I have a new General 650, a very nice saw. While I'm sure it was set up
perfectly at the factory, I had to remove the motor to get it into my
ground level basement.
I put the motor back on, and set it so the drive pulley's are square to
each other and inline. When I push on the belts in the centre, they go
in about 0.75".
The saw runs with just a whistle from the blade and no vibration.
However when the 3HP motor first starts, there is a fairly loud 'whump'
sound and then it immediately spins up to speed. The motor is 220V on a
40A circuit.
Strangely enough, if the motor has *just* stopped and I restart it,
there is no whump.
I know that motors draw high current when they start up so I expect some
'kick' but is this normal? Is there some way to soften the startup with
a capacitor say?
Rob
In article <[email protected]>,
Mike Marlow <[email protected]> wrote:
>
>"Edwin Pawlowski" <[email protected]> wrote in message
>news:[email protected]...
>>
>> "Rob Mitchell" <[email protected]> wrote in message
>> >
>> > Strangely enough, if the motor has *just* stopped and I restart it,
>there
>> > is no whump.
>> >
>>
>> That's because of the check valve in the whump circuit. The saw has to be
>> shut down for a while for the reservoir to refill with more whump. A
>> whumpless start is OK as long as the whooosh did not drain down, a rare
>> occurrence.
>>
>>
>
>This is only true with the economy whump circuit check valves, and it's
>because they employ a simple one way valve. Better designs typically employ
>a feedback circuit that modulates in direct proportion to the remaing
>coeffiecient of the inverse propogator and resolves the issues of a large
>delta between the static whump value and the anticipated whoosh values as
>determined by the rotational latency divided by the height of the blade.
>
But *that* one is an option only if you have the 3ph motor installed.
I've never looked at a cabinet saw too closely. But on my contractor's
saw, the motor pivots on a hinge and the weight of the motor tensions
the belt (I think this is pretty standard). Anyhoo, when I first turn
the saw on the torque and stretch of the belt cause the motor to jump a
bit. Is that the whoomp you're hearing? I wired my motor for 220. I
don't have those fancy three-belt pullys and it'll chirp the belt when
I have 3/4" of stacked dado on the arbor. :)
"Swingman" <[email protected]> wrote in message
news:[email protected]...
> "Mark Howell" wrote in message
>
> My Unisaw does the same thing. The startup thump is not uncommon on higher
> powered saws ... I recall hearing that distinctive sound back in woodshop
> some 40 years ago. This is not something to worry about, or go to extra
> expense to "cure", IME.
I remember back in the late 70's when I had gone to work for an Olds dealer
in Corpus Christi the guys sent me up to turn on Bertha. I knew something
was up, no Bertha was not a woman, Bertha was "The COMPRESSOR". This thing
must have been a 5 or 6 hundred gallon monster with a 20 hp motor. The tank
was about 4' tall laying down and 7 or 8' long and the compressor was in a
rather confined low ceiling room above the parts department. Just before I
grabbed the lever on the electrical box I noticed 2 ropes tied to the lever
going down through a hole in the floor and down to the parts department
below. I grabbed the lever and pushed it up. With a loud explosion
sound the monster started up and as I got back up off the floor I checked my
pants for a deposit. When I came back down stairs a crowd was gathered to
see the expression on my face and they then indicated that the ropes on the
lever were used to turn the compressor on from down stairs.
Rob Mitchell wrote:
>
> I have a new General 650, a very nice saw. While I'm sure it was set up
> perfectly at the factory, I had to remove the motor to get it into my
> ground level basement.
>
> I put the motor back on, and set it so the drive pulley's are square to
> each other and inline. When I push on the belts in the centre, they go
> in about 0.75".
That, of course, depends on how hard you push... :)
Sounds like the belts may be a little loose to me. My PM 66 has never
made any unusual noise on starting that I recall from the beginning...5
hp/3-grooved matched belts.
i have a one year old 650, but with a 5 HP motor. i get the same whump.
no worries. runs smooth, whump is normal. great saw.
just out of curiosity, how flat is your table top?
enjoy.
--- dz
Rob Mitchell wrote:
> I have a new General 650, a very nice saw. While I'm sure it was set up
> perfectly at the factory, I had to remove the motor to get it into my
> ground level basement.
>
> I put the motor back on, and set it so the drive pulley's are square to
> each other and inline. When I push on the belts in the centre, they go
> in about 0.75".
>
> The saw runs with just a whistle from the blade and no vibration.
> However when the 3HP motor first starts, there is a fairly loud 'whump'
> sound and then it immediately spins up to speed. The motor is 220V on a
> 40A circuit.
>
> Strangely enough, if the motor has *just* stopped and I restart it,
> there is no whump.
>
> I know that motors draw high current when they start up so I expect some
> 'kick' but is this normal? Is there some way to soften the startup with
> a capacitor say?
>
> Rob
>
<[email protected]> wrote in message
news:[email protected]...
> I've never looked at a cabinet saw too closely. But on my contractor's
> saw, the motor pivots on a hinge and the weight of the motor tensions
> the belt (I think this is pretty standard). Anyhoo, when I first turn
> the saw on the torque and stretch of the belt cause the motor to jump a
> bit. Is that the whoomp you're hearing? I wired my motor for 220. I
> don't have those fancy three-belt pullys and it'll chirp the belt when
> I have 3/4" of stacked dado on the arbor. :)
>
Different animal.
On Wed, 02 Feb 2005 02:34:19 GMT, david zaret
<news@__REMOVE__.zaret.com> vaguely proposed a theory
......and in reply I say!:
remove ns from my header address to reply via email
>i have a one year old 650, but with a 5 HP motor. i get the same whump.
> no worries. runs smooth, whump is normal. great saw.
>
>just out of curiosity, how flat is your table top?
>
>enjoy.
It's got a ruddy great whump in the middle............
"Edwin Pawlowski" <[email protected]> wrote in message
news:[email protected]...
>
> "Rob Mitchell" <[email protected]> wrote in message
> >
> > Strangely enough, if the motor has *just* stopped and I restart it,
there
> > is no whump.
> >
>
> That's because of the check valve in the whump circuit. The saw has to be
> shut down for a while for the reservoir to refill with more whump. A
> whumpless start is OK as long as the whooosh did not drain down, a rare
> occurrence.
>
>
This is only true with the economy whump circuit check valves, and it's
because they employ a simple one way valve. Better designs typically employ
a feedback circuit that modulates in direct proportion to the remaing
coeffiecient of the inverse propogator and resolves the issues of a large
delta between the static whump value and the anticipated whoosh values as
determined by the rotational latency divided by the height of the blade.
--
-Mike-
[email protected]
"Mark Howell" wrote in message
>
> "Rob Mitchell" wrote in message
> > Strangely enough, if the motor has *just* stopped and I restart it,
> > there is no whump.
> >
> > I know that motors draw high current when they start up so I expect some
> > 'kick' but is this normal? Is there some way to soften the startup with
> > a capacitor say?
> >
> > Rob
> >
>
> I noticed alot less 'whump' after I replaced the belts with link belts.
I have always been of the opinion that you don't really need link belts on a
high quality cabinet saw ... the General 650 should certainly qualify in
that regard.
My Unisaw does the same thing. The startup thump is not uncommon on higher
powered saws ... I recall hearing that distinctive sound back in woodshop
some 40 years ago. This is not something to worry about, or go to extra
expense to "cure", IME.
--
www.e-woodshop.net
Last update: 11/06/04
Robert Bonomi wrote:
> In article <[email protected]>,
> Mike Marlow <[email protected]> wrote:
>
>>"Edwin Pawlowski" <[email protected]> wrote in message
>>news:[email protected]...
>>
>>>"Rob Mitchell" <[email protected]> wrote in message
>>>
>>>>Strangely enough, if the motor has *just* stopped and I restart it,
>>
>>there
>>
>>>>is no whump.
>>>>
>>>
>>>That's because of the check valve in the whump circuit. The saw has to be
>>>shut down for a while for the reservoir to refill with more whump. A
>>>whumpless start is OK as long as the whooosh did not drain down, a rare
>>>occurrence.
>>>
>>>
>>
>>This is only true with the economy whump circuit check valves, and it's
>>because they employ a simple one way valve. Better designs typically employ
>>a feedback circuit that modulates in direct proportion to the remaing
>>coeffiecient of the inverse propogator and resolves the issues of a large
>>delta between the static whump value and the anticipated whoosh values as
>>determined by the rotational latency divided by the height of the blade.
>>
>
>
> But *that* one is an option only if you have the 3ph motor installed.
>
>
Guys, I'm in Canada. Whump is a proper SI unit of measure.
milliwhump, centiwhump, deciwhump, WHUMP, decawhump...
"Swingman" <[email protected]> wrote in message
news:[email protected]...
> "Mark Howell" wrote in message
> >
> > "Rob Mitchell" wrote in message
> > > Strangely enough, if the motor has *just* stopped and I restart it,
> > > there is no whump.
> > >
> > > I know that motors draw high current when they start up so I expect
some
> > > 'kick' but is this normal? Is there some way to soften the startup
with
> > > a capacitor say?
> > >
> > > Rob
> > >
> >
> > I noticed alot less 'whump' after I replaced the belts with link belts.
>
> I have always been of the opinion that you don't really need link belts on
a
> high quality cabinet saw ... the General 650 should certainly qualify in
> that regard.
>
I replaced the belts not to reduce the startup jolt, but rather to reduce
vibration.
> My Unisaw does the same thing. The startup thump is not uncommon on higher
> powered saws ... I recall hearing that distinctive sound back in woodshop
> some 40 years ago. This is not something to worry about, or go to extra
> expense to "cure", IME.
>
I agree, it's more of an annoyance than a problem...
> --
> www.e-woodshop.net
> Last update: 11/06/04
>
>
"Rob Mitchell" <[email protected]> wrote in message
news:[email protected]...
>I have a new General 650, a very nice saw. While I'm sure it was set up
>perfectly at the factory, I had to remove the motor to get it into my
>ground level basement.
Oddly this is normal. Norm's TS on TOH does it. Mine does it and most
every one with a Cabinet saw with 3 V-belts sees this happen. Basically
you have plenty of power available to the motor and it starts INSTANTLY.
Jet and I tried to remedy this on my TS and they sent me a new motor. I
started the new motor prior to mounting to be sure that it turned in the
correct direction and noticed that this thing does not wind up so to speak
like the smaller 110 volt models. When I flipped the switch the motor was
instantly up to speed. With than in mind, starting the belts and blade from
a dead stop to instantly on, makes noise. You may notice that as you use
the saw during a typical sawing operation and the belts warm up that the
Bang will start to subside until the belts cool off. I do not know if the
remedy is to loosen the belts or make them tighter. I believe loosening
them will help. Many use link belts to eliminate or help eliminate the
problem. Seems to me that the link belts would fit some what looser how
ever I could be wrong.
"Rob Mitchell" <[email protected]> wrote in message
news:[email protected]...
> I have a new General 650, a very nice saw. While I'm sure it was set up
> perfectly at the factory, I had to remove the motor to get it into my
> ground level basement.
>
> I put the motor back on, and set it so the drive pulley's are square to
> each other and inline. When I push on the belts in the centre, they go
> in about 0.75".
>
> The saw runs with just a whistle from the blade and no vibration.
> However when the 3HP motor first starts, there is a fairly loud 'whump'
> sound and then it immediately spins up to speed. The motor is 220V on a
> 40A circuit.
>
> Strangely enough, if the motor has *just* stopped and I restart it,
> there is no whump.
>
> I know that motors draw high current when they start up so I expect some
> 'kick' but is this normal? Is there some way to soften the startup with
> a capacitor say?
>
> Rob
>
I noticed alot less 'whump' after I replaced the belts with link belts.
david zaret wrote:
> i have a one year old 650, but with a 5 HP motor. i get the same whump.
> no worries. runs smooth, whump is normal. great saw.
>
> just out of curiosity, how flat is your table top?
>
Well, I wouldn't be able to measure it to any precision, but when I
looked at light glaring off of it, there were no noticable undulations.
The top was a thing of beauty, and probably the biggest reason that I
bought the General over an import 'King' that I was considering. The
King table was already rusting on the edge.
Why, did you have a problem? My General had a hidden wiring problem
which I discovered when I removed the motor.
"Rob Mitchell" <[email protected]> wrote in message
>
> Strangely enough, if the motor has *just* stopped and I restart it, there
> is no whump.
>
That's because of the check valve in the whump circuit. The saw has to be
shut down for a while for the reservoir to refill with more whump. A
whumpless start is OK as long as the whooosh did not drain down, a rare
occurrence.