Router Data (Full of Sound & Fury, Signifying Nothing)

[revwarguy]

I got a hold of a digital tachometer, and sound meter, and dusted off my "Kill a Watt" meter to make some measurements of some tools that I was curious about. Thought I would post them on the off chance someone else might find it interesting.

(Notes: All of the machines I tested have an initial surge in power, a sound output surge, and work up to a steady state rpm. For each test I waited well past the point the readings steadied out, took a reading, and did this 3 times and averaged them. This is especially true for the variable speed router, where each different speed setting didn't always result in the same speed, but the dial was detented, so there wasn't too much variation. The averages should indicate a good relative reading. The sound meter was kept at the same distance from the tool for all readings. Note that a 10 dB difference doubles the volume of sound that you hear, and that 90-95 dB is the level that can begin hearing loss. Also, 1 hp = a little over 745 watts, and I never saw any of these even peak near that, but they weren't cutting anything.)

I had these routers on hand, and made the following measurements while the routers were running under a steady state, no-load condition:

Harbor Freight "1 hp" trim router #44914:

30,482 RPM, 98 dB, 172 watts.

Bosch Colt 1 hp trim router #PR10E (single speed version):

34139 RPM, 104 dB, 221 watts.

Bosch Colt 1 hp trim router #PR20EVSK (variable speed version):

At setting 6:
33,551 RPM 103 dB, 240 watts.
At setting 5:
28,535 RPM 100 dB, 165 watts.
At setting 4:
23,749 RPM, 96 dB, 114 watts.
At setting 3:
20,524 RPM, 94 dB, 90 watts.
At setting 2:
17,553 RPM, 90 dB, 83 watts.
At setting 1:
15,526 RPM,86 dB, 77 watts.

Just for comparison, a 30 year old Craftsman 1.5 hp router #174921
25,646 RPM, 104 dB, 416 watts

And my "6.5 hp peak" ShopVac makes 87 dB of noise so while I stand there with the shopvac and the router table running, I am getting an earful.

My Ridgid 2424 tablesaw only makes 84 dB!

Anyway, that's that!

[doorknob]

I don't know about anybody else, but I have found your info to be useful...

The Harbor Freight trim router is on sale right now, and I have been considering getting one to play with, even with no detailed idea of what I'm going to do with it once I get it.

So I've been looking for any info at all, and stumbled across your post...

[CarveOne]

revwarguy,

There is no db value shown for the Bosch Colt single speed model. Thanks for posting this information.

doorknob,

I use one of these on my smaller CNC machine as do a lot of other people. The plastic case is not as stiff as I would like, but Grizzly Industrial sells a metal case version at a higher price if I should need one, but I recently bought a Bosch Colt variable speed model. I haven't had a need to check run-out on mine but I would not expect very close numbers.
The clear plastic adjustable base won't hold position so I tossed that since I don't use it anyway.

The good thing about them is that they are cheap to replace and seem fairly tough to kill for something of that price range.

CarveOne

[CarbonKevin]

The Colt has a very aggressive fan design...it needs every bit of cooling it can get due to the small packaging! No question that's where the vast majority of noise is generated.

I wonder if a Colt could be switched over to a liquid cooling system...??

Very interesting post, thanks for sharing!

[ger21]

Note that a 10 dB difference doubles the volume of sound

I thought it was 3dB, so I googled it. 3dB is double the SPL (sound pressure level) but it takes 10dB for the ear to perceive it as double the volume.

[revwarguy]

Thanks, CarveOne for the good catch. No matter how many times I check over something like that, I seem to quite consistently affirm all the mistakes. I was still able to edit the original post, so I added it there.

Nice catch to, you, too Ger, as I wondered if anyone would wonder about it being a 3 or 10 dB difference. I decided to go with what we perceive the sound as, since I was mostly interested in this from an environmental viewpoint.

[revwarguy]

Originally Posted by CarbonKevin The Colt has a very aggressive fan design...it needs every bit of cooling it can get due to the small packaging! No question that's where the vast majority of noise is generated.

Yeah, it does have a fan on it.

The first time I cut aluminum I had a bit/feed combo that created very small swarf, and I was using a spray lube (WD40) so I removed my dust shoe. I started noticing little flashes of orange light coming from inside the router! It was some of the swarf being kicked up high enough to get sucked into the top of the router. I wrapped a paper tube around the top to make its intake even higher and that fixed the problem. The bearings on that router do get very warm.

[revwarguy]

Originally Posted by doorknob The Harbor Freight trim router is on sale right now, and I have been considering getting one to play with, even with no detailed idea of what I'm going to do with it once I get it. So I've been looking for any info at all, and stumbled across your post...

The HF trim router is a good motor, and I've seen folks using it on a CNC table as an inexpensive way to drive a separate spindle. However, I stopped using it on my table for two reasons - you can feel the runout on it, and about the only way to mount it is to clamp the sides, which deform easily and you start putting pressure on the winding frame, both of which work against you for rigidity. Its ok for cutting wood. I use mine now in a dedicated fixture with a fence and a roundover bit in it for quickly dressing board edges.