J-Tip Calibration: How important?

[Patrick Garner]

So, this question arises from my attempts to calibrate the tip. I noticed the other day that instead of the tip's calibration numbers hovering around 100, two of three were in the 400-500 range. No big deal--I'd just recalibrate the tip. But it proved difficult. After failing earlier today (after repeated tries), I decided to test the uncalibrated tip anyway to see how poorly it performed.

I proceeded to test it with a couple iron rods (vertical ½") and a ⅝" rebar. Somewhat to my surprise the tip found everything flawlessly. It certainly was as good as my trusty Schoenstadt. I'd put its accuracy horizontally at within a couple hundredths.

So my question is... How important is the recommended calibration? The tip seems to perform nicely even when well outside the parameters.

 

[Patrick Garner]

Oh, I'd love some clarification on what Javad means by the x, y, z axis. I suspect how I'm rotating the tip may be contributing to my inability to calibrate it. Nowhere in the instructions is there a simple illustration of the 3 axis requirement. Thanks ahead of time!

 

[Matt Johnson]

I am surprised it would work at all if it is not calibrated. I would expect it to be singing constantly. What error message do you see when trying to calibrate it? Be sure that you are not near any ferrous metals or magnets when calibrating it.

x, y, z axes are just your typical 3 dimensional axes

 

[Patrick Garner]

Matt, the message is "Calibration failed. Please try again."

 

[Shawn Billings]

Remember
Spin it like a drill straight down. Spin it like a drill straight ahead. Spin it like a drill to the right (or left).

Then
End over end like a spoke on a wheel straight ahead. End over end to the right and end over end flat (like it was laying on a table).

Also remember to be away from any magnetic interference (iron or magnets) while performing the calibration.

 

[Patrick Garner]

Shawn, great description of what to do. Something just like that should be added to the J-Tip how-to. You've just demystified the process, my friend.

 

[Nate The Surveyor]

Wellllll, maybe that will help.
I did not do that... Maybe 1/2 way.

 

[Mikhail Drakin]

Do not forget to remove any metal accessories like wrist watch while calibrating. Usually "unable to calibrate" means you are within magnetic field of some object other than Earth. On the other hand, if you ever place J-Tip near a strong magnet, it may become too magnetized to produce reasonable output, in this case it must be demagnetized somehow.
Uncalibrated J-Tip will _probably_ (depending on luck) work if you always hold it in the same orientation (vertical) without even rotating around vertical axis.

 

[Patrick Garner]

Thanks, Mikhail. The tip has never been near a magnet so the calibration prob is likely my rotational technique. I'll be following Shawn's direction later today.

 

[John Evers]

Just to add to Mikhail's comment. One day I noticed that my fathers old smoking pipe holder would hold the J-Tip perfectly while plugged in and charging.

Unfortunately the pipe holder was sitting on top of an old stereo amplifier, directly above the transformer for its power supply. I did not notice this fact at first. The result was that I would have to re calibrate my J-Tip every time that I charged it.

I moved my charging location, and this has not happened since.

 

[Matt Johnson]

Calibrating it is not complicated. It just needs to be rotated and twisted along a variety of different axes so that data can be stored from the sensors in all orientations. There is no set pattern of rotating that needs to be followed. A good calibration should have a RMS of about 0.2%. I typically rotate it 360 degrees over about 2 seconds while slowly twisting it too, then rotate it a along a different axis every 2 seconds while continuing to twist it until the procedure is complete.

 

[Patrick Garner]

I'll report back at end of day. Thanks for all the comments. John, great story!

 

[Patrick Garner]

Shawn, the end over end technique did it. Sync'd and calibrated once again.

Matt, yes, the tip is quiet now. Why does calibration matter? Now I know.

 

[Steve Douty]

I would suggest that a video showing the calibration of the J-tip and the LS (compass. tilt, camera, and anything else that can be calibrated) would be helpful. I can misinterpret almost any written instruction. "a picture is worth....".

 

[Patrick Garner]

Could be brief. 30 sec per calibration type (or less). And yes, instructions say one thing to one person, and something else to another. I got pretty good at spinning the J-Tip, but had forgotten about the end-over-end detail. Once I incorporated that with the "drilling" part, it calibrated in a single attempt. The "x y z" axis stuff can be interpreted in too many ways. Add this one to your list, Shawn!