PDA

View Full Version : Fish Scale Calibration


cujays
03-23-2010, 06:53 PM
I am borrowing a fish scale calibrator so I can calibrate my Gamma x2. This is NOT digital scale. I am not sure where to start. Can some one explain to me the process of how to calibrate the machine? I don't understand what to do. Thank you

SW Stringer
03-24-2010, 01:18 PM
First of all drop weight machines really don't need to be calibrated. Assuming the scale is never moved, whatever tension you get with any particular setting will remain constant forever. As opposed to spring lock-out machines where the spring constant will change with time, and electronic units whose load cells may drift with time or malfunction, both these need to be checked periodically.

But if you absolutely must know what the actual pulling force is for all marked settings on the scale then a calibrated fish scale could be used. Attach the scale to one of the mounting posts and attach the other end to your gripper. Take readings at 5 pound increments from 5 pounds below the lowest up to 5 pounds above the highest tension you'll ever use. Plug the list of data pairs into the LINEST function in an EXCEL spreadsheet. The function will calculate the slope and intercept of the equation y = m*x + b. Where y is the actual force, x is the indicated (scale) force, m is the slope, and b is the y intercept of the line.

Sound simple enough?

Nanshiki
03-24-2010, 02:44 PM
A drop weight never needs to be calibrated. Just make sure that your drop weight is always level with the ground, and you'll always have consistent string jobs.

Calibrating is only needed for crank and electronic machines that have to be adjusted in order to stay consistent.

Standupnfall
03-24-2010, 03:36 PM
A drop weight never needs to be calibrated. Just make sure that your drop weight is always level with the ground, and you'll always have consistent string jobs.

Calibrating is only needed for crank and electronic machines that have to be adjusted in order to stay consistent.

The markings for the weight could be off, even way off so this statement is incorrect.

It should never need to be calibrated after the initial check though.

jackson vile
03-24-2010, 03:56 PM
It is a very good idea to see what tension you are actually pulling.

SW Stringer
03-25-2010, 06:49 AM
The markings for the weight could be off, even way off so this statement is incorrect.

It should never need to be calibrated after the initial check though.

I'm inclined to disagree with you on this based on my experience with the Klipper, so what in your opinion is "way off" ? For example, the scale label on the Klipper pretty much covers the whole rod (see http://www.klipperusa.com/images/products_small/M100a1.jpg ) so it can't be too far off even if misapplied.

schenkelini
03-25-2010, 09:45 AM
I own an X-2 also. Since the tension scale is etched in the tension rod by some sort of automated process, I would imagine if one were to measure the actual tension for an X-2, you would have a universal measurement for all X-2's.

cujays
03-25-2010, 10:27 AM
How do I use the clamps for the process that have been listed above?

Nanshiki
03-25-2010, 12:04 PM
The markings for the weight could be off, even way off so this statement is incorrect.

It should never need to be calibrated after the initial check though.

Not true.

As long as your markings line up when the bar is flat (like I said, make sure your bar is level!), and you use the same markings every time, your string jobs will always be the same. I adjusted my sticker the other day since the bar looked a little low when the arrows lined up, but this was because I was doing it in a different house, with different carpet.

A string job is based on a reference tension, not an ACTUAL tension. So a string job at 60 on one machine might be 56 on another machine. It doesn't matter as long as you use the same machine and stringer, which you should, unless you're a tournament player... at which point you just have to adjust the tension slightly based on the type of machine (cranks should be adjusted up since they string loose).

Lambsscroll
03-26-2010, 05:00 AM
The way i do it is I first lock the swivel clap then attach the calibrater to the clamp then to the string puller and then pull. The scale should read the same tension as the tension set on the machine.