Topics

1

General Mach Discussion / First cut always in the air - how to get rid of it

« on: September 29, 2013, 03:23:43 PM »

Hey folks.  Someone out there knows the simple answer I'm sure

I've been having good luck with Mach3 on my BlackToe 2' x 4' machine, but there is one semi-annoying (note really) issue I've been having, and that is, after setting X,Y, Z DRO's to zero at the top face and lower left corner of my work piece and starting the first G-code run, the Z axis ALWAYS does an air cut and resets the Z DRO to zero - so its doing what it thinks it should - just 1.5 inches above the work.  When I again re-zero and start again, its fine, but not knowing how to avoid those first air cuts is getting to be a drag.

Any good suggestions?

cheers


Derrick

2

General Mach Discussion / Mach3 variable list

« on: September 07, 2013, 04:09:26 PM »

Please.  Can someone point me to a doc that lists the Mach3 internal variables, such as used in getvar(2002) to get the location of the z probe with contacting a touch plate.

I've looked everywhere I can think of and don't see a list or explanations of what they represent.  It would be a great help in understanding how the many scripts available on the forum work.

thanks in advance


Derrick

3

General Mach Discussion / X and Y axes jump when reversing directions

« on: March 31, 2013, 12:56:19 AM »

Hi everyone.  This is my first post, so glad to be in good company

In the last few weeks I've got my BlackTow 2x4 running smoothly with Mach3 - until today.  I've only had a short time to actually play with it, but managed to have the simple g-code spiral drill example on page 3-10 of the Using Mach3Mill manual run smoothly.

This evening though, when I went to run it again - or when moving the gantry with the keyboard arrow keys - the gantry jumps every time it changes direction in either X or Y;  Z remains smooth as silk.  I've checked that motor tuning is correct and inverted drive signals are selected as with my original setup, but it appears that I have managed to mess up some configuration somewhere and I have no idea where to look.  When I slowed the drive speed way down so the gantry moves at a crawl, it still jolts at each axis change of direction.  It acts as if there are a fixed number of steps introduced at the start of each direction change - then it runs smoothly again until the next direction change when it jumps (in the new direction) and then continues on smoothly.  The jump is very short, but rather more violent than makes any rational sense - and as I mentioned earlier, this is not the action I saw initially.  All the drive shafts and chains appear to be tight and well adjusted, and I don't believe its clocking - surely not in Y since there's only one drive.

I was looking at a bunch of configuration stuff last time I used the machine, so am afraid I've set something wrong.   

Anyone have any suggestions?

cheers


Derrick