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Author Topic: Mach 3 cutting text backwards or mirror image tool path  (Read 4583 times)

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Mach 3 cutting text backwards or mirror image tool path
« on: May 09, 2014, 04:50:11 AM »
Hi
I have just built my second CNC machine and have a problem.
On my previous machine the the X axis went from left to right and the Y Axis from bottom to top, The home point was set to bottom left.
G code files were created using vectric aspire and XY origin position was set to bottom left. All worked well.

On my new machine the the X Axis goes from right to left, the Y axis is set the same as before so hence the home position is now bottom right. This is the only change.

When i cut a test piece on the old machine with home in bottom left all is good, when i cut the same test piece (changing the XY origin position to bottom right in Aspire) the cut is a mirror image of what i see in the tool path window in Mach 3.

changing the XY origin in Vectric aspire only seems to change the start point.

i am guessing i have a setting wrong somewhere in Mach 3

My motor setting are in normal mode and not reversed
My Home limits are set normal and not reversed and the home limit is set to negative.

This all works fine with the DROs with the direction correct (X axis going right is + and Y axis going up is +)
Home all works fine homing to the bottom right hand corner.

The machine has to be set this way as i have retro fitted mach 2 to this machine and this is where the home switches are fitted and the orientation of the machine so please do not say change the axis, this is how it has to work

i need to get this set so that what i see on the screen is what i cut.

i have tried changing the setting in the motor settings and Homing by reversing the motor direction but this makes the table direction wrong.

Can anyone help me on this problem, i am sure that this has come up before and is a really frustrating problem.

i look forward to any help offered

Thanks

Gary

Offline Tweakie.CNC

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Re: Mach 3 cutting text backwards or mirror image tool path
« Reply #1 on: May 09, 2014, 05:10:59 AM »
Hi Gary,

Directions relate to the tool movement over the work piece rather than the movement of the machine table.

If the tool moves to the right over the work then that is axis + direction : if the tool moves to the top over the work then that is axis + direction.

I see no reason that you cannot home bottom right but this position will not be X zero, Y zero as far as the work is concerned and your offsets should reflect this.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Mach 3 cutting text backwards or mirror image tool path
« Reply #2 on: May 09, 2014, 05:34:36 AM »
HI
thanks for the reply, i understand what you are saying regarding the tool movement over the work piece but i don't understand what you mean regarding offsets, if i home to the bottom right then this will not be 0,0 are you saying that i home to the bottom right which will give me the bottom right of the table and then apply an offset to this ?

if this was your machine with this problem how would you do this.

thanks

Gary

Offline Tweakie.CNC

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Re: Mach 3 cutting text backwards or mirror image tool path
« Reply #3 on: May 09, 2014, 05:49:24 AM »
Quote
if i home to the bottom right then this will not be 0,0 are you saying that i home to the bottom right which will give me the bottom right of the table and then apply an offset to this ?

Yes, apply the offset to arrive at your work datum then zero the DRO's.

I don't actually use machine homing routines, never have - all my work is either one off's or jigged for multiples and my datum (X zero, Y zero, Z zero) is always set-up at run-time.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Mach 3 cutting text backwards or mirror image tool path
« Reply #4 on: May 09, 2014, 06:00:01 AM »
Thanks for the reply
got my head round it now, effectively i am homing to 1220 (x) and 0 (Y) as this is the bottom right hand side of the table, this is done by adding an offset in the homing tab X axis.

This also means that you have to redo the park position, tool change position and fixed plate as they will also now be wrong as they use the machine coordinates.

Just done another test cut and it works perfectly.

thanks for your help, sometime a point in the right direction is all that is needed

Hope this is useful to someone else as well

Regards

Gary

Offline Tweakie.CNC

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Re: Mach 3 cutting text backwards or mirror image tool path
« Reply #5 on: May 09, 2014, 10:01:07 AM »
Hi Gary,

I am pleased that you have it sorted.  ;)

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.