Climb milling

[Pete.]

A picture is worth a thousand words-

View attachment 409430
Best way I find to think about it, is with climb milling, the cutter will want to 'climb' out of the cut.

Practically, you only want to be climb milling on something with next to no backlash, otherwise it's a recipe for damaged cutters and ruined workpieces, which can lead to even more damage.
I only ever climb mill on the CNC mill, as I know it's only got under 0.02mm of backlash, which for any cutter I'm ever likely to use on it, is negligible.

Strangely whilst that pic does show it. It would make more sense to me to have a pic with the table direction altering and the cutter always rotating clockwise as that what going to happen in the real world.

I think this one will help me more.
View attachment 409436

The thing here is, in the first example of climb milling you run a very high risk of pulling the work into the backlash but in the second example the depth of cut means it's much less likely.

 

[Screwdriver]

Strangely whilst that pic does show it. It would make more sense to me to have a pic with the table direction altering and the cutter always rotating clockwise as that what going to happen in the real world.

I think this one will help me more.

It's really not that complicated an issue but drawing arrows on the table is not going to help one bit. Certainly the cutter will most likely stay constant in its direction, typically clockwise as viewed from above but that does not tell you which direction the table "has" to go to avoid a climb cut.

You might be milling along the front edge of the workpiece, or the rear, that changes the direction of the cut relative to the table. Same goes for the left and right edges when the table traverses forwards or back.

I really can't see where the difficulty is. If you are moving the workpiece in the same direction as the cutter would like to drive it, it's a climb cut.

 

[Pete.]

Put the cutter against the work and imagine it's a wheel driving along the road. If you're moving forwards it climb cutting.

 

[Beanwood]

Would this be right ?

 

[Screwdriver]

Would this be right ?

View attachment 409493

It would be right if the arrows show the direction of travel for the tool. Wrong if they denote the direction of travel for the table.

 

[doubleboost]

This may help.
One of my early vids

 

[ukracer]

It's really not that complicated an issue but drawing arrows on the table is not going to help one bit. Certainly the cutter will most likely stay constant in its direction, typically clockwise as viewed from above but that does not tell you which direction the table "has" to go to avoid a climb cut.

You might be milling along the front edge of the workpiece, or the rear, that changes the direction of the cut relative to the table. Same goes for the left and right edges when the table traverses forwards or back.

I really can't see where the difficulty is. If you are moving the workpiece in the same direction as the cutter would like to drive it, it's a climb cut.

It's not about understanding it. It's about how my brain copes with a 50/50 option.
But yes I agree arrows probably won't help. A little image will though as will using the mill more often but sadly the second option is not that likely especially as kids are off for 6 weeks.

My fusion use might be more though.

 

[smashweld]

I get the 50/50 thing, only got it 6 months ago but sometimes in 'the heat of the moment' I'll wind the cross slide on the lathe the wrong way, ie clockwise instead of anti so pushing it in to the work rather than taking it out, usually after disengaging the power feed/half nut

a few friends have problems with left/right, one of them has to say 'righty tighty, lefty loosey' for anything

sometimes need to think twice with screws/bolts etc if they're not straight infront of me!

 

[Morrisman]

'Back lash eliminator, for use when climb cutting'.

Labelled on most old milling machines I used in the 70's and 80's.

Effectively the cutter is trying to 'climb' over the work piece, it is pulling it in, picture a horizontal milling machine cutting a keyway, so if your feed screw has clearance in it the slide/bed will be dragged into the cutter, with rather unruly and erratic results.
The back lash eliminator uses two 'nuts' to take any backlash out, which works, but also produces more wear and tear on all the threaded components.

Climb milling takes more even depth cuts per tooth, and is far more efficient than the more conventionally used milling, which takes a tapered cut.

 

[Agroshield]

...arrows show the direction of travel for the tool. ...direction of travel for the table.

Arrows are problematic as you say. You have to decide in which direction to rotate the handwheel to produce movement that corresponds with the arrow. And you are likely to have a handwheel at both ends of the X-axis...

Climb milling takes more even depth cuts per tooth...

How? Look well at the diagram shown above by m_c. The cross-sectional area (volume) of metal removed in both cases is identical.

The difference is in the chip formation. Climb milling starts with a thick chip, which then thins out. Conventional starts thin and gets thicker. The chip thinning of climb milling contributes to a better finish.

 

[Keith 66]

You can still feed it from the wrong direction on a router table. If you're particularly stupid

This can be especially exciting if you are machining curved boat parts freehand with a bearing guided radius cutter & no fence. Having the rotation marked on the table with a big arrow does help. You have to be careful to keep your fingers.

 

[Guineafowl]

This can be especially exciting if you are machining curved boat parts freehand with a bearing guided radius cutter & no fence. Having the rotation marked on the table with a big arrow does help. You have to be careful to keep your fingers.

Best practice when doing that is to have a fixed guide pin in the table. It cuts down on freedom of movement and allows you to pivot the part into the cut.

 

[not done it yet]

To answer the OP’s question. On a mill the cutter is stationary wrt the work-piece, so easyto tell which.

Look from the end with the work piece moving away - climb milling will be when the cutter is rotating towards you on the cutting side. If the cutter is rotating away from you, it is conventional milling.

Swarf direction is another way to tell - it it is going to be thrown along the new cut, it’s climb milling and more away; out to the side or in front of the cutter is conventional. Milling cutters only rotate in one direction, so just looking should be enough to decide. I cut conventional for most cuts and climb only for a very light finishing cut. Usually a very rapid traverse across the cut while returning to start the next cut is made - it takes little time and will not wear the cutter, by rubbing.

This all, of course, if the juddering from the cutter/table doesn’t tell you! Cutting a slot is neither climb nor conventional - it is slot cutting.

 

[Morrisman]

How? Look well at the diagram shown above by m_c. The cross-sectional area (volume) of metal removed in both cases is identical.

The difference is in the chip formation. Climb milling starts with a thick chip, which then thins out. Conventional starts thin and gets thicker. The chip thinning of climb milling contributes to a better finish.

Not what I was told when I was doing my apprenticeship. Climb milling is done for faster stock removal, not to give a better finish. The chip depth starts off a certain size and because the cutter is moving forward the chip stays a more uniform thickness throughout the whole cut, thus more feed can be used.

 

[not done it yet]

Not what I was told when I was doing my apprenticeship. Climb milling is done for faster stock removal, not to give a better finish. The chip depth starts off a certain size and because the cutter is moving forward the chip stays a more uniform thickness throughout the whole cut, thus more feed can be used.

A good enough reason for a trainee, I suppose - and they believe it.

The cutter will wear less with climb milling - as the cutter will not be rubbing - like it does at the start of a conventional cut. Material removal is simply down to power available, not much else. If the machine is sufficiently rigid.