polionda figures are stripped

[Pioerpaolo]

Good morning guys, someone can tell me why my polionda figures are stripped ??? I used a CNC of a carpenter friend of mine that works at 15/18000 rpm at most, with a 6 mm tool. Someone can help me, thanks.

[default]

Your picture doesn't show whether the "frills" left on the cut are on the bottom or top side of the cut. You also don't mention some key factors for a good cut. So this response is going to be generic, but should give you idea of things to check.

You say your speed is 18,000 which should be fine. I use 20,000 (mainly because our router will go that fast) A 6mm bit is close to a 1/4" bit in which I use, so that should be ok also.

Is this a new bit or recently sharpened bit? You mention it is a friends CNC, does he use this same bit to cut hardwood, alum? We cut alum and plastics and have bits for both. We never intermix them.

Does the cutting blade area of the bit extend above and below the thickness of the material? Is this 4mm or 10mm Corex? (material) You also don't mention what your feedrate or chip load is. I can't remember of the top of head what I use for a feedrate, I will look it up in the next few days when I am back in the shop.

You chipload rate helps determine your feed rate, and spindle speed, so that as much material as possible is moved away from the cutting area to prevent the material from melting.

Are the frills melted? or just not cut all the way? Is the bit getting clogged up? i.e. too much material melting to the bit.

How is the material attached to the table? glued? vaccuum, taped? etc. If the material is not solid on the table and can move, it can bounce giving a bad cut.

If the frills are on the bottom, it could be a dull bit, the cutting depth may not be deep enough ( I usually go .002 - .003 into the sacrifice sheet of the table to ensure the cutting edge cuts a little below the bottom of the material)

If the frills are on the top, again it could be a dull bit, and/or the cutting edge of the bit is not tall enough for the thickness of the material.

This is more questions than answers but with limited info, it's really hard to say for sure. This should give you some food for thought.

The video show a new bit, and yet is still leaves very little frills in the material that easily removed.

Hope this helps.

Alan...

Edited August 27, 2020 by default

[Pioerpaolo]

I do not know the problem well because I was not present at the tests, among other things I understand little. I am attaching other photos, where it is clear that it is the internal rooms that are not cut, however we will try again with my friends, trying, first to understand well your writing, which translated online obviously leaves something on the street, then to follow your advice , thank you so much