Science Buddies: "Ask an Expert"

Hello
I am a student and I want to make the Bump! Make an obstacle avoiding robot.
First of all I live in Saudi Arabia, Jeddah, and Sparkfun Electronics nor Jameco Electronics dont have a retail shop in Jeddah. It says we need a Two-wheeled robot chassis. I dont know where to get it from and I can't buy it online. We have a science fair and me and my friends are planning to do this.
Do you have any solutions for this? Or do you know any shop in Jeddah that can sell this for me cause I don't know?
Thank you
Please contact me as soon as you get this. ☺

Sorry, I don't know Jeddah, but according to my poking around on the internet, there's a mail order place that seems to be one of the big electronic distributors in Saudi Arabia. I know *nothing* about them, but you can check around and see what people think of them.

http://sa.rsdelivers.com

You can make your own robot chassis by starting with a piece of foam or light wood and sticking two motors to the bottom. If you look at https://www.sciencebuddies.org/science- ... p021.shtml you'll see a line follower that uses a home-built chassis instead of the storebought one. I'm sure you can use your own motors and something sturdy but light to do this yourself. The trick is finding suitable motors.

You want something that will run at low voltage and turn at 60 to 90 RPM. http://sa.rsdelivers.com/product/como-d ... 89642.aspx is one geared motor they carry. It's about 43SR, or $11.50 in the US which is not a terrible price. You build it according to the instructions to get the gear ratio you need. You should be able to find the other parts for the project at this same place or maybe you'll find some others. (this is the detailed datasheet on the motor: http://www.mfacomodrills.com/pdfs/multi ... earbox.pdf)

Think of the projects here as a springboard for your own ideas and turn them into something of your own. In this case, the availability of parts presented a problem for you but I think you can find what you need. Make your own wheeled chassis if you can't find that one and then follow the rest of the instructions - you should be fine.

Howard

You are experiencing a very common problem in real science, where either the tool you want for your experiment is no longer sold, or nobody ever sold it and you have to build it yourself (or it is too expensive to buy, but you can afford to make it yourself, or a simpler version of it)

The advice in the prior post is sound - I built a tracked vehicle myself along similar lines in college, using scraps from a machine shop and odd things I found in an auto store (the tracks were fan belts, the wheels the geared parts that engage with the fan belts, the chasse plexiglass scraps, which was cut with a hand-saw and glued together with an alcohol-based solvent. The motors I had to buy, there was no getting around that - I've actually built an electric motor from pieces in grade school, but it would not have been sturdy/reliable enough compared to just buying one).

Do your best to replace the things you can not buy with the things you can find, or have adults you know help you find/build. A surprising amount can be done with just a few pieces of wood, some glue, nails, screws, a hand-saw and a hand-drill. If you have access to a machine shop or carpenter tools or similar, you can make a much more professional-looking vehicle, but it'll still work with cruder tools/materials.

Hi rorospnfan,

According to Google Maps, there are two Radio Shacks in Jeddah:

https://www.google.com/maps/search/radi ... a=!3m1!4b1

I know they are going out of business in the United States, but some of the stores are still open. Sometimes they carry the type of electronic parts (like motors) that you need to do a project like this.

Howard and Bradley had some good suggestions. There are other places you can try to scavenge to find motors and other parts - for example, take apart an old computer and use the motors that open and close the CD tray. There are some parts for the project, like the "6-element inverter" and "H-bridge motor driver", that are very specific and I'm afraid might be harder to find though. If there is a college or university nearby with an engineering department, you might be able to ask them if they could spare a few parts.

Good luck!

Ben