Conventional vs climb. When to use what?

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Auarhau
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Conventional vs climb. When to use what?

Post by Auarhau » Fri May 02, 2014 8:00 pm

This is not clear to me. When reading about it I even find completely contradicting info. But I think knowing which way to mill is a pretty essential parameter, right?
When do I choose conventional and when do I choose climb for general use? Is there differences on inside/outside profile and pocket operations? Makercam help section say:
"Clockwise or counterclockwise? If you're cutting an inside profile, choose counter clockwise. For an outside profile, choose clockwise. More on this later..." But don't explain why, or which of these are considered climb/conventional strategies).
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twforeman
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Re: Conventional vs climb. When to use what?

Post by twforeman » Fri May 02, 2014 8:09 pm

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Re: Conventional vs climb. When to use what?

Post by twforeman » Fri May 02, 2014 8:18 pm

Here is a video that really explains the difference. It doesn't explain why you would use one over the other.



The previous article I posted states that Climb milling is bad on machines with backlash, because it will pull the cutter into the work.

It also states that climb milling will give you better tool life and better surface finish.

I've been doing all my cutting using conventional until now, I'm going to regen some of my tool paths to try climb milling.
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WillAdams
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Re: Conventional vs climb. When to use what?

Post by WillAdams » Sat May 03, 2014 1:35 am

We've got a page on this on the wiki: http://www.shapeoko.com/wiki/index.php/ ... al_Milling

The CNC Cookbook folks have a .pdf which gathers a bunch of information together: http://www.cnccookbook.com/img/CNCCookb ... okbook.pdf

The nature of the material plays into this as well, as the Materials page notes:
A further note: "With HDPE you want to use conventional milling. It does leave a fuzzy, stringy edge when you use climb milling."
Other materials w/ notes on direction include Aluminum, Corian and I believe Foam.
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twforeman
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Re: Conventional vs climb. When to use what?

Post by twforeman » Sat May 03, 2014 2:40 am

Well I tried climb milling on my project tonight. I quickly went back to conventional.

I'm milling maple with a two flute carbide router bit. Climb milling caused chatter marks, and fuzz at the bottom of the cut.

I would guess that my ShapeOko is not rigid enough to climb mill. I do know that my Z axis has more flex in it than I like.
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Auarhau
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Re: Conventional vs climb. When to use what?

Post by Auarhau » Sat May 03, 2014 12:14 pm

So if I get this correctly now, makercam is telling us to use climb milling always?

Inside profile CCW = Climb
Outside profile CW= Climb
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Re: Conventional vs climb. When to use what?

Post by WillAdams » Thu May 15, 2014 11:19 am

Yes, that was my take / understanding on it.

I think that it's probably best to be finer-grained on this and it should be subject to:

- the material you're cutting
- whether you're making a roughing or finishing pass
- how fast a cut you're taking

so I'd liefer see recommendations for conventional/climb on the Materials (Feeds and Speeds) page.
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Llamas
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Re: Conventional vs climb. When to use what?

Post by Llamas » Thu May 15, 2014 4:30 pm

From CNC Cookbook: Climb vs Conventional Milling
Consider Conventional Milling When Micromachining

For all the same reasons, but considering deflection is much worse micro-milling, you should prefer conventional over climb milling most of the time when micro-milling.
And from CNC Cookbook: Climb Milling vs Conventional Milling
Cutters smaller than 1/8" or about 3mm are used for micromachining.

...

Conventional Milling is Preferred Over Climb Milling

There are a variety of arguments for this but the primary issue is one of which way the tool deflects. Since micro-mills are particularly susceptible to deflection, a conventional milling approach is preferred since deflection will be along the tool path and not into the workpiece. Deflection into the workpiece leads to inaccuracy as well as encouraging chatter if the workpiece is very thin.
When I read this a while back, I interpreted it (and the rest of the information that followed) to mean that I should consider work done with 1/8" and smaller end mills in this category. I may have read too much into that, though.

Nigel K Tolley
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Re: Conventional vs climb. When to use what?

Post by Nigel K Tolley » Thu May 15, 2014 9:12 pm

Micro milling can use Mills that are hair thin. But the arguments remain the same up until you have rigid tools. Of course, 'rigid' is down to your requirements!

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Auarhau
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Re: Conventional vs climb. When to use what?

Post by Auarhau » Mon May 26, 2014 10:24 am

Did some test too, cut same piece with both methods. Material 13mm ply. Conventional works best. Climb gives some more chatter, but worst is the irregular circles and other shapes. I also get a dent on all the spots where the Z plunges. I already have problems with oval or irregular circles, but climb milling makes it much worse. Some of the errors I get when climb milling are also sort of random. I think this is the endmill being "sucked" into the work piece when climbing.
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