Pros and cons of climb milling in wood

[Ger21]

Generally, conventional cutting will almost always give a better quality cut than climb cutting, but there are exceptions.

The most important factor when cutting wood is preventing tearout.

To avoid tearout with conventional cutting, you need to make sure there is always some wood on both sides of the bit. Say you use a 6mm bit to remove 3mm from the edge of the board. With conventional cutting, the tool is pulling the wood towards the edge, which will result in splintering. So any time I cut rebates, I always climb cut. It gets more complicated when going across the grain, though, as both climb and convention cuts can result in tearout at the end of the part. If possible, I use the method in the third pic for crossgrain rebates.

For best results when cutting a proile, conventional cut and always have more material than the tool diameter outside the profile to eliminate tearout. Attempting to trim 3 sides of a board will almost alway result in one chipped corner, whether climb or conventional cutting. Climb cutting will chip at the start of the cut, and conventional at the end of the cut.

[Richie]

Thanks for some useful tips.

I've just tried cutting a few shapes both conventional and climb cutting.

Climb cutting seems easier on the ear, less vibration, but it tries to pull the wood into the cutter when going across the the grain. I beefed up my clamping a bit to fix that.

There was a bit of fuzziness along the grain, but I can live with that, and it seems to have improved after the cutter had done a few hundred pieces, not sure why that should be (I'm using solid carbide, compression spiral, two flutes).

I'm leading into the start of the profile with a radius, and also breaking out with a radius, to blend with a straight edge. That eliminated the tearing problem at the start of the cut with climb cutting, but it didn't with conventional cutting when breaking out at the end of the cut.

So after some experimenting I've chosen climb cut.

It's down to trial and error I know, but your insights helped inform some of my guesswork.

Thanks again.

[Ger21]

Climb cutting seems easier on the ear, less vibration, but it tries to pull the wood into the cutter when going across the the grain.

Are you sure you were climb cutting? Climb cutting will push the board away from the tool, not pull it towards it.

[HiltonSteve]

Are you sure you were climb cutting? Climb cutting will push the board away from the tool, not pull it towards it.

Gerry,

In my experience climb milling always wants to drag the material, table etc towards the cutter.... get an old milling machine with a bit of backlash, put a decent size cutter in and put a good size cut on. Watch what happens when you try to climb mill... you end up tightening the bed locking screws to stop it from jerking towards the cutter. When toolmaking and using aluminium I always used to rough the sides of plates by conventional milling as you could rip the material off quick but left a rough finish, then leave 0.5mm or so on for climb mill finishing which left a nice smooth finish.

Nice screenset by the way....