cutting air...?

[ricphoto]

Cutting air?...

as I continue stumbling along in my quest for the cleanest finish cut (see: fuzzy fish") I tried a new file incorporating the tips I got from my last attempt...

Changed to a higher density wood (western big leaf curly Maple) and went smaller on my finish pass bit (from 1/16th @ 8% TO 1/32'BN AT 6%)...

That seemed to help some with the major fuzzies but I noticed that it seemed to spend a lot of time just cutting air...I was afraid to stop and try to re-Z not knowing if that was even possible...seems that I read somewhere on here that someone had to re-zero his Z for each letter in a sign but he didn't elaborate beyond saying that...

Is it possible? I'm running VCP (latest) and have the Richauto controller running the Axiom AR8 Pro+...

looks an extra 1/100th or so on that last pass would have gotten me closer to my finish goal...

Thanks all...

[Deleted]

I think you're adding a lot of time to your machining for no benefit. Take a look at the tip of your bit, use a magnifier, there isn't much flute left at the very tip. Metal is more rigid than wood so it will make more difference with metal but with your tiny step-over the fibers will bend out of the way instead of being cut, causing rubbing and shortening tool life. Run some numbers at this site:

www.custompartnet.com/calculator/step-over-distance

0.0625 tool, 0.005 step (8%) leaves a scallop height of 0.0001"
0.03125 tool, 0.001875 step (6%) leaves a scallop height of 0.0000" (round off error)
0.03125 tool, 0.0025 step (8%) leaves a scallop height of 0.0001"
0.03125 tool, 0.003125 step (10%) leaves a scallop height of 0.0001"

A tenth of a mil is pretty small and gets tough to measure or remove accurately. It's so small that things you think are rigid and inflexible, like a chunk of steel is easily deflected that amount with just hand pressure. Also keep in mind that you're getting to the motion limit resolution of the machine, as it can not move in 0.0015625" increments exactly. So going beyond half a thousandth or perhaps even a full thousandth is unrealistic. The only reason I can see going to half a thousandth resolution is that it may help a little when you take into account round off when mapping to the machine's minimum step resolution.

Don't get me wrong, you're work is beautiful but you can do more of it with no less quality when you take into account what the machine is capable of and work to optimize your throughput.

[ricphoto]

Mar 17, 2018 10:05:51 GMT -5 @fean said:

I think you're adding a lot of time to your machining for no benefit. Take a look at the tip of your bit, use a magnifier, there isn't much flute left at the very tip. Metal is more rigid than wood so it will make more difference with metal but with your tiny step-over the fibers will bend out of the way instead of being cut, causing rubbing and shortening tool life. Run some numbers at this site:

www.custompartnet.com/calculator/step-over-distance

0.0625 tool, 0.005 step (8%) leaves a scallop height of 0.0001"
0.03125 tool, 0.001875 step (6%) leaves a scallop height of 0.0000" (round off error)
0.03125 tool, 0.0025 step (8%) leaves a scallop height of 0.0001"
0.03125 tool, 0.003125 step (10%) leaves a scallop height of 0.0001"


Don't get me wrong, you're work is beautiful but you can do more of it with no less quality when you take into account what the machine is capable of and work to optimize your throughput.

Thanks again...this is the kind of knowledge I'm looking for. and yes...The last pass was almost useless. It got rid of the bigger fuzzies but still left a rougher spots in nearly inaccessible areas...so less is more/there's a balance/and now I have another chart to help me along ;-)

Thanks...Ric

[Deleted]

Sometimes changing the angle from pass to pass can help reduce fuzzies as the scallops change direction. It may make things worse because of pyramids instead of scallops, who knows, just something else to try. The tends to be more useful when doing lithopanes.