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Old Aug 23, 2004, 06:11 AM
Steve
Guest
n/a Posts
CNC Home Build Again

In terms of positional feedback for X-Y, it occurs to me that a) Inkjet
printers get thrown out when the ink runs out and b)they have a high
precision gray code(or similar) band for precise head positioning. Might be
worth salvaging when the opportunity arises?

Steve



Old Aug 23, 2004, 06:11 AM
Peter Fairbrother
Guest
n/a Posts
Re: CNC Home Build Again

Steve wrote:

> In terms of positional feedback for X-Y, it occurs to me that a) Inkjet
> printers get thrown out when the ink runs out and b)they have a high
> precision gray code(or similar) band for precise head positioning. Might be
> worth salvaging when the opportunity arises?
>
> Steve


Sadly, no.

Typically inkjets only have one positional reference point, a microswitch at
the right hand edge of the carriage's travel. Sometimes they have an optical
or microswitch leading -edge -of -the -paper detector too. There are usually
no other positional encoders.

The rest is done with two stepper motors, one to control the sideways
movement of the carriage, one to control the up-and-down movement of the
paper.

They don't ususally use ball/leadscrews either. Toothed belts on a cog
rotated by one of the steppers controls the sideways motion, and a paper
roller controls the up/down motion.



They're ok for used cheap low-power steppers though, but you can buy them
new for a few pounds each, and if you buy them they will match and have
known performance (the two steppers in one inkjet are usually different).

Used scanners tend to have slightly more interesting bits, but again they
will have no grey-type encoders.


--
Peter Fairbrother

Old Aug 23, 2004, 06:11 AM
Steve
Guest
n/a Posts
Re: CNC Home Build Again


"Peter Fairbrother" <zenadsl6186@zen.co.uk> wrote in message
news:BD4F807C.5C584%zenadsl6186@zen.co.uk...
> Steve wrote:
>
> > In terms of positional feedback for X-Y, it occurs to me that a)

Inkjet
> > printers get thrown out when the ink runs out and b)they have a high
> > precision gray code(or similar) band for precise head positioning.

Might be
> > worth salvaging when the opportunity arises?
> >
> > Steve

>
> Sadly, no.
>
> Typically inkjets only have one positional reference point, a microswitch

at
> the right hand edge of the carriage's travel.


The reason I mentioned it was because the last "90" HP Inkjet I had did
have an optical "gray code" strip, it looked like a long loop of 16mm film
(without the sprocket holes!) the width of the carriage. The printer failed
because this strip had a dollop of gunk on it, causing the printer to lose
correct position. Having resolved this I donated it to the local school.

How can I tell determine stepper type when looking for salvage?

Steve


Old Aug 23, 2004, 04:11 PM
Bob Minchin
Guest
n/a Posts
Re: CNC Home Build Again


Steve wrote in message <2otrqfFea9lcU1@uni-berlin.de>...
>In terms of positional feedback for X-Y, it occurs to me that a) Inkjet
>printers get thrown out when the ink runs out and b)they have a high
>precision gray code(or similar) band for precise head positioning. Might

be
>worth salvaging when the opportunity arises?
>
>Steve
>
>
>


I guess as most inkjet printers are colour now they won't be able to use
Gray code?

Sorry about that - i'll get my coat and go now

Bob


Old Aug 23, 2004, 04:11 PM
Peter Fairbrother
Guest
n/a Posts
Re: CNC Home Build Again

Steve wrote:

> The reason I mentioned it was because the last "90" HP Inkjet I had did
> have an optical "gray code" strip, it looked like a long loop of 16mm film
> (without the sprocket holes!) the width of the carriage. The printer failed
> because this strip had a dollop of gunk on it, causing the printer to lose
> correct position. Having resolved this I donated it to the local school.


What's a "90" printer? A cheap inkjet costs 30 these days.

I haven't much experience with HP, mostly Epson, but I haven't seen one of
those in an inkjet printer before.



> How can I tell determine stepper type when looking for salvage?


Count the wires, and measure the resistance between them. Very occasionally
the case is also connected, best to check that too.

http://www.cs.uiowa.edu/~jones/step/ is a bit old but is still a good online
reference to stepper motors, and will give details of the wirings of the
different types. Most of the ones I have come across in printers are
bipolar.

Assume that any stepper fram a printer will take less than 500 mA. They will
most likely be either 5V or 12V, you have to take the size and weight and
resistance together to guess which - or just try it, and see if it gets hot.

Steppers from printers are not high power or high torque. They will operate
a X-Y -(Z) for a Dremel (just) or a film or foam cutter, but no more.


--
Peter Fairbrother

Old Aug 23, 2004, 04:11 PM
Tim Auton
Guest
n/a Posts
Re: CNC Home Build Again

"Bob Minchin" <bob.minchin@OEnewsreader.com> wrote:
[snip]
>I guess as most inkjet printers are colour now they won't be able to use
>Gray code?
>
>Sorry about that - i'll get my coat and go now


Would you mind awfully waiting a moment while I beat you senseless
with this Ikea boingy armchair thing?


Tim
--
Google is not the only search engine.
Old Aug 23, 2004, 06:11 PM
Steven Crook
Guest
n/a Posts
Re: CNC Home Build Again

Peter Fairbrother wrote:

> Steve wrote:
> =20
>=20
>>The reason I mentioned it was because the last "=A390" HP Inkjet I had =

did
>>have an optical "gray code" strip, it looked like a long loop of 16mm =

film
>>(without the sprocket holes!) the width of the carriage. The printer f=

ailed
>>because this strip had a dollop of gunk on it, causing the printer to =

lose
>>correct position. Having resolved this I donated it to the local schoo=

l.
>>

>=20
> What's a "=A390" printer? A cheap inkjet costs =A330 these days.
>=20
> I haven't much experience with HP, mostly Epson, but I haven't seen one=

of
> those in an inkjet printer before.
>=20
>=20
>=20
>=20
>>How can I tell determine stepper type when looking for salvage?
>>

>=20
> Count the wires, and measure the resistance between them. Very occasion=

ally
> the case is also connected, best to check that too.
>=20
> http://www.cs.uiowa.edu/~jones/step/ is a bit old but is still a good o=

nline
> reference to stepper motors, and will give details of the wirings of th=

e
> different types. Most of the ones I have come across in printers are
> bipolar.
>=20
> Assume that any stepper fram a printer will take less than 500 mA. They=

will
> most likely be either 5V or 12V, you have to take the size and weight a=

nd
> resistance together to guess which - or just try it, and see if it gets=

hot.
>=20
> Steppers from printers are not high power or high torque. They will ope=

rate
> a X-Y -(Z) for a Dremel (just) or a film or foam cutter, but no more.
>=20


I have built a foam cutter with motors from Epson dot matrix=20
printers. The source was a pile of 80 column printers en=20
route to the skip. The 132 column printers have bigger=20
steppers and would doubtless do a mini CNC setup. I=20
couldn't get 4 of these though. As for inkjets the print=20
head and paper feed motors are different.

Discussion and software for foam wings....

http://groups.yahoo.com/group/CNCFoamcutters
http://gm.cnc.free.fr/index_en.html

Regards,

Steve
Salisbury

Old Aug 25, 2004, 10:11 PM
Peter Fairbrother
Guest
n/a Posts
Re: CNC Home Build Again

Peter Fairbrother wrote:

> Steve wrote:
>
>> The reason I mentioned it was because the last "90" HP Inkjet I had did
>> have an optical "gray code" strip, it looked like a long loop of 16mm film
>> (without the sprocket holes!) the width of the carriage. The printer failed
>> because this strip had a dollop of gunk on it, causing the printer to lose
>> correct position. Having resolved this I donated it to the local school.

..
> I haven't much experience with HP, mostly Epson, but I haven't seen one of
> those in an inkjet printer before.


Bad form to reply to oneself, but:

I just took a real cheapie Lexmark apart, it has a "filmstrip" about 6 mm
wide with lots of lines on it. The carriage traverse motor is not a stepper.
The strip is not an encoder, just a lot of lines. Perhaps the electronics
just counts the lines crossed, perhaps they do how-far-between-the-lines as
well (the strip is grey overall; but not Gray).

I haven't seen the like before (well, not recently), it's a weird mix of
stepper counting and encoder feedback technologies. Maybe I'm just
out-of-date!


--
Peter Fairbrother

Old Aug 26, 2004, 08:11 AM
Andrew Mawson
Guest
n/a Posts
Re: CNC Home Build Again


"Peter Fairbrother" <zenadsl6186@zen.co.uk> wrote in message
news:BD52F99B.5CD2E%zenadsl6186@zen.co.uk...
> Peter Fairbrother wrote:
>
> > Steve wrote:
> >
> >> The reason I mentioned it was because the last "90" HP Inkjet I had

did
> >> have an optical "gray code" strip, it looked like a long loop of 16mm

film
> >> (without the sprocket holes!) the width of the carriage. The printer

failed
> >> because this strip had a dollop of gunk on it, causing the printer to

lose
> >> correct position. Having resolved this I donated it to the local

school.
> .
> > I haven't much experience with HP, mostly Epson, but I haven't seen one

of
> > those in an inkjet printer before.

>
> Bad form to reply to oneself, but:
>
> I just took a real cheapie Lexmark apart, it has a "filmstrip" about 6 mm
> wide with lots of lines on it. The carriage traverse motor is not a

stepper.
> The strip is not an encoder, just a lot of lines. Perhaps the electronics
> just counts the lines crossed, perhaps they do how-far-between-the-lines

as
> well (the strip is grey overall; but not Gray).
>
> I haven't seen the like before (well, not recently), it's a weird mix of
> stepper counting and encoder feedback technologies. Maybe I'm just
> out-of-date!
>
>
> --
> Peter Fairbrother
>


The 'film strip' is used to generate a trigger signal that unloads the
buffer holding the 'stripe' of data to be printed by firing the print head
pins. The motor drives the head across the carriage and pins fire as and
when a line is recognised on the film strip.

Put a mark on the film and you will generate a corresponding white space on
your print-out. This (and also dust on the sensor) used to be quite a common
fault on Centronic 101 and 101AL printers 25 years ago when I used to look
after them.

Andrew Mawson


 


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