scaling fixture ideas?

Hunter82

Member
OK so I just bought me 4 of those digital bathroom scales - the kind that immediately displays a readout within seconds of putting weight on. Not ideal I know but I got them for $16 each and couldn't afford professional racing scales right now. My idea is to put them on a level shop floor, get in the kart and have someone roll me on and off them likely once for each side to record readings. I know I need something either I can make or buy to put right behind each scale the same height as scales to make it easy to roll me onto and off of scales quickly without moving the scales in order to get an accurate reading. I'm sure other budget racers on here use this method as well so would like some ideas as to what to use to make it easier. My wife will likely be who's rolling me on and off scales so it needs to be quick and simple lol. Any tips?

-Rowdy Wayne
 

LynnRacing

Member
the scales are probably in the 1-1/2 t0 2" thick range ? Maybe just use some 2x12s and /or plywood ? Just be sure the floor your using is perfectly level between all 4 scales or your efforts are useless
 
One of the essentials in scaling is consistency. To optimize your particular setup, it would help to label all 4 scales with their particular positions to ensure use in the same position every time. It also helps if you use a paint marker to outline all 4 pads on your floor so that everything is always in the same perspective. Lynn's suggestion of plywood is probably the best solution to roll-offs.
 

alvin l nunley

Premium User
Some sort of ramp, (pretty easy to fabricate from half inch plywood) to get on the scales, then something between the scales, front to back, the same height of the scales. This allows the front wheels to roll from one scale to the other. Pretty easy to fabricate.

A 50 pound weight to calibrate the scales each time you use them is handy. The ambient temperature will affect the accuracy of the scales, but if you calibrate them each time they're used, you should be okay.

A quick way to find if all four scales are level is to put the kart on the scales, take the readings, then turn the kart 180 degrees and see if the readings are the same. You can adjust the height of the scales by placing binder paper under the scales if the floor is not perfectly level.
 
Al, when you say to "calibrate" the scales each time you use them is inferring that adjustments are made. Perhaps a better term would be to say that we would verify them with a known weight. The original poster related that he purchased bathroom scales to save money in the first place, so I feel like a set of stands, as nice as they are, may be a little above the means of some. While I would agree that being level will help with accuracy, it is not as essential as some would imagine. As long as you perform the same procedures in the same way each time you weigh, with the same pads in the same positions, you should be able to attain a degree of consistency that will help you when making adjustments to the kart. A known weight is helpful, but somewhat unnecessary in a low-budget case. We can use body weight to ensure consistent readings from pad to pad.
 

Hunter82

Member
Thanks for all the ideas. I wish I had the money for a nice scale stand right now but with having to buy everything else to get back racing after being out so long it just isnt in the budget. What Im going to try in the next week or so using youalls ideas is making scale pads from plywood and nail 2 10 inch 2x4 pieces to the bottom of the plywood for height to roll off of onto the scales and see how that works, my bigger concern now is how to keep the scales from sliding forward as I roll onto them but I may have to fabricate some piece of wood to hold them there too. I'll let youall know how it works out as if I make it work maybe itll help someone else reading this later.

-Rowdy Wayne
 

sundog

Member
The kart will not have time to settle before the scales freeze the weight if they are the type I'm thinking of. Any kind of cheap bathroom scale is pretty much a waste of time, they could be off 5-6Lbs from each other if they are set up perfectly which probably won't be the case. A general idea is all you're going to get.

Sundog
 

LynnRacing

Member
Thanks for all the ideas. I wish I had the money for a nice scale stand right now but with having to buy everything else to get back racing after being out so long it just isnt in the budget. What Im going to try in the next week or so using youalls ideas is making scale pads from plywood and nail 2 10 inch 2x4 pieces to the bottom of the plywood for height to roll off of onto the scales and see how that works, my bigger concern now is how to keep the scales from sliding forward as I roll onto them but I may have to fabricate some piece of wood to hold them there too. I'll let youall know how it works out as if I make it work maybe itll help someone else reading this later.

-Rowdy Wayne
Build a frame around the scale and make in part of the pad
 

Peter21X

Member
If anyone reads this...
I know this is an old post but in my experience with using bathroom scales to scale out cars in years past, we used bathroom scales with a levered jig and calibrating with a known weight. Using old grain scales worked well too.
Digital scales that do all of the math for you are great, but a calculator works fine for checking the balance is fine.
As mentioned above, what we are looking for is consistency because there is no magic numbers. Whether oval track or sprint karts, there are so many variables.
I have always searched for a good starting point, be diligent and make changes one at a time to make progress.
Fight the urge to make multiple changes at a time. Progress will be quicker. Later as you make shop changes and multiple changes in the shop, you can get an idea of what effect changes make in weight.
And, those changes may or may not be beneficial on the track. An urban legend had Gordon Johncock winning the Indy 500 turning the chassis adjustment knob the wrong direction...true or not. Experience has taught me talented drivers can overcome some surprising things too.
Being new to sprint karting, we are learning the ropes. We can draw off of friends, past experience for information, but this site and the Briggs site has been a godsend....thank you all.
Peter
 

alvin l nunley

Premium User
The kart will not have time to settle before the scales freeze the weight if they are the type I'm thinking of. Any kind of cheap bathroom scale is pretty much a waste of time, they could be off 5-6Lbs from each other if they are set up perfectly which probably won't be the case. A general idea is all you're going to get.

Sundog
I have access to 4 analog, very accurate, new, scales for $200. I'll even throw in my weights and percentages software & kit.
alvinnunley62@gmail.com
 
Top