Problem with x and y speed

[Carld]

I have a problem with my homemade plasma cutter cnc table .
If i set my speedrate 70 ipm in sheetcam , my x axis travel 70ipm and my y axis travel at 100 ipm

Both axis have same setting in mach 3 . Y axis have a slave motor A

How to solve the problem ?

Thanks

[acourtjester]

You will need to redo the steps per inch for the 2 axis there seems to be a different drive ratio between the X and Y. The Y and A will have the same numbers as they should have the same ratio. A simple test is to mark the rails and time the distance moved for each X and Y. If you tell X to move at 24 IPM is should take it one minute to move 24 inches.

[vmax549]

You DO NOT redo the steps per for SPEED . It is ONLY used to setup distance. IF that part is accurate then LEAVE it alone. What controller are you using and exactly how did you test this. You would normally test each axis in a straight line one axis at a time.

(;-) TP

[Carld]

My Step and my speed are exactly the same in in X , Y , A
When i cut a part , my x is travel slowly than my Y , based on the feedrate on the screen on mach 3
that give me inconsistant result .

[exapprentice]

Hi Carld

Are all your / do all of your axis have exactly the same gearing
Have you checked that if you want each axis to move say 100mm (4") then each axis actually moves 100mm (4")have you checked each axis for this
look up MDI input
if the gearing is different then your steps/per will be different

[Carld]

Yes is the same rack and pinion .
Video of my feedrate :
http://youtu.be/MGwRSJ2MH0M

[Carld]

How do you love your powermax 45?
I'm thinking about uprading my old powermax 380 how much you can pierce and cut ?


Another video of my problem
http://youtu.be/r9Xn5Gjy-eM

[acourtjester]

Next question does your drivers have switches for setting the pulses per revolutions?
switches 5 through 8 are they the same for the two axis X and Y??

[Carld]

Yes , they are the same

[tcaudle]

Confirm calibration on both axis by cutting a 4" square. should be the same on all sides. Or a 3" circle should be ROUND. The axis in MACH are coordinated meaning it figures out what the speed of each one needs to follow the toolpath. Depending on the shape you can have different speeds on an axis and the "blended" speed MACH shows is the vector sum of the two axis. Cutting at a 45 deg angle the actual blended speed is greater than either of the XY speeds. If you are having toolpath inaccuracies then either the calibration is wrong or one axis can't do the speed its tuned for and is missing steps. BTW having an axis out of calibration (wrong steps per unit) will make it appear to move slower or faster because its moving in IPM and its set so it moves less than 1" it will think it arrives at the 1" sooner and the relative speed will be lower So calibration can effect speed but it also shows up in the distance too.

[Carld]

Tcaudle , i have made a test cut with 4x4 square and all is square
I think i have find the problem
I have set my x at 100 ipm and my y to 75 ipm . The sound pitch is not the same but mach 3 show me the same speed on x and y

If i set my x and y to 75 ipm , the sound pitch is the same and seem to cut same speed but is possible the slave A axis on y false my "feedrate" speed on mach 3 screen ?