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Author Topic: part damaged when rotation axis mach4 (Rot 360 rollover and; Short Rot on G0)  (Read 2774 times)

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Hi,  i'm having problems with my machine when i use G-code generated by Deskproto 6.1.

I got feedback from the developers of desk proto and they said i need to change the settings:  Rot 360 rollover and Ang Short Rot on G0 in my mach3,  the problem is I use mach4  and i don't find  a setting like this.

Here is the problem and solution from the FAQ at deskproto:

 My part is damaged when rotation axis machining on a Mach3 driven machine.
It seems like some of the rotation axis toolpaths are incorrect, though on the DeskProto screen all looks fine. This problem may be caused by an optimization setting in Mach3.
Please check dialog "General Logic Configuration" of the Mach 3 Software. On this (huge) page you can find a section "Rotational" with two checkboxes, called "Rot 360 rollover" and "Ang Short Rot on G0".
If one of these options is checked this may be the cause of the error.
Here is what the Mach3 manual says about these two options:
Rot 360 rollover: if checked, it will measure a rotary axis modulo 360 (0 to 360 then restart at 0). Otherwise, it will keep counting up (for example, two revolutions would be 720).
Ang Short Rot on G0: if checked, it makes any rotary axis treat the position given as an angle modulo 360 degrees. Moves will be by the shortest route to that position. For example, if the axis were at 0 degrees and a request was made to rotate to 359 degrees, it would rotate -1 instead of +359.
The Rollover option introduces an extra movement to A=0 for every A-movement, which may destroy your part (and will take very long).
The Ang Short option needs to be unchecked as well: rotating via the shorter route may destroy your part, as DeskProto checked only the route that was prescribed.

The only related settign i can see in mach4 is in general config: rotary axes: rollover A ;B and C   i have rollover A checked...
Is this that settign or ....?


« Last Edit: March 16, 2016, 04:15:10 AM by bartvano »

Offline Mauri

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I have tested the Mach4 on Rotary Continuous for you and you must Not tic Rotary Axis Rollover A.
If you tic it, then it will only go -360 to 360 no matter what the G-code says.
If unticked it will run continuously in line with the G-Code. i.e. if the G-code says A 720.0000 then it will do 2 revolutions on the A Axis and also displays this on the Mach4 screen going to 720.
My test was with Mach4/Controller and one Motor attached to the A Axis.
I am awaiting some changes to Mach4 before I do a complete test on my Mill but I think this test confirms my findings.
Hope this helps.

ok thanks for the test,   i will test it myself with a part this week.

it works now:  if i untick Rotary Axis Rollover A  my G-code works fine,  altough i never had any A values more than 360 in my program. but when t was for example at 249° and  the next move was to A360  it whent backwards instead of continuing in the same direction.