one person kart scales

joseph hollinger · Posted: Mon May 05, 2008 10:37 pm Post subject: one person kart scales

Longacre scales cost way too much. At least for me. So I bought four of these:

Each one is a used Fairbanks Ultegra shipping scale. Total cost for the set was about $350. Other Fairbanks models are available for even less on Ebay and other sources. I hooked them to my laptop using four USB serial ports and a USB hub. That's about another $75:

Here's a gratuitous shot of the kart sitting on the scales with the laptop in the background:

To run the scales, I wrote a windows interface using MS Visual C++. Here's an actual screen shot:

I'm pretty proud of the results. It's super accurate (five times more accurate than commercially available scales) and has a unique countdown feature that stops measuring and freezes the display 60 seconds after I click a countdown button. That way, I can click the button, get into the kart, wait about thirty seconds and the program measures and saves the results. No more need to get a second person to read the scales or for me to write down anything while measuring.

Anyway, besides just plain bragging, I'm more the willing to give my program to anyone who wants a copy. Not that it's a piece of art, but it works and obviously there's no need to reinvent the wheel. Just send me a PM if you are interested.

Randy Lyon · Posted: Tue May 06, 2008 2:41 am Post subject:

That is nice!

What's the best way to shim the individual scales so they are level and at the same hight?

Rick Worth · Posted: Tue May 06, 2008 4:02 am Post subject:

Spare floor tiles work good.

Chuck Bunnell · Posted: Tue May 06, 2008 9:26 am Post subject:

Old magazines work well to if they're the glossy type. Just another reason to keep all those karting magazines.

joseph hollinger · Posted: Tue May 06, 2008 9:32 am Post subject:

The scales I used (Fairbanks Ultegras) have four feet that allow them to be individually leveled. If your floor is reasonably level, you can use that method to do scale to scale adjustment. I do that and use floor tiles as well. The combination allows me to make the scales as level as time and patience allows.

It makes me wonder how super level surfaces are constructed. I bought a pretty good level, but there's a limit, right? I mean, the level is really only as good as your eyes. On a kart, a very, very small height difference at one corner can make a pretty big difference in readings.

bo rougeou · Joined: 27 Jan 2006 Posts: 443

THAT IS SWEET!!! they make scale stands that we use. got four leveling legs with bolts to give you an infinite adjustment. mine are homemade. with your skills it would be a snap.

Steve O'Hara · Posted: Tue May 06, 2008 5:35 pm Post subject:

Joeseph,

Nice! No need for anything more complicated than that. What is the maximum weight limit on those scales? Have you experimented with the position of the wheel (tire) on the scales to see if they are sensative to placement? Some of the older digital race car scales were single strain gauge designs that gave different readings depending on the position of the tire on the scale. Some of them use more than one gauge now to eliminate that problem. The price is so high on the current race car scales that it makes your system much more attractive even if you have to be careful about the tire placement.
I would like to try your system ... please send me your program.
Regards,
Steve O'Hara
steveohara@msn.com

Steve O'Hara · Posted: Tue May 06, 2008 5:37 pm Post subject:

Oops..... Either Joe or Joseph.... not Joeseph.... Embarassed

joseph hollinger · Posted: Tue May 06, 2008 10:15 pm Post subject:

joseph hollinger · Posted: Tue May 06, 2008 10:17 pm Post subject:

Thanks everyone for all the positive feedback. As I've told many of you by PM, I'm going to clean up the program a little and send it to everyone next week.

Jacob Hennie · Posted: Tue May 06, 2008 11:49 pm Post subject:

Joseph, VERY IMPRESSIVE!! Did you use MFC? Which VC++? 6?

Been a C++ programmer myself, signal intelligence/electronic warfare systems, In-flight entertainment systems, now a software manager for a GPS company. The funnest stuff was always multi-threaded apps in WinCE........

Again, great job, and very cool!

Tom Hennie

Gary Lawson · Joined: 21 Aug 2001 Posts: 542

While it looks like a decent setup you have $425 tied up in them. Compared to a new set up scales for 1200 that sounds good. But, right now you can find used scales for sale very easily. You even said your scales were used. I just sold a set up scales that were just recalibrated (intercomp) for $600. That is about the going rate right now for used scales. Again, not really knocking your idea, I just want to let you and others know the options that are out there. 4cycle.com has some scales for sale in the misc. section pretty often.

Dan Davis · Posted: Wed May 07, 2008 9:03 am Post subject:

Very Cool Joeseph!!
The type of ingenuity that you applied here is a large part of this sport....keep it up. It seems like the scales that can be connected to a PC cost more than the std. $900-$1000 new. I really like the delay or countdown feature too.
The only thing I see that might be a problem is the tread plate type surface on the pads/load cells. Getting all of the scales on the same plane might be difficult when using a level that depends on surface contact with the pads to be accurate. Most Racing scales have machined flat surfaces that might make leveling using a long bubble level easier to get more accurate using the eyes.......but I see you added the tiles over the top of the tread plate surfaces of the pads in the "gratuitous" pic.....That should help.
Impressive....I like. Wink

Seth Blackburn · Posted: Wed May 07, 2008 9:18 am Post subject:

Hey, could you send me the program too? I'm taking C at college this semester, and it would be neat to see how you programed it, and I may use it if I buy some of those scales in the future. What OS's is it compatible with?

joseph hollinger · Posted: Wed May 07, 2008 9:46 am Post subject: Re: re