extended cut times

Hello all,
I have a toolpath that cuts flat 2D "donuts" from 3/8' Polycarbonate material. The project consists of two toolpaths; a pocket toolpath that cuts 1.000 center holes and a profile toolpath that cuts the outside perimeter leaving four micro tabs 0.0625" x 0.0625" The technician who supervises the use of the CNC suggested a progressive ramp when cutting the perimeter. I use a Onsrud 63-712 which is a 0.125" Single O Flute upcut bit. I have access to a Laguana table at a local maker space and Vcarve Pro is the software used.

The projected cut time of all toolpaths equate to 28 minutes on the software estimated time. In real time the total cut time is upwards of 90 minutes. I head and feel a "downshift-Upshift" with each peripheral cut - I believe it occurs before the tab cut. The finish is perfect; my concern is the sounds I hear from the spindle/router and the time being so much more than projected. I had the tool tech listen and he thinks that the ramp isn't needed and may be the source of the gearing up and down anomaly.

So, I understand that ramping is used to prolong the bit life and create a better finish. Is there more to ramping?

Thoughts?

Thanks,
Clint

Thinking out loud (I know bad idea on my part) if you're getting a good part from the path then you might just play with the 'safe z / clearance' setting for the tool. I know that on my older machine it can cut the total time down quite a bit. Russ
http://www.talkshopbot.com/forum/att...id=33657&stc=1

Clint…

If you’re interested in more accurate times, read vectrics explanation of “Scale factor”. Essentially, calculated time is meaningless due to how different machines handle ramping, rapids etc. You can come closer by spending time messing with the scale factor…

For me, a spiral toolpath eliminates stepdown “watermarks” but does take longer because it lands up doing one complete extra pass.

It looks to me like the fastest way to cut time on your project would be to use a larger diameter bit.

SG

Thank you both.

I have Table time reserved today after work - I will tweak the mentioned suggestions independently to see if there is a change.

Clint