Build Diary and some questions that may appear - BW/MW

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

Oh! I toght that you were spanish, now i understand why you build robots and take such long trips to go from M¡laga to the UK.

It would be awesome if there was some competition in Spain, depending on the exact place i would be able to travel there.

A TV channel called SIC Radical transmitted BattleBots from season 1 to 4, i was just a kid, but ever since it as become my interest along with computers. But i have never had a chance to fight against anyone, even if with wired robots or made out of toys and recycled stuff.

This year i have the feeling that i will find someone here that wants to build a robot too. Even if i have to build this robot and another one, then i would just have to find a guy to drive it.

[PJ-27]

Re: Build Diary and some questions that may appear - BW/MW

Most Chopping boards market themselves as High Density but are in reality LDPE or another more brittle plastic.

[Marien]

Re: Build Diary and some questions that may appear - BW/MW

It is nice to see that there are active Roboteers in the south of Europe. Please keep us informed of your (building and event) activities.

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

Hi guys.

Today i spent the afternoon rebuilding my RX and making my batteries.

The radio is a 27Mhz band with interchangeable crystals. It might look like a toy RX but its not. The only diference is that instead of the regular 3 pins per channel, it has integrated ESC's, so there are just 2 pins per channel.


Besides that, i finally found my Ni-cd cells and i have assembled two 4.8v 1200mAh baterry packs. I still have 14 1000mAh cells left. I have to buy a piece of heatshrinking tube large enough to cover the batteries.




I have also improved my 3D design, reducing the wheels from 100mm to 75mm, making the body as small as possible and lowering the wedge angle.


Cheers!

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

So, i just found out that the internal Esc's on my RX handle 20v and 8A. No external H-Bridges needed anymore, and i will have speed control instead of 100%, 0%, -100%.

I still have to check my motors amperage under load but i am pretty shure that they will draw 3/5A at max. Hopefully my mom doesn't forget o bring me a multimeter from her school today.

Some pics of the final(ish) 3D design:




This weekend i am planning to go to a store to buy all the materials i need and start the build process.

[PJ-27]

Re: Build Diary and some questions that may appear - BW/MW

What Rx is that?

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

It's from a X-Mods Evolution car. High quality 1:27 car, like the Mini-Z's, that look like toys because of the size.

For +/- $40 or so you can get the TX and RX from many web sites.

If you want them to be able to handle more amperage you just have to buy some more MOSFETS and stack weld them on top of the stock ones. But i think they can only delivery 4.8v to 6v. The RX with the onboard ESC's is about the same size as a regular one.

I think they seem pretty good for small robots without active weapons like mine.

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

Little update on this build diary.

Today i bought my 75mm colson wheels, 1000mm of L shapped steel and a 1000x200mm steel sheet for top/bottom/wedge. The chopping board i had around the house waiting for the old one to break, so it was free.

I also replaced the wires on the motors, cutted the motors/gearboxes housings, fitted the axles on the wheels and made a cardboard model of the robot to make sure everything fits.

Some photos:














Tomorow i will start the building process or i will buy two more relays and make the second H-bridge (one of the internal ESC's on my RX only handles 2A).

Cheers!

[Bodge Job]

Re: Build Diary and some questions that may appear - BW/MW

Are you planning to run the relays of the speed controller?
if so it wont work, the speed controller controls the motor by pulsing the current to cause a change in speed.
so If you use the relays and do anything other than 100% forward or backward then it will cause the relays to weld solid after being triggered to fast. if you not using the relays of the esc then dont worry

other than that its looking good!

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

I knew that, but thanks to you Bodge Job, i tested the h-bridge that i already have again, this time in both channels.

When i first tested the h-bridge, i connected it to the steering channel, because the integrated ESC on that channel was the weakest (2A) and it worked fine on both directions, so i assumed it would work fine too on the accelerate/reverse channel without actually testing it.

Now that you replied, i tested the h-bridge on that channel. If i accelerate on the pistol controller the relay works fine, but if i reverse the relay just flickers (the ESC doesn't fully open).

This is a major stepback on my project. In about 3 days my robot would be ready, but now i lost my radio system...

I could use a real a real RX with servos/microswitches to save the money of the ESC's, but a TX/RX/servos pack is TOO expensive in stores here in Portugal. I could go for used parts, but there's almost no one with RC planes/cars in my city... So if i find someone selling used parts, they will be too expensive for me too, as i am unemployed and my lowclass family can't help me with money.

On HobbyKing there's a TX/RX pack for just $25 (19‚): http://www.hobbyking.com/hobbyking/s...arehouse_.html
(It's the only one on the european warehouse)
I can afford it just fine, but with postage the price rises to almost $50, so no way for me...
I will try to find a cheap used radio system in my city, but buying an old crystal system is going to be like a stab on my heart (another one)...

For now i think i will use the h-bridge on the ESC with only 2A and the other motor connected directly to the ESC that can handle 12A.

I was really happy to start the build tomorrow, but now i am vary sad. Lets see what the future as for me...

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

The TX/RX problem will be solved by buying a used system.
The two relay h-bridges will be activated using 2 old servos PCBs.

Today i had +/- three hours to start cutting the side panels and temporarily screw them together so i could make every thing line up neatly using a rasp. Tomorrow i will have the full day to to finnish the plastic work, make the drive train support and make the steel bottom with the wheel holes.



(it was 18:30 when i took the photos, and the lighting was bad)

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

Body build day 2 (last photos are a bit dark because they were taken at the end of the day):

[PJ-27]

Re: Build Diary and some questions that may appear - BW/MW

Looking good!

[shakesc]

Re: Build Diary and some questions that may appear - BW/MW

photos very dark

just getting text saying


image
image
image.....

[Merkabah_PT]

Re: Build Diary and some questions that may appear - BW/MW

Sorry for the last photos being so dark... Tomorrow i will continue the work on the robot and i will take photos with better lighting.

Hum... You can't see all the photos? That's strange, on my computer they appear.

BTW, just found a portuguese web-store that sells FlySky/HobbyKing/RedCat (they are just rebrands) radio systems! They are more expensive than on internatiol web-stores, but the shipping is much cheaper, so it compensates. All the other radio systems that i find here in Portugal cost atleast 100‚ for a 2 channel system. I think i will buy a 6ch flysky/hobbyking/redcat system for 50‚.

Cheers!