Checking Settings
The first stage of chuck height compensation is checking to see if any adjustment is necessary. Using the calibration shape (the 48mm by 48mm square) cut out a left 6 base lens and an 8 base left lens. They do not need to be exactly 6 and 8 but should be near. You should write on each lens which base curve they are to make sure they do not get confused later.
Click the Manual button, select “CR-39” as the material, “Calibration” as the mfg, “calibration check” as the model, “Chuck Height Compensation Test” as the size. Click the “Right” button to disable the right lens. Set the left Front Curve to be the exact measurement for the 6 base lens. Put the 6 base lens in the left chuck of the drill. Secure the clamp, close the hood, and click “Start Drilling” in the software.
Once complete, replace the 6 base lens with the 8 base lens in the drill. Click the “Last” button on the computer and click the “right” button to disable the right lens. Change the front curve to be the exact base curve of your 8 base lens. Click “start drilling”.
While the 8 base is drilling, measure the length of the notch on the 6 base lens. Its very important to measure this notch length by measuring based on the front of the lens. Your measuring device should be perpendicular to the edge of the lens.
Write this value down on a sheet of paper as your 6 base value.
When the 8 base completes, measure the same way you measured the 6 base and record the length. Make a third column that is the difference between these two values. If this value is zero or within 0.04mm, you do not need to continue onto Chuck Height Calibration. If the length is not 3mm, skip to the Length Calibration section.
Chuck Height Calibration
Click the “Settings” button at the bottom of the software. Click the “Fine Tune” button in the upper left hand corner. The password is “test”(without parentheses). Click the “Calibration” tab at the top. On your sheet of paper that you’d recorded the lengths of the notches on the 6 base and 8 base, write the “Chuck Sag Left Comp” value on the same line as these two values.
First try decreasing the “Chuck Sag Left Comp” value by 1.0. Write this new value on your sheet of paper giving a spot for new 6 base and 8 base values. Click “Save”, then click “Save” again to get back to the main screen.
Click the “Last” button, set the “Adjust 180” value to be +3, and follow the “check settings” section above to redo your 6 base and 8 base lenses. Did the difference between the 6 base and the 8 base decrease? (The individual lengths may be different, we only care about the difference between the two. the true length is adjusted later).
If the values have gotten further apart, go back to fine tune and increase the chuck sag left comp to be 1.0 greater than the original value and retest.
If the values have gotten closer together, go back to fine tune and decrease the chuck sag left comp value by another 1.0 and retest.
On each retest, increase the Adjust 180 value by 3mm. If you run out of lens material, switch to negative Adjust 180 values. Your first test will have picked the direction to go for changing the chuck sag comp value. As you increase/decrease, you’ll eventually hit the point where the difference starts increasing again. When this occurs, go the other direction in 0.5 increments rather than 1.0 increments. Then 0.1 increments.
As you adjust these values, your chart of values will allow you to see how the difference between the length changes based on the chuck sag value. The further you get from the perfect chuck sag value the greater the difference between the 6 base and 8 base lengths become.
Once you arrive at a value that produces the same length of notch, copy this value into the Chuck Sag Right Comp area. If you find that your left and right sides produce different notch lengths, you can redo these same tests for the right side. This is normally not required as the clamping assembly is pre aligned at the factory.
Length Calibration
If both the 6 base and 8 base lenses cut the same length notch but the notch length is not 3mm, you’ll need to configure the Chuck Offset.
Click the “Settings” button at the bottom of the software. Click the “Fine Tune” button in the upper left hand corner. The password is “test”(without parentheses). Click the “Calibration” tab at the top. The “Chuck Offset Left Comp” value will need to be increased or decreased based on the length of the notch produced.
For example, if your 6/8 base are generating a 3.6mm notch and your Chuck Offset Left Comp value is 0.5, change the Chuck Offset Left Comp to be -0.1. If the 6/8 base is generating a 2.6mm notch and your Chuck Offset Left Comp is 0.00, change the Chuck Offset Left Comp to be 0.4.
Once set, duplicate the value for the Chuck Offset Right Comp.
Post Configuration
After changing any of these values, its highly recommended you run a full calibration.