770 tuning vfd for spindle speed

[Advil]

Just followed the manual's instructions to set the vfd. I need a sanity check because this was crazy:

Manual says, put Pathpilot in low mode, put the belt in low mode, set spindle speed to 500 RPM.

Watch the VFD and turn the pot screw until between 34 and 36.

Ok. Easy. Problem is, when I first looked at it, it was at 17 !?!. I had to turn that screw a LONG way to get it to 35. It's right on now, but obviously the spindle speed changed a --->LOT<---.

Have I spent the last 6 months using this machine with my commanded RPM being what audibly sounds like 30+% different?

It's like no one ever even turned the screw to a default location. It was just at minimum like it came off the assembly line.

Is this normal?

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[syscore]

Sounds like you were at half speed. I got a cheap (~$15) laser tachometer on amazon to check the RPM directly. It almost seems that wither the original adjustment was done on the wrong pulley, or this one was.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[GLCarlson]

I mounted a reflective sensor and digital tach inside the spindle housing, as did a few other 1100 owners. Most of the time, knowing rpm isn't critical; 10% or so either way won't matter. It's very handy if you're tapping. And rpm drop works as a load meter, too.

[CountrySmith]

Just followed the manual's instructions to set the vfd. I need a sanity check because this was crazy:

Manual says, put Pathpilot in low mode, put the belt in low mode, set spindle speed to 500 RPM.

Watch the VFD and turn the pot screw until between 34 and 36.

Ok. Easy. Problem is, when I first looked at it, it was at 17 !?!. I had to turn that screw a LONG way to get it to 35. It's right on now, but obviously the spindle speed changed a --->LOT<---.

Have I spent the last 6 months using this machine with my commanded RPM being what audibly sounds like 30+% different?

It's like no one ever even turned the screw to a default location. It was just at minimum like it came off the assembly line.

Is this normal?

From what I see in the online manual for the 770, (page 171) the readout should be 17.5-18.5 for the 770 and 34 -36 for the 1100.

RJ

[Advil]

From what I see in the online manual for the 770, (page 171) the readout should be 17.5-18.5 for the 770 and 34 -36 for the 1100.

RJ

Woah! Good, good catch.

The 770 manual I was using was April 2016. The latest one is September 2016. Sure enough, there was NO indication whatsoever in the April version that it should be set to anything other than 36.

Now, suddenly in the September manual it's on a different page with side by side pictures... one showing the 1100 VFD at 36, and one showing the 770 VFD at 18.

I'll be putting it back to 18hz right now. And getting a basic tach just so I can see what I'm really getting.

Glad I havn't run anything on the mill since changing it yesterday.