Just getting started..

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PudseyBear
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Joined: Wed May 09, 2018 9:34 am

Just getting started..

Post by PudseyBear » Mon May 14, 2018 11:22 am

Morning

Just about to start our first Ant build so have a few questions if anyone wouldn't mind answering.

My son would like to make a 4 wheeled vertical pincer/grabber Ant. I've got the motors (30:1 500rpm) and a nano2 esc sorted. Can anyone recommend a servo that will have enough power to hold a competitor if it gets a good grip? Secondly will the Turnigy Nano-tech 2s 180mah be ok to run 4 wheels and the weapon?

We don't have the means of accessing a 3d printer so will be making the shell from Polycarbonate. Is 1.5mm ok to use for the chassis or should we look to use something else?

Transmitter wise I've been looking at the Devo 7e on ebay which are under £40 but from Hong Kong. Has anyone bought one from here and if so did you get stung for custom charges on delivery? Anyone know a Uk or European supplier in the similar price range if so?

Many thanks

PudseyBear

EddieJ
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Re: Just getting started..

Post by EddieJ » Mon May 14, 2018 12:08 pm

Hi Pudsey,

I'm pretty new here also, but i think i can answer one of your questions, from what I have been told recently :D

180mah 2S will be fine for the battery.

If you want to 3D print a chassis, send me the CAD file (STL or OBJ) all set up and i will print it free for you on the Ultimaker :) Are you UK based for shipping?

Paulmchurd
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Re: Just getting started..

Post by Paulmchurd » Mon May 14, 2018 12:14 pm

For £60 you can get an orangeRX from hobby king. Which does both dsm2 and dsmx. I think they are the types.

. I've only ordered something over £15 and it got hit by customs. However it was tracked mail. I had to pay %20 tax and £10 handerling fee. 🙈

Most Chinese suppliers lie about the cost on the package and if you get it delivered untracked quiet often it gets through unnoticed.

You can work out if the battery is the right size by deviding the captivity by the C number. Then compare it with the current draw of the motors.

E.g

180/25 = 7.2 amps. 5 motors will probably be around 2amps max(stall current) So that battery will be more then enough.

Hopefully all my information is correct. Some one please correct me if I'm wrong

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Ocracoke
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Re: Just getting started..

Post by Ocracoke » Mon May 14, 2018 12:22 pm

For £60 you can get an orangeRX from hobby king. Which does both dsm2 and dsmx. I think they are the types.
The OrangeRX system only does DSM2 and DSMX if you get the international version which is a bit more expensive I think in terms of postage. You can get a UK version which only does DSMX (apparently, there is a thing about DSM2 in the UK apparently). I have a UK version which works perfectly well with the NanoTwo v3 but equally, any DSMX receiver should work with it.
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DieGracefullyRobotics
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Re: Just getting started..

Post by DieGracefullyRobotics » Mon May 14, 2018 1:07 pm

I'll answer the grabby part as I've built a few in the past.
I find that the design of the grabber is much more important for getting a grip than the servo powering it. You don't need a lot of "force" to hold an ant but you do need something to clamp it to IE. a floor, a flap, a wedge or a lip. Seems obvious I guess, but worth mentioning.
If you're running a Nanotwo v3 though, you will need a HV servo to cope with the full voltage at the connection and that means pretty much anything you pick will be good for purpose anyway.
Dave
Die Gracefully Robotics - Barely Even a Proper Team.

PudseyBear
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Re: Just getting started..

Post by PudseyBear » Tue May 15, 2018 6:24 am

EddieJ - Thanks that is a generous offer. Zero CAD skill though, we are designing on paper and cardboard! It was a off the cuff comment and Extreme Robots 'we could make one of those Ants' now my son won't let it go and is holding me to it. I think we will see how the first one goes and if he stays interested we can look into a more professional build. I've had a brief look at Onshape but will need a few hours to work out how to use it by the looks of it.

Paulmchurd - Thanks for the battery calculation. Think i might take a chance on the ebay Devo 7e. If it gets through great, if not its still less than other alternatives and I prefer the small size of it.

DieGracefullyRobotics - Nice one. We're thinking of doing a flipper at some point so were looking at the TGY306HV on others recommendation. Will this be ok for a grabber too?

Thanks guys

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Shakey
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Re: Just getting started..

Post by Shakey » Tue May 15, 2018 6:29 am

The TGY306HV will work for a grabber but be aware it doesn't really appreciate repeated sudden stopping of the servo arm. It's best used with arms that have a bit of spring to them to make it more gentle on the servo (They have a small tendency to sheer their own output shafts).
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PudseyBear
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Re: Just getting started..

Post by PudseyBear » Tue May 15, 2018 9:37 am

Thanks Alex. Is that why some ants have a bit of elastic on the flipper? Sure i've sen this somewhere

What hv servos make good grabbers then?

Cheers

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Shakey
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Re: Just getting started..

Post by Shakey » Tue May 15, 2018 5:02 pm

PudseyBear wrote:
Tue May 15, 2018 9:37 am
Thanks Alex. Is that why some ants have a bit of elastic on the flipper? Sure i've sen this somewhere
No the elastic is fine for retracting. Flippers don't need any extra care for the TGY306HV as they can take that fine, no sudden stops in its travel (in theory). It's only grabbing that poses a risk, it's perfectly fine, you just need to know mounting a metal arm directly to the servo isn't goping to promote a long life.

I don't really look at other HV servos TBH.
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