Unit Values - would you change them?

[drodda]

I was doing some routine matienance on my bot today. I was edgeing the spoil board to clean the two alignment edges and I decided to check the bot by cutting a large square. The square cut into the spoil board and measured exactly square to the best of my measing ability. However the square cut was .09 inches bigger than the one I had drawn in autocad. This was kind of a surprise as I was not even concerned with the size.

To make a long story short, do I play with my unit values to correct this discrepecy or do I just leave it alone. Everything cut is relative to this error so unless I am cutting something to place in an exact dimension parts seem to fit together.

The bit measured .248 on the calipers. I also type the coords into the cutting file manually so that there would be no offset in Parts wizard for the bit size. The bit being smaller accounts for .003" of the size error.

MY current UNit Values on X and Y are 2482.8171 with 5 multipliers.
Z= 1273.2395 with 4 multipliers.
PRT Alpha with new motor and driver upgrades.

Would you mess with it?

Could this be caused by the pinions wearing down?

-D

[rhfurniture]

I did this when I changed my racks for longer ones in UK. I have an accurate 1 meter steel rule.
1. Write down the current UV's in case you want to go back.
2. Drop 2 shallow holes with any straight bit 900 mm apart along the axis in question.
3. Measure the distance between the same side of the holes avoiding using the end of the rule. The result is say 900.x mm
4. NewUV = OldUV*900/900.x
Repeat the above until x=0
Doing it this way should avoid error through bit deflection.
Worked for me.

R