Roughing Vs Finishing toolpath

[TReischl]

I missed it, did someone suggest programming a low feed rate ?

Yup, you missed it:

"using Zenbot CNC 4X4 with Hitachi Metabo router 11 Amp
roughing using 1/4 end mill down cut at 100 FR and 100 Plunge rate
Finish toolpath using 1/8 Ball Nose at 100 FR and 100 Plunge rate
Profile toolpath using 1/8 End mill down cut at 50 FR and 20 Plunge rate
"

Notice he is using a 1/4 end mill at 100 IPM and also finishing with a 1/8 ball nose at 100 IPM.

Maybe that is as fast as a ZenBot can go ::::shrug::::?

The reason I made the comment is that quite often in this sort of thread I read how "the machine will never get up to full speed on 3D work. . . ." Well, that is not always true by a long shot. If you look at his part there are a lot of flat areas on it that the finishing bit has to traverse. If you look at the chart I included it is obvious that on a lot of those areas the machine could easily get over 100 IPM.

I can run my machine on 3D at a programmed 300 IPM rate. Even when I do detailed stuff I set it to that feed rate. It may never get past 150 but I sure as heck don't want to make sure it never goes over 100 IPM.

[dealguy11]

I did make a comment above about the maximum speed likely to be achieved. It's true that when there are flat areas in a carving the bit can get close to maximum speed. For example, I set my 1/4 ballnose to run at 600 ipm for MDF doors which are nearly all straight cuts. Your comment on setting higher speed makes sense, and I do the same as you - I set a high feed rate for the bit just in case there are flat areas. If his machine is capable of >100 ipm then he should go for it.

Having said that, on a carving like the one the OP showed, I'd be surprised if it gets anywhere near top speed because of the amount of vertical movement and changes in direction. My machine, which is capable of 900 ipm cutting speed, never really achieves above about 200-250 ipm on this kind of carving after you average out the entire time spent carving.

[TReischl]

Steve, I agree 100% with you.

I remember back to when I first started running the router. Oh, I was ever soooo careful to not: (the list is endless). Took me darn near forever to cut anything .

Then one day it occurred to me, I was not going to wreck the machine, maybe just break a bit so I started going faster, and faster. Never did break a bit amazingly. When I got to a .5 diameter bit running 800 IPM I stopped. I do not run anywhere near those speeds, just too nerve wracking watching it. Oh, I did break an itty bitty tiny engraving bit when I pushed it up to 45 IPM in aluminum. Didn't like that, LOL.

Interesting thing, when we moved to NC I set up the machine a bit too close to the back wall. The first time I sent it all the way back I moved the whole darn machine forward about an inch and a half. It weighs a lot, I cannot even pick up one end of it but those motors had no problem skidding it across the floor. I have no doubt it lost a few steps in the process.