homebrewed quiet spindle

[Tristar500]

Hi All,

I'm going to share my experience here of building a quieter, better and longer lasting spindle for your home brewed CNC router/mill.

After a couple of weeks listening to the angry drone of the mounted Ryobi router for hours on end and then witnessing it’s torturous final demise. It finally whirred to a grinding halt after several hours cutting a mold from a block of MDF. (medium density fiberboard) I unceremoniously tossed the aforementioned unit into the trash as it spewed forth its “magic smoke” into the passing breeze. Ah, quiet at last!

I was faced with purchasing another noisy router or look for an alternative. A better router might have been an acceptable alternative and if so it would probably be a Porter Cable.

After careful consideration and upon looking at literally dozens of various types of motors from A/C 3 phase to DC brushed units I settled on a 3 HP DC servo motor I had sitting around the shop. I was able to salvage the motor and it's matching controller from a nearby scrapyard a year or so before. The unit is manufactured by Aerotech designated BM1400.

Here are a couple of pics showing the modifications. An additional bearing on the front end of the motor is essential if the spindle is going to last any length of time. I turned a bearing housing from a piece of 6061 T-6 aluminum on my lathe and drilled and taped a series of holes to fasten it to the front end of the motor cap.

The shaft of the motor had to be turned down and threads cut so it would accept the chuck. This is the tricky part. I turned to a nearby machine shop that specializes in aerospace quality work as I wasn’t completely comfortable doing this part of the job myself. Everything this spindle would machine in the future was only going to be as accurate as its placement on the motor shaft. I chose a ½ inch Rohm chuck made in Germany. Nice unit, I’m looking forward to using it.

I’m in the stages of mounting the unit on my home brewed gantry mill/router and sometimes plasma cutter. More pics as I progress.

[Tristar500]

another pic

[Tristar500]

Here's one on the machine

[Tristar500]

Here's a shot of the whole machine in progress. Tools everywhere!

[RotarySMP]

Nice job. Looks like that motor cost the original purchaser a fortune!

Are you mounting milling bits in a drill chuck?

[ynneb]

Welcome to the forum Tristar. I see you have made your first 4 posts in the one thread. Good effort. Great pictures too. This is just what we like.

So how much noise does it make?
How fast does it spin?
How hot does it get?
Does it do the job you want it to do?
Do you have electronic speed control?
Can you please post a mp3 file of its sound? ( Just kidding )

I have been thinking along the same lines as you about a less noisy spindle.

[marvinstov]

Me too. I want to know more.

Thanks,
Marv

[Boros]

Great job and nice work with the front bearing housing.

I've been thinking along the same lines for a while now as I have quite a few spare servo motors and drives sitting around.

The thing which concerns me is the max RPM.

Most servo motors are rated to around 6000 RPM max.
The armature starts to self destruct after this.

I don't think this would be fast enough for a small 2 flute cutter.

Most hight quallity/ priced spindles are induction squirrel cage rotors which allow for greatter RPM.

What is the max RPM of your spindle?

Thanx

Boros

[Al_The_Man]

Originally posted by Tristar500 Hi All, . I settled on a 3 HP DC servo motor I had sitting around the shop. I was able to salvage the motor and it's matching controller from a nearby scrapyard a year or so before. The unit is manufactured by Aerotech designated BM1400.

That is actually a DC brushless, its wound like a 3 ph motor, nice motor, no brushes to worry about, its top speed is rated at 6000rpm.
Al

[ESjaavik]

Should do very nice as a spindle motor. It keeps the speed dialled in. Does not slow down at all under load. Unless it goes in overload, when it will just shut down. Most drives will look after the motor so it does not overheat. And it's rated for continous use.

One warning though since you mentioned machining the shaft. Don't dismantle a BLDC (or stepper) motor! That will demagnetize it with loss of power as a result. Unless left to companies doing this kind of service of course, they have the right equipment.

[arvidb]

Thanks for sharing your project!

I've been thinking about using a 400-800 W servo motor for driving a spindle, with a belt drive coupling. A switchable 2:1/1:2 ratio and 4000 RPM motor should make a nice spindle drive for both aluminum and MDF cutting, I think?

Well, perhaps I should finish the machine itself first...

Arvid

[Al_The_Man]

Another trick you could use if this motor has the encoder option included as well as the commutation (and most have).
If you are not using the encoder you could (or get someone) to whip up a ratemeter circuit and you can read the actual rpm. you could probabally just use the marker pulse (one per rev). Also there are a lot of cheap off-the-shelf ratemeters.
Al