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

Hi!

First, let me introduce myself. My name is Hugo, i am 20 years old and i am from Portugal.
From the age of 12 to 14 i have build some robots with parts from old rc toys and sush, and at 15 years old i built 2 better robots using cordless drill motors and motors from car refrigeration system as weapon motors, but all those were controlled by rc toys electronicas and relays...
Now, at age 20, that spark in my heart reappeared!

There is no one here in Portugal to compete or to fight against, but i hope that building this robot and showing it will encourage people in my city or cities next to mine to do the same. :roll:

Introductions made, lets start the build talk.

My plan is to build a beetleweight according to the FRA rules but, if i can't build it up to 1.3kg, i will pass to mantisweight, 2.6kg. It will be a wedge robot, because of the simplicity, lower cost and i already have a 2ch 27mhz band radio system with changeable crystals.

Parts/Materials i intend to use:
Radio: 2ch 27mhz band (have)
Chassis/body: HDPE mainly with top and bottom aluminium and stell for the wedge
Motors: 2 electric screwdriver motor and gearbox (have)
Wheels: 2 colson like (will be bought this week)
Esc: i will make 2 h-briges using transistors that can handle 24v 10a
Batery: 4.8v or 6v ni-mh (not sure how many mah's my cells have)

It will look like the wedge on this video, but much faster.
http://www.youtube.com/watch?v=HGodbVbgo6I

I bought the 2 electric screwdrivers today and dissasembled one to analyze the motor and gearbox.
http://i1272.photobucket.com/albums/...psc5ac1fd0.jpg
http://i1272.photobucket.com/albums/...psdd797322.jpg
http://i1272.photobucket.com/albums/...ps4ecbe911.jpg

Typical insides like you can see on the photos, with the motor and gearbox held together by the shell.
This is where i start to need your help. Has anyone used this before? I am thinking of two ways to use them on my robot:

First one is to make two mounts like these:
http://i1272.photobucket.com/albums/...ps43e8d691.png

The second is to used two of these:
http://www.repincol.pt/userfiles/ima...1247565009.jpg
to attach the shell of the screwdrivers to a L shape piece of aluminium or stell like this:
http://i00.i.aliimg.com/img/pb/412/5...537412_361.jpg

I think that the second way is better, besides being simpler will hold much better. Those two little supports with the holes on the gearbox look very fragile and they may break very easely. But, what do you guys think will be the better way to use these motors/gearboxes? I am open to any suggestions.

My second question is: the screwdrivers are 3.6v but by the size of the motors, i think they are undervolted 6v motors... What do you think they are? should i run them at 6v or 4.8v overvolting them a little? I don't want to take the risk of burning them...

This concludes my first entry on this build diary and i hope anyone can help me with these and maybe some future questions.

P.S. My english is not the best, but i try hard to make no mistakes. I think you can understand my writting and grammar...

I think the HDPE mounts are more commonly used (in feather weights anyway), but both should work in a beetle. And are the motors actually attached to the gearbox? or is it just held together with the outer blue plastic casing?
and i have little or no experience with over-volting, so someone else will have to help you there. Hope this helps

Has i said, the motor and gearbox are held together by the shell, the blue casing.

I know that the hdpe mounts are most common for drill motors for example, and i am pretty sure i could old mine together using the same method, but those two parts on the gearbox look like they will break very easely...
Maybe i will go with the L shape piece, but i will wait for more responses.

I am currently sorting some ideas and this week i will start the 3D design on SolidWorks, so i have time to figure things out. I will design the 2 options on SolidWorks, i enjoy using this piece of software very much.

Thanks for the help :wink:

Hi Hugo, my name is Guilherme and i'm also from Portugal.

You can find the Portuguese site/forum of robot combat here: http://www.robotextrem.webs.com/

For me is a pleasure saw another portuguese making robots.

I don't know if you already saw the FRA Rules, but you can find the Translated rules in Robot Extreme Competition too.

For which city you are?

HI!
I know you, we talked some years ago, along with Firo. I am portuga from the robocore brazilian site. :lol:
I didn't know you were still active.
Better we talk in English so the other guys can understand. ;)
I live in Viana do Castelo, up in the North.

Hi, i suspected =)

Firo also still active, if you want you can send me your mail for PM and we can talk more.

But i will give you an opinion, build a Featherweight haha

Now i have to go to bed, tomorrow i have to wake very early, but send me your facebook link on a pm so i can add you and talk in portuguese. :lol:
I want to keep this thread clean, just for my build. :wink:

Cheers!

Hi Hugo, welcome to the forum!

Guilherme makes some pretty impressive robots so I'd recommend having a chat with him.

Couple of things I'd say. No one I know has a MantisWeight and there isn't an established competition for BWs although some of us are building have built them.
Feathers on the other hand do have an established competition.

Screwdriver motors and gearboxes are a good choice for BWs if they're not too heavy. The only limiting factor for overvolting DC motors is heat, if you can keep them cool then you're safe. In the robot world we say 1.5 times rated voltage max.

Thanks for the hints PJ-27. I know that there are no competitions with mantisweight.
My plan is to build my robot as a beetle, but if it gets heavier than 1.3kg, i will make it a mantis (2.6kg).

Guilherme and another guy from Portugal only have Feathers and those are too expensive for me because i am unemployed at the moment... Currently i have zero change of going to the UK for a competition, when i get a job i will do my best to go and take part on a competition, so weight is not a problem.

For now, i will concentrate on building a wedge beetle/mantis that looks professional and could have the chance of surviving a full round or maybe even winning one. :rofl:

I want to build this robot and show it to people in my city and cities near mine personnaly and throgh the internet, so maybe this way some people will start pondering building one themselfs to fight on someones garage, backyard or even on a empty parkinglot.

My stepmothers son is taking the same school course as i did, electromechanics and industrial maintenance technician, so after seeing my robot may be he will be interested in bluiding one too, i hope.

P.S. I will start working on SolidWorks today.

Cheers, and thanks for the hints.

So... I decided to go with the L shaped piece because it is the safest and most robust way of mounting my motors.

Here are some pics taken from SolidWorks (i think i have 2 colson 100mm wheels some where on my garage). If i can't find them, i will try to find 80mm ones on a store or make them myself.

Motor:
http://i1272.photobucket.com/albums/...ps3f695159.png

Motors Support:
http://i1272.photobucket.com/albums/...pse9a7085b.png

Motors on the Support:
http://i1272.photobucket.com/albums/...ps8d06116f.png

Motors with Wheels on the Support:
http://i1272.photobucket.com/albums/...ps7bda03bc.png

Later i will post some pics of the batteries and HDPE sides with the aluminium bottom.

For the top and bottom i will go with 3mm aluminium because i have some on the garage.
Do you think 10mm HDPE is good enough for the sides?

See you later. :wink:

10mm is more than enough, some people even use less than 10mm with feathers weights.

Ok, i will try to find 5mm or a bit more HDPE.
Instead of buy the raw material, i will buy meat cutting boards because i can get them really cheap and a 15x30cm one will be enough.
I hope e can find one thinner than 10mm, this way i will save money and weight. :)

Here are some pics of what i have in mind for the body:
http://i1272.photobucket.com/albums/...psbeca1a60.png
http://i1272.photobucket.com/albums/...psb1fa6a33.png
http://i1272.photobucket.com/albums/...psba35545a.png
http://i1272.photobucket.com/albums/...ps02f47d88.png

The batteries will go on the back and the RX/H-Bridges on the front protected under the wedge.
As it is on those pics, the body is 300x150x60mm.
If someone could post links for your beetle and their dimensions it would be great, thay way i will be able to compare sizes. :roll:

Cheers!

Just a note, chopping board, in our experience, isn't good for use in a robot that will take on spinners. If you won't be fighting in spinner events it'll be fine, but high velocity impacts will shatter the material like glass, as we learned very quickly with our first robot:

First battle ever: http://www.youtube.com/watch?v=Juwzrg7rhyo

And just a week later: http://www.youtube.com/watch?v=Hdayz4qX_w8
(another angle: http://www.youtube.com/watch?v=rW5bR4FWVMM)

Use with caution!

Good luck with your build. :)

Hum... Normally chopping boards are made of HDPE, like the HDPE bought in raw...
Maybe some aren't made of it or made out of low quality HDPE? I will see if i can find some store in my little city that sells true HDPE, but if i find one, i bet it will be expensive as hell... Every thing is very expensive here in Portugal! :uhoh:

Like radio systems... A 6ch HobbyKing TX/RX costs $22.99, but portuguese stores sell the same TX/RX still with the stickers at 60‚, $80... It's just crazy... :angry:

Like you can read on my previous posts, only two more guys here in Portugal build robots (feather vertical spinsers) and they are from far away. With this robot i intend to show it to people in my city, especially my stepmoms son and is friends, to see if someone gets interested. So it will be more to keep me occupied with the planning/build as i am unemployed and to paly around...

I see that you are from Spain, do you regularly go to the UK for competitions? Are there any events in Spain?

We are English, and live in Spain, yes. We have made two big trips so far to robot events (April '12 and September/October '12) in the UK, and we intend to do another one this April.

Sadly there is nothing at all here in Spain related to robot combat. As far as we know we are the only people ever in Spain to have started this hobby. It's sad. :(

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. :rofl:

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

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.

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.
http://i1272.photobucket.com/albums/...psec02db69.jpg

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.
http://i1272.photobucket.com/albums/...psd850c62e.jpg
http://i1272.photobucket.com/albums/...pseaac84c3.jpg
http://i1272.photobucket.com/albums/...psb3c72b74.jpg

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.
http://i1272.photobucket.com/albums/...ps39bd255e.png

Cheers!

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%. :o

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:
http://i1272.photobucket.com/albums/...pse14f3fec.png
http://i1272.photobucket.com/albums/...ps2f6a776c.png
http://i1272.photobucket.com/albums/...ps33144348.png

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

What Rx is that?

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.

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:
http://i1272.photobucket.com/albums/...psd630571d.jpg
http://i1272.photobucket.com/albums/...pseb806754.jpg
http://i1272.photobucket.com/albums/...ps3a9c0c0b.jpg
http://i1272.photobucket.com/albums/...ps30187095.jpg
http://i1272.photobucket.com/albums/...ps90afb621.jpg
http://i1272.photobucket.com/albums/...psd910cc3d.jpg
http://i1272.photobucket.com/albums/...ps2675e042.jpg
http://i1272.photobucket.com/albums/...ps4b1f7ef8.jpg
http://i1272.photobucket.com/albums/...psc072b9c2.jpg
http://i1272.photobucket.com/albums/...psebd343b2.jpg
http://i1272.photobucket.com/albums/...ps577e02ef.jpg
http://i1272.photobucket.com/albums/...ps4730ddba.jpg
http://i1272.photobucket.com/albums/...psda8ae635.jpg

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!

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!

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. :cry:

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...

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.

http://i1272.photobucket.com/albums/...ps78621f0f.jpg
http://i1272.photobucket.com/albums/...psd2fe6a5c.jpg
(it was 18:30 when i took the photos, and the lighting was bad)

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

http://i1272.photobucket.com/albums/...ps697dc749.jpg
http://i1272.photobucket.com/albums/...psd716c1df.jpg
http://i1272.photobucket.com/albums/...psa8d4949e.jpg
http://i1272.photobucket.com/albums/...pse8d288d0.jpg
http://i1272.photobucket.com/albums/...ps8f488fc7.jpg
http://i1272.photobucket.com/albums/...psc92103b0.jpg
http://i1272.photobucket.com/albums/...ps445c5d50.jpg
http://i1272.photobucket.com/albums/...ps86416289.jpg

Looking good!

photos very dark

just getting text saying


image
image
image.....

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!

Body build day 3:
Now this is starting to look like a combat robot! :D

http://i1272.photobucket.com/albums/...psc42e03c1.jpg
http://i1272.photobucket.com/albums/...psf8b91a78.jpg
http://i1272.photobucket.com/albums/...ps75b9f951.jpg
http://i1272.photobucket.com/albums/...ps3731f79b.jpg
http://i1272.photobucket.com/albums/...ps45c854c2.jpg
http://i1272.photobucket.com/albums/...ps960802bf.jpg
http://i1272.photobucket.com/albums/...ps1087469a.jpg
(Don't mind the sandwich, working makes me hungry :rofl: )

Today i also ordered my radio system, a FlySky CT6B 2.4Ghz 6-Channel Transmitter+Receiver, and a bunch of Deans Ultra Plugs (60‚/£50 with registered shipping).
(review some guy made)
http://www.youtube.com/watch?v=BbjfC2ecWt8

http://cdn.memegenerator.net/instanc...x/27566823.jpg

Cheers!

I received my package today, just 1 day after making the order!

6ch 2,4Ghz FlySky Radio System, 5 Deans Ultra Plugs and some Futaba connectors.

http://i1272.photobucket.com/albums/...ps5ff3c5b6.jpg
http://i1272.photobucket.com/albums/...ps4e76a6ad.jpg
http://i1272.photobucket.com/albums/...ps43d07cc5.jpg
http://i1272.photobucket.com/albums/...ps099b9676.jpg
http://i1272.photobucket.com/albums/...ps57af1673.jpg
http://i1272.photobucket.com/albums/...ps74a5acaa.jpg
http://i1272.photobucket.com/albums/...ps6169a479.jpg

I haven't tested the radio because i will buy the batteries support this afternoon.

Yesterday i worked a little more on the robot body, i made 2 axel supports and added 1 triangle on each side so the robot doesn't get stuck if it lands on its side.

http://i1272.photobucket.com/albums/...ps89604c20.jpg
http://i1272.photobucket.com/albums/...ps7bdd35c8.jpg

Later today i will update this build diary again.

Cya later! :wink:

Radio system tested and every thing appears to be good, still have to try the software to program the TX from the computer (elevon mixing to control the robot with just one stick).

I also finished building the H-Bridges, they don't look very good but they work great. I have to find a small plastic box to put them in.

(The two relays at the right are old ones, 5/6 years old, i was a kid and didn't know how to properly solder :lol: )
http://i1272.photobucket.com/albums/...ps0c0f9a7d.jpg
http://i1272.photobucket.com/albums/...ps9326f943.jpg
http://i1272.photobucket.com/albums/...ps65a8b977.jpg
http://i1272.photobucket.com/albums/...ps4318f095.jpg
http://i1272.photobucket.com/albums/...pscc057c10.jpg
http://i1272.photobucket.com/albums/...psac334ed2.jpg

Small video of the first test drive (my smartphone sucks at filming...).
http://i1272.photobucket.com/albums/...ps23a2c6c5.jpg

The robot is much faster than i tought it would be. It's running at 6V at the moment, but i might use a 7.2V battery because my cells haven't been used for 5/6 years and they don't hold the charge (1/1:30minutes of use and they go empty).

The robot weights around 2.2kg with the batteries and all the electronics. It can't be a beetle but i will make it an mantisweight with active weapon. Now i can because of the 6ch radio. :D But i will leave that for a near future, now i have to save money to buy two 6/7.2V batteries and a proper charger.

I have a 550 motor from a broken 12/18V drill, i am thinking of using it to power a vertical spinning bar/disk.
Maybe something like this:
http://i1272.photobucket.com/albums/...ps5b42e173.jpg
(I know the disk teeth are wrong :lol: )

Cya.

So, i forgot that i should put a protective diode on my relays coils to protect the servo pcb/receiver.
My circuits look like these, how should i install the diodes? Any help? I don't want to destroy my receiver.

http://i1272.photobucket.com/albums/...ps8259d571.jpg
(It was drawn very quickly on paint)

Reverse bias parallel to the coils (backwards across the coils)

Like this?

http://i1272.photobucket.com/albums/...ps38575cba.jpg

The two relays are connect to a servo pcb, instead of the servo motor, and the two wires change polarity. Will the pcb/receiver be protected this way?

I have seen some people from RC forums doing this exact same schematic (without the protection diodes on the coils) without any problems. May be the protection diode only works/is requiered when using microprocessors and such? I don't see how the diode will protect the pcb on a changing polarity circuit like this...

Tomorrow my 7.2v 1800mah battery should arrive, so i am checking my wiring. Currently its done with 22awg (0.644mm) wire, but it looks to thin for me. I was thinking of replacing all the wires with 18awg (1.024mm) i have.
Holding the wheel on the motors they pull about 10A each, will wiring be fine with the 22awg or should i really replace with 18awg?

Every thing i find on the web is different from site to site, some say 22awg only handles 1A, other say it handles 7A others say it handles around 14A.

You guys have personal experience, so i am asking you.

i use something overly thick (after all my wiring melted at an event) , i use 2 mm wire (i dont know the gauge) but if its only 10 amps, the 1mm would probably do as its a lighter weight robot

So, today my new battery should have arrived, but the mailman didn't ring my appartement bell and forgot to leave the warning for me to withdraw my package at the postoffice. Tommorow morning i will go to the postoffice with my delivery code and try to withdraw it, but i expect it to be a pain in the a**, as portuguese workers tend to over complicate things...

Today i replaced the wiring with 18awg just to be shure nothing melts and couses a short-circuit. Better off this way.

My build it on standby until i get my battery, and 3 days doing nothing is killing me.

After this first fase of building Primogenito as a wedge robot, i will have to save some money to get 2 pulleys, a belt and a 12v battery to power the weapon (vertical spinning bar). After that i will start to design and build the upgrade so i can have some fun with the robot destroying things. :rofl:

Cheers.

Phase one at 95%! :D

Primogenito is as compact as it could be, it was almost impossible to fit the receiver batteries. I am considering making a BEC so i only use the main battery and it's much smaller than 4AA batteries. What amperage you guys think i should chose on a voltage regulater to build the BEC? 1, 2 or 3amps?

Just need to make the main battery removable link, program the elevon mising and sand/paint the steel bottom and wedge (their surface is rusting pretty bad).

My father showed me a trick to remove rust using lemon juice, but i will sand the metal so that the paint will adhere better.

I was going to make a small test drive video, but batteries only come with a little charge and it died on me...
I will leave you with some photos (this time they were taken with a digital camera :rofl: ):

http://i1272.photobucket.com/albums/...pse716c0b7.jpg
http://i1272.photobucket.com/albums/...ps87690c31.jpg
http://i1272.photobucket.com/albums/...ps8948c34b.jpg
http://i1272.photobucket.com/albums/...ps1d0b6ef5.jpg
http://i1272.photobucket.com/albums/...ps204c380b.jpg
http://i1272.photobucket.com/albums/...ps8b928b15.jpg