change speed of stepper motor

[Niklas Bjornestal]

Does anyone know if there is any "easy" way to make a stepper motor take double steps? I have a chines laser with higher resolution in 1 direction which isnt good when cutting (cuts much deaper in 1 dir). So is there a simple (and cheap) way to fix the "slower" motor to take 2 steps each time?

[Roy Brewer]

Does anyone know if there is any "easy" way to make a stepper motor take double steps? I have a Chinese laser with higher resolution in 1 direction which isn't good when cutting (cuts much deeper in 1 direction). So is there a simple (and cheap) way to fix the "slower" motor to take 2 steps each time?Niklas,



While I wouldn't be astounded if a Chinese laser had different stepping rates for the different axes, but is there a chance it is simply a matter of the beam being elliptical? One of the specifications of a "well made" laser delivery system (tube itself and supporting optics) is that it is close to round; probably no laser beam is perfectly round, but the closer to round the more uniform the cut.



To test this hypothesis, make a very light mark on anodized Aluminum; a cross would be an excellent shape then with a loop focus on where the horizontal and vertical axes meet. If one is noticeably wider than the other then the opposite axis will cut deeper. If it turns out that this is the case, check with your supplier and see if all the tubes have the same characteristic.

[Niklas Bjornestal]

Niklas,
While I wouldn't be astounded if a Chinese laser had different stepping rates for the different axes, but is there a chance it is simply a matter of the beam being elliptical?

It has 2000 dpi in one direction and 1000 dpi in the other. This makes the laser move twice as fast in the 1000 dpi direction compared with the 2000 dpi direction. I would like it to have 1000 dpi in both directions.

[Roy Brewer]

It has 2000 dpi in one direction and 1000 dpi in the other. I would like it to have 1000 dpi in both directions.Niklas,
Driven by stepper motors, right? One is probably 1/2 pitch and the other is 1/4 pitch. If you have any communication with the manufacturer or supplier, ask them for different lead screw and lead screw nut.

[Kim Vellore]

Does anyone know if there is any "easy" way to make a stepper motor take double steps? I have a chines laser with higher resolution in 1 direction which isnt good when cutting (cuts much deaper in 1 dir). So is there a simple (and cheap) way to fix the "slower" motor to take 2 steps each time?

Niklas,
I was thinking all lasers have lower resolution in the Y axis maybe I am wrong but normally this is not a problem except in some specific cases. You have a few options if it is belt driven you could change the sprocket to have twice the number of teeth which will also increase the load on the motor. If you are familiar with electronics you could hack into their electronics and it should be fairly easy to modify to change the resolution except you got to make sure the motor can respond to the new speeds reliably. I have been doing a very similar thing on my Epilog, I needed a high resolution Y axis motion so I used the rotary axis and put in a linear slide and put a black box between the motor and the connector, In the black box I have a microcontroller which reads the motor signals and drives the motor at a slower rate, it took me a while to get all the timings right. But it works well.

Kim