Center ain't center


(Steven Bowen) #1

Another total newbie here…no exposure what-so-ever to routers, CAD or CAM, etc…
However, happy to report that my SO3 went together perfectly with no problems at all… everything seems perfectly square, centered, and my first couple projects this week have turned out surprisingly well… (just artsy craftsy stuff to give an old retired guy something to do…)

However, something is puzzling me… (using CC and CM)
If I use rapid position and mark the 4 corners, it seems reasonable to think that the center button would take me to the spot where an ‘X’ between these 4 points would intersect… but it doesn’t…

The X axis is centered exactly…
But the Y axis… the center button takes me to a point a little over 2" behind where the true center would be…

Is this how it is supposed to be?
Is there a reason for this?
Is there a way to change it so the rapid position center point actually takes you to the real working center?


(William Adams) #2

If I understand what you are saying, there is an offset from the front of the machine due to the ~2 3/16" overhang at the front of the machine.

I wrote up a bit about the coordinates for the rapid position points at: https://wiki.shapeoko.com/index.php/SO3_Function_Test#Distance_of_travel

(it would be nice to have the numbers for an SO3 and XXL filled in)

Unfortunately, the numbers are hard-coded — the only adjustments are adding physical stops or relocating the homing switches or adjusting the stand-off from the switches after homing.


(Steven Bowen) #3

I guess it still doesn’t make sense to me, but I guess that’s the way they are programmed…

For the XL in your link, you have a S of 405,0 and a N of 405,350… so the center should obviously be 405,175… but you show 405,215… but this is what I was talking about.

For me (a definite beginner), it seems like it would be more usual if it used the true center of 405,175 (just because I’ve been using the center and centering my projects off of it… fine with small projects, but will be a problem with larger items…I suppose this is probably one reason people use the front left corner as zero)


(William Adams) #4

I believe the center is offset towards the front to be at (or closer to) the center of the supported work area.


(Steven Bowen) #5

But the offset is to the rear and away from the work area… at least it seems like it to me… I only have less than 5 inches from the center button point to the rear of my work area on a SO3…