Anyone using one of those 60,000 rpm spindles on homemade CNC machine?


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Thread: Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

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    Default Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

    I'm curious about these ultra high frequency spindles. You don't see much info on them here. I get that the ones made by Yager, GMN, Weiss and IMT are probably too expensive for your average hobby user but I noticed that cheaper copies from China and Taiwan have started appearing on eBay recently. ATC variants start as low as $1100. Is anyone here planning to buy one?

    I had assumed that they were of little use outside of micro-engraving applications but Datron machines use them for full-on milling applications in aluminum and steel. I wonder if there would be any benefit in using one instead of your typical 24,000 rpm CNC router spindle on a machine for aluminum projects.

    If anyone here has one, is it your main spindle or a 2nd spindle? What sort of project do you use them for? Why did you choose a 40,000 - 100,000 rpm spindle over a 24k one? Do you notice better results in terms of speed or part finish?

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    Default Re: Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

    I guess nobody here uses one. Perhaps the affordable ones are still too new.



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    Community Moderator ger21's Avatar
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    Default Re: Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

    Most people don't have machines capable of properly utilizing a 60,000 rpm spindle, unless you plan on using them for really, small tooling, like 1/16" or smaller.

    Gerry

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    Default Re: Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

    Quote Originally Posted by ger21 View Post
    Most people don't have machines capable of properly utilizing a 60,000 rpm spindle, unless you plan on using them for really, small tooling, like 1/16" or smaller.
    Please can you explain what you mean by that?

    My understanding is that higher speed spindles with smaller tooling produce less cutting forces. This is why Datron machines (the only brand I know that uses high frequency spindles) can be half the weight of other machining centers while offering twice the work envelope. I would have thought that this would make them ideal for the lightweight benchtop machines people use here.

    I can see that many high speed spindles are limited in tool size but, like other types of spindle, this goes up when you buy more powerful variants. Some of the Datron 60,000 rpm spindles can rough with 20mm face mills while the smallest ones only hold up to 6mm end mills.

    The smaller tooling doesn't seem to limit the overall speed on Datron machines though. That YouTube video where they mill an aluminum quadcopter mold in less than an hour is as fast as I have seen. It got me thinking that I had been too concerned with being able to fit larger end mill sizes and not concerned enough with speed.



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    Registered CitizenOfDreams's Avatar
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    Default Re: Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

    Quote Originally Posted by Goemon View Post
    My understanding is that higher speed spindles with smaller tooling produce less cutting forces. This is why Datron machines (the only brand I know that uses high frequency spindles) can be half the weight of other machining centers while offering twice the work envelope. I would have thought that this would make them ideal for the lightweight benchtop machines people use here.
    If you increase your spindle RPM, you would have to increase your feed speed accordingly, otherwise the tool will be rubbing and burning instead of cutting. Lightweight benchtop machines are not usually capable to run at the speed and acceleration required for a 60000RPM spindle.

    The quadcopter mold milling you mentioned was done on a Datron M8Cube. 1.7x1.7x1.9 meters, 1300kg, 22000mm/min feed rate - in other words, nothing like "lightweight" or "benchtop".



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    Default Re: Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

    Quote Originally Posted by CitizenOfDreams View Post
    If you increase your spindle RPM, you would have to increase your feed speed accordingly, otherwise the tool will be rubbing and burning instead of cutting. Lightweight benchtop machines are not usually capable to run at the speed and acceleration required for a 60000RPM spindle.

    The quadcopter mold milling you mentioned was done on a Datron M8Cube. 1.7x1.7x1.9 meters, 1300kg, 22000mm/min feed rate - in other words, nothing like "lightweight" or "benchtop".
    I wasn't comparing cheap benchtop machines to the M8cube. I was pointing out that at 1300kg, it is a fraction of the weight of other VMCs and that Datron says this is because their high speed spindles generate a fraction of the cutting forces that typical VMCs generate when cutting aluminum and steel. I'll also point out that Datron puts high speed spindles on all their machines (including the tiny Neo), not just the M8.

    So.... carrying on from that thought.... and again, without comparing a $4000 benchtop machine to a $150,000 Datron.... if a higher speed spindle with smaller tooling reduces cutting forces which enables you to get away with a lighter design, I was asking why more speed wouldn't be beneficial to cheaper benchtop machines (as they are limited by lightweight aluminum gantry beams etc).

    Now... you are suggesting that the primary limitation is that it's not possible or practical to make a lightweight benchtop machine travel fast enough to cut with a 45,000 or 60,000 rpm spindle. But why is that?

    Is it not easier to increase the speed on a 75lb gantry or a 60lb table than it is on machines with a 500lb table? Why can't you just get higher lead ballscrews, larger motors and, if needed, higher gearing ratios until it moves fast enough to cut at 45000 or 60000 rpm?



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    Community Moderator ger21's Avatar
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    Default Re: Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

    Why can't you just get higher lead ballscrews, larger motors and, if needed, higher gearing ratios until it moves fast enough to cut at 45000 or 60000 rpm?
    For the same reason you can't put an 800HPmotor in a KIA and end up with a Ferrari.

    You can't just take a machine designed run at 300ipm, and start running it at 1200ipm. Everytime you upgrade a component of a machine, it exposes the next weakest link.


    if a higher speed spindle with smaller tooling reduces cutting forces
    "Reducing Cutting Forces" is a bit misleading. It reduces cutting forces by taking lighter cuts. You can get the same effect with a 24,000 rpm spindle by lowering the feedrate.

    Since 99% of the users here are not doing high production, they can live with lower feedrates at 1/3 the cost of a high speed machine.

    Gerry

    UCCNC 2017 Screenset
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    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

    Quote Originally Posted by ger21 View Post
    For the same reason you can't put an 800HPmotor in a KIA and end up with a Ferrari.

    You can't just take a machine designed run at 300ipm, and start running it at 1200ipm. Everytime you upgrade a component of a machine, it exposes the next weakest link.




    "Reducing Cutting Forces" is a bit misleading. It reduces cutting forces by taking lighter cuts. You can get the same effect with a 24,000 rpm spindle by lowering the feedrate.

    Since 99% of the users here are not doing high production, they can live with lower feedrates at 1/3 the cost of a high speed machine.
    That makes sense.

    It sounds like you are not saying that it isn't possible, just that you have to design a machine to handle it from the ground up. I.e. It's a similar priniciple to why you can't put a 10hp motor on an LMS mini mill. You would need a significantly larger, stronger and stiffer frame etc.

    It also sounds like you are saying that the upgrade is not worth the effort over what you can achieve with a 24,000 rpm spindle.

    What would you say is the main limitation that would need to be addressed before you can double the speed on a machine? Is it about strength and stiffness or is it about the bearings?



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Anyone using one of those 60,000 rpm spindles on homemade CNC machine?

Anyone using one of those 60,000 rpm spindles on homemade CNC machine?