Homebrew PCBs

Hi Guys,

I've been following the pcb driller discussion. I've been wanting to 
build one for a long time. But so far the designs seem too complicated 
or too heavy duty for my needs. And too expensive too. I want to throw 
out a couple of ideas. I'd appreciate any thoughts on them. (Yes, 
Stefan, I wouldd like yur thoughts too, as long as they don't include 
anything about a chicken grill. :)

I use EAGLE free version for my boards. That means they are under 3" x 
4". When drawing the layout, I set EAGLE at a 0.10" grid (sometimes I 
cheat and go  0.05"). I lay out my components to fit this grid. This 
works well, but I don't like to manually postion the board for driling 
on my drill press.

It occurred to me that what I needed was something that could drill 
holes on a 3" x 4" grid. At 0.10" spacing the grid would be 30 by 40, 
and on 0.05" spacing the grid would be 60 x 80.

I will say, for now, I am not interested in milling, just drilling 
holes. And I would be willing to "pull the handle" on the drill press. 
My boards are small enough with not too many holes. So what would it 
take to build a grid based driller.

My first thought was converting an old printer. Attaching a small 
dremel to the print head. I would move the print head across the page 
stoping at the appropriate spot and the pulls the handle. Afte all the 
holes on one line were drilled, go to the next line. After all if you 
cn print a grid of dots on a page, you could move the print heaad with 
simple commands.

The second idea I had, after looking at all the drivers chps and 
software and discussion about half stepping and choppers, was that the 
driller could be very light duty due to the size of the board and the 
coarseness of the steps.

Looking at the old Nasa stepper design, that uses 2 flip flops and a 
couple of nor gates, I realized that 2 lines would be all that i 
really need for single stepping.

I've been playing woth the PICAXE chips. They are programmed in basic 
and only need a 3 wire cable for programming. Best of all they (the 
08M)are only about $3 each, and has 5 i/o lines.

I've been thinking about using one of these as the controller. If I 
download the coordinate of the holes, program, The PICAXE could 
convert the coordinates to steps I could position the drill using just 
4 of the 5 lines. The 5th line would be an input to start or go to the 
next holes. A driver chip or transistors would be needed for the power 
to run the servovs. 

For the driller bed, a light duty X-Y table about 6" x 6" could be 
driven by some small servos and screws.

It would be a small, inexpensive, semi automatic pcb driller.

What do you see as the pitfalls with these two ideas?

Myc

1st: if Eagle doesn't produce a DRILL file, chuck it, I can't remember if it
does.

2nd: if you are going to go into programming, might as well follow the
conventional technique using steppers, that way you can copy existing code,
same thing for the stepper motor control circuits.

3rd: you can use the same technique as the others, but drastically reduce in
size everything, that in itself will make a LOT of things easier, for
example, a 12" rod of aluminium 1/4" thick will be plenty for you.  Same
thing with the screw, a 1/4" diameter screw would be fine.

4th: make it all out of wood, REAL easy to cut & drill, using holes in the
wood as bushings for the rods.

5th: polish the aluminium rods slightly, just to give them that extra shine,
which translates into less friction (maybe a little dab of lubricant).


Myc, I've looked at a lot of ways to skin this chicken, and if you have a
DRILL file, can program PICs, can download the file, can assemble a basic
stepper controller like this one:
<http://www.xavierkamial.com/Videos/Stepper%20Motor%20Controller.htm>, then
steppers are the way to go.

Everything is out there for a rinky-dink system, I am just looking for
something with a little more ooomph.  But for drilling, el-cheapo steppers
cost no more than $5.  Using servos, you'd be all alone in left field, with
probably no samples from the web to get ideas from.  With steppers, you'd
get pretty darn close to the same precision as a lot of us will get.  The
only difference is that we will be able to maintain that precision over a
longer surface; which you don't need anyways.

Robert
:)



-----Message d'origine-----
De : Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com] De
la part de mycroft2152
Envoyé : juin 11 2005 20:10
À : Homebrew_PCBs@yahoogroups.com
Objet : [Homebrew_PCBs] PCB Driller - Looking for comments


Hi Guys,

I've been following the pcb driller discussion. I've been wanting to 
build one for a long time. But so far the designs seem too complicated 
or too heavy duty for my needs. And too expensive too. I want to throw 
out a couple of ideas. I'd appreciate any thoughts on them. (Yes, 
Stefan, I wouldd like yur thoughts too, as long as they don't include 
anything about a chicken grill. :)

I use EAGLE free version for my boards. That means they are under 3" x 
4". When drawing the layout, I set EAGLE at a 0.10" grid (sometimes I 
cheat and go  0.05"). I lay out my components to fit this grid. This 
works well, but I don't like to manually postion the board for driling 
on my drill press.

It occurred to me that what I needed was something that could drill 
holes on a 3" x 4" grid. At 0.10" spacing the grid would be 30 by 40, 
and on 0.05" spacing the grid would be 60 x 80.

I will say, for now, I am not interested in milling, just drilling 
holes. And I would be willing to "pull the handle" on the drill press. 
My boards are small enough with not too many holes. So what would it 
take to build a grid based driller.

My first thought was converting an old printer. Attaching a small 
dremel to the print head. I would move the print head across the page 
stoping at the appropriate spot and the pulls the handle. Afte all the 
holes on one line were drilled, go to the next line. After all if you 
cn print a grid of dots on a page, you could move the print heaad with 
simple commands.

The second idea I had, after looking at all the drivers chps and 
software and discussion about half stepping and choppers, was that the 
driller could be very light duty due to the size of the board and the 
coarseness of the steps.

Looking at the old Nasa stepper design, that uses 2 flip flops and a 
couple of nor gates, I realized that 2 lines would be all that i 
really need for single stepping.

I've been playing woth the PICAXE chips. They are programmed in basic 
and only need a 3 wire cable for programming. Best of all they (the 
08M)are only about $3 each, and has 5 i/o lines.

I've been thinking about using one of these as the controller. If I 
download the coordinate of the holes, program, The PICAXE could 
convert the coordinates to steps I could position the drill using just 
4 of the 5 lines. The 5th line would be an input to start or go to the 
next holes. A driver chip or transistors would be needed for the power 
to run the servovs. 

For the driller bed, a light duty X-Y table about 6" x 6" could be 
driven by some small servos and screws.

It would be a small, inexpensive, semi automatic pcb driller.

What do you see as the pitfalls with these two ideas?

Myc







Be sure to visit the group home and check for new Links, Files, and Photos:
http://groups.yahoo.com/group/Homebrew_PCBs

If Files or Photos are running short of space, post them here:
http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
Yahoo! Groups Links

On Saturday 11 June 2005 08:10 pm, mycroft2152 wrote:

> My first thought was converting an old printer. Attaching a small dremel to
> the print head. I would move the print head across the page stoping at the
> appropriate spot and the pulls the handle. Afte all the holes on one line
> were drilled, go to the next line. After all if you cn print a grid of dots
> on a page, you could move the print heaad with simple commands.

If you're talking about the use of the hardware platform,  and maybe the 
circuitry to drive it with,  giving it your own commands rather than relying 
on the logic in the printer,  you might be able to make this work.  Biggest 
problem I see is that the mass of any dremel is going to likely be *way* more 
than that of any printhead,  unless you're talking about a really old 
printer.  I have a couple of those in storage presently awaiting their turn 
to be scrapped,  but I don't expect that they're especially common these 
days,  and the newer stuff uses as little material as they can possibly get 
away with,  including much smaller motors.

Dunno what you mean by "a small dremel",  they all seem to be pretty much the 
same size to me.  And the mass of moving that is where you may run into 
trouble.  Way more than just a print head.  So in addition to slowing down 
compared to the speed of a print head,  you'll probably want to modify those 
components as well.

> The second idea I had, after looking at all the drivers chps and
> software and discussion about half stepping and choppers, was that the
> driller could be very light duty due to the size of the board and the
> coarseness of the steps.
>
> Looking at the old Nasa stepper design, that uses 2 flip flops and a
> couple of nor gates, I realized that 2 lines would be all that i
> really need for single stepping.

That sounds like the design that I'm probably going to end up with here for 
any number of things.

Hi Roy,

By a small dremel, i was thinking of either the handpiece extension 
or the little battery powered dremel. Since this in a light duty 
machine, the battery version could work.

I agree that modern printers are moving very small masses with the 
ink jet print heads, but i have a couple of very old massive 
printers, one is a daisy wheel type, the other is a wide carriage 
dot matrix. Both used a ribbon.

The idea came from the old days of drawing with ASCII characters 
uning the Print command in Basic.

Myc


--- In Homebrew_PCBs@yahoogroups.com, "Roy J. Tellason" 
<rtellason@b...> wrote:
> On Saturday 11 June 2005 08:10 pm, mycroft2152 wrote:
> 
> > My first thought was converting an old printer. Attaching a 
small dremel to
> > the print head. I would move the print head across the page 
stoping at the
> > appropriate spot and the pulls the handle. Afte all the holes on 
one line
> > were drilled, go to the next line. After all if you cn print a 
grid of dots
> > on a page, you could move the print heaad with simple commands.
> 
> If you're talking about the use of the hardware platform,  and 
maybe the 
> circuitry to drive it with,  giving it your own commands rather 
than relying 
> on the logic in the printer,  you might be able to make this 
work.  Biggest 
> problem I see is that the mass of any dremel is going to likely be 
*way* more 
> than that of any printhead,  unless you're talking about a really 
old 
> printer.  I have a couple of those in storage presently awaiting 
their turn 
> to be scrapped,  but I don't expect that they're especially common 
these 
> days,  and the newer stuff uses as little material as they can 
possibly get 
> away with,  including much smaller motors.
> 
> Dunno what you mean by "a small dremel",  they all seem to be 
pretty much the 
> same size to me.  And the mass of moving that is where you may run 
into 
> trouble.  Way more than just a print head.  So in addition to 
slowing down 
> compared to the speed of a print head,  you'll probably want to 
modify those 
> components as well.
> 
> > The second idea I had, after looking at all the drivers chps and
> > software and discussion about half stepping and choppers, was 
that the
> > driller could be very light duty due to the size of the board 
and the
> > coarseness of the steps.
> >
> > Looking at the old Nasa stepper design, that uses 2 flip flops 
and a
> > couple of nor gates, I realized that 2 lines would be all that i
> > really need for single stepping.
> 
> That sounds like the design that I'm probably going to end up with 
here for 
> any number of things.

Hi Robert,

Thanks for the encouragement. Yes, I looking for a "rinky dink" 
system. It fits my basic needs.

Thanks for the link, on the stepper driver. I had seen it previously 
and that is what got me thinking that the 8 pin PICAXE with 5 i/o's 
might do the job. I understood from that write up, that for single 
stepping it took just 4 2 bit numbers along with a couple of 
inverters.

For single stepping the two lines can be used for each of the 
motors. By adding an inverter to these lines you get the 4 lines 
needed for the steppers. Since for single stepping they always are 
inverted.

The PICAXE website has schematics for this type of circuit. It uses 
a 2003 or 2803 for the low power drivers, with the spare gates used 
as inverters. It also has the short program to output the 2 bit 
pattern to drive the steppers in single step mod.

The 8 pin 3 dolalar picaxe could work for a small number of holes, 
fur to its limited memory. But the 18 pin 18X version (about 10 
bucks) has more memory and enough i/o pin to drive all 8 lines, thus 
voiding the need for the inverters.

The key here is the simplicity and light framework needed, thus the 
low cost. The trade offs include preplanning the layout and loading 
the coordinates into the Picaxe program before downloading. But once 
its done, you have permanent drill file.

Bu using one i/o line for start, goto next hole, a pc is not needed 
to run the program. the PICAXE would be all that is necessary. For 3 
bucks, yo could keep each drill program on a chip and change chips 
when needed.

There would be some initial calculations to get the stepper's 
rotation converteed to linear values, but I don't think that shuld 
be too bad.

Thanks again,

Myc




--- In Homebrew_PCBs@yahoogroups.com, Robert Hedan 
<robert.hedan@v...> wrote:
> 1st: if Eagle doesn't produce a DRILL file, chuck it, I can't 
remember if it
> does.
> 
> 2nd: if you are going to go into programming, might as well follow 
the
> conventional technique using steppers, that way you can copy 
existing code,
> same thing for the stepper motor control circuits.
> 
> 3rd: you can use the same technique as the others, but drastically 
reduce in
> size everything, that in itself will make a LOT of things easier, 
for
> example, a 12" rod of aluminium 1/4" thick will be plenty for 
you.  Same
> thing with the screw, a 1/4" diameter screw would be fine.
> 
> 4th: make it all out of wood, REAL easy to cut & drill, using 
holes in the
> wood as bushings for the rods.
> 
> 5th: polish the aluminium rods slightly, just to give them that 
extra shine,
> which translates into less friction (maybe a little dab of 
lubricant).
> 
> 
> Myc, I've looked at a lot of ways to skin this chicken, and if you 
have a
> DRILL file, can program PICs, can download the file, can assemble 
a basic
> stepper controller like this one:
> <http://www.xavierkamial.com/Videos/Stepper%20Motor%
20Controller.htm>, then
> steppers are the way to go.
> 
> Everything is out there for a rinky-dink system, I am just looking 
for
> something with a little more ooomph.  But for drilling, el-cheapo 
steppers
> cost no more than $5.  Using servos, you'd be all alone in left 
field, with
> probably no samples from the web to get ideas from.  With 
steppers, you'd
> get pretty darn close to the same precision as a lot of us will 
get.  The
> only difference is that we will be able to maintain that precision 
over a
> longer surface; which you don't need anyways.
> 
> Robert
> :)
> 
> 
> 
> -----Message d'origine-----
> De : Homebrew_PCBs@yahoogroups.com 
[mailto:Homebrew_PCBs@yahoogroups.com] De
> la part de mycroft2152
> Envoyé : juin 11 2005 20:10
> À : Homebrew_PCBs@yahoogroups.com
> Objet : [Homebrew_PCBs] PCB Driller - Looking for comments
> 
> 
> Hi Guys,
> 
> I've been following the pcb driller discussion. I've been wanting 
to 
> build one for a long time. But so far the designs seem too 
complicated 
> or too heavy duty for my needs. And too expensive too. I want to 
throw 
> out a couple of ideas. I'd appreciate any thoughts on them. (Yes, 
> Stefan, I wouldd like yur thoughts too, as long as they don't 
include 
> anything about a chicken grill. :)
> 
> I use EAGLE free version for my boards. That means they are under 
3" x 
> 4". When drawing the layout, I set EAGLE at a 0.10" grid 
(sometimes I 
> cheat and go  0.05"). I lay out my components to fit this grid. 
This 
> works well, but I don't like to manually postion the board for 
driling 
> on my drill press.
> 
> It occurred to me that what I needed was something that could 
drill 
> holes on a 3" x 4" grid. At 0.10" spacing the grid would be 30 by 
40, 
> and on 0.05" spacing the grid would be 60 x 80.
> 
> I will say, for now, I am not interested in milling, just drilling 
> holes. And I would be willing to "pull the handle" on the drill 
press. 
> My boards are small enough with not too many holes. So what would 
it 
> take to build a grid based driller.
> 
> My first thought was converting an old printer. Attaching a small 
> dremel to the print head. I would move the print head across the 
page 
> stoping at the appropriate spot and the pulls the handle. Afte all 
the 
> holes on one line were drilled, go to the next line. After all if 
you 
> cn print a grid of dots on a page, you could move the print heaad 
with 
> simple commands.
> 
> The second idea I had, after looking at all the drivers chps and 
> software and discussion about half stepping and choppers, was that 
the 
> driller could be very light duty due to the size of the board and 
the 
> coarseness of the steps.
> 
> Looking at the old Nasa stepper design, that uses 2 flip flops and 
a 
> couple of nor gates, I realized that 2 lines would be all that i 
> really need for single stepping.
> 
> I've been playing woth the PICAXE chips. They are programmed in 
basic 
> and only need a 3 wire cable for programming. Best of all they 
(the 
> 08M)are only about $3 each, and has 5 i/o lines.
> 
> I've been thinking about using one of these as the controller. If 
I 
> download the coordinate of the holes, program, The PICAXE could 
> convert the coordinates to steps I could position the drill using 
just 
> 4 of the 5 lines. The 5th line would be an input to start or go to 
the 
> next holes. A driver chip or transistors would be needed for the 
power 
> to run the servovs. 
> 
> For the driller bed, a light duty X-Y table about 6" x 6" could be 
> driven by some small servos and screws.
> 
> It would be a small, inexpensive, semi automatic pcb driller.
> 
> What do you see as the pitfalls with these two ideas?
> 
> Myc
> 
> 
> 
> 
> 
> 
> 
> Be sure to visit the group home and check for new Links, Files, 
and Photos:

> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links

Hi robert,

Hadn't thought of using servos for this, just steppers. But that is 
an interseting idea. For hobby robots, the servos are modified for 
continuous rotation. May just be possible.

The picaxe has built in servo routines and is programmed in BASIC. 
Should be easy to hook up a couple of servos to the screws to try it 
out.

Myc


--- In Homebrew_PCBs@yahoogroups.com, Robert Hedan 
<robert.hedan@v...> wrote:
> 1st: if Eagle doesn't produce a DRILL file, chuck it, I can't 
remember if it
> does.
> 
> 2nd: if you are going to go into programming, might as well follow 
the
> conventional technique using steppers, that way you can copy 
existing code,
> same thing for the stepper motor control circuits.
> 
> 3rd: you can use the same technique as the others, but drastically 
reduce in
> size everything, that in itself will make a LOT of things easier, 
for
> example, a 12" rod of aluminium 1/4" thick will be plenty for 
you.  Same
> thing with the screw, a 1/4" diameter screw would be fine.
> 
> 4th: make it all out of wood, REAL easy to cut & drill, using 
holes in the
> wood as bushings for the rods.
> 
> 5th: polish the aluminium rods slightly, just to give them that 
extra shine,
> which translates into less friction (maybe a little dab of 
lubricant).
> 
> 
> Myc, I've looked at a lot of ways to skin this chicken, and if you 
have a
> DRILL file, can program PICs, can download the file, can assemble 
a basic
> stepper controller like this one:
> <http://www.xavierkamial.com/Videos/Stepper%20Motor%
20Controller.htm>, then
> steppers are the way to go.
> 
> Everything is out there for a rinky-dink system, I am just looking 
for
> something with a little more ooomph.  But for drilling, el-cheapo 
steppers
> cost no more than $5.  Using servos, you'd be all alone in left 
field, with
> probably no samples from the web to get ideas from.  With 
steppers, you'd
> get pretty darn close to the same precision as a lot of us will 
get.  The
> only difference is that we will be able to maintain that precision 
over a
> longer surface; which you don't need anyways.
> 
> Robert
> :)
> 
> 
> 
> -----Message d'origine-----
> De : Homebrew_PCBs@yahoogroups.com 
[mailto:Homebrew_PCBs@yahoogroups.com] De
> la part de mycroft2152
> Envoyé : juin 11 2005 20:10
> À : Homebrew_PCBs@yahoogroups.com
> Objet : [Homebrew_PCBs] PCB Driller - Looking for comments
> 
> 
> Hi Guys,
> 
> I've been following the pcb driller discussion. I've been wanting 
to 
> build one for a long time. But so far the designs seem too 
complicated 
> or too heavy duty for my needs. And too expensive too. I want to 
throw 
> out a couple of ideas. I'd appreciate any thoughts on them. (Yes, 
> Stefan, I wouldd like yur thoughts too, as long as they don't 
include 
> anything about a chicken grill. :)
> 
> I use EAGLE free version for my boards. That means they are under 
3" x 
> 4". When drawing the layout, I set EAGLE at a 0.10" grid 
(sometimes I 
> cheat and go  0.05"). I lay out my components to fit this grid. 
This 
> works well, but I don't like to manually postion the board for 
driling 
> on my drill press.
> 
> It occurred to me that what I needed was something that could 
drill 
> holes on a 3" x 4" grid. At 0.10" spacing the grid would be 30 by 
40, 
> and on 0.05" spacing the grid would be 60 x 80.
> 
> I will say, for now, I am not interested in milling, just drilling 
> holes. And I would be willing to "pull the handle" on the drill 
press. 
> My boards are small enough with not too many holes. So what would 
it 
> take to build a grid based driller.
> 
> My first thought was converting an old printer. Attaching a small 
> dremel to the print head. I would move the print head across the 
page 
> stoping at the appropriate spot and the pulls the handle. Afte all 
the 
> holes on one line were drilled, go to the next line. After all if 
you 
> cn print a grid of dots on a page, you could move the print heaad 
with 
> simple commands.
> 
> The second idea I had, after looking at all the drivers chps and 
> software and discussion about half stepping and choppers, was that 
the 
> driller could be very light duty due to the size of the board and 
the 
> coarseness of the steps.
> 
> Looking at the old Nasa stepper design, that uses 2 flip flops and 
a 
> couple of nor gates, I realized that 2 lines would be all that i 
> really need for single stepping.
> 
> I've been playing woth the PICAXE chips. They are programmed in 
basic 
> and only need a 3 wire cable for programming. Best of all they 
(the 
> 08M)are only about $3 each, and has 5 i/o lines.
> 
> I've been thinking about using one of these as the controller. If 
I 
> download the coordinate of the holes, program, The PICAXE could 
> convert the coordinates to steps I could position the drill using 
just 
> 4 of the 5 lines. The 5th line would be an input to start or go to 
the 
> next holes. A driver chip or transistors would be needed for the 
power 
> to run the servovs. 
> 
> For the driller bed, a light duty X-Y table about 6" x 6" could be 
> driven by some small servos and screws.
> 
> It would be a small, inexpensive, semi automatic pcb driller.
> 
> What do you see as the pitfalls with these two ideas?
> 
> Myc
> 
> 
> 
> 
> 
> 
> 
> Be sure to visit the group home and check for new Links, Files, 
and Photos:

> http://groups.yahoo.com/group/Homebrew_PCBs
> 
> If Files or Photos are running short of space, post them here:
> http://groups.yahoo.com/group/Homebrew_PCBs_Archives/ 
> Yahoo! Groups Links

On Sun, 12 Jun 2005 15:28:51 +0200, mycroft2152 <mycroft2152@...>  
wrote:

> Hi robert,
> Hadn't thought of using servos for this, just steppers. But that is
> an interseting idea. For hobby robots, the servos are modified for
> continuous rotation. May just be possible.
> The picaxe has built in servo routines and is programmed in BASIC.
> Should be easy to hook up a couple of servos to the screws to try it
> out.
> Myc


I thing the reference to servos was meant more general, not RC model  
servos.
They often use DC servo motors on larger CNC machines, for faster speeds  
and more power.
There is a severe increase in control circuit complexity (you need  
rotational feedback and a closed loop control).

If you do not need to advantages of servos (power and speed) it is MUCH  
easier to go the well tried route of using steppers.

RC servos would not last very long, in this application, and would not  
move very fast or with any amount of force. They are more expensive than  
steppers with no advantages, so i would not suggest using them.

Now.... you could use a chicken grill motor..... ;-) just joking!


ST

On Sunday 12 June 2005 09:01 am, mycroft2152 wrote:
> Hi Roy,
>
> By a small dremel, i was thinking of either the handpiece extension or the
> little battery powered dremel. Since this in a light duty machine, the
> battery version could work.

I don't think I've ever seen the battery version,  but then I don't get out 
shopping much like I used to.  :-)

> I agree that modern printers are moving very small masses with the ink jet
> print heads, but i have a couple of very old massive printers, one is a
> daisy wheel type, the other is a wide carriage dot matrix. Both used a
> ribbon.

Yeah,  the old daisywheel type printers would definitely get you some useful 
stuff.  I scrapped one of those,  and have two more sitting in storage,  
though one is technically a "thimble" printer rather than a daisywheel,  an 
NEC "Spinwriter".  I look forward to getting some useful stuff out of those 
when the time comes.

> The idea came from the old days of drawing with ASCII characters
> uning the Print command in Basic.

Heh.  :-)

On Sunday 12 June 2005 10:37 am, Stefan Trethan wrote:
> On Sun, 12 Jun 2005 15:28:51 +0200, mycroft2152 <mycroft2152@...>
>
> wrote:
> > Hi robert,
> > Hadn't thought of using servos for this, just steppers. But that is
> > an interseting idea. For hobby robots, the servos are modified for
> > continuous rotation. May just be possible.
> > The picaxe has built in servo routines and is programmed in BASIC.
> > Should be easy to hook up a couple of servos to the screws to try it
> > out.
> > Myc
>
> I thing the reference to servos was meant more general, not RC model
> servos.
> They often use DC servo motors on larger CNC machines, for faster speeds
> and more power.
> There is a severe increase in control circuit complexity (you need
> rotational feedback and a closed loop control).

I believe that some of the motors I have salvaged are servo motors -- there 
being only two wires instead of the usually larger number for steppers, and 
also the encoder on one side gives it away.  :-)

> If you do not need to advantages of servos (power and speed) it is MUCH
> easier to go the well tried route of using steppers.

Which is why I plan to use those first!

> RC servos would not last very long, in this application, and would not
> move very fast or with any amount of force. They are more expensive than
> steppers with no advantages, so i would not suggest using them.

To some people those _are_ "servos",  the term having been distorted into tha 
context,  I guess.

Hi Roy,

My more modern inkjet has the head driven by a 2 wire
motor, and rides along a clear plastic encoder strip
with black lines for feedback.

I was thinking along the lines od a hobby servo that
was modified for continuous rotation.

Since I'm building a light duty xY table, it might be
powerful enough. Some of the mini sumo's can bush a
brick. As for as cost goes, I've got a couple in my
junk box if I want to try them out.

Myc



--- "Roy J. Tellason" <rtellason@...> wrote:

> On Sunday 12 June 2005 10:37 am, Stefan Trethan
> wrote:
> > On Sun, 12 Jun 2005 15:28:51 +0200, mycroft2152
> <mycroft2152@...>
> >
> > wrote:
> > > Hi robert,
> > > Hadn't thought of using servos for this, just
> steppers. But that is
> > > an interseting idea. For hobby robots, the
> servos are modified for
> > > continuous rotation. May just be possible.
> > > The picaxe has built in servo routines and is
> programmed in BASIC.
> > > Should be easy to hook up a couple of servos to
> the screws to try it
> > > out.
> > > Myc
> >
> > I thing the reference to servos was meant more
> general, not RC model
> > servos.
> > They often use DC servo motors on larger CNC
> machines, for faster speeds
> > and more power.
> > There is a severe increase in control circuit
> complexity (you need
> > rotational feedback and a closed loop control).
> 
> I believe that some of the motors I have salvaged
> are servo motors -- there 
> being only two wires instead of the usually larger
> number for steppers, and 
> also the encoder on one side gives it away.  :-)
> 
> > If you do not need to advantages of servos (power
> and speed) it is MUCH
> > easier to go the well tried route of using
> steppers.
> 
> Which is why I plan to use those first!
> 
> > RC servos would not last very long, in this
> application, and would not
> > move very fast or with any amount of force. They
> are more expensive than
> > steppers with no advantages, so i would not
> suggest using them.
> 
> To some people those _are_ "servos",  the term
> having been distorted into tha 
> context,  I guess.
> 
> 
> 
> 
> 
> 
> 
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On Sun, 12 Jun 2005 19:33:03 +0200, Roy J. Tellason  
<rtellason@...> wrote:

> To some people those _are_ "servos",  the term having been distorted  
> into tha
> context,  I guess.


not really, those people just don't know.

ST