Problem- Motor Noise Issue

[dsnellen]

Here is what’s happening.

The Z motor has started to stall/skip several beats on a random basis and then work ok. It was a Dec 2009 replacement for a motor that had the same characteristics. For example, on the up cycle, it will stop moving, growl loudly, and may start moving again. I am using Mach3. To test, I swapped the Y -> Z and Z -> Y leads and both motors ran ok. Z was still loud. I swapped them back and Z ran (loudly), up and down, for a dozen cycles and then it would stall/growl again before continuing. I have tuned the steps accurately so I am tinkering with are the velocity and acceleration. The acceleration is set between 8-11 for all the motors. With the Z velocity set at 80, it will run for numerous cycles and then stall. I reduced the velocity downward in a series of steps all the way to 20. The most noticeable change was the motor growled louder as the velocity decreased. At a velocity of 26 it seemed to perform without stalling but was very loud. Has a lot of motor created vibration. It is the "quietest" and "smoothest" at around 80 where it will run for a while and then stall. Will run at 100 too, but stalls much faster. The error doesn’t seem repeatable in that it may run for an hour before skipping/stalling. Additionally, the missed beats seem to be on the up cycle which then drives the router into the wood on the next down cycle.

I am not sure it’s the motor although the motor removed from the machine is quite noisy and vibrates excessively. When I installed it last December, it ran quietly and would zip up and down smoothly. I have poured over the Mach3 documentation, their forums, this forum and tried numerous combinations of steps to isolate the problem. On Saturday it seemed to work ok and I was finally able to cut one simple house number sign. Yesterday, I was unable to successfully complete a single project. It would zip along, maybe 30-45 minutes, then miss/skip the up command only to drive itself into the wood on the next down command. Eat up a lot of cedar. Frustrating to say the least.

The hardware:
Dedicated computer and not connected to a network
Chinese CW250 Drivers
C10 Parallel Port Breakout
SKSP 500 28 power supply
5/8" 4TPI single start screws
KL23H286-20-8B motors

Kelinginc.com will replace the motor but before I declare the motor defective after 15-20 hrs, I want to ensure I have tried everything and eliminated any other possibilities. Looking to you guys for ideas. Have any?

Thanks
Dave Snellen

[H500]

It sounds like you need a stronger motor or a higher supply voltage. How high will your drives support?

[dsnellen]

Originally Posted by H500 It sounds like you need a stronger motor or a higher supply voltage. How high will your drives support?

Thanks H500. The drive & power supply has been in use for several years so a stronger motor is not likely the answer. But the power supply could be getting weak. I bought the machine used in Sept 2009 and it ran fine until Nov 2009 when the Z motor started acting up. Thinking it was normal wear and tear, I just replaced the motor. It ran fine until about a week ago when it started acting up. Are there any Mach3 setting I should try/look at before declaring the motor defective? It sounds/acts like it is being run at too high a velocity but when I reduce the velocity it growls louder. This is backwards of what I expected.

Thanks
Dave

[ger21]

Is it colder than when it was working good? Have you lubricated the screw?

[dsnellen]

Originally Posted by ger21 Is it colder than when it was working good? Have you lubricated the screw?

Thanks for the input. It can get very cold in the shop. The temp is within the specs of the motors, drivers and power supply. However, the computer will not boot when it’s too cold. The heater will only raise the temperature about 25-30 degrees above ambient so when it’s below about 40' F I don't even bother. That's why the time on the motor is low.

I also suspected the screw may be jamming and detached the motor from the screw. I was able to turn the screw by hand easily both up and down. I do use a dry lubricate on the screws. I don’t recall the name, but I spray it on and after five minutes it has dried and will not attract dust. When the motor was detached from the screw it ran very rough and had, what I think was excessive vibration.

I think the motor is defective, but I want to ensure I have eliminated any other possible cause or combinations of events that could cause the results or would cause a replacement motor to also stop working after 20 +/- hours. X, Y and A run fine so I moved the power supply down the list. Same with the driver as it has no problem driving the Y motor. Are there any Mach3 setting I should review? Any other troubleshooting steps I should take?

Thanks