After all the other niggling problems that I have encountered I now have a machine that is coupled and working with Mach3 and has a MPG controller. Great.
So, this weekend I thought I would do some axis tests to ensure that my programmed movements equated to the physical movements. Not great!
First of all my native and operating units are metric.
Using my Imperial (inch) DTI I positioned it on the X axis and moved the table left and right using MDI mode. The distance I moved was 12.7mm (1/2") to both keep the movement within the range of the DTI and to allow the DTI needle to fall on the same point of the scale.
Unfortunatley every time I moved from 0 to 12.7mm I was showing around 0.004" (0.1mm) short.
I have tried moving the table by hand and there is no play as witnessed by no movement of the DTI needle.
I have adjusted the axis acceleration down to single figures (5mm/s^2), have the velocity around 500mm/min, step and dir pulse as 5us but still i'm losing.
Tonight I double checked all the mechnicals and found 5mm pitch ballscrew (RM1605-UF), 2.5:1 timing belt drive (12x30T) and 400step/rev motors so I would expect that my steps per mm box is correct at 200.
I can solve the problem by 'tuning' the steps per mm to some spurious figure like 201.838 but that can't be correct as it has obviously been built to a round number and it should be 200, shouldn't it??
![Huh ???](https://www.machsupport.com/forum/Smileys/default/huh.gif)
Sweep