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Posted by Gunner Asch on May 5, 2008, 3:01 pm
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On Mon, 5 May 2008 01:54:46 -0800, "SteveB"
>I have two of the Singer sewing machine foot speed controls. Would these
>work on a drill press? I guess one would just wire them directly to the
>cord. Yes? No? Definitely? Maybe? I bought them, along with two
>barbecue spit motors to someday make a welding positioner. Although my
>latest idea is to make a gas tank tumbler to clean out my welder gas tank
>with some sand and metal nuts and washers.
>
>Steve
No. Most of those foot controls are a variable resistor of some sort
IRRC and will likely burn out in short order under the load of a big
motor.
You need a simple pushbutton switch with something like a pedal to
push down on that switch, and a stop so you dont mash the switch.
A hinge, a switch, some wire, a bit of sheetmetal...
Ebay has a number of them. You really should put a foot guard on it
if you are making up one..an easy project.
I use these as I get them fairly regularly
http://cgi.ebay.com/1-LOT-OF-2-USED-Hercules-Foot-Switch-531-SWH_W0QQitemZ380024466464QQihZ025QQcategoryZ92150QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Or similar ones.
Gunner
Political Correctness is a doctrine fostered by a delusional,
illogical liberal minority, and rabidly promoted by an
unscrupulous mainstream media, which holds forth the
proposition that it is entirely possible to pick up a turd by the clean end.
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Posted by on May 5, 2008, 8:42 pm
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> I have two of the Singer sewing machine foot speed controls. =A0Would thes=
e
> work on a drill press? =A0I guess one would just wire them directly to the=
> cord. =A0Yes? =A0No? =A0Definitely? =A0Maybe? =A0I bought them, along with=
two
> barbecue spit motors to someday make a welding positioner. =A0Although my
> latest idea is to make a gas tank tumbler to clean out my welder gas tank
> with some sand and metal nuts and washers.
>
> Steve
>
> --
> "...the man who really counts in the world is the doer, not the mere
> critic-the man who actually does the work, even if roughly and imperfectly=
,
> not the man who only talks or writes about how it ought to be done."
> Theodore Roosevelt 1891
Sewing machine motors have brushes, all but the tiniest drill presses
use induction motors. You can't control an induction motor's speed by
controlling the voltage, all you can do is burn it out. Sewing
machine speed controls are just resistors, which work with the AC/DC
brush motors on the machines. These motors also draw a lot less
current than a decent drill press' induction motor. You CAN control
induction motor speed to a certain degree with solid state controls
that control the frequency of the applied AC voltage, these cost a lot
more than a variable resistance foot control, though. Search on "VFD"
in the r.c.m. archives on google groups for more info on those. Best
bet is to come up with a combination of pulleys and belts to get your
speed reduction. You CAN make large slow-speed pulleys from plywood,
it's been done with home-made cement mixers. Just don't underestimate
loads when sizing the bearings.
Stan
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Posted by DoN. Nichols on May 6, 2008, 11:43 pm
Please log in for more thread options On 2008-05-05, SteveB <toquerville> wrote:
> I have two of the Singer sewing machine foot speed controls. Would these
> work on a drill press? I guess one would just wire them directly to the
> cord. Yes? No? Definitely? Maybe?
No! Even
# # ###
## # #### ###
# # # # # ###
# # # # # #
# # # # #
# ## # # ###
# # #### ###
if you can read it (proportional space fonts probably will render it
difficult to read, fixed should be fine.
The motors on the Singer sewing machines (e.g. my 221
"Featherweight") are brush equipped universal motors, and will vary
speed with applied current and with load to some extent. These motors
will work with either DC or AC.
The foot speed controls are variable series resistance -- done
by a stack of carbon blocks which get squshed together by the foot
pressure to reduce their resistance and allow more current through to
the motor.
And since there are three pins on the connector from the
controller to the sewing machine, yet only two pins on the power cord
(long before the common grounded outlets), I strongly suspect that the
foot speed controller is varying the current only to one of two places
which get power in a universal motor. Those two pieces are the rotor
(through the brushes and commutator) and the field (stationary magnetic
frame).
Hmm ... the power cord is on those three pins too, so it may be
just to get power to the light on the sewing machine. Skip the idea of
the split rotor and field windings.
Any reasonable sized drill press will have an induction motor --
no brushes, AC only, and their speed is mostly controlled by the power
line frequency (within a narrow range, unless the drill press is large
enough to have a three-phase motor which can be speed controlled by a
VFD.) Your sewing machine foot speed control will at most change the
torque load at which the motor stalls. And given the relaive size of
the sewing machine motor and the drill press motor, it will quite likely
burn up the foot speed controller fairly soon.
Now -- an exception to this is my little Cameron Precision
sensitive drill press, with a fairly small universal motor. This would
probably work with the foot speed control. But -- it works fine on a
little speed control box designed for the Dremel tools from before they
came with speed controllers built in. :-) This keeps me from being
tempted to render my sewing machine useless.
> I bought them, along with two
> barbecue spit motors to someday make a welding positioner.
Do the spit motors have brushes? I thought that they were
AC-only motors, so I don't think that the sewing machine speed
controllers would work with them either.
> Although my
> latest idea is to make a gas tank tumbler to clean out my welder gas tank
> with some sand and metal nuts and washers.
Again -- make sure that the spit motors are brush type if you
want to control the speed.
Good Luck,
DoN.
--
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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Posted by on May 7, 2008, 12:22 pm
Please log in for more thread options <SNIP>
>
>> I bought them, along with two
>> barbecue spit motors to someday make a welding positioner.
>
> Do the spit motors have brushes? I thought that they were
>AC-only motors, so I don't think that the sewing machine speed
>controllers would work with them either.
>
>> Although my
>> latest idea is to make a gas tank tumbler to clean out my welder gas tank
>> with some sand and metal nuts and washers.
>
> Again -- make sure that the spit motors are brush type if you
>want to control the speed.
>
> Good Luck,
> DoN.
>
>--
Unlike the typical induction motor found on a machine tool a shaded
pole motor can be controlled for speed by varying the voltage. It will
slip more with the same load applied and so slows down. But if the
load is not constant the speed will not be constant. A fan will apply
a constant load at a particular rpm. So the speed control will be
good. If you set the speed on your weld positioner and then rub
against the rotating parts it will slow down. Shaded pole motors are
also not very efficient devices. One big advantage though is that they
will not draw excessive current when stalled. Which means they will
not smoke like your drill press motor would if it was stalled.
ERS
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Posted by Don Foreman on May 7, 2008, 3:48 pm
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>
> The motors on the Singer sewing machines (e.g. my 221
>"Featherweight") are brush equipped universal motors, and will vary
>speed with applied current and with load to some extent. These motors
>will work with either DC or AC.
>
> The foot speed controls are variable series resistance -- done
>by a stack of carbon blocks which get squshed together by the foot
>pressure to reduce their resistance and allow more current through to
>the motor.
>
You might find this of interest, DoN:
http://users.goldengate.net/~dforeman/footpedal/
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>work on a drill press? I guess one would just wire them directly to the
>cord. Yes? No? Definitely? Maybe? I bought them, along with two
>barbecue spit motors to someday make a welding positioner. Although my
>latest idea is to make a gas tank tumbler to clean out my welder gas tank
>with some sand and metal nuts and washers.
>
>Steve