Measuring bit wear

[bill_lumley]

I was told today by support that some folks are monitorinng when to change a bit by the amount of power(current) the spindle is drawing . A typical cabinet job can be upwards of 20 or more sheets and it would be nice to have an indicator to tell when the bit needs replacing . Has anyone used such a method and if so what device have you used to measure power consumption and where was it placed ?

Thanks Bill

[harold_weber]

Bill, if you run a spindle, then you use an inverter (VFD) to power it, and the VFD display can be set to show the current it is delivering to the spindle. The way to set up the VFD to display current depends on the brand, if you have trouble tell us your brand of VFD, and perhaps someone here can help.

[dlcw]

I determine bit change time based on cut quality. A dull bit will create a ragged cut whereas a sharp bit creates a clean cut. At 6-8ips I'm cutting around 25 sheets of plywood before I change bits. With particle board and MDF your bit change rate will be less as these materials eat bits for breakfast.

Don
www.dlwoodworks.com (http://www.dlwoodworks.com)

[rhfurniture]

I have my VFD set to tell Hz (rpm). But I have a large meter (voltage driven) on the outside of my control box that is connected to a lv output on the VFD that is set to display amps with the help of a small resistor. It is very useful. My VFD is a basic Hitachi.
R.

[bill_lumley]

I have the Yaskawa set to display RPM at the moment but I have the spindle control add-on that I need to install that should give me RPM readings on the control PC so in theory I could set the VFD to read current (once I know how) .

Yes Don cut quality is a good measure but much more subjective and I would rather change before the cut quality got to that point . I cut mostly partical core melamines and have got about 20 sheets from a bit but I am finding bit wear can affect more than cut quality on a standard tool .

Bill

[dlcw]

Bill,

You've got email.

Don

[kubotaman]

Bill when you figure out how to change the VFD to read current can you pass that info on to me. Sounds like you and I have the same setups.