I am in the market for a new DC.
The local Woodcraft had Delta and Jet 1 and 1.5hp.
The Delta motor were 11a and 15a; about what one might expect.
The Jet were 11a and 11a. Thats right, they were the same. They are also
the same diameter, length, and class. Looks to me like they are the same
motor.
So how is one 1hp and the other 1.5hp?
mac davis said:
>On Fri, 11 Nov 2005 13:28:20 GMT, B a r r y
><[email protected]> wrote:
>
>>Greg G. wrote:
>>>
>>> Yes. HP figures for Air Compressors comes to mind...
>>>
>>
>>And Shop-Vacs...
>
>And cars...
>Back in 80, we bought a new Chrysler Le Baron... the one we drove was peppy, the
>one my wife bought was a dog...
>Salesman said that the difference between the "American" and "Japanese" (Mitso)
>engines was 4 hp..
>
>Found a report a few months later that said the difference was 5 hp and that the
>Mitso engine developed peak hp 1,000 rpm lower than the other engine... a LOT of
>rpm difference, even for a 4-banger..
>(I figured that before you could get peak hp from ours, the engine would self
>destruct)
Yeah, it's pretty handy to have a charted printout of the torque
curve. And since (torque*RPM)/5252 equates to HP, it is also quite
relevant to driveability. As are gear ratios, course maps, etc...
HP figures have become like CPU speeds - or maybe it's the other way
around... Advertising Hyperbole. Nevertheless, the basis for almost
all hot-rodding attempts, baring more displacement.
I built a rotary engine years ago that developed peak torque at 6200
RPM. It would spin up to 8000RPM. Scary stuff. And it hauled...
Wasn't so good off the line... Made a really cool sound as well.
Oh, how I wish I still had it - it was a kick.
As for the self-destructing aspect - hey, it sells cars.
I think it is Detroit's mantra these days...
I've never been a fan of four bangers, due to the rocking couples and
harmonics, and I'm not that fond of V and in-line engines either. My
preference is horizontally opposed 6/12 cylinder engines and rotary's.
Naturally balanced. I guess I'm a high RPM durability kinda guy. But
try finding one these days - for less than 100 big'ens. And fuel
costs... ugghh...
And if I touched upon issues you are intimate with, please excuse me
and consider it a rhetorical discussion with myself. ;-)
Greg G.
I can't give a direct answer regarding the difference/similarity of the
two Jet motors. However, as general advice, the CFM and HP ratings
provided for most consumer grade DCs are fairly meaningless. Advertised
CFM numbers are usually based on completely unrestricted airflow, i.e.
with no ducts, filters, etc. Sometimes, they're pure fiction. As a rule
of thumb, under realistic working conditions, most consumer DCs deliver
no more than 50-60% of their rated flow
HP ratings are something of a non-issue, because a blower is basically
a fixed load. It takes a certain amount of HP keep the impeller
spinning at a given airflow. Increasing motor HP above this required
minimum will not increase performance. So don't sweat the motor specs
too much. I agree that the 11A number for the Jet is strange, but this
machine has performed comparably to others in tests, with nothing to
indicate that the motor is underpowered, so I wouldn't worry.
In any case, I'd pick either of the larger machines, whichever comes
with good felt filter bags.
"My Penn State 1.5hp 8a (240v) DC measures 3.3a. I can get it up to
3.8a by
taking the bag off.
I was blaming the single bag for it's less than stellar performance,
but it
is actually lies about the motor."
You seem to be assuming that an 8A motor should always draw 8A. Not so.
Motor current draw depends on load: a motor will draw it's rated
current only when it's under full load. In a DC, the load is the
airflow, which is limited by the impeller size and blower design. I
think you have a PSI DC-3, which has a 9" impeller. That, and the 4"
inlet/outlets, are the limiting factors, not the motor specs.
Toller wrote:
> The Jet were 11a and 11a. Thats right, they were the same. They are also
> the same diameter, length, and class. Looks to me like they are the same
> motor.
>
> So how is one 1hp and the other 1.5hp?
11A at 120V is 1320W. 1.5HP is 1120W. That would require 85%
efficiency, which is pretty high. I call either BS or typo.
Chris
On Fri, 11 Nov 2005 13:28:20 GMT, B a r r y
<[email protected]> wrote:
>Greg G. wrote:
>>
>> Yes. HP figures for Air Compressors comes to mind...
>>
>
>
>And Shop-Vacs...
And cars...
Back in 80, we bought a new Chrysler Le Baron... the one we drove was peppy, the
one my wife bought was a dog...
Salesman said that the difference between the "American" and "Japanese" (Mitso)
engines was 4 hp..
Found a report a few months later that said the difference was 5 hp and that the
Mitso engine developed peak hp 1,000 rpm lower than the other engine... a LOT of
rpm difference, even for a 4-banger..
(I figured that before you could get peak hp from ours, the engine would self
destruct)
mac
Please remove splinters before emailing
"Greg G." <[email protected]> wrote in message
news:[email protected]...
> Toller said:
>
>>I am in the market for a new DC.
>>The local Woodcraft had Delta and Jet 1 and 1.5hp.
>>
>>The Delta motor were 11a and 15a; about what one might expect.
>>
>>The Jet were 11a and 11a. Thats right, they were the same. They are also
>>the same diameter, length, and class. Looks to me like they are the same
>>motor.
>>
>>So how is one 1hp and the other 1.5hp?
>
> Creative Marketing.
>
Don't you just _love_ conspiracy theories?
Depending on type and application, I would say.
http://www.iprocessmart.com/leeson/leeson_singlephase_article.htm
All induction-run begin with "slip," which is one place to begin.
"Greg G." <[email protected]> wrote in message
news:[email protected]...
>>> Creative Marketing.
>>>
>>
>>Don't you just _love_ conspiracy theories?
>
> Yes. HP figures for Air Compressors comes to mind...
>
>
There are many "standards" for measuring HP. There are also many types of
motors. The idea is to be smart enough not to be fooled. If the words peak
and developed don't key you into thinking, I guess you're one of those folks
the inflated numbers are intended to fool.
If you don't care to be manipulated, inform yourself. Good site on motor
applications and efficiency was offered.
George said:
>
>"Greg G." <[email protected]> wrote in message
>news:[email protected]...
>> Toller said:
>>
>>>I am in the market for a new DC.
>>>The local Woodcraft had Delta and Jet 1 and 1.5hp.
>>>
>>>The Delta motor were 11a and 15a; about what one might expect.
>>>
>>>The Jet were 11a and 11a. Thats right, they were the same. They are also
>>>the same diameter, length, and class. Looks to me like they are the same
>>>motor.
>>>
>>>So how is one 1hp and the other 1.5hp?
>>
>> Creative Marketing.
>>
>
>Don't you just _love_ conspiracy theories?
Yes. HP figures for Air Compressors comes to mind...
Greg G.
On Fri, 11 Nov 2005 22:51:58 -0500, Greg G.<[email protected]> wrote:
>George said:
>>
>>"Greg G." <[email protected]> wrote in message=20
>>news:[email protected]...
>>>>> Creative Marketing.
>>>>>
>>>>
>>>>Don't you just _love_ conspiracy theories?
>>>
>>> Yes. HP figures for Air Compressors comes to mind...
>>>
>>
>>There are many "standards" for measuring HP. There are also many types=
of=20
>>motors. The idea is to be smart enough not to be fooled. If the words=
peak=20
>>and developed don't key you into thinking, I guess you're one of those =
folks=20
>>the inflated numbers are intended to fool.
>>
>>If you don't care to be manipulated, inform yourself. Good site on =
motor=20
>>applications and efficiency was offered.
>
>Look, you old fart. You were OK until I said something in another
>thread about Bush being the dim bulb that he is. And then you got
>your diapers in a wad and have been answering my posts at every
>opportunity with smart-ass responses like this. You are not the God
>Head of enlightenment, and you're not even that freaken smart. So go
>back to your basement, fire up a log, relax - and quit reading and
>responding to my posts. Or go feed the gulls around Lake Superior.
>
>I've worked in electronics and mechanical engineering for almost 30
>years, and I don't need to read some neophyte level web site to know
>you are an angry, lonely old troll with nothing better to do. I come
>here for entertaining conversation, not trolls. But just FYI, I have
>an _inkling_ about hysteresis, stall, efficiency, slip, AC phase, ohms
>law and many other terms you looked up on the net only yesterday.
>
>I have never done this before, and hope to never do it again (but I
>feel there's another one coming up) - Welcome to my killfile.
>
><PLONK>
>
>
>Greg G.
I thought that a horsepower was 746.04 watts, or there abouts. To my =
knowledge, (which is
limited I will agree...) no one has dispelled and proven wrong that =
relationship. Now if
you are referring to things like the capacitor laden little motors that =
HF and others sold
as 5hp, but only 15amps @220v, just marketing hype I am afraid. HF has =
ceased selling the
one that was "rated at" 5hp, it is now their "3hp that we used to sell as=
5hp", so someone
must have threatened with a lawsuit or something. HF is not alone on =
this, I think there
were at least 2-3 others doing the same thing, most of them don't even =
sell them at all
any more an have only the 5hp motors that are in the 21-23amp range which=
is in the
ballpark, just barely. Semantics become some antics just like good old =
GW, don't matter
how much power you got if there is a wingnut loose on the steering wheel,=
or a nut loose
on the control panel. Got a bad feeling about this one, god bless our =
young men and women
who have to live with that harsh reality daily, here is to them, may they=
come home
safely. Joe
Joe Brophy
CountryTech Computer
email: [email protected]
<[email protected]> wrote in message
news:[email protected]...
> "My Penn State 1.5hp 8a (240v) DC measures 3.3a. I can get it up to
> 3.8a by
> taking the bag off.
> I was blaming the single bag for it's less than stellar performance,
> but it
> is actually lies about the motor."
>
> You seem to be assuming that an 8A motor should always draw 8A. Not so.
> Motor current draw depends on load: a motor will draw it's rated
> current only when it's under full load. In a DC, the load is the
> airflow, which is limited by the impeller size and blower design. I
> think you have a PSI DC-3, which has a 9" impeller. That, and the 4"
> inlet/outlets, are the limiting factors, not the motor specs.
>
I also tested a 8a Tufo; it drew 7a with the filter on, it probably would
have been close to 8a without it.
And an 11a (120v) Jet. It drew 9.5 with the bags on; presumably 10+ without
them. It also has a 9" impeller (it is small, I think it is 9") and a 4"
inlet.
So, the Tufo did what it claimed, and the Jet did nearly so.
The PS might be somewhat reduced by the small impeller and inlet, but not by
the 60% I actually measured. There was only a 25% hit by going from no bag
or hose to completely blocked!
Besides, the 8a PS motor is half the size of the 8a Tufo motor (or my 8a
table saw motor for that matter); it might even be smaller than the Jet
DC650 motor. No way to explain that except that PennState is simply making
up numbers.
Bear in mind that PennState claims their DCs are half as loud as anyone
elses, which certainly isn't true with my DC-3. It claims 62db, but is
significantly louder than my 68db generator.
Toller said:
>I am in the market for a new DC.
>The local Woodcraft had Delta and Jet 1 and 1.5hp.
>
>The Delta motor were 11a and 15a; about what one might expect.
>
>The Jet were 11a and 11a. Thats right, they were the same. They are also
>the same diameter, length, and class. Looks to me like they are the same
>motor.
>
>So how is one 1hp and the other 1.5hp?
Creative Marketing.
Greg G.
Greg G. said:
<snip>
>HP figures have become like CPU speeds - or maybe it's the other way
>around... Advertising Hyperbole. Nevertheless, the basis for almost
>all hot-rodding attempts, baring more displacement.
Darned, I'm starting to proofread myself now...
Should have said...
Nevertheless, shifting the torque peak towards a higher RPM is the
basis for almost all hot-rodding attempts, baring more displacement.
NOW the formula... ;-)
Greg G.
George said:
>
>"Greg G." <[email protected]> wrote in message
>news:[email protected]...
>>>> Creative Marketing.
>>>>
>>>
>>>Don't you just _love_ conspiracy theories?
>>
>> Yes. HP figures for Air Compressors comes to mind...
>>
>
>There are many "standards" for measuring HP. There are also many types of
>motors. The idea is to be smart enough not to be fooled. If the words peak
>and developed don't key you into thinking, I guess you're one of those folks
>the inflated numbers are intended to fool.
>
>If you don't care to be manipulated, inform yourself. Good site on motor
>applications and efficiency was offered.
Look, you old fart. You were OK until I said something in another
thread about Bush being the dim bulb that he is. And then you got
your diapers in a wad and have been answering my posts at every
opportunity with smart-ass responses like this. You are not the God
Head of enlightenment, and you're not even that freaken smart. So go
back to your basement, fire up a log, relax - and quit reading and
responding to my posts. Or go feed the gulls around Lake Superior.
I've worked in electronics and mechanical engineering for almost 30
years, and I don't need to read some neophyte level web site to know
you are an angry, lonely old troll with nothing better to do. I come
here for entertaining conversation, not trolls. But just FYI, I have
an _inkling_ about hysteresis, stall, efficiency, slip, AC phase, ohms
law and many other terms you looked up on the net only yesterday.
I have never done this before, and hope to never do it again (but I
feel there's another one coming up) - Welcome to my killfile.
<PLONK>
Greg G.
Joe Brophy said:
>On Fri, 11 Nov 2005 22:51:58 -0500, Greg G.<[email protected]> wrote:
>>>>>> Creative Marketing.
>>>>>
>>>>>Don't you just _love_ conspiracy theories?
>>>>
>>>> Yes. HP figures for Air Compressors comes to mind...
>
>I thought that a horsepower was 746.04 watts, or there abouts. To my knowledge, (which is
>limited I will agree...) no one has dispelled and proven wrong that relationship. Now if
>you are referring to things like the capacitor laden little motors that HF and others sold
>as 5hp, but only 15amps @220v, just marketing hype I am afraid. HF has ceased selling the
>one that was "rated at" 5hp, it is now their "3hp that we used to sell as 5hp", so someone
>must have threatened with a lawsuit or something. HF is not alone on this, I think there
>were at least 2-3 others doing the same thing, most of them don't even sell them at all
>any more an have only the 5hp motors that are in the 21-23amp range which is in the
>ballpark, just barely. Semantics become some antics just like good old GW, don't matter
>how much power you got if there is a wingnut loose on the steering wheel, or a nut loose
>on the control panel. Got a bad feeling about this one, god bless our young men and women
>who have to live with that harsh reality daily, here is to them, may they come home
>safely. Joe
Briefly (and sloppily...),
HP and Watts are direct measurements of work force.
But with a motor that converts electrical force into mechanical force,
there are other factors to consider. Motor design and efficiency come
to mind. Heat generation, losses from friction (=heat) and other
conversions skew that one to one relationship.
The problem with "Creative Marketing" comes from manufacturer's
attempts to push for higher and higher advertised HP ratings because
they see it as a primary sales and marketing 'talking point' to an
uninformed public. Same as the IHF/RMS/Peak power output ratings which
were bandied about in the early days of audio. So they came up with
stall HP ratings, which are totally meaningless, and are based upon
the stalled rotor current draw of a motor - typically it's peak
current consumption mode. From this they extrapolate the HP ratings
you see on numerous appliances. Particularly things that appeal to
the Tim Allen in all of us. More Power.
These methods of measuring HP ignore usability, real world power
output, and logic in general.
FWIW,
Greg G.