[hoffm472]

So I am relatively new to CNC mills, I just picked up an Enco mill with the flashcut conversion along with a box full of other mounts, tools and accessories. The stepper motors are the 5000-3xxx series. I have a couple quick questions.

1.) I have no issues when using the jog command in any of the 3 directions at high speed (currently limited to 20 ipm in the system configuration) I can run it down and up the z-axis with absolutely no issue. However when I hook up my tool length sensor and use the z-axis for the sensing function it appears to act differently. After touching the probe and initiating a rapid move in the z direction upwards (immediately after tripping the sensor) the motor stutters and starts going crazy. I assume it is doing it's rapid move at the systems limited 20 ipm. The weird part is, is that it performs this function fine when using the jog command. I temporarily reduced the max Z speed to 5 ipm to resolve this issue, but now when jogging it is obviously painfully slow to sit through. Does anyone know a solution or reason why the z motor would be having issues like this?

2.) Would anyone happen to know the max speed for this setup? 20ipm seems slow for the xy travel, I am curious if I can set it higher without damaging anything, but I do not know the acceptable methods as to determine what the max speed can be set to. Is it simply increase until you start losing accuracy or are these values recommended by the manufacture?

Thanks for the help!

[109jb]

Not sure how the flashcut system works, but it should have settings for max velocity, an acceleration/deceleration. This will greatly affect performance. Also, if the machine had the gibs too tight, or if there is some other mechanical binding the that will affect it too. 20IPM is really slow. I think mine is slow at 70 IPM.

I assume the Z axis just operates the quill. If so, is the quill lock tight or loose and how tight is the spring? My benchtop uses the quill for z too and I have the quill lock just barely snug to take up slop, but not cause too mich drag. My spring is reversed so that the sping provides down force on the tool, so the motor is fighting the spring as z goes positive. Again, i have the spring pretty loose so that it just provides a little down force but not too much.

Let us know how the machine is set up and you will get better answers. For example: Ballscrews? Direct drive from steppers to screws? How is quill hooked up? Any mor info on steppers like oz-in rating, power supply used, what drivers, etc.

[hoffm472]

Not sure how the flashcut system works, but it should have settings for max velocity, an acceleration/deceleration. This will greatly affect performance. Also, if the machine had the gibs too tight, or if there is some other mechanical binding the that will affect it too. 20IPM is really slow. I think mine is slow at 70 IPM.

I assume the Z axis just operates the quill. If so, is the quill lock tight or loose and how tight is the spring? My benchtop uses the quill for z too and I have the quill lock just barely snug to take up slop, but not cause too mich drag. My spring is reversed so that the sping provides down force on the tool, so the motor is fighting the spring as z goes positive. Again, i have the spring pretty loose so that it just provides a little down force but not too much.

Let us know how the machine is set up and you will get better answers. For example: Ballscrews? Direct drive from steppers to screws? How is quill hooked up? Any mor info on steppers like oz-in rating, power supply used, what drivers, etc.

Thanks for the reply! Yeah I agree 20ipm is painful to sit through, that's why I was curious how to determine what my max speed can safely be set to. Yes the Z axis is attached to a stepper with gear reduction to lower/raise the spindle. I leave the quill lock loose during operation. My spring is set up to the reverse of yours. as the spindle moves down towards the table (neg Z) the spring compresses. That is a good point you brought up, I wonder if having the spring loaded when the spindle is down and having that extra force pushing the spindle in the direction of the motor movement when it goes to do its rapid retract is somehow affecting or overloading the motor? I will have to look closer at it to see how I could go about swapping the spring like you have described.

I picked up the machine from an estate auction here a few weeks ago, the previous owner was a gentleman that unfortunately passed away this year. He has keep pretty detailed records and taken great shape of everything but there is no way to know if I got all the information he may have had on the machine. All I know right now is that the machine is running an older flashcut cnc conversion package (serial version of the signal generator). The Stepper drive box is the 5000-3xxx series and the motors are unmarked. I believe now flashcut cnc has upgraded their site with newer models so I cannot seem to find any datasheets on them. I will contact Flashcut here in a minute and see if they can provide anything. The machine is also equipped ballscrews for the x,y & z axis.

[109jb]

If the system has reduction drives and steppers, that may be part of your problem. When I initially did my Z-axis, I had a 2:1 reduction which gave me 0.00025" per full step. What I found with this setup was that I could only get about 20 IPM reliably without occasionally losing steps. I changed it to just the opposite, a 1:2 ratio which gives me 0.001" per step and now I can reliably run about 80 IPM. In both cases the motor is turning the same RPM, but the travel speed is 4X. The reason for the above is because steppers have their highest torque at low RPM.

What are the ratios on each axis on your machine?