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1

FAQs / z position

« on: March 20, 2017, 02:23:06 AM »

Hi again everyone,
Another wee problem.
After referencing all axes home, I then move the x,y and z axes to the start position for my workpiece. I set zero for all axes .
I then load gcode for my work.  Hook up digitiser and check that it works ok.

Load autoleveller and it runs fine except it is about 10mm above work piece. Stop programme. clear file and load straight gcode.
programme runs and looks like board is being milled, but about 10mm above the workpiece.
Where have I gone wrong. All of my home switches 0.0 but z is homed up. Is this a problem. I assumed no matter where the z home position was as long as the head was told to move negative and the correct amount of offset (obtained by the digitiser) then bob's your uncle. Apparently not.
Attached gcode.t Please Tell me where I am wrong.

Thanks....Cobber

2

FAQs / Home and limit switches

« on: March 13, 2017, 11:38:36 PM »

Hi everyone Newbie,
I am an retired electronics tech and to keep my brain active design and make controllers for my and my friends pleasure.
To help facilitate this I bought a little chinese router cnc 3020t which I hoped would speed up board fabrication.
This unit had no home or limit switches and the internal bob has no circuit diag and would probably require reverse engineering to get one. I therefore inserted another parallel card into my hp desktop and another known bob with cct diagram to run my home and limit switches.
My problem is that when I ref all home in mach3 the x and y axes move as they should. x to the left and y down. So 0,0. as per convention. Great Now when i go to jog either the x or y axis I must use the opposite key i.e left arrow for x right  right arrow for x left. the same for the y axis. I can remap the keys ok but the DRO reads negative when I move the x axis to the right and the y axis to the top. Its like mach3 thinks the table is reversed. The homing switches work fine. All of the axes touch on the switch and back off so 0,0,0 can be set fine. If I reverse the motor settings active low in ports and pins, the unit then tries to set home at the top right hand corner of the bed. I know I have the unit facing the right way as all of the connections are at the rear looking at it, and standard home signals send it to bottom left, so mach 3 can drive it to home position and the thinks it is going the other way when jogging. All my limit switches and estop work fine in diags. I have not set any soft limits as yet. Would like to work out what I am doing wrong.
Any ideas or help would be greatly appreciated  as I can't quite get my head around the negative/reverse direction reading of the gantry, because with 0, 0 set for x and y any movement of the gantry i.e right or back should show up as a positive following convention.
P.s I have also tried reversing the direction in the homing/ limits section and the unit tries to set home top right.