Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old February 17th 06, 05:56 AM posted to alt.machines.cnc,rec.crafts.metalworking
Proctologically Violated©®
 
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Default Do VFD's make pulleys obsolete?

ergo the distinction between variable speed/stepped pulleys moot (at least
w/ 3 ph motors)?

One thing is for su VFD is lot more expensive than stepped pulleys!
But mebbe the way to go, if there are no other disadvantages.
--
Mr. P.V.'d
formerly Droll Troll



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Old February 17th 06, 06:50 AM posted to alt.machines.cnc,rec.crafts.metalworking
William B Noble (don't reply to this address)
 
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Default Do VFD's make pulleys obsolete?

pulleys also affect torque - sllowing a motor down with a VFD does not
amplify torque, using a pulley to do so does amplify torque
proportionately. you need both.

On Thu, 16 Feb 2006 23:56:28 -0500, "Proctologically Violated©®"
wrote:

ergo the distinction between variable speed/stepped pulleys moot (at least
w/ 3 ph motors)?

One thing is for su VFD is lot more expensive than stepped pulleys!
But mebbe the way to go, if there are no other disadvantages.

Bill

www.wbnoble.com

to contact me, do not reply to this message,
instead correct this address and use it

will iam_ b_ No ble at msn daught com
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Old February 17th 06, 07:12 PM posted to alt.machines.cnc,rec.crafts.metalworking
Jim Stewart
 
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Default Do VFD's make pulleys obsolete?

Proctologically Violated©® wrote:
ergo the distinction between variable speed/stepped pulleys moot (at least
w/ 3 ph motors)?

One thing is for su VFD is lot more expensive than stepped pulleys!
But mebbe the way to go, if there are no other disadvantages.


Depends totally on how much power your
cutter needs. I have a 1hp VFD and motor
with a stepped pulley and I go for weeks
without moving the pulley. I do mostly
AL and small cuts.

If you do lots of steel with big cutters,
then you need to 'downshift'.


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Old February 17th 06, 08:32 PM posted to alt.machines.cnc,rec.crafts.metalworking
Proctologically Violated©®
 
Posts: n/a
Default Do VFD's make pulleys obsolete?

Would you recommend a stepped pulley system in conjuction w/ VFD over a
trad'l split pulley/variable speed drive system for most situations?
--
Mr. P.V.'d
formerly Droll Troll
"Jim Stewart" wrote in message
...
Proctologically Violated©® wrote:
ergo the distinction between variable speed/stepped pulleys moot (at
least w/ 3 ph motors)?

One thing is for su VFD is lot more expensive than stepped pulleys!

But mebbe the way to go, if there are no other disadvantages.


Depends totally on how much power your
cutter needs. I have a 1hp VFD and motor
with a stepped pulley and I go for weeks
without moving the pulley. I do mostly
AL and small cuts.

If you do lots of steel with big cutters,
then you need to 'downshift'.




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Old February 17th 06, 09:45 PM posted to alt.machines.cnc,rec.crafts.metalworking
Jim Stewart
 
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Default Do VFD's make pulleys obsolete?

Proctologically Violated©® wrote:
Would you recommend a stepped pulley system in conjuction w/ VFD over a
trad'l split pulley/variable speed drive system for most situations?


I've been told by a machinist I trusted that
the vari-speed heads are more trouble than
they are worth. I'm sure we'll hear from
everyone that has had a vari-speed for 30 years
and no problems, but I'd stick with a stepped
pulley and VFD.


Mr. P.V.'d
formerly Droll Troll
"Jim Stewart" wrote in message
...

Proctologically Violated©® wrote:

ergo the distinction between variable speed/stepped pulleys moot (at
least w/ 3 ph motors)?

One thing is for su VFD is lot more expensive than stepped pulleys!

But mebbe the way to go, if there are no other disadvantages.


Depends totally on how much power your
cutter needs. I have a 1hp VFD and motor
with a stepped pulley and I go for weeks
without moving the pulley. I do mostly
AL and small cuts.

If you do lots of steel with big cutters,
then you need to 'downshift'.







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Old February 18th 06, 12:00 AM posted to alt.machines.cnc,rec.crafts.metalworking
SAMMM
 
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Default Do VFD's make pulleys obsolete?

keep in mind that the torque of the motor is pretty well fixed and
at speeds below it's normal rated speed, it may overheat, and may not have
enough
torque to do the job it's requested to do.
this is when the pulleys come into use.
for light duty you CAN run in a high gear and run the motor at a low rpm but
the motor speed times the torque is what determines the real horsepower.
i use VFDs from automationdirect.com for relatively small stuff.
they're cheap and good, and you can run small stuff from single phase mains.
sammm

--

"Proctologically Violated©®" wrote in message
...
ergo the distinction between variable speed/stepped pulleys moot (at least
w/ 3 ph motors)?

One thing is for su VFD is lot more expensive than stepped pulleys!
But mebbe the way to go, if there are no other disadvantages.
--
Mr. P.V.'d
formerly Droll Troll



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Old February 18th 06, 12:04 AM posted to alt.machines.cnc,rec.crafts.metalworking
Polymer Man
 
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Default Do VFD's make pulleys obsolete?

I've been told by a machinist I trusted that
the vari-speed heads are more trouble than
they are worth. I'm sure we'll hear from
everyone that has had a vari-speed for 30 years
and no problems, but I'd stick with a stepped
pulley and VFD.





One of my mills has a vari-speed head on it. And I hate it. It needed a
rebuild with less than 2000 hours on it. Though it is rated at over
7000 RPM, anything over 3000 sounds pretty bad.


I'd stick with a stepped
pulley and VFD.


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Old February 18th 06, 02:20 AM posted to alt.machines.cnc,rec.crafts.metalworking
john
 
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Default Do VFD's make pulleys obsolete?



Jim Stewart wrote:
Proctologically Violated©® wrote:

Would you recommend a stepped pulley system in conjuction w/ VFD over
a trad'l split pulley/variable speed drive system for most situations?



I've been told by a machinist I trusted that
the vari-speed heads are more trouble than
they are worth. I'm sure we'll hear from
everyone that has had a vari-speed for 30 years
and no problems, but I'd stick with a stepped
pulley and VFD.


Mr. P.V.'d
formerly Droll Troll
"Jim Stewart" wrote in message
...

Proctologically Violated©® wrote:

ergo the distinction between variable speed/stepped pulleys moot (at
least w/ 3 ph motors)?

One thing is for su VFD is lot more expensive than stepped
pulleys!
But mebbe the way to go, if there are no other disadvantages.


Depends totally on how much power your
cutter needs. I have a 1hp VFD and motor
with a stepped pulley and I go for weeks
without moving the pulley. I do mostly
AL and small cuts.

If you do lots of steel with big cutters,
then you need to 'downshift'.







He probably never read the directions. "adjust speed only while spindle
is running"




John

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Old February 18th 06, 07:26 AM posted to alt.machines.cnc,rec.crafts.metalworking
William B Noble (don't reply to this address)
 
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Default Do VFD's make pulleys obsolete?

absolutely - the reeves drive is much noiser than a pulley (I have a
reeves drive on my metal lathe, don't like it given that I also have a
VFD), and you have no need for a phase converter since the VFD does
that for you, and it also will start/stop smoothly, saving wear and
tear on machinery and also reducing loading on your electrical system
- AND, it will protect the motor from overcurrent, etc. If you are
going to run the motor slow (say 100 RPM) for a long time, you will
want to add a muffin fan to cool it - I do this with my wood lathe - I
set the motor to turn at maybe 5 RPM to dry stuff that I've just
lacquered so I don't get any runs - the motor can run this way for a
long time without overheating with a 5 inch muffin fan blowing air
through it, but without the fan, even with minimal load, it gets
pretty hot since the motor's own fan doesn't do anything at low RPM.

hope this helps.

(oh, my mill has a 20something speed gear box so I don't use a VFD on
it, just a capacitor (aka static converter) to get it started)


On Fri, 17 Feb 2006 14:32:31 -0500, "Proctologically Violated©®"
wrote:

Would you recommend a stepped pulley system in conjuction w/ VFD over a
trad'l split pulley/variable speed drive system for most situations?

Bill

www.wbnoble.com

to contact me, do not reply to this message,
instead correct this address and use it

will iam_ b_ No ble at msn daught com
*** Free account sponsored by SecureIX.com ***
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Old February 18th 06, 08:00 AM posted to alt.machines.cnc,rec.crafts.metalworking
Gunner
 
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Default Do VFD's make pulleys obsolete?

On Thu, 16 Feb 2006 23:56:28 -0500, "Proctologically Violated©®"
wrote:

ergo the distinction between variable speed/stepped pulleys moot (at least
w/ 3 ph motors)?

One thing is for su VFD is lot more expensive than stepped pulleys!
But mebbe the way to go, if there are no other disadvantages.


The only issue you have with VFDs..is lower torque at low rpms..and
possible heating issues if you are turning the motor too slow for the
internal fan to move much air. Which can be solved by adding a simple
muffin fan at the fan end of the motor.

Check Ebay for VFDs.


My Gorton Master Mill (step pully) is controlled by a Yuskawa PC-3
VFD. The belt is set on the middle pully and the VFD does all the
work, from dynamic braking (1 second stop from 5000 rpm) to virtually
instantanious reversing for tapping.

My nice big Rockwell drill press has an older Emerson VFD, which gives
me universal speed control

My little Kitakura second ops lathe (4C collet) is run by a Hitachi
1/2hp vfd, with universal speeds, instant reverse etc

I dont think Ive got $100 in any of the drives.

Gunner



"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3


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