Brushless Spindle

Hey

I'm 17 and for my year 11 project, making a 600 x 800mm CNC router...

I have noticed a lot of people have just bolted dremels/routers onto their z axis carriage but instead, I was thinking
of using a 10a ESC with a 1550kv x 11.1v brushless outrunner to power the spindle to
8-10k rpm. Even if the motor has a life of 50-60hrs (or less) an a cheap import router 150hrs for about $50-60, their only $6 each!

Someone got any experience with brushless motors as Spindle's?

Any help would be much appreciated

Well, it would probably be fun to try. My prediction is very early bearing failure due to high radial loads. Also, they're probably not very rigid, which will cause chatter in a lot of cutting conditions.

Now then, using it to power a well-supported spindle shaft might be successful. I'm not sure what to use for a coupling though. A belt drive would create the radial load problem again. Maybe don't use an outrunner, but something with a bearing right near the output shaft.

Have a look here
(and ignore watercooling and all for a moment)


Regards
Reinhold

Thanks for the reply's

I was just having a look and a lot of people have just run the motor straight shaft to the tool bit, but that would just transmit the load straight to the motors bearings.





this is the sort of the same but using a toothed belt would tent to chatter an skip..



I was thinking of using a round stretchy belt ( I did have a picture of one but I cant find it) around 2 aluminum pulleys with a 6-7mm dia half moon slot in them
that way the tension in the belt would hold it their an it could slip if it ran into any trouble. (2:1 ratio)



An I would mount 2 x 9mm bearings on both ends of the shank of this an the pulley in the middle



Thanks for all the help

Hey, Formulavee. I am actually doing the same. I am currently using a brushless outrunner on my CNC (hopefully soon to be 3D printer. I designed my machine with printing in mind.). Right now I use it to cut out foam. It works really well for me.

You may want to go with a stronger motor, though, if you are planning on using it with wood, metal, acrylic, etc. I am not sure but some the DIY brushless spindles I have seen use big 80-100 A speed controls and much larger motors. Just a suggestion.

Thanks, jtoombs

I was hoping to use a outrunner with a max of 10a of current because then I could use the PC power supply that's powering my Gen 7 board.
I read somewhere that you would only need so much as 5-10w of power (dont quote me on this ) to cut through PCB but this motor pumps out about a 100w


their was a much bigger motor that did about 300w @ 30a but to power that I would need to use a much bigger power supply
like a few server PCU's

Yeah, it really depends on what material you are planning to cut. I would assume that you are probably fine with that motor and a small end mill to cut PCBs. If you are planning to use the exchangeable bit shank thing ( I don't know what it's called. The silver shank thing in your picture.) and pulleys that you are also adding a lot of rotational inertia. It may not be enough to worry about, though...

What I did was actually replace the shaft of my brushless outrunner with the same diameter end mill as the shaft was. It doesn't exactly allow for easy change of bits as a shank would provide. It works well but the radial load is probably not good for its bearings but I am hoping that it is temporary. Just an idea to take into consideration if you aren't looking to mill your own motor block with bearings, shank, etc.

Thanks for the reply I found the picture of that spindle:








I think it uses a sewing machine belt...

What I was hoping to make would just replace that DC motor with an outrunner

there is a way making a brushless motor openbuild

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