See the latest updates at http://nc2.u13.net
Latest pics and info:

I got the sprockets today, now I am really just waiting on the frame to get shipped back up to me from home.

Drive Sprocket:
[IMAGE]

Motor with collar and drive sprockets:
[IMAGE]


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Ok, I have some update-worthy progress to report.

The frame now has the motor mount plates welded on, and I have finished a basic program to run on the NetCar laptop to allow network control. Now that I'm at college, I have access to the metal shop here and can machine whatever aluminum parts I need to very small tolerances. So far I have made the shaft collars for on the motor shafts and I ordered almost all the other parts I need from McMaster-Carr.

I decided not to use normal bike parts because the sprockets will take a long time to come across, and they are much more expensive than machine sprockets. I purchased 20' of chain, some taps, screws, nuts, washers, bolts, and almost all of the other hardware I should need from McMaster-Carr. Below are pictures of materials I bought.


Latest CAD Image:
[IMAGE]

Test Circuit:
I got bored so I decided to put together the control circuit for the parallel port and write the control program.
[IMAGE]

Chain:
ANSI #41 Single Strand Riveted Roller Chain
[IMAGE]

[IMAGE]

Shaft Collar:
Made from AL-6061 on a lathe with a digital readout. 1"x2" with 3/8" hole in the center and 2 small holes for the 8-32 set screws. This one is really just my practice one, the final 2 will be made out of aluminum with a dark hard-anodized finish to prevent scratching. It will also be a harder alloy so that the set screws do not strip out the holes inside.

[IMAGE]

Test Setup:
This is the test setup I have laid out on my dorm room floor. Yes, that is a ATX12 computer power supply. They make awesome test power supplies because they provide 3.3v,5v, and 12v. All you have to do is jumper the motherboard connector so it stays on, then use the switch on the back for on/off. Good for up 13 amps on the 12v rail and 25A on the 5v rail.

Basically the parallel port goes from the laptop to the first breadboard to split up the inputs. Then those 4 are jumpered over to the voltage amplifiers (ULN2803, Darlington Pair) where 3 of them work in parallel to step up the voltage from the 3.3v parallel port trigger to the 12V for the motor coils. Eventually I will draw up a schematic for the wiring of it all (for future reference). This circuit can be used for any voltage amplification and is very useful for simple parallel port controls. It can input up to 5v and output up to 40, .5A per transistor pair, so 4A per chip.

[IMAGE]

Motor w/ Shaft Collar:
This is the stepper motor with the shaft collar attached. there are 2 8-32x1/4" set screws in the small holes on the side of the collar. The reason the collar is needed is to allow 2 chain sprockets to fit side by side on the shaft (which would otherwise be too short) and to make the shaft wider (shaft is 3/8", the sprockets have a 1" bore)

[IMAGE]

Battery:
by MK Battery Corp. Model ES 12-12.
12Amp-Hours, 12V. good for 3-4 hours of usage, less if I use half-stepping or higher torque step patterns. I have 2 of them so if i plan to run with high torque (2 phases on all the time) I can run them in parallel for extended run time.

[IMAGE]

Next update should have pictures of the frame (brushed and with motor plates) and also the frame assembled with the motors, sprockets, and possibly the chain

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I FINALLY got the frame from home, and could put together the car, somewhat.

I bought a ton of hardware I figured I would need from McMaster-Carr. I highly reccommend them for online sale of hardware, hand tools, and just about anything else. McMaster-Carr and Mouser are both great for any projects because they do not have a minimum sale limit, and between the two you can buy just about anything you need.

Anyway, back to the NetCar. I went to WalMart (college students' saviors), bought a sign stake for $1.14, and 7 paint stirrers for $0.24 each. I made a makeshift deck for the car for now out of those. Oh yeah, and some brass finishing nails for $0.88. the pictures really explain everything else. Currently I do not have the other motor yet, that is the only thing I am waiting for now.

As you can see below, the frame now has the motor mount plates welded on, thanks to a former coworker of mine. As you can see in the pictures, the car is assembled in college-student fashion, but is capable of driving down the hall, even though it only has one tread. It just doesn't go straight, yet. All that is left now is to make a proper deck for it, maybe a sheetmetal or plexiglass body, and brush up some of the programming to make it more efficient. The whole project should be wrapped up within a couple weeks.

Isometric overview of progress:
[IMAGE]

Front overview of progress:
[IMAGE]

Side overview of progress:
[IMAGE]

Top overview of progress:
[IMAGE]

Circuit board:
[IMAGE]
I just redid the circuits today with an extra logic chip in there to help speed up the switching. When the parallel port switches as fast as is needed to drive the car, it tends not to put out the full 3.3v, thus not triggering the full 12v to the phases of the motor, thus not putting out the full amount of torque. The extra logic IC steps the voltage up to 5v from a trigger as small as .5v, which then switches the full 12v, giving the full amount of torque.


Closeup of Drive:
[IMAGE]
This is a closeup of the motor attaced to the two 14-tooth sprockets, as well as one of the idlers on the bottom.

Closeup of tensioner design:
[IMAGE]
Just a closeup of the tensioner for your viewing pleasure.

Look for another update within a week and a half.



Original Post-----------------
I got bored as soon as school was over so I designed this car and I am currently making good progress. I hope to have it done by the end of the summer, and maybe if some of you i know ask real nicely ill hook up a video camera and let you drive it around a bit.
All the information is at http://netcar.u13.net



Update:

The website was recently updated with some more information, pictures, and CAD images. If you would like to see more detailed specs from CAD or just talk to me about the project, feel free to IM or e-mail me.

I just recieved the motors on 8/5/04, and boy are they heavy, but at the same time i can just imagine how much power they will put out and how awesome they will sound. Mounting them has been comletely figured out, as showin in the CAD drawings. I talked to one of the machinists at work and they are going to stamp out that plate for me, to my exact specifications out of high quality aluminum, then weld it onto the body for me at no cost! The VP heard about it and has no problem supporting my project.

My recent problem is finding an adequate power source for the motors. If you are interested in helping, more information on that is found here


http://netcar.u13.net


Oritinal Post:
So far I have put almost $500 into it, and I think it shouldnt need too much more money:
$276 - For the 2 stepper motors (high torque 12V)
$30 - Stock box aluminum 3/4" sq. x 1/8"
$75 - getting the frame welded (could have cost a lot more, aluminum welding is rare and expensive, let alone custom stuff)
$50 - Motorcycle battery (YTX7A-BS) 9th in that list

It uses normal WinSock connections so it can be controlled over a LAN (recommended, under 1 millisecond lag on controls) but over the internet will work fine, just with a 100-200 millisecond lag. Since there is a laptop onboard the car, it would be really easy to add a USB webcam and voilá, live video feed from the car.

i'll have more pics as it becomes more complete. Right now the parts are on their way and I am completing the coding of the second program. The first program has been written and tested.

Overall:
Top speed: Could be 20mph, but im limiting it to 8mph for now so it is more powerful and more safe for the laptop.
Weight: 35-40lbs
Dimensions: 18"x11.5"x5.5"
Estimated Cost: $600 +/- $50
Torque: 972 oz-in = 5 ft-lb
Best Feature: It's rugged design and treads


Once it is done I will definately have video of it.
Thoughts?
-Brick

Whats a 100-200 ms....millisecond? Thats not bad then.

thats coool! :) post updates as you go how long u think it will take you to finish?

site isn't working

no, your computer isnt working.

My goal was to make this a summer project, so I hope to have it done by the end of August.
-Brick

Wow! A real handyman here.

It's a bit heavy for a "camera car" but I can't do better so that's awesome! (and expensive)
You could make a spy device for Pierce 007... :)

hah, 100-200 ms lag is better then what a lot of people get in soldat

hail brick!

Sweet! If only I had the money to make something like that...
I hope you let us drive it when it's done. ;)

cant wait to show my hidden rally formula super skills

Car in a bocks!

my only problem is finding a 12V battery that can be completely or almost completely used and then recharged without ruining it. Most batteries for cars and motorcycles are meant for small changes in its charge, not to be entirely used up, and that tends to ruin them very quickly.
-Brick

Edit: The search is on! help look for batteries. details: http://archive.forums.soldat.pl/topic.php?topic_id=16365

hey can we drive it when your done? lol that would be so cool u could let the soldat community drive ure car arround

Thats what he said "maybe if some of you i know ask real nicely ill hook up a video camera and let you drive it around a bit."

hey btw brick how are you gonna mount the laptop inside the frame?

because i came up with an idea while i was in the shower (eheh) that could possibly allow it to go at its top speed without damaging or jostling the laptop too much, in fact i was thinking about it so much the hot water ran out in the shower

worm, hit me up on AIM FliesLikeABrick. I'm pretty sure that no matter what, a solid framed car without suspension running into something hard at 20mph would shock the laptop pretty hard, but I'm curious what your idea is.
-Brick

remember in cub scouts they did that "egg drop" thing? where you take an egg and put it in a box so they can drop it from 30 feet up on a firetruck. the objective was to prevent the egg from breaking.

so i was thinking, you could do like i did -- cheat. hardboil the laptop.

Hardboil the laptop? Genuis. Pure genuis...

You said it yourself though, suspension. That would help.
Perhaps put a lot of light foam around the laptop so it doesn't hit anything else.

yeah i have a bunch of that textured black anti-static shipping foam im gonna put around it. Once the project nears completion im gonna pop-rivet some sheet metal aluminum to the bottom and top of the frame for the laptop to sit in, and then stuff the foam in around it
-Brick

well yes, i havent thought actually thought out much the actual technical side of my idea, but it might work

i really dont know

and related to this, are you planning to keep the laptop in there for an indefinite amount of time, as in, will it only ever be used for giving directions to the car?

and yes the foam thing could help, if you surrounded the entire laptop in say a foot of high impact foam, and then just for redundancy, somehow attached some screweyes to the laptop or foam (most likely the laptop), you could suspend the laptop/foam block using bungee cords through the screweyes attached to the frame surrounding the laptop

that should give it some swing room, but not too much, and the foam around it would help if for some reason it actually did hit something

probably it would be best not to ram it into things at 20 mph

Update:

Here is what has been done:

brushed the frame to give it a cooler look.

designed the custom motor mounting plates on CAD so that it would be easier to mount the motors to the frame. I showed a machinist these at work and 2 days later he punched them out on a machine for me (for free).

Said plates were then welded on for free by the same machinist

ordered hardware online to mount the motors to those plates

ordered and received the correct hardware

ordered and received the battery.

designed the shaft collar to allow the cogs to slide onto the small shaft.

designed the battery cage

see the updated project page at http://netcar.u13.net/ - updated CAD images, parts pictures, and documentation.

Teh yay! Netcar lives!

w00tars! i cant wait for this thing to be finished

I'll post all the new material here later, but for now read everything here:
http://nc2.u13.net

Wooooooooooooooooooooah.


...


That is awesome...=>

If I were you FliesLikeABrick I would not let a bunch of psychotic hostiles drive a 600$ car around... :) But I want too :D

yeah, i would have a kill switch if i let them. It already is worth almsot $1000 US, and that isnt couning the $2500 laptop

http://nc2.u13.net updated again! The project is almost done. In its current state it can drive around in semi straight lines, but that is because it only has half its drive train right now. Stay tuned for the conclusion.

you should put a bb gun cannon on it ^__^

OMFG Teh Vehicles! With the Barret in the Vehicle!

But anyways, good job, maybe add a cover on if you have extra time so it'd look like a ricer car.