Basic 540 CNC. Motors skipping pulses?

Im slightly new to the CNC world. This may be a normal situation but can anyone help me.
Ive got a basic 540 cnc router. Link for is http://en.step-four.at/hp2/index.php?action=1482
The problem i'm having is that when i increase the speeds of the motors, my motors dont run smoothly across the axis, this is for the Y and X axis. This is on Mach3 and i specifically increase the velocity. Below 100 in/min it runs smoothly. above that it appears as if the motor is becoming jammed on the way but it is going faster. Is this normal for this type of router?

Thanks

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Originally Posted by Skydeals

Im slightly new to the CNC world. This may be a normal situation but can anyone help me.
Ive got a basic 540 cnc router. Link for is http://en.step-four.at/hp2/index.php?action=1482
The problem i'm having is that when i increase the speeds of the motors, my motors dont run smoothly across the axis, this is for the Y and X axis. This is on Mach3 and i specifically increase the velocity. Below 100 in/min it runs smoothly. above that it appears as if the motor is becoming jammed on the way but it is going faster. Is this normal for this type of router?

Thanks

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The way I read this and the specs is that the machine is only capable of 78"/min and you are saying it runs ok at 100"/min which is better than the spec of the machine. Unless I am missing something. ..Clive

The spec says it can do;
"positioning speed 2000 mm/min"

so as you quoted inches that's 78.7 in/min

That's why it works below 100 in/min.

Edit: Ha ha it happens all the time, posted same time as Clive S

ahh. I didnt carefully read that webpage to find what speed it can do. So ill stick to 78in/min at the most.
thanks for the prompt response