Foredom foot pedal

On , in õ "C Ryman" wrote:

I got the pedal apart this morning and it's not a carbon pile. It has some
electronics with a twisted strip of metal going into the chip board and a
regular spring for the pedal.
I cleaned it a little with air and put it back together and it is still very
balky. When it does manage to turn the motor it causes the motor or shaft
to shriek.

Connie, if it runs the motor at all, then at least the driver componants, transistors,
SCRs, etc, are not burned out. Quite possibly, what has happened is similar to what can
happen to audio controls on older radios, etc, where turning a volume or balance (etc)
control results in uneven changes and often a lot of noise. It's caused by oxidation
and corrosion on the contact surfaces of either rotary or sliding rheostats, or similar
variable resistance controls. While you usually cannot practically disassemble the
actual control and effectively clean it or restore it, you CAN obtain, from shops like
Radio Shack or more serious TV/radio/electronics places, spray cans of contact cleaner.
These things sometimes can improve such situations, though generally they won't fully
fix it like new. But in general, the simple electronic speed controls like that are
rather simply and cheaply made, and often just not worth the bother to try and fix. You
might contact Fordom and ask what they'd charge you for a new module to instal in your
pedal. But the Lucas is still by far the better way to go.

I AM a bit puzzled by your description of the motor making a shrieking sound. That
might be the pedal, I don't know, but it makes me wonder about the health of the motor
too. Make sure the motor turns easily on it's bearings, and when just plugged in, runs
nicely without undue or unusual noises. It used to be that a CC model fordom could be
relied on to give you a good decade of daily frequent usage, and need several new
shieths and shafts and brushes and perhaps pedals too, before the motor gave up the
ghost. The last ten or fifteen years, maybe more, they've just not been made that well
any more. More plastic parts, less solid construction, or something. In our shop, we
seem to get around 3-4 years out of the cheaper fordoms. It's one reason we now buy the
rioflex or ottoflex machines, rather than fordoms. Those are, if I recall, made by
Buffalo Dental company, and seem a good deal longer lasting than Fordoms.

Now the motor might be making funny sounds if the control is giving it a higher
frequency on/off signal, so the motor might be chattering or something, but again, that
doesn't sound like something I've seen due to a bad pedal. So before sinking a lot into
the pedal, make sure the motor is OK. You might want to see about trying to borrow a
good pedal from someone to test the motor.

Peter

C Ryman wrote:
I got the pedal apart this morning and it's not a carbon pile. It has some
electronics with a twisted strip of metal going into the chip board and a
regular spring for the pedal.
I cleaned it a little with air and put it back together and it is still very
balky. When it does manage to turn the motor it causes the motor or shaft
to shriek.


Aha, ... ze shrieking motor zyndrome!

Zis meanz, zer iz zomzing kaput wiz ze motor!

Abrasha
http://www.abrasha.com