What are the constraints on cutting aluminum?

Does the same logic apply to steel then? Any CNC can do it provided it has the right feeds/speeds/depth-of-cut?

I guess I’ll need a feeds and speed calculator then? If so, which one(s) do people here like the best?

 

Take, for example. maybe this one? https://zero-divide.net/?page=fswizard

Most are written for Large steel machines in mind. I have not seen one that would work well, until we have proper router PID control. There are no shortcuts.

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Are you referring to PID for the spindle speed, or something else?

Will your router PID make it possible? https://github.com/Allted/Router_PID

There’s SuperPID, and maybe others as well. I imagine you’ve already looked into them, and they fell short or something?

I thought some routers might already have constant RPM control built into them. Maybe it would be easier to just pick one of them for the MPCNC spindle?

Take, for instance,

  • "Variable-speed dial delivers up to 35,000-RPM, and Constant Response™ circuitry monitors and maintains speed under load"
for https://www.lowes.com/pd/Bosch-Colt-1-HP-Variable-Speed-Fixed-Corded-Router/1062825

 

At some point you just have to get dirty and try things for yourself. You are asking all the right questions but an hour or two of using your own machine you would learn a lot more.

I guess the issue is that the colt has a minimum RPM of 16,000, whereas you may want to go to a much lower RPM (say, 5000RPM, like the SuperPID supports). Or, perhaps, even lower than that. Hence, the need to find some other way.

Yes the rotational speed of the endmill.

If I ever get to finish it.

Perfect solution.

I like to make things, that’s all.

they do not tell you how fast they are turning and I have no idea how fast they actually react. Most people are not doing tricoidal milling with them.

The 611 660 is $50 and has a 1/8" collet and easily replaceable brushes. You are forcing me to justify every decision I have ever made. I don’t just do things I do my research before recommending and supporting something.

Or I think I can come up with a less expensive option so more people can try CNC all over the globe.

 

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I use the Makita RT0701C. Weight isn’t a whole lot more than the the Dewalt 660 (I think that is what Ryan was referring to above, not the Dewalt 611). And the Makita has constant speed control with a range from 10K to 30K RPM. Uses 1/4" bit by default but you can get a range of collets for it for smaller bits as well.

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I may try doing a build with this relatively light weight, 48VDC motor, because it will operate at lower RPM’s and does appear to come with a hall effect RPM sensor and DSP PID of some kind:

If anyone has interest, I can post the results.

 

 

That is a very interesting motor/driver. The pwm input says it’s 0-5V. It can switch direction. Some too changes require small reverse moves to unscrew the old bits. That would be interesting.

If be interested to see how it goes for you, and what speeds you can get effectively.

Here’s the manual for it: https://www.casogo.com/Manual/DS_NVBD_EN.pdf

This morning I used a piece of white tape, a photo resistor, and an oscilliscope to measure the unloaded RPM of the spindle that came with my 2418. It came out at 8333RPM. It wouldn’t be hard to come up with something more permanent, using the same technique with an Arduino Pro Mini instead of an oscilliscope, to capture RPM for a PID. It’s plenty accurate, and it’s certainly cheap to make, that’s for sure. You could do this, or similar, with almost any spindle I would think.

 

 

Something like that ? https://www.v1engineering.com/forum/topic/hardware-needed-for-a-software-fix/ ? :smiley: (see latest posts) Ryan has done some work n something like that indeed, which gets the RPM and feed it into a PID algorithm + get the PWN for cntroling a target RPM, and some triac to adjust power fed to the router… Not yet finished, but SOOOO promising.

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Wow, I was just reading a crazy long github post involving servos…

 

As for the PID thing, there is another coming along on the social page on instagram. I have no idea how he is getting the reading as he is pointing the lights at a metallic surface though. So one way or another a new PID will be available soon.

The controller in that spindle is not a PID but does have some acceleration control. Hall effect sensors are needed for the brushless spindles to start up going the correct direction, and then can be used for speed detection.

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Brushless motors have built in speed control, in that they have to move the current through the motors at a certain speed, not the current based approach DC motors use. So it’s still possible that spindle will have speed control, not just “torque control” for lack of a better word. It depends a little on the software in the box.

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I used a large high torque brushless without sensors in another project and it was kinda of a bummer that you needed to give it a bump to get it going and a big enough bump to make sure it went the right way. That is the most promising out of the box solution I have seen yet and looks to be leaps and bounds better than the quiet cut. Add $50 or so for the power supply and it might be a solid solution for under $200 if the quality is there. I need to triple check the specs but I would like to try one.

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Wow, talk about synchronicity. I just now read that thread (thanks to you) and it felt like deja vu.

I wonder why all the high speed spindles are AC rather than DC. I guess a spindle needs higher voltage than 60VDC to get to the >24,000RPM speeds?

I’ve heard that for milling PCB’s, those high RPM’s tend to work better. I found some aliexpress spindles that go up to 60,000RPM, but they’re all AC.

Anyhow, doing a PID for a DC spindle does seem like it would be a little easier than for an AC spindle, so I guess I’ll start with a DC PID. Maybe by then Ryan will be done with the AC PID. :slight_smile:

If the motor controller that comes with the DC brushless spindle doesn’t satisfy, then it looks like there are other off-the-shelf solutions that might :

Have you convinced yourself yet why I am trying to make a less expensive PID controller for any AC router?

Links and things you have read are nice but really, try it out. Tell us if it works or if it burns out, or if it ships at all, is it really enough power, does the control work? Do the instructions actually tell you how it works? We have all bought things from aliexpress, and the experience is not always good.

For hopefully right around $100-$120 total you would get a 660, WITH a warranty, and a PID and it’s code that you can change and edit the way you want.

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Well, sure, that sounds great. I hope you do.