Step by step
Measure a distance using the machine
A real measurement off the bed, taken with the machine you already have, accurate to what the machine itself is accurate to.
Before you start
Anybody who needs to know how far apart two things on the bed actually are, and does not want to trust a tape measure held over a honeycomb.
- The machine connected and homed.
- The thing you want to measure, sitting on the bed and not going to move.
Home the machine first
Every position the machine reports is counted from the corner it finds when it homes. If it has not homed since it was switched on, the numbers mean nothing.
Home it, and do not push the head by hand afterwards. A hand-moved head is a head the controller has lost track of.
Put the head on the first point
Jog the head until the pointer sits over the first point. Use the slowest jog for the last few millimetres; the fast one overshoots and the backlash in the belts shows up as a reading that changes depending on which way you came.
Always approach from the same direction for both points, for the same reason.
Mark it, move, and read
Take the first point, jog to the second, and take that. The distance is shown in both axes and as a straight line between them.
It is measuring where the head is, which is what the machine believes. That is exactly the number you want when you are checking whether the machine and the drawing agree.
Every setting, and what it does
3In the order you meet them. The second line on each is what goes wrong when it is set badly, which is usually the more useful half.
Measure from this stored position
Starts at origin
Measure to this stored position
Starts at target
Layer to draw the measurement line on
Starts at 0
How to know it worked
- Measuring the same two points twice gives the same answer.
- Measuring a known object, a steel rule laid on the bed, gives its real length.
When it goes wrong
2The answer changes each time I measure.
You are approaching the points from different directions and reading the backlash. Jog the last stretch the same way both times.
A known 100 mm object reads 98 mm.
That is the machine's own geometry, not this tool. Run the axis calibration and the correction is applied to every job afterwards.
The tools this used
Check the real distance between two points you marked on the bed.
Calibrate axisFix cuts that come out slightly bigger or smaller than the size you typed.
Find material centrePut the head in the middle of a part that is not square to the bed.
Save head positionRemember a spot on the bed so you can send the head back to it later.