contaminated by draw on the batteries).

I'm using a lemon and 2 servo boards for drive on my current build. As for materials? Yeah, ebay. Getting discs cut? I have no idea. Make your own with a hacksaw and file:p
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Ocracoke
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by Ocracoke » Wed Jan 15, 2020 1:58 pm

I'd worry about balancing it accurately if it was done with a hacksaw and a file. I used a CAD file drawn with LibreCAD and then submitted that to a water cutting company to have it made accurately, which hopefully results in better balance.
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EddieJ
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by EddieJ » Wed Jan 15, 2020 2:08 pm

3. Receiver.
Ok this depends a lot on your transmitter. You say you have the Taranis X9D - which is the exact one i am using also (exclusive club! high five!)
A lot of people in antweights use DSM2 receivers (no technical reason, just what has become the norm) so you will need to install a OrangeRX module to use.
OrangeRX on Ebay
I keep the module in at all time and bind it with Shakey's Nanotwo ESC/RX combo for when I am using that.

Or easier option for you is to get a FrSky RX which is compatible with your Taranis. I use this one, but any with over 4 channels will be fine for most bots.
https://www.banggood.com/2_4G-4CH-Mini- ... rehouse=CN
BUT it is a bit of a pain to set up the failsafe, even though it says its automatic on channel 3. Be prepared to tinker if you are making a spinner and need the FS option.

Whatever RX you decide on, you really need PPM which will give you the signal wires you want to plug into your ESCs. SBUS is the other common type and is not compatible with things like DasMikro or Nano2.

Writing this from memory so someone may come and fact check me that last bit :P

2. Metals. Unless it is for a weight sensitive part - Id go with the ebay specials. You are building an antweight, not a fighter jet ;)
But if you want to treat yourself
https://www.metals4u.co.uk/
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JoeHLloyd
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by JoeHLloyd » Wed Jan 15, 2020 5:47 pm

@jes thank you for that, good to know all receivers are up to the job. I'll need to check the wiring diagram, but I think the battery is connected across the receiver and weapon ESC to make a complete circuit? With rc cars the reciever is powered by the ESC output alone. I'm surprised the receiver isn't fried when the weapon ESC is drawing full current?

@ocracoke which waterjet company did you use? did you supply the material?

@EddieJ thank you for this - I think I'll get one of those receivers as it's only 2g, small footprint, and Taranis (woop exclusive club!) compatible out of the box. I'm duly warned abouthe failsafe issues. What are PPM and SBUS? Connector types? Also, it's all weight-sensitive! And the beauty of antweights is that messing about with tiny amounts of aircraft-grade materials isn't cripplingly expensive. Still not sure where to source the Ti sheet as metals4u does not seem to list it :(

JoeHLloyd
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by JoeHLloyd » Wed Jan 15, 2020 5:53 pm

Also, it may transpire the Ti sheet for armour is just not appropriate for a variety of reasons, but I'll learn by experiment I guess. Looking for something that is lightweight that will repel spinners without letting them bite.

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Ocracoke
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by Ocracoke » Wed Jan 15, 2020 6:25 pm

@ocracoke which waterjet company did you use? did you supply the material?
K-Cut (https://k-cut.co.uk/). You can supply the material or they can (I do recommend supplying it yourself at this scale because them supplying can be expensive). I originally wanted 2mm Grade 5 Titanium for a spinning bar but that would have been them supplying the material. I eventually went for 304 Stainless Steel 2mm. Cost me about £28.80 with them already having the material in stock.
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Kyro
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by Kyro » Wed Jan 15, 2020 6:53 pm

i recently had a disk and 2 bars cut from 2mm ti. that cost about £15 with me supplying the titanium.

i did it through a friend who can actually cad. the Ti cost me about £12 so overall it was about £27 for 2 bars and a disk.

this included tax and shipping costs, so i was £27 all in for my bars and disk.

like i mentioned, i got it done through a friend, so she would be able to help better with advice and stuff, but she doesn't frequent this forum so much.

i can probably get some details from her if you needed them
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JoeHLloyd
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Re: Little help requested with a new bot - receiver, material sourcing etc. thanks.

Post by JoeHLloyd » Thu Jan 16, 2020 9:58 am

@Kyro yes please, if your friend is interested in picking up a little extra business that would be great. Was it G5 Ti you sourced? Where did you get it?

@ocracoke thanks for the recommendation, I'll look into it.

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