I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.

You are quite welcome.

Have you been reading any Sears advertisements by chance?


RonB



"boorite" wrote in message
oups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.

"boorite" wrote in message
oups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.


I'm going to take the motor off of my shopvac and put it on my tablesaw. Not
only is it more powerful, it's smaller! Technology is wonderful.

"boorite" wrote in message
oups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.



Since HP is the result of a calculation that includes RPM, bizarre ratings
can occur.
http://www.reliance.com/mtr/flaclcmn.htm
Good site for formulas.

Dave

RonB wrote:
You are quite welcome.

Have you been reading any Sears advertisements by chance?

My God! How did you know?

Have you been reading any Sears advertisements by chance?

My God! How did you know?

Sears has had more ways to sidestep specifications and other features than
any distributor I can recall. Remember 'starting horsepower'? That is
probably what started their credibility gap with us older farts. You never
know what they are talking about.

RonB

boorite wrote:

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw,

If you're measuring electrical input power, then I've got a 4
horsepower kitchen toaster, and that doesn't even move. If you allow
electricity wasted as heat into the calculation, then you can get some
perverse measurements. As vacuums move a lot of air that they also use
for cooling, they're usually designed to be woefully inefficient in the
search for cheap power. It might even _be_ mechanically quite powerful
- some of them are, despite their small size and weight.

My table saw is not only rated at 3HP, that's real 3HP at almost any
speed, without risk of burning out.

"boorite" wrote in message
oups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.

Me too. Perhaps you should understand more about horsepower ratings.

The purveyors of this stuff rate motorins things like the Shop Vac as the
product of the maximum amperage times the maximum voltage. And, they don't
worry about such niceties as temperature rise.

However, motors for machinery such as table saws are rated at the average
power (which is 1/2 of what the above calculations show) and for an
intermittent load. This load results in a temperature rise of 60F above
ambient temperature. Thus, machinery motors are conservatively rated
whereas those other are wildly optimisticall rated.

Jim

"RonB" wrote in news:_NDQg.1487$Go3.1277@dukeread05:

Have you been reading any Sears advertisements by chance?

My God! How did you know?

Sears has had more ways to sidestep specifications and other features
than any distributor I can recall. Remember 'starting horsepower'?
That is probably what started their credibility gap with us older
farts. You never know what they are talking about.

RonB



From RepairFAQ.orgs humour page:
About Sears Shop Vac HP Ratings
(From: Kevin AstirCS "1U" KO0B ).) I note that
air compressor manufacturers have taken after the vacuum sweeper folks,
and are re-inventing the horsepower. Imagine, 6HP at 15A, 115VAC!

(From: sam).

Have you seen Sears shop vacs lately? I think they are also up to 6 HP.
Every week or so, they seem to come out with one that is a little higher
in their HP ratings - I guess internal cold fusion or something.

(From: Pin 2 Hot ).)

Let's see, RPM X Torque = Horsepower.

Thus: No-load RPM X Locked-rotor Torque = Sears Horsepower

Notes:

1. testing done at 177V DC, equal to peak of 120V AC (AC-DC motors).

2. Sears Horsepower: How "hoarse" you get trying to talk over one of
their shop-vacs while it's on.

Or maybe it's got something to do with vacuuming performance out at the
stables.

Source (again) RepairFAQ.org's humour page.
http://repairfaq.org/sam/humor.htm

Puckdropper
--
Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm

So, looking at realistic HP ratings (not shop vac sensationalized
values), my table saw is a 230 volt, 3hp motor. My router is a 120v
3hp motor. TS spins about 3 to 4 000 RPM, router can go up to 22K. I
still find it difficult to comprehend that the two motors are rated the
same. (And I trust Porter Cable!).
Does the output speed make the router rate as high as the TS?
Obviously it is not turning as heavy a cutter as the TS.
Marc

Jim wrote:
"boorite" wrote in message
oups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.

Me too. Perhaps you should understand more about horsepower ratings.

The purveyors of this stuff rate motorins things like the Shop Vac as the
product of the maximum amperage times the maximum voltage. And, they don't
worry about such niceties as temperature rise.

However, motors for machinery such as table saws are rated at the average
power (which is 1/2 of what the above calculations show) and for an
intermittent load. This load results in a temperature rise of 60F above
ambient temperature. Thus, machinery motors are conservatively rated
whereas those other are wildly optimisticall rated.

Jim

You shouldn't. On a 120 volt, 15 amp circuit, even 2.5 horsepower is
impossible.

"marc rosen" wrote in message
ps.com...
I
(And I trust Porter Cable!).

On Thu, 21 Sep 2006 16:49:26 -0400, "Locutus" wrote:


"boorite" wrote in message
roups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.


I'm going to take the motor off of my shopvac and put it on my tablesaw. Not
only is it more powerful, it's smaller! Technology is wonderful.

I might put mine on the wife's blazer *g*

Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm

On 21 Sep 2006 18:15:50 -0700, "marc rosen" wrote:

From what Jim said, if I understood it, the table saw could actually max at
maybe 6 hp...

So, looking at realistic HP ratings (not shop vac sensationalized
values), my table saw is a 230 volt, 3hp motor. My router is a 120v
3hp motor. TS spins about 3 to 4 000 RPM, router can go up to 22K. I
still find it difficult to comprehend that the two motors are rated the
same. (And I trust Porter Cable!).
Does the output speed make the router rate as high as the TS?
Obviously it is not turning as heavy a cutter as the TS.
Marc

snip
Jim wrote:
Me too. Perhaps you should understand more about horsepower ratings.

The purveyors of this stuff rate motorins things like the Shop Vac as the
product of the maximum amperage times the maximum voltage. And, they don't
worry about such niceties as temperature rise.

However, motors for machinery such as table saws are rated at the average
power (which is 1/2 of what the above calculations show) and for an
intermittent load. This load results in a temperature rise of 60F above
ambient temperature. Thus, machinery motors are conservatively rated
whereas those other are wildly optimisticall rated.

Jim

Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm

mac davis wrote:
On Thu, 21 Sep 2006 16:49:26 -0400, "Locutus" wrote:

"boorite" wrote in message
oups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.

I'm going to take the motor off of my shopvac and put it on my tablesaw. Not
only is it more powerful, it's smaller! Technology is wonderful.

I might put mine on the wife's blazer *g*

Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm
You'd spend all your savings on it buying extension cords:-)
Joe

hello,


"marc rosen" wrote in message
ps.com...
So, looking at realistic HP ratings
my table saw is a 230 volt, 3hp motor. (spins at 4000 RPM)

formula: HP = T * RPM / 5252 (T in lb/ft). Thus T = (HP*5252)/RPM

Let us assume that the peak HP is at 4000 RPM (induction engine), this means
that to generate 3 HP, the ST will need around 4 lb /ft of torque. with a 10
" blade (5" radius), this mesures to 9.5 lbs at the teeth...

My router is a 120v 3hp motor. (spins at 22K)
same calculation: .7 lbs /ft of torque on the router, with a 1/2 radius bit,
this is 17 lbs of pressure at the teeth...

I still find it difficult to comprehend that the two motors are rated the
same. (And I trust Porter Cable!).
Does the output speed make the router rate as high as the TS?
yep, directly proportional... note, it is easier to make a fast spining
engine have high power than a slow spining engine as less power torque needs
to be generated...

Obviously it is not turning as heavy a cutter as the TS.
the overall weight of the cutter is negligeable compared with the weight
distribution (ie: how far from the axis is the weight).

note, 1 HP = 745 W and 1 W = 1 V*A so if your tool is rated to draw up to
15A at 120V = 1800W = 2.4HP, you know, that, because of various losts in
heat, friction and the fact that this is a maximum that probably never gets
reached, the tool is capable of at max 2.4HP, and likely to be much closer
to 1/2 to 3/4 of that value.

cyrille

On Fri, 22 Sep 2006 07:53:58 -0400, Joe Gorman wrote:

mac davis wrote:
On Thu, 21 Sep 2006 16:49:26 -0400, "Locutus" wrote:

"boorite" wrote in message
oups.com...
I know it's a commonplace around here, but I just have to vent.

I would like to meet the marketing people who expect me to believe that
a 16-gallon ShopVac is 4 times more powerful than a $500 contractor's
saw, which also is supposedly just a shade over half as powerful as my
$50 skilsaw. Who the hell makes this stuff up?

That's all. Thanks for letting me get that off my chest.

I'm going to take the motor off of my shopvac and put it on my tablesaw. Not
only is it more powerful, it's smaller! Technology is wonderful.

I might put mine on the wife's blazer *g*

Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm
You'd spend all your savings on it buying extension cords:-)
Joe

Good point, Joe... I don't think our 400 watt invertor would run it.. lol
Mac

https://home.comcast.net/~mac.davis
https://home.comcast.net/~mac.davis/wood_stuff.htm