forget about HP ratings

HP ratings are just not an accurate way of determing power and different manufacturers may use different methods for their ratings.
The best measure is the Amperage draw at the operating voltage stated on the motor's plate. Most household circuits will only carry 15 AMPs, The newer homes may have a dedicated circuit at 20 AMPs.

So, here's what you need to determine. If your circuit has only 15 AMPs , and that's what the motor says on the plate, it's the equivalent of a really good 1 HP motor. That's the most you can run on that circuit.

If you have a 20 AMP circuit you can run a larger motor.
If the saw draws 18 AMPS, that's about 1 1/2 to 2 HP. If the saw draws 20 AMPS, it's a solid 1 3/4 to 2 HP motor.

There are no 3 HP motors that run on 120 volts, that I know of, they all require 220 volts. So a "rating" of 3 HP on a 120 volt saw is bogus.

 

You are wise to do research on getting a table saw - or any tool, and it can get confusing. First start with the style of woodworking projects you plan to do now and in the future to determine your needs. Two good choices IMO are a contractor saw or a stationary saw, which may decide your HP issues of each style, but usually require a different electrical power - 110 or 220. Fitting any TS into your work area can be another factor. Next, check the quality of the unit (up close) which would be a good indicator too. Check the throat plate for stiffness, the adjustment wheels/rip fence for smooth quick operation. Better brand names (usually) offer better quality units. Which ever TS you choose, be certain to read & understand how/why of all the workings of the unit. Consider getting a copy of Jim Toplin's book "Table Saw Magic" to give you more info on getting the most from your TS. Be safe.

 

The HP is a pretty good start but you need to evaluate what you want to do with the saw. You could spend a lot of money on a 5hp saw when you might only need one once in a blue moon. A smaller saw will get the job done but may take longer if you are cutting 8/4 hard maple. If you rarely cut 8/4 maple it doesn't make sense to buy a saw that you could cut it all day. I have a little Ryobi portable saw that would cut 8/4 maple but it would probably take me 5 minutes to make a 8' rip. We just don't know what your needs are. At one time I had a 12" Craftsman table saw. It was a direct drive with a 2hp motor and it would cut anything for a while. Cutting wood for an extended time the saw would get hot and trip the thermal breaker on the motor. The 12" blade didn't help as far as height. It wouldn't cut any thicker stock than a 10" saw, it just had to be 12" because the blade was on the motor. A belt driven saw will do as well as long as the belts were kept tight and in good order so they wouldn't slip. Really the only way you would need a 3hp motor is if you were cutting hardwood hours on end. For the hobbyist I think the size of the table and the fence system is far more important than hp.

 

I don't know what your experience is with a table saw but if it's on the low end then you probably don't need anything more than a 3 HP saw (true 3 HP, as woodnthings pointed out). Be aware that a 5 HP saw will throw a board into the next zip code, but not quite that far if you're standing in the path of that flying board.

 

Nameplate or measured current draw at full load X voltage = power in watts. Divide power in watts by 746 = true horsepower.

 

Hey all,

From what I've read, reading amps or horsepower may not give you a true representation of how powerful a saw can be.

Can anyone give me a hand and help explain how to compare power on different saws?

Nameplate or measured current draw at full load X voltage = power in watts. Divide power in watts by 746 = true horsepower.

So, there Ya go. How much power you need or want is a whole different question. I had a 1 HP 10" Craftsman Model 100 table saw for 45 years and it didn't die, I "killed"it. I wanted the table for my sawzilla and the motor for another project. It cut through thousands of feet of boards and plywood. Back then I didn't even have carbide blades, just HSS. I didn't cut a lot of 2" or 3" thick stock, but when I had to, I just let the saw blade work it's thing. When carbide blades came along at a price I could afford, that made a big difference.

How much "power" you need depends to a large degree on what blade you are using. A thin kerf blade removes less material and requires less power to make a cut. A rip blade is more efficient at ripping... go figya? A crosscut blade has too many teeth, too close together to carry away the sawdust and long strand fibers in a length wise cut on a hard wood board. It will heat up and bind up, but for plywood it's fine.

I have found for the best results you need 2, maybe 3 blades. A rip 24 tooth, a general purpose 40 tooth or 50 tooth combination and a fine 60 tooth/crosscut. The Freud Diablo thin kerf blades are the best bang for the buck I have found and I have several of each type.... they are that reasonable.

So, it's not always as simple as how much "power" a motor makes.

 

Nameplate or measured current draw at full load X voltage = power in watts. Divide power in watts by 746 = true horsepower.

If I'm not mistaken it takes 746 watts to make 1 hp at 100% efficiency. Electric motors are not 100 percent efficient so using this formula will result in a over rated hp number.

 

True, but not by much. Motors under 5 HP are typically 80 - 85 % efficient. If you want the true output, it has to be measured at the motor shaft. For a rule of thumb its pretty close, a lot closer than the nameplate. To be totally accurate requires metering the voltage and amperage under load to make the calculations. Depends on how far you want to go splitting hairs.

 

You have already had some excellent advice, so not much point in adding more except that saws come in small (1.5 - 2 HP), medium (3 HP), and large (5 HP) sizes.

If you "need" a medium size saw and get a small size you will not be happy with any brand, if you get a large size you will be wasting money unless it is a deal you can't pass up.

Saw manufactures usually source motors so the brand of motor used is more important than the brand of saw, performance wise.

 

You have already had some excellent advice, so not much point in adding more except that saws come in small (1.5 - 2 HP), medium (3 HP), and large (5 HP) sizes. If you "need" a medium size saw and get a small size you will not be happy with any brand, if you get a large size you will be wasting money unless it is a deal you can't pass up. Saw manufactures usually source motors so the brand of motor used is more important than the brand of saw, performance wise.

I haven't noticed name brand motors on any current saws. Even Powermatic is using generic "Powermatic" motors. Powermatic used to use name brand motors which were mostly Baldor.,

 

Another question is how much better will a true 3 hp motor cut over a true 2 hp motor on a 10" saw? 5 hp motors are usually on 12" saws so we will exclude those from the comparison. My saw is rated at 3 hp and still doesn't like ripping thick stock. I think a 10" blade is only good for so much, and at some point more power doesn't help. My saw pulls about 13 amps at 220 volts which is 2860 watts. 2800 divided by 746 = 3.8. Considering the efficiency being less than 100 percent 3 hp is pretty accurate for my saw.

 

Have you ever actually used a 10" saw with a 5 HP motor, from your comments I rather doubt it.

 

Have you ever actually used a 10" saw with a 5 HP motor, from your comments I rather doubt it.

No, I haven't. If 5 hp is better than 3 hp than 10 hp should be better than 5 hp. At some point more power on a 10" blade won't help. And the point of my question was figuring out where that point is. The local cabinet shop has a big 5 hp Powermatic. I usually buy my plywood from there and ask them to rip it in half for easier handling. Their 5 hp saw doesn't rip plywood one bit better than my 3 hp saw. Actually it does because of larger tables, but not the power difference.

 

There is a "pucker factor" with table saws, you can argue with a 1.5 HP saw, a bit with a 3 HP but a 5 HP has a mind of its own. :grin:

 

What do you mean "argue" with a table saw? I try not to argue with a table saw because spinning blades always beat flesh. I have two abrasive saws. One is a typical 12" abrasive miter saw. Plugs into a regular 110 volt outlet and wimpy to say the least. My other saw has a 10 hp motor on it and will cut a solid 3" steel rod in about 45 seconds. When I say 10 hp this isn't something shopvac rated for them. It pulls 25 amps on 240 volt 3 phase.

 

As stated, go by amperage. I have a Delta 36-650 I really like, it comes with Delta's default motor which is a 15-amp "1.5hp" motor on 110. The 1.5hp rating is a little generous.

It's true that a lower-amp motor could be higher-horsepower by being more efficient, but I doubt there's really that much of an efficiency difference between most of the commonly available hobbyest motors.

Either way, I'd be more concerned with the quality of the saw rather than the motor in it - you can swap out induction motors pretty easily if you had to, and if you find a good saw, it will probably have at least a 12 or 15 amp motor in it anyway.

With a sharp thin kerf blade, my Delta has had no problems going through pretty thick hardwood, for whatever that is worth.

 

Wow! This is great info guys thank you so much!

Just a little background on what I am looking in for a saw. I would not be looking for anything at all above 3 HP. That would be the epitome of a shop saw for me. Right now I am looking for a good 1 - 1.5 HP maybeeee 2HP if I can find one for a good price. I do not do much work on 2" thick hardwood. Usually its 1" thick or a softwood like pine or spruce when I am renovating the house.

From what I gleaned from what you all chipped in, I can get the approximate HP rating by using the amperage rating and volts and doing a bit of math to find that out. I had no idea that that was the case! I do have an <b>important</b> question that I am confused by with that though:

I have seen some tool manufacturers brag that their tools are powerful but draw a lower amperage. Is this a matter of efficiency as discussed by hwebb? Or is this something that needs to be taken into consideration?

 

Take it with a grain of salt. Most advertising is a mixture of fact and hyperbole. Whatever sounds good to the masses is what's hyped. Power is power. There are small considerations as to bearing types, drive types, etc, but by and large, amps is a good indicator of actual power.

 

Yeah, go find any decent contractor saw with a cast iron table and an induction motor, and you'll be fine, honestly. If you find yourself short of power, you could always bolt in a bigger motor very easily, but I think you're overthinking it.

The only way you could really go wrong here is to get a cheap saw with a universal motor or a plastic table, and you're already aware that you shouldn't do that.

Honestly, worse case with a table saw, if you really ran short on power you could always make successive cuts, raising the blade further each time. But like I said, my "1.5hp" 15amp Delta has cut through 2" of white ash most recently - with a good Freud rip blade on it, that was no problem.

 

I am curious about this and fully look forward to seeing other opinions on this. I currently have a Dewalt 2hp 15 amp table saw and am looking at getting a Laguna F1 1.5hp 20a table saw. I know that my current table saw has a few issues at cutting through thick hardwoods and I am wondering if the Laguna saw will have the same issue? Does the 20a 1.5hp motor in the Laguna cut better than the 15a 2hp?

 

Does the 20a 1.5hp motor in the Laguna cut better than the 15a 2hp?

Welcome to the forum.

I believe the amp rating is more reliable than the HP number.

 

So if understand correctly I wouldn't be taking a step back on cutting power by going to the Laguna F1 saw, Correct?

 

I would expect the F1 to have at least the cutting power and likely a bit more than the DeWalt.

It might be good to start your own thread in Power tools with the title something like "Considering a Laguna F1 saw". Describe the kind of wood working you do, the species and thicknesses of what you want to cut, are you cutting thick wood multiple times a month or a few times a year etc.

Power Tools & Machinery

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I'm not familiar with either saw. I think you also need to consider blade diameter. I think a larger diameter blade needs more power. So if the blades are different diameters, that would make it harder to compare cutting ability.

Agree with @Bob Bengal about starting a thread.

 

Yeah, 6 yr old thread

Describe thick hardwood. If your constantly ripping 3" hard maple, you need a 3hp, 240v saw min. That said, a 20A motor will have more power than a 15A motor. Manufacturers play games with up numbers. You can buy a 6hp shop vac in many brands, that run on 120v and a 16 gauge cord. go for the amps, it's hard to lie about amps

6hp vac at harbor fright not picking on hf, all manufacturers have them
Same goes for router specs. 3hp 120v motor is mathamagic dreaming

 

I apologize for jumping into another discussion, as soon as I can figure out how to start a new Thread I will do that, but thanks for the information thus far.

 

No need for apology. When you look at a sub forum etc to start a new thread look for the Create Post button towards the upper right.

Power Tools & Machinery

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You might check out this thread as there is similar discussions there that may help in your decision process.

Amps vs Horse Power? which provides better judge of...

I have been using a Dewalt 10" 120v 15amp jobsite tablesaw for several years now and I am starting to see that as I get into cutting more and more hardwoods that are various thickness but for the sake of comparison. I spend 90% of my time cutting oak, walnut, ipe, cumaroo, on my table saw and I...

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