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Discussion Starter #1 (Edited)
Why is it that a 2 HP router is needed to put an edge profile on hardwood in one pass, or hog out wood for a mortise over several passes, but I can use only a 3/4 HP garage door opener to lift a door so heavy I cannot do it myself and it never slows down one bit?

I'm not disputing the fact, because I have personally experienced a 1 1/2 HP router bogging down in a cut. What makes the difference though? I see one motor doing a heavy chore with less than half the power rating, while another only needs to shave off wood slivers as I feed it through, and yet it may struggle.

Incidentally, I used to work for Sears, and I went to a training seminar one day where they told us they were going to roll out 3/4 HP garage door openers as a marketing ploy. At that time they said the current 1/2 HP openers would lift any door made, but people would buy into the "more power is better" idea and make their openers easier to sell compared to the competition. Seems funny to me that over time I have seen an increase in HP in almost everything, from garage door openers, routers and other power tools, lawn mowers, and even cars and trucks. Makes me wonder if the whole thing isn't geared towards just making more money somehow.

Has a 2 HP router always been available from the beginning? Sure seems that every old one I see is rated pretty weak by today's standards, and way back when dad was young (say 50 years back), older growth hardwood would have been more readily available, seemingly making it more common and therefore more power needed more often to work it. There is a thread right now where someone just bought an old used 3/4 HP Sears router. That's about as low as I've seen yet.

EDIT--One thing that just occurred to me is that HP rating itself may be what has changed. The load vs. no load rating, decimal figures rounding up to make a figure appear larger, and even such things as peak power vs. a more consistant output come into play also. With no set standards, I suppose anything is possible to see in HP ratings.
 

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Duane, garage door openers use gears to reduce speed and multiply torque. Router bits are powered straight off the motor shaft.
 

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Discussion Starter #3
Since I posted this, I was driving to work and thinking about it and I figured it must have something to do with that.
 

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One other related issue is that when using 110 volt power HP ratings are all BS. The real rating for 110V equipment should be in amp draw....so many companies say incredible HP ratings, Sears comes to mind......

Bryan
 

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One of the problems is that when the company tests their tool they have unlimited amp draw. 1 HP is = 746 watts, volts x amps is = watts, 120v x 15amp = 1800 watts. But then you have to consider that is under ideal conditions with no line loss. Most of the time if you measure the volts in your plug it will be less than 120v. I have a shop vac that says it has 6.5 HP and runs on 120v 15amp circuit. Which would be around 4849 watts draw would need to be 40.41 amps. All I know is that my 3.25 HP routers will hog out material with sharp bit and my 3/4 HP router needs multiple passes for the same job.

Regards Bob
 

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One other related issue is that when using 110 volt power HP ratings are all BS. The real rating for 110V equipment should be in amp draw....so many companies say incredible HP ratings, Sears comes to mind......

Bryan
Amps... so lets bring you up to speed on amps and a whole lotta misconceptions you have...
 

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Duane, you can sum that up to advances in technology. The size of old 1/2 hp electric motors is about the same as a new 1-1/2 hp motor.
 

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Why is it that a 2 HP router is needed to put an edge profile on hardwood in one pass, or hog out wood for a mortise over several passes, but I can use only a 3/4 HP garage door opener to lift a door so heavy I cannot do it myself and it never slows down one bit?

I'm not disputing the fact, because I have personally experienced a 1 1/2 HP router bogging down in a cut. What makes the difference though? I see one motor doing a heavy chore with less than half the power rating, while another only needs to shave off wood slivers as I feed it through, and yet it may struggle.

Incidentally, I used to work for Sears, and I went to a training seminar one day where they told us they were going to roll out 3/4 HP garage door openers as a marketing ploy. At that time they said the current 1/2 HP openers would lift any door made, but people would buy into the "more power is better" idea and make their openers easier to sell compared to the competition. Seems funny to me that over time I have seen an increase in HP in almost everything, from garage door openers, routers and other power tools, lawn mowers, and even cars and trucks. Makes me wonder if the whole thing isn't geared towards just making more money somehow.

Has a 2 HP router always been available from the beginning? Sure seems that every old one I see is rated pretty weak by today's standards, and way back when dad was young (say 50 years back), older growth hardwood would have been more readily available, seemingly making it more common and therefore more power needed more often to work it. There is a thread right now where someone just bought an old used 3/4 HP Sears router. That's about as low as I've seen yet.

EDIT--One thing that just occurred to me is that HP rating itself may be what has changed. The load vs. no load rating, decimal figures rounding up to make a figure appear larger, and even such things as peak power vs. a more consistent output come into play also. With no set standards, I suppose anything is possible to see in HP ratings.
3/4HP... gear reduction is a marvelous thing...
so heavy.. you need to adjust your door springs... if you don't, expect your opener to die an early death...

struggle... tool not sized to feed/speed/load/bite....

Sears.. what a joke.. I'd consider their word worthless no mater what they tried to tell me...
in retrospect a 3/4 horse over a 1/2 horse has an easier life if it's teamed up w/ the correctly sized/strengthened hardware...

money... I believe you have answered your own question but in it's defense more HP often has it's place...

2HP... yes, 3HP was too, ie, (16) -00, 11, 13, 18, 19 and 90300 from 4+ decades ago... so weren't 5's and 7.5's in the Stanley 240V 90,000 series... (commercial market)....
FWIW... a lot of trim routers were 1/2HP... IIRC 10 series Bosch from the 70/80's... I think PC had them too...

1618 - 2HP
1613 - 2HP
1619 - 3.25HP
1600 - 2.25HP
1611 - 3HP
90300 - 3 HP

HP ratings... please read the PDF's and pay close attention to what is said about amps...
 

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As Stick points out the information plates on tools are for comparison between models. There is a lot of fudge factor in most ratings but it is something to work from. A good example of this would be to compare the PC 690 series routers which are rated at 1-1/2 hp to the Bosch 1617's which are rated at 2 hp. (the 1617EVS is rated at 2-1/4 hp due to the electronic controller and the motors are different) The Bosch is quieter and you can feel the power difference when routing. This makes sense, right? 2 hp should have more usable energy than 1-1/2 hp.

Now compare the 1617EVS (2-1/4 hp) to the Bosch MRP23EVS (2-1/3 hp) and it gets confusing. The usable power should be close to the same based on these numbers but the 23 has a lot more usable power. In terms of amps the 23 should be closer to 3 hp and it does feel like it when routing. Then add in the 1619EVS which is rated at 3-1/4 hp with a lot of reserve power and yet the amps draw is very close to the MR23.

There is no service factor rating or efficiency rating on routers. All you can depend on is the hp rating will give you a general idea when comparing tools. Hands on is the best way to choose a router.
 
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Yeah. stick is totally on about amps vs hp.

My favorite example of HP-lies are in shop vac marketing. How it is possible for a 120 Volt shop vac to be 6 HP??? That works out to be at least 6 * 768 watts which works out to 38.4 Amps. More than twice your typical wall outlet capacity. I've not heard of a rash of people blowing their breakers when cleaning up the shop... (the answer lies in the mealy mouthed wording which almost no one pays attention to.)
 

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Re your comment, Stick, re the garage door springs. Twice I've been in a garage when the spring on an overhead door (underground parking) let go. the falling doors scared the living bejeesus out of me! If anyone had been under them when they came down they'd have been crushed. So yeh, the springs do a tremendous amount of the work.
 

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I have a couple of 3 hp Baldor motors. One of them is driving my air compressor. Either one of them is about all an average man would want to try and lift. Both run on 220 volt and 20 amps. Obviously we aren't comparing apples to apples. I don't know if one of my 3+hp routers would even turn my compressor over.

Routers are probably measured in peak hp, but there is also brake hp which is how much energy it takes to stop it. Neither one is a very good indicator of how much work the machine will do. Amps or watts are better and the best, IMO, is output watts which is how much power is actually being applied to do work. BTW, output watts/input watts gives you motor efficiency in percent. A lot of manufacturers are probably afraid to put this kind of info on their machines as routers are around only about 65% efficient. Generally I ignore router hp ratings and just look for watts or amps. Drills and C saws are rated this way so maybe router makers will eventually switch over. I think Festool already has? I don't think they give a hp rating.

All of the early Sears routers that I remember, and my first one was a Craftsman, would only take 1/4" shafts. They were meant for hobbyists who would normally only use them a few times a year on average. The market they targeted didn't really need a lot of power and didn't want to spend a lot of money. Over time the router has become a more important tool and needs more power now than before and mass production has brought prices down in relative dollar value terms so that they are more affordable.
 
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I think our woodshop in High School (early 60's) had a Porter Cable router(?). Maybe it was Stanley? Someone posted a pic of the Stanley, with its domed top, a couple of weeks ago, and the memories came back.
 

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I only had a chance to scan a little bit of that and it looks quite interesting, particularly how they get efficiency. I have a bit of a leg up on some of the material as I was a physics major at university for a couple of years and am a power engineer part of the year these days. The simple calculation I gave for efficiency is the one found in my power engineering manuals. As your article states,the calculations are imprecise and can vary 2% from one method to another but for our purposes I think 2% is more than accurate enough.
 

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Discussion Starter #17
Re your comment, Stick, re the garage door springs. Twice I've been in a garage when the spring on an overhead door (underground parking) let go. the falling doors scared the living bejeesus out of me! If anyone had been under them when they came down they'd have been crushed. So yeh, the springs do a tremendous amount of the work.
Based on what my springs look like when the door is lifted, I can see they do a lot of pulling it up. They are nearly relaxed when it is up. But that means that when the door goes down, the motor has to work against the springs, so one way or the other, the motor sees some stress, although I'm sure gravity on the door must be helping out some also.
 

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If I remember correctly spring tension goes up exponentially as its length increases which would mean that there isn't a lot of load on the motor until the spring reaches around 50%+ extension which is about the time that gravity starts helping out.
 

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When a garage door is properly set up, the springs come close to perfectly counteracting the weight of the door. You should be able to easily open the door with the opener detached The motor doesn't have to work hard when newly installed, but springs fatigue and stretch/sag. Pay no attention and that is what leads to a failing motor as it has to work harder and harder to lift the door. It is why you can buy replacement springs, and also why you can buy replacement openers.
 

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One thing that has been over-looked in this discussion is the improvement in electric motors windings that have allowed manufacturers to increase power in a smaller size casing.

Buck
 
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