Pros and cons of climb milling in wood

[Richie]

Hi everyone,

All my previous experience in machining has been with metal cutting, but now I'm working with solid hardwood which is proving to be an altogether different creature.

I was wondering what peoples views are on the pros and cons of climb milling when profiling wood. For instance changes in the direction of grain, keeping the cutter cool, snatching the cutter, pushing the feedrate to the max, getting a tidy breakout etc, etc,... so much to learn, so little time.

Do you prefer climb milling or conventional, and why? Any thoughts appreciated.

Thanks

Richie.

[Tenson]

For hardwood, climb milling I think.

[Jonathan]

Google it?

http://www.cnczone.com/forums/woodwo...l_cutting.html

http://www.woodweb.com/knowledge_bas..._Rotation.html

http://www.woodweb.com/knowledge_bas...l_Cutting.html

[JAZZCNC]

Completely different ballgame to metal and choosing wrong can wreck wood in blink of an eye.!!
I nearly always 99% conventional cut in soft woods and man made boards MDF etc. Hard woods then I rough with Climb and then do a finish pass conventional, this cleans up nice any fuzzy bits.
You have to be carefull and mindfull of the grain and how the woods been cut in some woods and use a bit of common sense to whether the direction choosen will rip and split on breakout.?? It's not rocket science thou and taking a bit of time checking the grain and programing accordingly can save some heartache and fire wood.!!

[Richie]

Thanks for your views,

I have some inch thick oak to profile. Most of the full diameter cutting is going along the grain, and less than half the cutter diameter is cutting across the grain.
I'll do some experimenting and see what works best.

Thanks.

[Tenson]

What do you mean by profiling? You mean like 3D engraving?

[Richie]

It's just a 2D shape cut out of a flat rectangular piece of planed oak. It's got one straight edge which I've pushed up against a location block, then clamp on top and whizz round three remaining sides to produce the profile.

[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.