67db at 5100 rpm? 2x better surface finish?

[popspipes]

Sorry to resurrect a somewhat old thread, but Phil asked if anyone had collected noise data and I just did that with the Sound Meter app (by ABC Apps - https://play.google.com/store/apps/d...ebasic.decibel) both with and without the fan. The results were:

With Without
Spindle, Fan, Fan,
rpm dB dB


2500 58 57
3000 62 60
3500 66 62
4000 70 59
4500 74 63
5000 75 64

This is on S/N 119 built in 2008 or so and is a Series I that has been electrically upgraded to a Series III running PathPilot. The fan was filthy and coated with oil and sawdust from a bout of wood milling a year ago or so. Before the test, I cleaned the fan and deburred the edges of the blades, many of which had sharp molding flash. I wish that I had measured the sound levels before cleaning and deburring the fan because it sounded quieter after that bit of maintenance. The readings are uncalibrated so probably only of comparative value withing this data set.

The motor was quite quiet without the belt and fan, which probably makes sense. I'm inclined to install a 220 VAC fan just because it is inexpensive and pretty easy to do but am not sure if I want to go to the trouble of balancing the pulleys or drawbar nut until I see how the fan affects things. As it is now, I'm reluctant to mill at higher than 3500 or 4000 rpm spindle speed because the noise doesn't sound good, but that was with a dirty fan.

Interesting Mike, I see that the fan/motor noise difference varies with rpm. My fan impeller needed balancing, really made a big difference at high rpm. It was so out of balance the swing arm would vibrate over to one side and I couldnt talk over it it was so loud when the machine was new, I hear a slight whine from the Fenner belt now, And I can talk over it with relative ease.......

The electric fans we installed on inverter motors did make a fair amount of noise, but they were on 15 hp motors, and it was in an industrial enviornment so a bit of noise was OK. This was in the earlier days of inverter drives, maybe that has changed somewhat now.

Did I mention that I dont hear too well these days, age and noise related? ha!

I downloaded an app for a db meter on the phone, it shows about 75 db at max rpm, but I dont know how accurate this is?? I think on the Radio Shack meter its a bit less......

[MichaelHenry]

The noise on mine at 4000+ rpm isn't quite bad enough for me to want to wear ear protection, but is just enough to have me worrying about vibration at the cutter.

Mike - so far as I know none of the smartphones is calibrated, but the one I used can be adjusted in +/- 1 dB increments if you can check it against a known good sound meter. The phone microphone is apparently most responsive to human voice frequencies and that probably throws another wrinkle into comparable measurements between devices. At least we can compare before/after in our own situations.

Also, how did you balance the fan impellor? That sounds like a good idea. I'd also thought about 3D-printing a new impellor from a nylon-like filament, though I'm not sure that it wouldn't self-destruct and just noticed that impellors are for sale on Amazon. They are $10 or less, so probably aren't much better than the one on the Tormach motor.

[popspipes]

Mike,
Mine was one of the single bolt fans and was very much out of balance. I drilled holes in the heavy side of it to balance it, I used a set of HDD bearings to make up an arbor to static balance it, worked pretty well. Its all in the thread "I love my Tormach but" of a couple years ago. I pretty much run at 5140 rpm except for drilling/tapping and cutters 1/2" and over.

I think they have changed the fan design now.

[MichaelHenry]

Mike Sr - that sounds like the same sort of fan that I have. Thanks for the thread reference - I'll look that up. Maybe Tormach will sell me an improved fan.

[Concepts_Design]

Get a 240V muffin fan and wire it directly (with an inline fuse) off the C2 contactor output. Any time the VFD is powered up, the fan will turn.

sorry for digging up an old thread.... When it comes to electronics, I am a complete dummy. why a 240v fan as opposed to a 220v or 230v ? Also, what size and type of inline fuse do you recommend?

[oneineight]

Line voltage will vary, a 240 volt rated fan will work at 220 or 230 volts.
A 240 volt fan would not last long running on 110-120V.
The fuse should be just a little higher that the rated amperage on the fan, so if the fan starts drawing to much, the fuse can prevent large doses of electricity being naughty.

[popspipes]

sorry for digging up an old thread.... When it comes to electronics, I am a complete dummy. why a 240v fan as opposed to a 220v or 230v ? Also, what size and type of inline fuse do you recommend?

duplicate of a May post earlier in the thread, sorry