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I found this video fascinating:
You can actually see those deformation zones…beautiful.
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Wow! That’s beautiful. You can see the changes that coatings make and that materials make. Thanks for finding and sharing that @Julien.
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Cool, chip porn…I watched it twice, so far.
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That is a fascinating video. Also, now I really want some ice cream. 
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Thanks for straightening me out on that! It caused me to dive a little deeper into the issue (“you don’t know what you don’t know”!) From Shaw’s 2nd Edition Metal Cutting Principles.
"THERMAL ENERGY IN CUTTING
Practically all of the mechanical energy associated with chip formation ends up as thermal energy. One of the first measurements of the mechanical equivalent of heat (J) was made by Benjamin Thomson (better known as Count Rumford). Rumford (1799) measured the heat evolved during the boring of brass cannon in Bavaria. He immersed the work, tool, and chips in a known quantity of water and measured the temperature rise corresponding to a measured input of mechanical energy. These experiments not only provided a good approximation to the mechanical equivalent of heat that stood as the accepted value for several decades but also provided new insights into the nature of thermal energy at a time when most people believed that heat was a special form of fluid called “caloric.” [How cool is that?] It is well known that some of the energy associated with plastic deformation remains in the deformed material. Taylor and Quinney (1934, 1937) using a very accurate calorimetric technique measured the residual energy involved when metal bars were deformed in torsion. It was found that the percentage of deformation energy retained by the bars decreased with increase in strain energy involved. When these results are extrapolated to strain energy levels in chip formation, it is estimated that the energy that is not converted to thermal energy is only between 1% and 3% of the total cutting energy. Bever et al. (1953) have directly measured the residual energy stored in metal cutting chips, and Bever et al. (1974) have discussed the stored energy in plastically deformed bodies from a broad point of view. All of these results suggest it is safe to assume as a first approximation that all of the energy associated with chip formation is converted to thermal energy. The energy retained in the chips and that associated with the generation of new surface area is negligible relative to the total energy expended in chip formation."
Doesn’t that say that, when cutting metal, 97% - 99% of the total cutting energy (and power) is expended in chip formation? I’m not sure if/how this relates to cutting plastics and wood though. But I also stumbled on this regarding cutting acrylic at 0.000545 IPT at 30 IPM (assuming no chip thinning).
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Have you checked your ancestry? I suspect that you’re related! 
Have the water police visited you yet?
Could be, I’ve a fair bit of DNA from that part of the world.
How about you? I’m guessing Tesla?
Don’t know what/who the water police are, common where you live?
Yup - San Diego - too much water on the sidewalk (no guns yet - just a note)! My ancestry - DGAF!
Really? You brought it up.
DGAF was wrt me (edited accordingly)- not you, sorry!
Oh, sorry for the knee jerk. I don’t particularly care either.
Let’s get back to educating, learning.
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This precisebits.com site keeps on giving, it’s a goldmine. Their conclusion is interesting:
As shown above, for a given spindle RPM (speed) and cutter geometry, the edge quality achieved when machining thermoplastics depends heavily on feed rate. Generally speaking, the faster you go (higher feed rate) the better. Extensive testing has shown that the best feed rate , in terms of edge quality and cutter life, for most of these materials is only 25% lower than the feed rate at which the tool breaks.
So one more penny in the “for plastics, just feed faster” jar.
These two sentences also lean towards using a reasonably high chipload, if only as a side-effect of feeding as fast as possible. PreciseBits specializes in micromachining and that specific article presents tests for a 1/16" endmill, so the 0.0005" makes sense for such a small tool, but it’s unclear whether this is the min chipload at which the cut started to be clean (compared to the lower initial value), or if it was established using their other rule of “breaking point minus 25%”
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It’s interesting that the endmill specs say “Max runout (TIR) - < 0.0005 in.” and that they don’t provide speeds and feed recommendations for their endmills (so how does one know how hard to push them?) I think that I recall them saying not to exceed 10% of cutter diameter deflection, but can’t find that now. I wish I had something to put in the workbook for maximum endmill deflection! 
BW says
“For roughing, a limit of 0.001″ is set for a typical solid endmill of 1/2″ or so, and this is scaled based on cutter diameter when you start talking really small endmills or really big ones. Since this is the most conservative limit on deflection, we can be assured that Tool Life, Surface Finish, and Tolerances are likely taken care of too with this limit”
But no indication (that I could find) on the nature of this scaling for smaller endmills.
Your new profile pic is great by the way, it speaks for itself 
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As I recall BW uses 0.001" for smaller endmills too. That’s kind of why I used that as the default in the workbook. HSMAdvisor allows much higher deflections, but I don’t know where they come from.
Note that it takes 480 lbf to get 0.001" deflection of a 0.5" carbide endmill with 1.5" stick-out! I wonder how much deflection that level of force would produce on even the most rigid CNC machines.
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I’m struggling to understand the interpretation of the [Count’s] (Cutting Thick Acrylic - #58 by gmack) and others’ experiment results. I.E. “All of these results suggest it is safe to assume as a first approximation that all of the energy associated with chip formation is converted to thermal energy.” If that’s the case, how was there any/much energy left to heat the Count’s water?
Pretty easy really, the energy commutes to the third continuum, translates to gravitonic wave conversion resulting in basic unobtanium. At this point we must digress into string theory to continue.
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Now why didn’t I think of that? 
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