CNC CW/CCW Tool Direction Question

[mark s]

The original training we got on operating our CNC called for clockwise travel on the outside of parts and CCW travel on inside cutouts.

We were wondering what the reason for this is.

Anyone know of a good reason for it?

thx
Mark in MN

[Joe Durfee]

I moved this question from the Members Lounge to the digital room so that we can get the tool guys input.

[Camzl1]

Good Question Mark.

The reason for those recommendations are this. When cutting with diamonds we really aren't cutting anything, as we are grinding with these tools. So Grinding creates pressure on the materials you are cutting as the diamonds are biting into the stone at any given feedrate. So if we look at this drawing as a better example below that comes from our basic cnc training manual.

Sec 3-A.jpg (91KiB)Viewed 2419 times

We call Clockwise cutting, Climb cutting. This is to say that we are climbing the natural direction the tool wants to go based on the rotation of how the spindle is turning. In stone cnc machines we turn the spindle clockwise also. This method is best for grinding stone as it puts all the grinding pressure towards the finished part itself, preventing many types of blowouts and eliminating the need for most relief cuts, but not all, that usually have to be done with conventional cutting.

We call Counter Clockwise cutting Conventional cutting or going the opposite direction the tool wants to naturally climb. The only benefit here is for the tool, as the slurry is removed instantly away from the tool exiting the side instead of in climb cutting being compressed to the back and then exiting. This method usually requires backcut/relief cuts on all large radius corners to prevent blowouts when using fingerbits and large shaped profile.

Hope this helps

[Joe Durfee]

So is there any reason to ever conventional cut? Who cares about slurry getting washed away quicker?

[SbergeronMG]

Tools life.
It won't affect it tremendously but with the data I have yes it will get you a 200 meter or more.

[Camzl1]

Glad to know I am not the only one who tracked this trend of conventional vs climb cutting tool life. We saw a 5% increase in life over several sets this way. But 5% increase in life disappears real quickly when you blow a corner out on an Ogee set.

[luke getz]

this definitely applies as well to hand fabbing - it is sometimes hard to get guys to understand that the direction the blade is going has a huge effect on chipping. some guys get it and some never do really get it

[Ger Vanderbas]

[Andy Ross]

So im still confused...climb or no climb?

[Joe Durfee]

Climb Cut = Better Cut

Conventional = Better Tool Life

You decide what's more important to you.

[Camzl1]

Climb Cut is better for the material. Less Blowout for those who do not utilize back cuts on materials like delicatus.

Hence the reason most cnc manufacturers teach you to climb cut, so you don't blame them for busted tops.

[SbergeronMG]

I'm not even doing it but best of all world.
Climb cut first diamond and then conventional for the rest.
Longer to program unless cam program can come with that preset in the tool.set.
I know alphacam might have something that comes close to.do it.

[Dave.Scott]

Anyone taking notes here?

You all are freek'n learning me stuff.

Is this a great place or what?

[Clyde Kingry]

This method usually requires backcut/relief cuts on all large radius corners to prevent blowouts when using fingerbits and large shaped profile.

Eric, what does this mean?

I usually 45 the corner on large outside radi, ( 3" to 6" ) clipping the corner, ... or clipping more than just once on a really big radius but what is backcut/relief cut process as it relates to this?... a breaker? or something else?

[SbergeronMG]

Relief cut is something cms brembana is doing quite well with easystone.
But it consists of entering the opposite side of what you will Fingerbit for 1 inch or less and then go back
To your normal machining and Fingerbit from the side you would do first.
We do this all day on euro seam so it doesn't chip on the final breakout it really consist of creating a weak spot exactly where you want it to break.

[Ben]

We do this all day on euro seam so it doesn't chip on the final breakout it really consist of creating a weak spot exactly where you want it to break.
[

Genius, I always just cut away from the face, which generally makes cutouts snap out into the waste direction, but I'll be employing this relief cut method from now on. Much more reliable and elegant way to do it.

I was taught to always try and make the bit be doing burnouts on the face you're cutting against, and it typically works out alright. I'll definitely be giving the climb method a go.

I've been having problems with curves, some turn out alright and others mill out a bit jaggedy, like the program is working in low resolution, could this be from milling curves conventional direction?

[CustomMarbleGranite]

We do this all day on euro seam so it doesn't chip on the final breakout it really consist of creating a weak spot exactly where you want it to break.
[

Genius, I always just cut away from the face, which generally makes cutouts snap out into the waste direction, but I'll be employing this relief cut method from now on. Much more reliable and elegant way to do it.

I was taught to always try and make the bit be doing burnouts on the face you're cutting against, and it typically works out alright. I'll definitely be giving the climb method a go.

I've been having problems with curves, some turn out alright and others mill out a bit jaggedy, like the program is working in low resolution, could this be from milling curves conventional direction?
[

Make sure your radius drawing isn't exploded
That will create segments the tool will follow

[Andrew H]

So on my older hsd northwood, we got it 12 years ago or so and we were always told to reverse/left when picking directions. So it looks like we're climbing down, am I correct Eric?

[Ben]

Make sure your radius drawing isn't exploded
That will create segments the tool will follow

By exploded do you mean curves translated in cad as hundreds of tiny linked straight line segments? We had that problem with splines in ICam 3D, but we've found work arounds. Our machine does perfect bottom right and top left corners, and the bottom left and top right corners come out jagged sometimes. Usually if we're running edge profile tools like a set of pencil rounds or federation edges, the polishing wheels get rid of them mostly, but not always.

[tgertken]

Mark,
When I spent some time with you on your original Alphacam training, I suggested a climb cut/grind over a conventional grind/cut for a couple different reasons. Blowout and spindle absorption were at the top of that list. If possible, I've found that moving in a clockwise direction on outside geometries and ccw inside sinks, will minimize spindle absorption . However, in certain applications, like seams, this is not always recommended. I would enjoy discussing this more with you during my next visit.

Troy G
Lackmond Stone Products.

[Rock Solid]

We have been running Cnc routers for about 6 years and have always ran outside edges CCW and all inside cut outs CW.

I'm confused as hell now.

[samhanbury]

we had the DEKTON Representative in yesterday for a training session.

at first we were always advised to do Dekton and all sinks CW

We had a lot of blowouts on the lead out, yesterday we were told to cut DEKTON sinks CCW and it cut like a dream.


very quiet pulling 6-8 amps all the way through.