I'm new to plasma cutter CNC

[SaidAb]

I'm new to this job , plasma cutter CNC machine, I noticed we have a regular problem in accuracy, we have a sheet of 6000 mm in 1500 mm , we cut from this metal sheet 3 pieces of 6000 mm in 485 mm , but we get in reality:
6000 mm in 485 mm
6000 mm in 487 mm
6000 mm in 489 mm ( in the other end 485 mm )

In our small factory 486 mm is accepted but 489 is not accepted.
How can we solve this accuracy problem ?
Any tips please ?
(Take in notice we use Max pro 200 hypertherm machine with UCCNC software for the machine. We use a process of marking 2 points in the two ends of the sheet by the machine laser pointer to put two references for the software and the machine to make the cutting accurate, I don't know how you guys call this process )
Thanks for the tips in advance.

[weldguy]

Am I correct in thinking you don't draw your rectangle in CAD software but instead you use a laser to mark the points the machine is to move to?

[tcaudle]

Not sure if he is trying ot use the material edge as one side ? 1500 divided by 43 is 500mm so you have kerf width to add in . Looks like simple lines like slicing bread if the 6000 length is the outside.

Its growing 2mm each cut so either they are not figuring in the kerf width or the cross axis calibration is off

[SaidAb]

Not sure if he is trying ot use the material edge as one side ? 1500 divided by 43 is 500mm so you have kerf width to add in . Looks like simple lines like slicing bread if the 6000 length is the outside.

Its growing 2mm each cut so either they are not figuring in the kerf width or the cross axis calibration is off

For kerf width, we put enough distance between every part ,
We have 6000 mm in X axis, 1500 mm in Y axis .
The 3 parts that we cut have a slight problem accuracy in Y Axis, in the first two parts it adds like one or 2 mm , in the third part we have in Y axis like 4 mm added. We did the calibration process by choosing one point in x=0 y= 0 and second point in y =0 X = 6000 .
Coworkers are saying it is maybe due to the slight movement of the whole sheet while the plasma cutting is cutting it , and this sheet has like 10 mm thickness.

Thanks for your reply.

[robertspark]

if you cut a 100mm square, does it measure 100x100 after the cut?

[adbuch]

Not sure if he is trying ot use the material edge as one side ? 1500 divided by 43 is 500mm so you have kerf width to add in . Looks like simple lines like slicing bread if the 6000 length is the outside.

Its growing 2mm each cut so either they are not figuring in the kerf width or the cross axis calibration is off

For kerf width, we put enough distance between every part ,
We have 6000 mm in X axis, 1500 mm in Y axis .
The 3 parts that we cut have a slight problem accuracy in Y Axis, in the first two parts it adds like one or 2 mm , in the third part we have in Y axis like 4 mm added. We did the calibration process by choosing one point in x=0 y= 0 and second point in y =0 X = 6000 .
Coworkers are saying it is maybe due to the slight movement of the whole sheet while the plasma cutting is cutting it , and this sheet has like 10 mm thickness.

Thanks for your reply.

Perhaps show us a photo of one of the parts along with posting the dxf or svg file so we can see exactly what you are working with. For this part, please tell us the actual dimensions you measure on the finished cut part.

Thanks,
David