Profiling axis distance corrections

[harryn]

Hi,

I am in the build phase of a DIY router.
- Sized for 4 x 8 sheet
- model airplane wings
- sheet plywood
- Various other hobby things.

This is for hobby use for routing wood and foam. I have an idea to also use it to improve my drilling results as it also incorporates a drill in the Z axis. (not a spindle, a hand drill, so not perfection use, just better than I am by hand)

Drive Method
- Tried to do them all the same, but in the end, they might all end up different, but most likely belt and rack and pinion.

Motors
- At this point, steppers running open loop. I have some linistepper driver kits already, but am open to options if other methods are significantly better, and I have the budget.


Question

Regardless of what method is used, there are always imperfections and non - linear areas of a drive mechanism. For example, even high end ball screws have a rating for "accuracy per foot or meter", and a belt has even larger errors, most likely, not consistent over a 8 foot distance.

I read the mach III manual last night (yes, I am a beginner) and found a setting to "fine tune" a local section of motion for a movement distance, but I wondered if there is a method to "fine tune" sections of the axis. Example, if I can manage to borrow a very accurate meter, can I somehow profile the axis, say 10 regions of the axis ?

I realize that my work may or may not need this, it is partially for my own learning.

I am sure this has been asked before, I just could not find it in the 10 pages of threads or the manual.

Feel free to just point me to the right section of the manual or an existing thread.

Thanks a lot

Harry

[ger21]

I think you're talking about screw mapping. Used by very few Mach3 users. In order to do it correctly, you need a way to accurately measure the location along the entire axis.
Imo, it's really not needed on a router.

[harryn]

Hi Gerry, Thank you for the response. I suspect that you are right, that it is probably overkill.

In the case where someone wanted to improve over the results from an open loop, stepper driven, somewhat imperfect positioning system (not backlash, but offset) what approach would make sense ?

Obviously things like a higher precision ball screw, etc, but what if you wanted to just improve a less precise method, such as a belt or rack ?

Do people put linear encoders on their systems ?

Thanks

Harry