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Very nice. Here's a link, click on "Kleinbauer":


Was this done on a milling machine made from one of your plans?

Steve Greenfield

--- crankorgan <john@...> wrote:

Hi All.
I uploaded a picture of a milled PCBoard to the photo
area. The board was milled using a Dremel tool and a homemade
milling machine. Milling speed 6" per minute at 16,000 RPMs. That
is how the boards looks before it is deburred. Notice the pre
drilled
holes done during milling. The board gets deburred using a steel
bristle brush the size of a tooth brush. That board is a Piker 4X
controller board. If you have any questions please ask them here.

John

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Hi All.
I uploaded a picture of a milled PCBoard to the photo
area. The board was milled using a Dremel tool and a homemade
milling machine. Milling speed 6" per minute at 16,000 RPMs. That
is how the boards looks before it is deburred. Notice the pre drilled
holes done during milling. The board gets deburred using a steel
bristle brush the size of a tooth brush. That board is a Piker 4X
controller board. If you have any questions please ask them here.

John

Here's a PDF from Don Lancaster's site that talks about using
dental turbines in plotters:



Steve Greenfield

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Hi Steve,
I am using 1/4-20 threaded rod with a tapped piece of Delrin
for a drive nut. It's all relative. Even if the threaded rod is
out ten thousands over a 6" length you will still get a good
board. After milling boards for over a year and selling them. I have
only found one problem. That is getting a good high speed spindle
to run the bit. I can't seem to find anything better than the Dremel
MultiPro. Let me know if you find one! Run out is the problem. Most
cheap routers have too much play in them for circuit boards. The also
have a problem if you run them too long. I have some boards that take
an hour to mill.

John

--- n4onl <umrk@...> wrote:

Hi John, All questions comments, ect. welcome.

-

Resolution and repeatibility (accuracy): Good points, and no I
don't
expect extreme accuracy and repeatability out of this setup,
especially using Acme rod, but i think it will be rather
accurate.
What Accuracy (resolution and repeatibility) is Really Needed?

Good point. Anyone have the answer? Repeatability I would imagine
will be mostly affected by backlash and stiffness. Resolution by
the thread pitch and whether you use pulleys to "gear down" the
steppers, and if you use full step or half. Using pulleys to gear
the steppers down has the advantages of both higher resolution and
more resultant power, at the cost of speed. For me, I can take the
cost in speed. Accuracy is not just repeatability or linearity. It
is also important that if the calculations say X steps move the
head 4 inches, that it not be 3.9 inches.

Going by lathes, mills... stiffness of the frame lends to
accuracy,
this is why i'm using 8020 and aluminum plate ($0.35/lb scrap
price).
It will be rather hefty. Also backlash is a factor so I'm going
to
use antibacklash nuts that I will make out of Delrin (for reduced
friction and wear of the Acme rod lead screws).

Boeing Surplus... Yeah! I live about 30 minutes from Boeing
Surplus. What they don't have, there are metal sheet suppliers all
around them.

My Guides: For X and Y axis (right and left), Thompson TWN 10
(5/8")
Super Pillow Block Bearings and Precision Ground Rod. their used
but
are in Excellent mechanical condition, smooth and tight.

for new stuff. I had a project
cancelled to build an ultrasmooth sliding door, I did a lot of
research for bearings like this. I should dig out the catalogs
again and post the links.

For Z axis (router verticle), used Robohand Inc. model PS-4-4-SH
(similar to these ) with 12mm
shafts and 4" travel. Very smooth and tight. I also have some
3/4"
supported linear rods and bearings but I think they would be
overkill. :)

Hey, if you have them already and don't have another project for
them, why not?

The part that I have the least knowledge about are the stepper
motors
themselves, so I'm going a bit larger than the ones I've seen on
commercial equipment I've found on the web. I have 2 new (old
stock)
Vexta 83 oz/in, 1 used 100 oz/in and 1 used 120 oz/in, all 200
full
steps per rev and NEMA23 frame. This one (
tech.com/products/quickcircuit/ ) appears to be using 60 oz/in
motors, .00025" resolition and .00025" (one halfstep ?)
repeatibility. Check out the PCBs it makes. :)

What makes you think they are using 60 oz-in, besides the size of
the steppers?

Here's that link fixed:


BTW, here's my secret source of good battlehardened 60 oz-in
steppers- Apple Imagewriter II! Two per printer. I checked them
with a constant current power supply and a balance, at 60 oz they
held, at 61 oz they'd slip one or two notches.

Speed of the cut is also a big factor in accuracy, so I intend to
keep my cutting inches/sec on the slow side, at least until I see
how
fast I can move and not affect accuracy to a great degree.
What Accuracy is Really Needed?

From the CAD_CAM_etc list, I think it is important to match cutter
speed to movement speed. IE, while it is bad to move too quickly
and so take too big a bit on each pass of the cut, it is also bad
to move to slowly and take too small a cut. So it would follow that
you'd need to slow down cutter rotation if you slow down inches per
second.

Don Lancaster has a great idea for
lightweight milling heads- dental turbines. Tiny flexible air hose,
tiny dental turbine, and you have a cutter head that is extremely
lightweight. Very high speed but the cutting head is small so
cutting speed isn't quite as high as it might seem. Maybe something
that could even be retrofit to an HP flatbed plotter? Very cheap so
when they wear out you just toss the turbine and install another.
Perhaps use the exhaust air to make a vacuum system to suck the
particles up.

BTW using a RTX for the spindle has been changed to using a small
laminate trim router. I found one (and a spare) at Harbor Freight
for
half the cost of a RTX ($20 ea.). Thats cheap enough to replace
as
needed. :)

Makes sense. A friend of mine bought a very expensive sabre saw a
few years ago. Since it was so expensive, he felt obligated to
repair it when various parts wore out. In that time, he's spent
twice the cost of the saw on parts. He's cutting 3/8" aluminum with
it, so it is hard on it. In that time I wore out three $25 sabre
saws and spent a fraction of what he did.

Steve Greenfield



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a tight cable and pulleys setup has worked for dot matrix printers for years for positioning back and forth. if you find the right old printer, that assembly can be removed and used, including the stepper.

for a tightly focused laser perhaps the laser assembly from a laser printer. it would work if you could mount it at the exact distance as it was in the original printer (it's focal point) from a new larger drum or platen(?i think that's the term).

of course, taking two printers apart to do the same thing a laser printer does anyway, may not be the most direct solution, but where's the fun in that?.

Try this a second time since it didn't appear to post...

Are you really able to get a repeatable and accurite resolution of
0.0005" on your ACME screw? What about motor oscilations and over

shoot

(gotta love steppers)? Then there is the question of your guides

and

play in them. You might be asking a lot to fabricate that. Take a

look a

Dadel / Parker and see thier specs. Then remember they are doing

this

for a living, granted in larger quantities with out the TLC. I am

just

asking the question.
John

Hi John, All questions comments, ect. welcome.

First off, this is my first stepper project, its a learning
experience that I plan on putting to use and basically a fun project.
Its for hobby use, not to compete with $5K+ commercial units that
intend to be sold to NASA, MIT... IOW It has to be Good Enough for me
and my use.

I estimate I'll have about $100-200 invested (less software) in the
unit. Steppers, linear rails and bearings, 8020 (
) and plate aluminum frame, drivers, power
supply... most scrounged from a local scrap dealer and some bought
new or as new old stock. The Camtronics PWM drive was donated by a
friend with a machine shop who wants to use it ocassionally, and will
help with any machining beyond my abilities. The computer to run it,
well, I have a lot of old parts that need put to use. Considering my
investment (time is not a factor since this is a for fun hobby
project) I will have a substantial savings over a commercial unit,
and can upgrade it when/if needed.

Resolution and repeatibility (accuracy): Good points, and no I don't
expect extreme accuracy and repeatability out of this setup,
especially using Acme rod, but i think it will be rather accurate.
What Accuracy (resolution and repeatibility) is Really Needed?

Going by lathes, mills... stiffness of the frame lends to accuracy,
this is why i'm using 8020 and aluminum plate ($0.35/lb scrap price).
It will be rather hefty. Also backlash is a factor so I'm going to
use antibacklash nuts that I will make out of Delrin (for reduced
friction and wear of the Acme rod lead screws).

My Guides: For X and Y axis (right and left), Thompson TWN 10 (5/8")
Super Pillow Block Bearings and Precision Ground Rod. their used but
are in Excellent mechanical condition, smooth and tight.

For Z axis (router verticle), used Robohand Inc. model PS-4-4-SH
(similar to these ) with 12mm
shafts and 4" travel. Very smooth and tight. I also have some 3/4"
supported linear rods and bearings but I think they would be
overkill. :)

The part that I have the least knowledge about are the stepper motors
themselves, so I'm going a bit larger than the ones I've seen on
commercial equipment I've found on the web. I have 2 new (old stock)
Vexta 83 oz/in, 1 used 100 oz/in and 1 used 120 oz/in, all 200 full
steps per rev and NEMA23 frame. This one (
tech.com/products/quickcircuit/ ) appears to be using 60 oz/in
motors, .00025" resolition and .00025" (one halfstep ?)
repeatibility. Check out the PCBs it makes. :)

Speed of the cut is also a big factor in accuracy, so I intend to
keep my cutting inches/sec on the slow side, at least until I see how
fast I can move and not affect accuracy to a great degree.
What Accuracy is Really Needed?

Last but not least the Acme rod. I won't be sure of its linearity
until I build this project and test it with a dial indicator. I can
also get some precision Acme rod if needed, and then theres
ballscrews. As long as its relatively linear I can adjust the overall
accuracy in software. I do have a long ways to go (cost wise) to get
close to the cost of a comercial unit. :)

The design is a Fixed Gantry, the table only moves in the Y axis
under the gantry. The gantry holds the X axis and the Z rides on the
X. I may modify this swapping the X and Y for added rigidity.

The power supply parts are scrounged (free) from old power supplies
from work.

BTW using a RTX for the spindle has been changed to using a small
laminate trim router. I found one (and a spare) at Harbor Freight for
half the cost of a RTX ($20 ea.). Thats cheap enough to replace as
needed. :)

What do you think?

mike

Hi,

That is just a drilling machine, not capable of milling at all. The
project has been published by Elektor Magazine.

Best regards,
Alexandre Guimaraes

yep close enough to $800 anyway

use the translation page at google

theres a space to enter the URL (2nd field of 2nd block)

looks like an interesting kit

Brian

Skateboard bearings!



Steve Greenfield

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Doesn't that price translate to approximately $800 USD?

Anyone here read German?

Steve

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Adam Seychell wrote:

Hello group,
Has anyone here thought about building or even built a drum
photoplotter based on a red LED laser diode ? This would be used for
making printing masks, et. There has been much discussion among amateurs
on building a CNC mill/drill machines, however I am under the impression
that this is definitely NOT an task for the beginner, even if he/she
has access the right tools. A drum photoplotter appears simpler in
construction as there is only 1 axis required to position the light
head. Basically the drum plotter works by rotating a relatively large
drum with a film sensitive to red light (available from Kodak)
positioned around the outside of the drum. The drum spins at fairly high
speed (> 10 rev/sec) and the light source (red LED laser diode and
focusing lens) slowly and accurately moves along the length of the drum
in a straight line. The spinning drum sounds relatively simple to build.
The moving light source looks a lot more complicated / expensive. My
only thoughts how to go about this is to use a ball bearing screw and
linear bearing. I priced some ready to go ball screw guided assemblies
but the costs were prohibitive. Is there no other option ? I own a drill
press and a small lathe in my workshop. I am open to all comments.

I've thought of doing it, but my epson is good enough for the moment.
It's currently used for some high resolution printers.

As for crappy light sources, you just focus the light to a converging
beam onto a *small* pin-hole in shim metal, then re-converge the
diverging
beam from the other side. The pinhole cuts out rays that are not
following
the ideal lens 'ray-trace' path. By choosing suitable focal lengths, the
dot on the film will be smaller than the pin-hole size. Other tricks can
be done to make use of laser pointers too.

The mechanics are easy but fiddly. Mount a laser diode to a platform
that
moves along a finely threaded rod, driven with a stepper. An
anti-backlash
nut is made with two nuts with a spring in between. A printer mechanism
could be used.

Hi,

speed (> 10 rev/sec) and the light source (red LED laser diode and

Usually cheap laser diodes are very bad source for points. The light
spreads unevenly and in a weird pattern. The optics to make it a point
source would probably end up being more expensive than using another laser
source.

Best regards,
Alexandre Guimaraes

Hello group,
Has anyone here thought about building or even built a drum photoplotter based on a red LED laser diode ? This would be used for making printing masks, et. There has been much discussion among amateurs on building a CNC mill/drill machines, however I am under the impression that this is definitely NOT an task for the beginner, even if he/she has access the right tools. A drum photoplotter appears simpler in construction as there is only 1 axis required to position the light head. Basically the drum plotter works by rotating a relatively large drum with a film sensitive to red light (available from Kodak) positioned around the outside of the drum. The drum spins at fairly high speed (> 10 rev/sec) and the light source (red LED laser diode and focusing lens) slowly and accurately moves along the length of the drum in a straight line. The spinning drum sounds relatively simple to build. The moving light source looks a lot more complicated / expensive. My only thoughts how to go about this is to use a ball bearing screw and linear bearing. I priced some ready to go ball screw guided assemblies but the costs were prohibitive. Is there no other option ? I own a drill press and a small lathe in my workshop. I am open to all comments.

n4onl wrote:

Hi everyone.
Just found this group and I have been skimming through the posts.
I'm interested in building a CNC PCB mill/drill. Stepper motors,
linear bearings/rods, antibacklash nuts on Acme rod... and a Black
and Decker RTX. The resolution works out to 0.0005" per full step and
0.00025" if I half step.

Is 1/2 or 1/4 of a thousands a good resolution for this project?

Does anyone have links to similar projects?

Hints? Tips? Insight?

Thanks
mike

Are you really able to get a repeatable and accurite resolution of
0.0005" on your ACME screw? What about motor oscilations and over shoot
(gotta love steppers)? Then there is the question of your guides and
play in them. You might be asking a lot to fabricate that. Take a look a
Dadel / Parker and see thier specs. Then remember they are doing this
for a living, granted in larger quantities with out the TLC. I am just
asking the question.
John

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--

John van Loon
Control Intelligence

john@...
(905) 521-5505

Hi Steve,
I am redoing one of my controller boards. It
will now drive 4 wire motors. I am drawing the isolation
paths in TurbCad. People ask me why I don't use Eagle
or one of the other programs. The reason is I can do
things with TurboCad those packages won't let me do!
Everybody has their favorite method. Scratch and
Etch is not for everybody. I just know that people who
use a plotter with a pen to layout their boards will
find the Scratch and Etch better. I found my pen
sometimes skips. Coating the board and Scratching off
the coating allows more control. More testing is needed
by people with open minds. They say if you build a better
mouse trap, people will beat a path to your door. The
truth is build a mouse trap that is as good and cheaper!

John

--- crankorgan <john@...> wrote:

Hi KPL,
You are using the wrong coating if it cracks. See
Denny's post! I mill circuit boards all the time. The
idea of Scratch and Etch came to me the other day. Mechanical
Etching bits have a limited life. Using the Scratch and
Etch method should be faster and cheaper for the home hobbiest.

Yeah! And very little to modify a plotter. Just take an empty pen
and drill out the center to fit a carbide tipped pen. Maybe cut off
most of the carbide pen to reduce the mass and so it fits within
the body of the pen.

I like the idea of just running it twice to widen the tracks and
ensure no bridges.

I have a couple of HP plotters here. Both unfortunately need some
work, one shuts down after about 10 seconds of plotting, the other
seems to slip, making angles into wierd curvy things. But good
enough to test the idea on.

Steve Greenfield


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Hi KPL,
You are using the wrong coating if it cracks. See
Denny's post! I mill circuit boards all the time. The
idea of Scratch and Etch came to me the other day. Mechanical
Etching bits have a limited life. Using the Scratch and
Etch method should be faster and cheaper for the home hobbiest.

John


--- In Homebrew_PCBs@y..., "Karlis" <krahabors@h...> wrote:

I've been working this way a few times, manually (have no plotter

yet) using

some kind of dentist tool, nearly 6000rpm, round-tipped cutter.
Just coat the board with thin layer of lacquer and "draw" all that

you need

with light strokes of the cutter.
It will make nice, sharp edges, width of insulation path depends on

cutter.

If you want only to scratch the lacquer with sharp-tipped tool, the
insulation paths will be too narrow and the lacquer can crack near

the

edges. It will never happen if using rotating tool.

So the idea is to use fast-spinning tool with round tip, you need

only to

push it lightly against the board, so it can be done very quickly

and

easily.

The other technique I have heard of is similar, only the traces

are "milled"

when there must be copper not where insulation will be. After that

the board

must be tin-plated. Then wash away the lacquer and etch the board

in some

kind of solution. Just I don't remember which one of the most

popular

etchant solutions doesn't dissolve tin. But it wasn't anything very

special.

KPL

I've been working this way a few times, manually (have no plotter yet) using
some kind of dentist tool, nearly 6000rpm, round-tipped cutter.
Just coat the board with thin layer of lacquer and "draw" all that you need
with light strokes of the cutter.
It will make nice, sharp edges, width of insulation path depends on cutter.

If you want only to scratch the lacquer with sharp-tipped tool, the
insulation paths will be too narrow and the lacquer can crack near the
edges. It will never happen if using rotating tool.

So the idea is to use fast-spinning tool with round tip, you need only to
push it lightly against the board, so it can be done very quickly and
easily.

The other technique I have heard of is similar, only the traces are "milled"
when there must be copper not where insulation will be. After that the board
must be tin-plated. Then wash away the lacquer and etch the board in some
kind of solution. Just I don't remember which one of the most popular
etchant solutions doesn't dissolve tin. But it wasn't anything very special.

KPL

Added to the bookmarks!

Steve

--- Tim Goldstein <timg@...> wrote:

If you are looking to go to a film there is a very nice product
sold by
M&R Marking. It is a negative film system that has extremely easy
to use
water based chemistry. To produce a film you print a positive
image
using a standard printer (I have always done it on a laser, but
an
inkjet would likely work). You then do a contact print using
standard
black light bulbs onto the negative film. Now to develop it you
just
spray on a water based fluid from a squirt bottle and wait 90
seconds
then rinse and scrub the film under cool water with a paper
towel. The
result is a completely negative film that is as opaque as the
films I
have had done by a commercial photo plotter. Product info at:

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