Apparently a soak in 50/50 laundry soap and water for 30 minutes can get the residue off.
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Seems to have loosened the crud, but might need a brass brush still.
Either that or a bit of wood to cutā¦
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So this explains why my HDPE cutting boards werenāt cutting properly
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Yep, melting your way through them backwards is likely to make them a little stringy 
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@CthulhuLabs Maybe you could request that this thread be reopened? 
Canāt wait to see your progress with the endmill spinning the right way!
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Cutting HDPE with a endmill spinning the right direct:
@gmack Here is the data file:
ODrive_Test_2020-07-26 11_39_02.zip (20.7 KB)
Some of the values are negative now because the spindle is going in the opposite direction. I will pass those through an ABS() function on the arduino in my next iteration.
If you could send me back the spreadsheet you are using to generate those graphs it would be really handy.
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The surface finish is flawless. God I feel like an idiot. lol
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What were you doing? Endmill and stick-out, depth and width of cut, spindle speed, and feed rate?
Whoopsā¦ actually no. It was not the #201. It was a 1/4in 2 flute down cut endmill. I thought i had the #201 loaded though.
Yay, and now itās less like Brie
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Just added vbus_voltage to the data output so I can see if that drops.
As shown below, your data indicates a K Factor of 37 ci-in. / HP / min. So I entered it on the SFPF spreadsheet for HDPE. Your and @Vince.Fabās BLDC data should provide quite accurate K Factors for speeds and feeds calculations. A more aggressive cut would probably be more accurate though.
Hereās what your ODrive data looks like:
I canāt figure out how to prevent Excel from using absolute (rather than relative) data queries, so youāll probably have to edit the source (and name if you like) to load new data.
Hereās everything 2020-07-26 ODrive and SFPF.zip (2.2 MB)
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This looks like really useful data, thereās a lot less in the way of fudge factor for inefficiency or power factor here getting power out compared to the VFD spindles.
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Since torque is proportional to current and power is the product of speed and torque, there is no fudge factor! 
Hmm. Be really neat to overlay these graphs on a video feed in real time.
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Force and Power would be the most important IMO.
@CthulhuLabs, @Vince.Fab, other BLDC users, and @Julien (FYI)
Iāve been trying for over two years to come up with good K Factors to help understand and enable good speeds and feeds guidance and calculations. Although plenty seem to exist for metals, few-none are available for other materials. Furthermore, I believe that most-all of those for metals come from old machinist handbooks, so they may not be very accurate for modern high speed milling with the small diameter endmills commonly used by hobbyists. So, since you guys have ready access to the technology and capability, Iād be happy to analyze your data, provide feedback to you, and add your K Factor results to the SFPF workbook. Thatās the āpath of least resistanceā for this old retired engineerās OCD endeavor (unless of course you do it yourselves)!
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