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  • Unit Watt Out???

    Does anybody have any idea what this means? Seems to be something Dewalt is trying to use as a selling point but their is no explanation of what it is. Anyone know?

  • #2
    RedBaron

    That is a very good question; it appears that it is specified primarily on rotational tools, i.e. drills, grinders and circular saws. Also noticed it is not limited to DeWalt; Makita and Hitachi also publish a “Max Watts Out” spec.

    Woodslayer

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    • #3
      Watts is a measurement of power. Although we mostly use it here in the U.S. in referance to electrical consumption (watts per hour), it is popular in Europe for specifications where we in the U.S. might use horsepower. Unless I am remembering wrong, I believe Watts is the ISO standard, rather than Horsepower. Companies meeting ISO 9001 standard would most likely be upgrading their specifications to the ISO Metric Standard... although here in the U.S., horsepower is still the norm.

      Horspower for electrical applications is figured differently than horsepower for machanical applications. 1 horsepower (electric) is equivalent to 746 watts. Here is a popular convesion site: http://www.onlineconversion.com/power.htm

      Hope this helps,

      CWS
      Last edited by CWSmith; 05-27-2006, 12:17 AM.

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      • #4
        I think your on to something there CW, they are probably trying to rate them similar to routers by giving the maximum output available at the self-destruction point. A 2200 max watt output would equate to roughly a 3 HP output, although even if the motor were 100% efficient it would still need to draw over 18 amps at that point.

        Woodslayer

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        • #5
          any help is always welcomed! and you guys gave me some great information to look at. Does anyone know how this compares to torque ratings on drills? Or does it all?
          Last edited by RedBaron; 05-27-2006, 10:49 AM.

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          • #6
            Here is DeWalt's marketing thing on the subject.

            http://www.dewalt.com/us/cordless/powerrating/

            Unit Watts out (UWO) is their rating for the (presumably sustainable) maximum power output at the chuck of the drill. You can read about it.. their explanation is basically technically correct.

            Yes, max torque is related. The maximum power in a permanent magnet DC motor system occurs at half the maximum speed when the system is loaded with half the maximum torque.

            1hp = 746 watts, DeWalt's DC900 36V drill is claimed to be 750 watts, close enough so let's call it 1 HP ok? Their max RPM is 400. So 200 RPM is the half-way point.

            1HP = 200RPM*Tmax(in-lbs)/(24*5252)

            Tmax = approx 630 in-lbs

            The equation I used is known equation for relating power (HP) to RPM and torque (in ft-lbs..I added in the factor of 1/12 to account for the in-lbs to ft-lbs conversion).

            By the way DeWalt make some bold claims about other manufacterers' drills.

            For example they claim the 18V Lok Tor by Milwaukee puts out 390 UWO compared to their DC988 model listed as 420 UWO. Yet I have read information from Milwaukee's own independent tests that claim the Lok Tor drills faster 2 9/16" self-feeds AND more self-feeds per battery than that very DeWalt model.

            This was posted on Milwaukee's Tool Talk forum (when it existed). I believe the Milwaukee official said that DeWalt averaged 7.2 seconds per hole while the Milwaukee averaged 6.4 seconds per hole. I make be off slightly but I do remember it was around a 1 second difference. Plus the Milwaukee apparently drilled 28 holes per batt where dewalt was 25.

            So who's right?

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            • #7
              Thanks Sceeter

              That website gives a clear explanation of a new (to the consumer anyway) marking concept that we will have to adapt to.

              Woodslayer

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              • #8
                To Sceeter W Wheels:

                To your theory about UWO's....I think know one knows the real way to find out torque ratings from that. Cause the reason why I say that is because if you call "DEWALT" they will tell you they dont even have a way to convert it to torque! When you ask how much they think of torque they have on the 36v....they say 4oo in.lbs. I called yesterday 3 times to get answers (1-800-4-dewalt) and all 3 times they game me different torque ratings...1st one was 350in.lbs, 2nd time it was 400in.lbs....and the last was 375in.lbs....

                So like I said, call them and they will say they dont even have a way to convert it to torque......thats Default(DeWalt) trying to make them sound like they have more power by saying 750 UWO's!!!!! Go figure!

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                • #9
                  DeWalt.. up to their yellow tricks again.

                  I'm just going by DC motor theory. Quite frankly the calculation is only as good as DeWalt's "honesty" and conditions of reporting their "power delivered at the chuck" (UWO) measurements.

                  I contacted DeWalt too and got a fluff answer about the issue. They fluff you off and say the tests were done by "an independent test lab". Yeah, ok guys. Funny, Milwaukee's "independent tests" show their drills performing better than DeWalt's, including the Lok Tor 18V. Do you think there's some fudging the numbers going on? I do. DeWalt cordless outdrilling a Milwaukee cordless? Doubt it. V28 with only a marginal performance advantage over DeWalt's 18V? Fat chance.

                  Funny they don't talk about motor efficiency in their article either. Woops, forgot about that one right guys? It should read "DeWalt: power wasted to help you go to the charger more often(TM)."

                  but the bottom line is that "UWO" numbers reported without them BACKING UP the claims by disclosing the test procedure and conditions are WORTHLESS. It basically amounts to DeWalt being up to their yellow marketing hype tricks again.

                  So... Any DeWalt reps around that care to discuss this? I'm all ears.

                  Originally posted by packers
                  To Sceeter W Wheels:

                  To your theory about UWO's....I think know one knows the real way to find out torque ratings from that. Cause the reason why I say that is because if you call "DEWALT" they will tell you they dont even have a way to convert it to torque! When you ask how much they think of torque they have on the 36v....they say 4oo in.lbs. I called yesterday 3 times to get answers (1-800-4-dewalt) and all 3 times they game me different torque ratings...1st one was 350in.lbs, 2nd time it was 400in.lbs....and the last was 375in.lbs....

                  So like I said, call them and they will say they dont even have a way to convert it to torque......thats Default(DeWalt) trying to make them sound like they have more power by saying 750 UWO's!!!!! Go figure!

                  Comment


                  • #10
                    The power rating terminology change thing is nothing new. You used to buy motorized tools like saws and drills by looking at the amps and rpm. Then they started rating them as horsepower because it made them look stronger. Then (I think it was Sears first) they started using "developed hp" or "max hp. It was all done to make it harder for the consumer to "compare apples to apples" and make their tool look better than the competition. Now, with battery tools, the "new" rating is UWO.
                    Its also done with cars (first it was hp then it was torque, etc), digital cameras (pixels vs ccds), and most everything else. As soon as the consumer gets to know what UWO ratings really say, they'll come up with a new term like "Usable energy reserve" "amp-second draw capacity" or the like. Its all just gilding the lily. The proof is how the tool works on the job.
                    Thanks to forums like this, it is a little easier to find out more quickly and to get unbiased reports on how the tool works in the field. I agree with Sceeter that unless you know the test protocol, you can't blindly take the company's word, and you also can't tell how it affects your needs. Does more UWO mean longer battery life, more torque, more power under resistance? The guy or gal buying the tool needs to know which so they can determine which they need for their purpose.
                    Keep up the good discussions so that we can all learn!
                    Practicing at practical wood working

                    Comment


                    • #11
                      DeWalt need to disclose how they run their tests instead of hiding behind the "independent test lab" card. Independent test lab doesn't mean jobsite performance. Sorry.

                      I have many technical questions and would like them to back up their claims. Especially their claims that their 18V drill is "more powerful" than Milwaukee and Makita. I seriously doubt that.

                      Comment


                      • #12
                        Hello,

                        I was looking thru your forums for something about a warranty, and came across this post.

                        I work for DeWALT, that is all I am going to say, I won't get on here to often, but will try and answer some of your questions, w/ my answer and the answer they give me. I use the tools on jobsites for my self, and also at "in house" facilities.

                        I will say this, each tool manufacturer has their plus and minus qualities.

                        Best overall quality I have found is Hilti, their new 15v Hammer drill driver kept up with the DeWALT 18v w/ a 2 9/16 holesaw on each, that is some serious power!

                        Please don't complain to me, as I can't do anything about it, Just ask ?, and I will try and answer them.

                        Who knows, the admins might kick me off!

                        Comment


                        • #13
                          Thanks for logging in...

                          At what RPM is UWO measured at? Is this at the absolute maximum POWER output of the tool or the maximum EFFICIENCY output?

                          For instance, the DC988 is rated at 420UWO according to DeWalt. This is much lower than the theoretical calculation based on the cataloged torque and RPM figures for the tool (even using the 52nm..460in-lbs "sustained torque" catalog data given on the European site).

                          Most 18V DC drill motors produced by, Johnson Electric or Mabuchi (both used by DeWalt) have max power ratings around 700W. The maximum efficiency power is much lower.

                          How does DeWalt measure this figure?

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