Help-Pocket with larger clearance tool

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MoHawk
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Help-Pocket with larger clearance tool

Post by MoHawk »

Recently I've cut 2 clocks using 1/16" end mill for detail and 1/4" end mill for milling larger clearance using 0.125" depth. I used the "Auto Tool Zero" function in Mach3 in the same spot for both tools. On each clock, the 1/16" end mill cut slightly deeper than the 1/4" clearance. It's enough deeper that there is a visible outline around each item in the clock. Since the depth of cut stays constant on both cutters with any change, is there a way to correct for this problem?
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Geese-Clock Detail 2.JPG

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dealguy11
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Re: Help-Pocket with larger clearance tool

Post by dealguy11 »

The problem is going to be 1) wood movement 2) bit moving in the collet, or 3) your zeroing routine is not as precise as it needs to be. As you cut wood away, it does move. Figuring out a good hold-down technique so it doesn't move in Z is important in this kind of cut. Not sure how your auto zero routine works - do you have a touch plate? Are you using the paper method? Whatever it is, work through carefully to confirm you're really getting the tool heights measured properly.
Steve Godding
D&S Artistic Woodworking http://www.dsartisticwood.com

MoHawk
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Re: Help-Pocket with larger clearance tool

Post by MoHawk »

The 1" thick circle is very flat and was held down with 6 Rockler clamps. The first, clearance pass was with 1/4" down cut end mill and is dead on 0.125" in depth. These facts don't indicate any bit movement in the collet. If the 1/16" end mill slipped there would be a higher area versus being cut to deep. I'm using a CNCRP touch probe with their script. The touch off is always accurate except when using a larger area clearance toolpath.

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adze_cnc
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Re: Help-Pocket with larger clearance tool

Post by adze_cnc »

MoHawk wrote:If the 1/16" end mill slipped there would be a higher area versus being cut to deep.
Steve mentioned bit movement, which could also be the bit moving out. Having once had a handheld router send a bit screaming for the floor (and my foot) because I neglected to tighten the collet enough I can attest to that possibility.

You could try cutting the smaller tool portion of the toolpath first then follow up with the larger area clearance.

Or you could cut with the 1/4" cutter then, if you have space in the pocket for the touch-off plate, set the Z zero to the cut surface. Then manually add 1/8" depth of cut (or measured depth in case it's different) and re-zero through your software. Clear as mud?

Steven

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dealguy11
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Re: Help-Pocket with larger clearance tool

Post by dealguy11 »

I can also attest that bits can slip out of the collet...have had it happen many times, especially when the collet is getting worn out.

What version of Aspire are you using? There was a long-ago, short lived bug that affected pocket toolpaths, but this doesn't look like it. Really looks like a mechanical issue to me.
Steve Godding
D&S Artistic Woodworking http://www.dsartisticwood.com

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Phil
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Re: Help-Pocket with larger clearance tool

Post by Phil »

If the problem is wood movement, which can happen as wood is removed, you may want to add double sided tape to the underside of the wood.
Anyhow that is a really nice clock design.

Phil

c1nel1
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Re: Help-Pocket with larger clearance tool

Post by c1nel1 »

The fact that a 1/4 in. down cut was used will push down on the material has to be taken into consideration. If the 1/16 bit was an
upcut then it will pull up.

MoHawk
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Re: Help-Pocket with larger clearance tool

Post by MoHawk »

I've had the same problem before when using both bits in upcut and both bits in downcut. I'm thinking it may be a problem with the very small bit and the spring loaded touchoff plate.

I'm going to setup a small file and do some testing.

Now I just need to wait for all the ice we have to melt so I can get outside to spray the masked area. My shop is in my basement, so my wife dislike me spraying paint inside.

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