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

[Merkabah_PT]

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.

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.




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:


The second is to used two of these:

to attach the shell of the screwdrivers to a L shape piece of aluminium or stell like this:


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...

[Bodge Job]

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

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

[Merkabah_PT]

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

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:

[RobotExtreme]

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

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?

[Merkabah_PT]

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

HI!
I know you, we talked some years ago, along with Firo. I am portuga from the robocore brazilian site.
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.

[RobotExtreme]

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

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

[Merkabah_PT]

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

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.
I want to keep this thread clean, just for my build. :wink:

Cheers!

[PJ-27]

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

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.

[Merkabah_PT]

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

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.

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.

[Merkabah_PT]

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

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:


Motors Support:


Motors on the Support:


Motors with Wheels on the Support:


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:

[Bodge Job]

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

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

[Merkabah_PT]

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

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:





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.

Cheers!

[Ellis]

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

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.

[Merkabah_PT]

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

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!

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...

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?

[Ellis]

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

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.