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scalesr1
17-01-2018, 11:41 AM
Having experimented on some pine I am now using some hardwood - not sure what sort - as used in hardwood window frames I believe.
I have a 3040 with a 6mm down cutting 2 fluted spiral cutter.
My question is around feed rates and depth of cut etc.
I understand that for a down cutter I should limit the depth of cut to something less than the diameter of the cutter - that's all fine but I find that if I try to cut 4mm it seems to struggle a little and the spindle appears to 'snatch' from time to time.

I am currently limiting the depth of cut to 1mm and I am using a feed rate of 75 in order to give the least stress to the tool etc.

However, this means that to cut a 55mm square pocket 33mm deep it is going to take over 5hrs to complete.

Is this normal and to be expected or am I out by an order of magnitude?

What sort of feed rates / depths should I hope to be achieving when cutting hard wood on a machine like this with the bit that I have?

If this is the way that it is with this kind of machine then I can live with that - I just don't want to take 3 days to cut something that I really should be turning out in 30 minutes!

Thank you in anticipation!
Richard

johngoodrich
17-01-2018, 08:34 PM
i wouldn't use a down cutter to cut a pocket as you are pushing all the chips downwards and recutting them. this isn't going to help at all. I would use an upcut tool and i would run at about 18000rpm and 3000mm/minute with 3mm doc at least

scalesr1
18-01-2018, 09:00 AM
i wouldn't use a down cutter to cut a pocket as you are pushing all the chips downwards and recutting them. this isn't going to help at all. I would use an upcut tool and i would run at about 18000rpm and 3000mm/minute with 3mm doc at least

Thank you very much for that.

I was using a down cutter as the wood would tear at the surface when using an up cutter.

Perhaps I should start the pocket with the down cutter for a few mm then switch to the up cutter for the rest of it?

My max spindle speed is 8000rpm and my cutter 6mm so I run at max rpm and cut 3mm with a feed rate of around 200mm/minute at present - should I be going a lot quicker?

The only reason that I have not gone quicker is that I worry about damaging stuff. I will try shallow cuts at higher speeds to see how it goes. The only real feedback that I have are the various noises that the cutting process makes - many suggest that is how one can tell if things aren't right. Unfortunately I lack the experience required to know what I am listening to!