fluctuation in the spindle speed ????

I have a IH cnc that has been having some fluctuation in the spindle . it sounds as if it just is starving for power to the motor . it still cuts good but the spindle speed drops off here and there.

Any thoughts ?

Do you have the VFD?

Yes it has a vdf

Check your VFD manual... There might be a way to display % load. You proofing your feeds and speeds with FSWizard or G-wizard to see how close to your rated HP your cuts are taking you?

I don't know anything about that to be honest. I'm a n00b when it comes to this stuff but not a n00b to programming and cutting. This is my first machine . It was already built

Both FSWiard and a wizard are programs to help calculate appropriate feed rate and spindle speed while cutting. They allow you to select your spindle HP, and limits the recommendations to avoid bogging down your spindle, which can turn into bad news in a hurry in the middle of a cut.

Both have demos available for download; sounds to me like you have been selecting too aggressive if a feed rate or DOC for the available HP of the mill.

With manual milling, you can feel when you start taking too much off too fast, but with a CNC you can't always respond quick enough. Calculating these setings in advance will help prevent bogging the spindle, breaking cutters, etc.

These programs go way bryond the simple mantra of the manual machine (RPM=FR*4/dia and FR=T*CL*RPM).

I don't need a wizard for feeds and speeds . I'm talking just turn on spindle and it starts to vary . I've meet machining for 15+ years but don't know jack about this stuff

It sounds like you have electrical noise on the 0-10vdc line that feeds the VFD. The control (most likely Mach3) uses either a step/dir signal or a PWM signal to control the spindle. This signal is output to a board that converts that signal into a 0-10vdc signal. VFD's can be programmed to get the speed source from this 0-10vdc signal. So for example if you have a 10k rpm spindle, 0v would technically be 0RPM and 10v would be 10k RPM. So say you want to run 5k RPM. If you were to measure the output on that board, it would read pretty close to 5v.

Hope that makes sense to help you better understand how it works.

Thanks I will check that wire . I know I had issues a while back with a bad connection. So that might just be the issue . Thanks

Did you ever figure out what caused the spindle speed fluctuation? I'm experiencing the same issue. I don't see issues with cutting but do hear a quick change in motor frequency at least once a day. Will have to put a scope on it someday... Bothers me cause I was getting an A30 error when I first turned the machine on. Turns out it was a loose wire in the VFD. I didn't notice it at first since the three VFD wires to the motor were zip-tied together.

some vfd has this

I remember my first spindle made it..
and I don't even could set to 400 hz

best you can do, use it as long as you can, and change it when you get chance.. I had a sunfair c300 vfd.. if it helps..
I wrote email to manufacturer , they answered.. but fluctuating were remain..

changing both, spindle and vfd I didn't experienced anymore..

I look around on other computers, because I remember the manual was discussing the fluctuation.. with settings you can reduce it..

i found it..

this is not your vfd probably.. however the cause is same..
around the 69 page or F4.14 youll find

theres the settings, automatic voltage regulation..
this does the input from your wall outlet coming is vary within the day or even minute by minute..

if this ""normal"" fluctuating not controlled or filtered then your spindle also will fluctuating..

hope it helps some..



http://www.kunaimpex.com/admin/image.../742148237.pdf

no I havent

we can try to help you here..

however the company who made or assembled this machine thye have manual about the vfd..

have you called them?
or email?