Very Computer

A two part question for those who may be able to help.

1.  Any tips on the best way to remove gears from small (size 16-23)
stepper motors.  They appear to be brass & pressed onto the shaft but
heating them up slightly did not help.

2.  Can anyone help me ID a stepper motor.  It is an astrosyn stepper
taken from a Epson printer.  The model is 17PM K 303 PIL.  It has five
wires which has me confused.  The resistance between a set of four wires
is approx 3.1 ohms.  Each wire measures 5.1 ohms to one common wire (red
stripe in ribbon cable wire). Hmmm.  Based on this it is not a 5 phase
motor from what I read so I wonder what it is.

Thank you for your help.

Quote:> A two part question for those who may be able to help.

> 1.  Any tips on the best way to remove gears from small (size 16-23)
> stepper motors.  They appear to be brass & pressed onto the shaft but
> heating them up slightly did not help.

> 2.  Can anyone help me ID a stepper motor.  It is an astrosyn stepper
> taken from a Epson printer.  The model is 17PM K 303 PIL.  It has five
> wires which has me confused.  The resistance between a set of four wires
> is approx 3.1 ohms.  Each wire measures 5.1 ohms to one common wire (red
> stripe in ribbon cable wire). Hmmm.  Based on this it is not a 5 phase
> motor from what I read so I wonder what it is.

Google search for Astrosyn leads to www.astrosyn.com... after clicking on
"Stepper" a rather nice page comes up with plenty of links... Have a good
look round - I'm sure you'll find what you're looking for.

Later.
--
Phil.

http://www.philpem.f9.co.uk/

An arbor press would be my choice.  Put a plate with a slot under the
gear (if there's clearance) then use a steel rod (punch) to press on the
end of the shaft.  If no clearance you can file the gear away on two
sides and lift the remains off. It could be brazed, soldered, or epoxied
to the shaft.  Dont just pull on the gear as it's likely to ruin the
bearings.

Quote:

> 2.  Can anyone help me ID a stepper motor.  It is an astrosyn stepper
> taken from a Epson printer.  The model is 17PM K 303 PIL.  It has five
> wires which has me confused.  The resistance between a set of four wires
> is approx 3.1 ohms.  Each wire measures 5.1 ohms to one common wire (red
> stripe in ribbon cable wire). Hmmm.  Based on this it is not a 5 phase
> motor from what I read so I wonder what it is.

From your resistance measurements I'd guess it's a normal 2 phase
stepper with the two centertaps tied common plus an ~3.5 ohm resistor in
series with the centertap to improve the speed performance.  That might
be done to use the motor body as a heatsink.   Looking at the original
driver and how it was wired should tell you if that's the case.

--
Lou Boyd

I am assuming you want to remove the gear and not use it again:

1. Cut throught the gear with a small cutting wheel i.e. Dremel tool.  Once
enough material is cut the press fit should relax enough for you to remove
the gear.

2. Grind a "flat spot" on the gear with a Dremel tool/file/grinder until you
get the same effect as above.  You can grind right down to the shaft if
necessary and the gear will slide off.

George Powell

Quote:> A two part question for those who may be able to help.

> 1.  Any tips on the best way to remove gears from small (size 16-23)
> stepper motors.  They appear to be brass & pressed onto the shaft but
> heating them up slightly did not help.

My local Home Depot rents tools, and I recall they rent a small
gear-puller. Maybe you have a Home Depot or other similar near you that
rents tools. Or, you could befrind some auto mechanic. They have gear
pullers.

Quote:> 2.  Can anyone help me ID a stepper motor.  It is an astrosyn stepper
> taken from a Epson printer.  The model is 17PM K 303 PIL.  It has five
> wires which has me confused.  The resistance between a set of four wires
> is approx 3.1 ohms.  Each wire measures 5.1 ohms to one common wire (red
> stripe in ribbon cable wire). Hmmm.  Based on this it is not a 5 phase
> motor from what I read so I wonder what it is.

One wire is common; the other four are the windings to the motors. As
such, all the wires will show some resistance across one another. To
test, nominate a wire as the common, and test the other four. Try this
again for the remaining possibilities. The set that shows equal and
lowest resistance should be the correct one. To determine the stepping
sequence for the four coils of the motor, do some trial-and-error
experimentation.

I imagine this is an ordinary four-coil two phase unipolar. Cheap to
make, which is about right for a later-model printer.

-- Gordon
Robot Builder's Bonanza, Second Edition
http://www.robotoid.com/