Learning the hard way

[DMS]

Climb milling/vs conventional milling is one of those things that some people have a problem with. This is how I remember. If you take a milling cutter, and place it against a piece of stock, then rotate it counterclockwise, the mill will roll in one direction along the part. If you look at the cutting edges, you can imagine they are arms, and the mill is "climbing" in that direction. Climb milling is milling where you feed the cutter in the direction it wants to go anyway. Conventional milling is when you go _against_ the direction that the cutter wants to go.

The distinction is important, as the original poster found out. When you are conventional milling, the forces are pushing the cutter away from the part, it only goes forward if you crank the handles hard enough to overcome those forces. When you are climb milling, the cutter can pull hard enough that it feeds itself, pulling the rest of the machine with it. The results can be exciting. To take anything but really light climb cuts on a mill, you need a machine that is built for it.

 

[Ray C]

And another way I like to think of it as... Climb cutting has the same effect as using a radial arm saw. As soon as the blade touches the wood, you need to hold the saw back to keep it from cutting (climbing) uncontrollably. -And by the way, I used a radial arm saw for a couple years during one of my part time jobs and along the way, a lot of people had mishaps with them and shortened some fingers. That piece of equipment in my opinion has probably taken more fingers and thumbs than any other -and I'm darn glad they're all but extinct due to the advent of the chop saw.

Sorry for going slightly OT...

Ray

 

[Malinkalauran]

I am embarrassed for asking but what is climbing? I'm a beginner, have only had my HF Micro Mill a few weeks and only used it about 15 minutes. REAL BEGINNER!

Thanks to everyone who provided information regarding my "beginners" question. The more time I get to spend in the shop, the more questions I come up with.

Malinkalauran

 

[Tony Wells]

One thing that seldom is discussed about conventional vs climb cutting is the advantage climb cutting has. If you think about it, the cutting edge of the end mill makes initial contact with the material in a fresh area, beyond any area that might be work hardened from the previous tooth pass. In conventional cutting, the edge must force itself into the material from a very low angle, starting with a zero chip thickness, right into the work hardened surface. As the material moves into the mill, the chip thickness increases, giving us the other term used for conventional milling - "up milling", meaning the chip thickness goes up as the mill turns. Climb cutting is also known as "down milling", because just opposite of up milling, the chip gets thinner as the cut progresses.

I have read that there have been studies regarding the deflection forces pushing either the work or the end mill more during climb (up) cutting than conventional, but I have not seen any evidence of that in practice. I generally try to take a finish cut by climb cutting. And for years, all of the programmers that I worked with preferred to use that method, to increase tool life. With a ball screw machine, the backlash that causes problems on manual machines isn't there, so it seems to be preferred in most instances. I have run two manual machines, one vertical and one horizontal made in Poland (can't recall the maker.....Mechanazy?) that had hydraulic dampening to allow climb cutting on them. The system worked beautifully. They were fairly large machines and had no problems with rigidity.