Side-By-Side Product Reviews. What gives?

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Blog entry by ChunkyC posted 07-04-2009 06:11 PM 997 reads 0 times favorited 10 comments Add to Favorites Watch

I’m in the market for a new table saw so like every other well informed consumer I’m reading everything that I can get my fat little fingers on. One great source of product information is product reviews from magazines and online sources.

I particularly like the side-by-side reviews but I’m a little skeptical of the results. When the newest edition of my favorite woodworking magazine shows up with a product review in it, it’s the first place I go. I love them and can’t wait for the next one!

One thing that I always keep in the back of my mind is bias. Now everyone is biased no mater how objective you try to be. If you ask me what brand of ROS you should buy next, I’m going to tell you that you should buy a XXXX. Why? Because that’s the one I use and it’s the one that I have the most experience with. So that’s why I always read more than one review from different locations and get others input as well from forums and the like. As Brian Dunnig says, “Be skeptical.”

So here’s my dilemma, and keep in mind I’ve been reading a lot product reviews for table saws. Take two of the same size saws and how can one have more “power” than the other? What gives?


The Situation: Brand X and brand Y saws, both are 2 hp let say. Both have the same blade, both have been sharpened to be as close to one another as possible, the same type of wood is used and each piece is matched as equally as is possible and the wood is fed through the saws “as fast as the saw would take it.” The feed rate is then measured.

The results: The feed rate is then used to make a comparison as to how powerful the two saws are. Does anyone else see the flaw in this logic? No? Then lets get out our calculators or slide rules if your of a certain age.


The simplest definition of horsepower that I know of is ”a unit of power equal to 746 watts.” Wait just one minute, aren’t both saws 2 hp? Then they should have the exact same “power” output. There must be something else, but what?

Are the motors identical in size? Is one motor rated in HP and the other in KW (Kilowatts)? Typically in the USA motors are rated in HP and in some other parts of the world, motors are rated in KW. So a 2 HP rated motor will be 1.5 kW after rounding. Maybe saw Y has a 1.2 kW rated motor or something not quite 1.5kW. If this is the case, then one saw is truly more powerful than the other because the motors aren’t identical.

Do both of the motors have the same speed rating? Maybe one motor is rated for 1725 RPM and the other 1600 RPM.

The list goes on and on, motor efficiency, motor slip, friction loss, blah blah blah.


So is there something else that causes one saw to be more powerful than another of comparable size? Education and experience tells me that two identically rated saws should have the exact same power output.
Is there a “hidden” underlying message that the reviewer is trying to convey that goes over my head because I’m so Obsessive and Compulsive that I can’t past the “more powerful” statement?


Just a little about me. I’m an electrical power engineer who specializes in medium and low voltage power distribution and in power quality.

-- Chunk's Workshop pictures:

10 comments so far

View lew's profile


11265 posts in 3177 days

#1 posted 07-04-2009 06:32 PM

Is there a possibility the saws being compared could have different pulley ratios and thereby changing the “power” (translate: feed rate) seen at the blade?

-- Lew- Time traveler. Purveyor of the Universe's finest custom rolling pins.

View bayspt's profile


292 posts in 3126 days

#2 posted 07-04-2009 06:34 PM

What about blade runout? Wouldn’t blade runout of any amount cause the saw to remove more material thus slowing feed rate and causing the end user to look at this as a loss of power? Even if runout was just .002 more on the one saw it would be like using a blade with .002 more kerf. Just my thoughts.

-- Jimmy, Oklahoma "It's a dog-eat-dog world, and I'm wearing milkbone underwear!"

View bayspt's profile


292 posts in 3126 days

#3 posted 07-04-2009 06:36 PM

And Lew has a good point as well? what is the rim speed of the blade, and how the pulley ratios effect speed and torque.

-- Jimmy, Oklahoma "It's a dog-eat-dog world, and I'm wearing milkbone underwear!"

View ChunkyC's profile


856 posts in 2676 days

#4 posted 07-04-2009 06:53 PM


I started a whole long section of this article on blade speed and the amount of work the saw was doing and decided that it was just “reading more into it.” Work = Force x Distance x cos(x) but the math gets pretty boring for something that is rotating. Besides, I don’t have my Statics and Dynamics books anywhere convenient so I axed that section. But RPM plays a HUGE role in how fast the saw cuts. A blade that is traveling faster removes material faster.

-- Chunk's Workshop pictures:

View jlsmith5963's profile


297 posts in 2770 days

#5 posted 07-04-2009 06:56 PM

I think you are expecting tool reviews to have a level of detail and accuracy that they don’t always have and in some cases aren’t capable of. These reviews shouldn’t be thought of as controlled experiments in the classical sense. I would suggest you leave your ‘electrical power engineer’ cap at the office and put your woodworking apron on when reading product reviews. (btw, unless the reviewer claims otherwise the listing of a machine specs in a review is usually taken directly from the manufacturer literature which can be influenced by their marketing department)

-- criticism: the art of analyzing and evaluating the quality of an artistic work...

View a1Jim's profile


115177 posts in 2999 days

#6 posted 07-04-2009 07:17 PM

It sounds like the reviewers could use you expertise have you tried letters to the editors?

-- Custom furniture

View jimp's profile (online now)


208 posts in 3183 days

#7 posted 07-04-2009 08:11 PM

Another thing to look at is how the motor company gets their horsepower rates. Brand X could be using peak horsepower, while Brand Y could be using the amount of horsepower that the motor develops under load. So you might also want to look at the amperage rating on the motors.

-- - Jim, Carroll, OH

View Don K.'s profile

Don K.

1075 posts in 2748 days

#8 posted 07-05-2009 06:08 PM

I think allot of it is also just the “Quality” of the motor and saw made….While both may be rated as “2hp” if saw “X” is made with better parts and has a better quality control when it is being put together….it will be a better running, more powerful and longer lasting saw than saw “Y” which while it may be rated at “2hp” will just not be the same saw in hp and quality as saw “X” regardless of what it claims to be.

-- Don S.E. OK

View Andy Brownell's profile

Andy Brownell

144 posts in 2674 days

#9 posted 07-07-2009 04:57 AM

My perspective is that you probably don’t need to spend as much time thinking about the level of detail on power as you have. I own a 1.5 HP SawStop contractors model that cuts through 3” cherry without too much trouble. If you really need to cut that much thick stock continuously, use a band saw, and finish with a planer.

Don’t overthink the electrical power aspect, and look at the overall reviews on the market. Finewoodworking and American Woodworker have posted some excellent reviews on a number of different models.

Although the price of entry is higher for all of SawStops models, their performance, tuning and quality right of out of the box is awesome. Thier safety is tops. No other brand on the market can compete with that selling advantage. Spend the extra money. It is worth the peace of mind, and you won’t sacrifice on quality.

Don’t let anyone tell you that safety is all about being smart and approaching the tools with caution. Everyone makes mistakes, regardless of age or experience. An $80 replacement brake cartrige is worth risking a $20.000+ hospital bill.

I’m sure many folks will have other opinions, but I know SawStops quality is awesome and the safety is untouchable. Take a look at the videos on their site for yourself.

-- Andy Brownell

View PurpLev's profile


8523 posts in 3071 days

#10 posted 07-09-2009 05:00 PM

Chunky – what you’re missing in your equations is “MOTOR EFFICIENCY”.

yes – both motors are rated as 2HP – for the INPUT! (HP = Kw = Amp x Volt into the motor) but depending on the brand, and the parts used to build the motor – each motor has a different OUTPUT.

add to that the pulley configuration on the different saws – and indeed, although both are rated as 2HP from the mfg. each saw cuts differently.

up till this point it was all electrical and scientific…. HP…Kw… once we pass the step of “each saw cuts differently” – enter the world of woodworking.

this is what the reviews are after, and this is what the woodworkers want to know – which saw will cut better – regardless of the number the Mfg. put on the motor.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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