Brushless Makita Mod (unsupported)

Ah, Polyethylene and High Density Polyethylene are different substances, one of them has the machining properties of French Cheese…

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I see no reason why that shouldn’t be @Julien’s next test material. I bet it won’t show the microstepping like acrylic does.

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That was turning out much better… Till the double sided tape let go. Lol

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I can’t hear you, your voice sounds a bit horse.

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@LiamN those isolators came in. Going to mess with them tomorrow. Hopefully by this weekend I will be able to set the RPM by PWM.

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Try to avoid slotting — the constant high tooling engagement makes workholding more difficult among other problems — add geometry and cut as a pocket:

Thanks for the advice! I know I’ve heard that a few times but didn’t actually think to do it.

Meaning it too is “easy to machine” as mentioned here on page 2? Eplastics also has fabrication/machining guides for some plastics that may be useful for acrylic.

I was more going on the lower melting point, tensile strength and hardness all of which can make cutting it with a high speed router bit quite tricky as chips will melt and go stringy very easily compared to it’s higher melting point, harder cousin. I have found that it saws very easily, laser cuts very well (with suitable fume extraction) and water jets nicely. Perhaps with water or air jet coolants it will also cut well on a router machine?

Honestly I think you guys are making too big of a deal about this. They are 3 dollar cutting boards. I got them because I figured the torque requirements to machine it are low so it would be a good initial test.

:wink:

For me it’s more about understanding which materials we can cut and how to cut them effectively.

I am keen to see the cheese experiments, particularly the workholding, I suspect some of the more Brie like cheese may need freezing before machining…

Would need to find food grade end mills if you want to eat the cheese. Not sure how well stainless steel would work for that. I know you can water jet cheese.

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What are you going to call this thing once it’s done?

A Modkita? Something else?

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Had not thought of a name, but I do like Modkita.

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So at 10k RPM plunging into oak with a 1/8th in single flute end mill the ODrive is maxing at 7.43A. I have it current limited to 20A so there seems to be quite a bit of head room.

Already got the hashtag going lol. The VESC is still working great with zero tuning but limited to manual app computer control.

Really really impressed on the performance, even without running a fan. Marv from KERN asked me to do some high power high rpm tests, after this Z is done we’ll push it!

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Force assumes 1/4" endmill:
image


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It was 1/4 in. Very nice graphs.

Sensorless Read Velocity is the electrical velocity (Ve).

RPM = Ve * ( 60 / ( PolePairs * 2 * pi ) )

This motor has two pole pairs so:

60 / ( 2 * 2 * pi ) = 4.7746

thus:

RPM = 4.7746 * Ve

I am curious how you are deriving the watts.

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Yup - I screwed that up - thanks:

Power is calculated from speed and torque. Torque is calculated from measured current and motor’s torque constant. Force is calculated from torque increase when cutting and endmill diameter. Do you want the spreadsheet?

I am already converting the Ve to RPM in the data as SensorlessRPM. I mostly included the Ve because that is what I have to send to the ODrive as the set point. This allows me to see how close to the set point the motor is actually running at.

I figured that is how you were calculating the power. Just wanted to make sure you were not basing it on the voltage.