Homebrew PCBs

Hello Group

I have a quick question about precision drilling of home made PCBs.

Because of poor eyesight, I use a CCD microscope next to my Dremel
Model 300 drill press stand.  Although this set up is a big improvement
over doing thing solely 'by eye', there is a parallax error introduced
between the location of the retracted drill tip and where it eventually comes in contact with the PCB.  Once I saw a milling machine where one
was able to sight straight down into a bulls eye.  Is there a way to 
rig mirrors to do this?  

P.S. Sincle sided boards are no problem, as I can hold them up to
strong light and position a hand held rotary tool with good enough 
accuracy.  

Any suggestions would be appreciated.

Cheers

Chris

A very long time ago commercial hand drilling was done with the drill
mounted under a table and a microscope with cross hairs was used on the top.
The drill was on an air cylinder so when things were lined up a footswitch
was pushed.  No parallax. A similar rig was also used to create a NC paper
tape so additional boards could be drill automatically.

Bertho

From: schenckcharles  Sent: Thursday, June 09, 2011 13:30



Hello Group
I have a quick question about precision drilling of home made PCBs.
Because of poor eyesight, I use a CCD microscope next to my Dremel
Model 300 drill press stand. Although this set up is a big improvement
over doing thing solely 'by eye', there is a parallax error introduced
between the location of the retracted drill tip and where it eventually
comes in contact with the PCB. Once I saw a milling machine where one
was able to sight straight down into a bulls eye. Is there a way to 
rig mirrors to do this? 
P.S. Sincle sided boards are no problem, as I can hold them up to
strong light and position a hand held rotary tool with good enough 
accuracy. 
Any suggestions would be appreciated.
Cheers
Chris 



[Non-text portions of this message have been removed]

> Hello Group
>
> I have a quick question about precision drilling of home made PCBs.
>
> Because of poor eyesight, I use a CCD microscope next to my Dremel
> Model 300 drill press stand.  Although this set up is a big improvement
> over doing thing solely 'by eye', there is a parallax error introduced
> between the location of the retracted drill tip and where it eventually comes in contact with the PCB.  Once I saw a milling machine where one
> was able to sight straight down into a bulls eye.  Is there a way to 
> rig mirrors to do this?  
>
> P.S. Sincle sided boards are no problem, as I can hold them up to
> strong light and position a hand held rotary tool with good enough 
> accuracy.  
>
> Any suggestions would be appreciated.
>
> Cheers
>
> Chris
>   
Hi Chris,

You might try to find a metallic  first surface mirror that you can 
drill a small hole into on a 45 degree angle
and mount onto your drill stand with the drill bit going through the 
hole. Position the camera so it looks into
the mirror from the side and down the drill via the mirror.

A less elegant method is to use two point source lights (small halogen 
desk lamps) mounted 90 degrees apart
and pointed toward the drill tip. As the drill tip approaches the board, 
the shadows will converge on the target.

Bruce

You could drill a hole and put a cross hair mark on the screen and you are done.

Kim

On 6/9/11, Bruce Parham <obparham@...> wrote:
>
>> Hello Group
>>
>> I have a quick question about precision drilling of home made PCBs.
>>
>> Because of poor eyesight, I use a CCD microscope next to my Dremel
>> Model 300 drill press stand.  Although this set up is a big improvement
>> over doing thing solely 'by eye', there is a parallax error introduced
>> between the location of the retracted drill tip and where it eventually
>> comes in contact with the PCB.  Once I saw a milling machine where one
>> was able to sight straight down into a bulls eye.  Is there a way to
>> rig mirrors to do this?
>>
>> P.S. Sincle sided boards are no problem, as I can hold them up to
>> strong light and position a hand held rotary tool with good enough
>> accuracy.
>>
>> Any suggestions would be appreciated.
>>
>> Cheers
>>
>> Chris
>>
> Hi Chris,
>
> You might try to find a metallic  first surface mirror that you can
> drill a small hole into on a 45 degree angle
> and mount onto your drill stand with the drill bit going through the
> hole. Position the camera so it looks into
> the mirror from the side and down the drill via the mirror.
>
> A less elegant method is to use two point source lights (small halogen
> desk lamps) mounted 90 degrees apart
> and pointed toward the drill tip. As the drill tip approaches the board,
> the shadows will converge on the target.
>
> Bruce
>
>
>

On 09/06/2011 20:51, Boman33 wrote:
> A very long time ago commercial hand drilling was done with the drill
> mounted under a table and a microscope with cross hairs was used on the top.
> The drill was on an air cylinder so when things were lined up a footswitch
> was pushed.  No parallax. A similar rig was also used to create a NC paper
> tape so additional boards could be drill automatically.

They had one of those at a French university where a friend of mine 
works. I tried it out when I was working there, and it works very well. 
They got rid of it when they closed down their in-house PCB fabrication 
facility. It was made by Excellon, who invented the drill file format 
that we still use. Someone in the UK actually offered me one of those 
machines three or four years ago, but I wouldn't be able to get it up 
the stairs here.

Leon
-- 
Leon Heller
G1HSM

If I understand the problem correctly...

An easier solution might be to map out the distortion using something like
grid paper and use a clear stencil for "cross-hair" like grid lines.


On Thu, Jun 9, 2011 at 4:30 PM, Leon Heller <leon355@...> wrote:

>
>
> On 09/06/2011 20:51, Boman33 wrote:
> > A very long time ago commercial hand drilling was done with the drill
> > mounted under a table and a microscope with cross hairs was used on the
> top.
> > The drill was on an air cylinder so when things were lined up a
> footswitch
> > was pushed. No parallax. A similar rig was also used to create a NC paper
> > tape so additional boards could be drill automatically.
>
> They had one of those at a French university where a friend of mine
> works. I tried it out when I was working there, and it works very well.
> They got rid of it when they closed down their in-house PCB fabrication
> facility. It was made by Excellon, who invented the drill file format
> that we still use. Someone in the UK actually offered me one of those
> machines three or four years ago, but I wouldn't be able to get it up
> the stairs here.
>
> Leon
> --
> Leon Heller
> G1HSM
>
>  
>


[Non-text portions of this message have been removed]

I have an old small miniature precision drill press.  I drilled a 3/8" 
hole on centerline with the drill bit and cut a pocket in the underside 
of the  base plate and put a piece of 1/8" thick plastic in the pocket.  
The plastic also has a 3/8" hole in line with the baseplate.  I lined 
the hole in the plastic with 3 white SMT LEDs cocked to throw their 
light up through the hole.   Next I took a cheap ($10) webcam that has a 
lens that can be hand adjusted to focus at about 1/2"  (Just keep 
screwing it out until it focuses on a board placed on the top side of 
the base.and pressure loaded it into place with a spring loaded clamp 
(made from 1/2 of a small desk fan clip-on clamp.)    There is still a 
problem in that the "boresight" will be likely  be twisted in relation 
to the flat of the lens.  I.e., when you look at the drill come down 
toward the lens, it will look like it is coming from one side or 
another.  The solution I arrived at to circumvent that (as I tried to 
physically adjust it, and it was just too much of a pain) is take a 
vacuum formed transparent carton of about 0.010" thick sheet such as 
sold in the grocery store that contains fruit like tomatoes, cherries, 
strawberries,  etc.  Cut out a clear, un-molded portion (typically in 
the lid) and preferably about  twice as big as the board you want to 
drill.   Tape it on the top side of the baseplate with a clear section 
over the 3/8" hole the camera is looking up through.  Set the drill to 
down stop just after drilling through this plastic (so you don't hit the 
lens below) and drill a hole with your smallest intended drill.  Now, 
although the drill moves through the image, the hole in the  plastic is 
fixed and exactly where the drill will be.  Put your PCB with the traces 
face down on the baseplate and center a spot you want to drill in the 
center of that hole.  Drill.  You' can easily drill within  0.005" or 
even better if you want to take the time, with no problem.  The 3/8" 
view allows you to see traces around the hole and allow you to know 
where you are on the PCB.

The particular web cam I used was a"Gear Head" unit that comes with 
AmCap software.  It is fairly low resolution, and noisy, but it has in 
addition to the screw lens with enough throw to focus close, the 
capability of having the left-right, up-down reversed in the AmCap 
software.  So when I slide the PCB left, the image moves left.  This 
definitely makes like easier.

Regards,
Charles R. Patton

  . On 6/9/2011 1:16 PM, Bruce Parham wrote:
>
>
> > Hello Group
> >
> > I have a quick question about precision drilling of home made PCBs.
> >
> > Because of poor eyesight, I use a CCD microscope next to my Dremel
> > Model 300 drill press stand. Although this set up is a big improvement
> > over doing thing solely 'by eye', there is a parallax error introduced
> > between the location of the retracted drill tip and where it 
> eventually comes in contact with the PCB. Once I saw a milling machine 
> where one
> > was able to sight straight down into a bulls eye. Is there a way to
> > rig mirrors to do this?
> >
> > P.S. Sincle sided boards are no problem, as I can hold them up to
> > strong light and position a hand held rotary tool with good enough
> > accuracy.
> >
> > Any suggestions would be appreciated.
> >
> > Cheers
> >
> > Chris
> >
> Hi Chris,
>
> You might try to find a metallic first surface mirror that you can
> drill a small hole into on a 45 degree angle
> and mount onto your drill stand with the drill bit going through the
> hole. Position the camera so it looks into
> the mirror from the side and down the drill via the mirror.
>
> A less elegant method is to use two point source lights (small halogen
> desk lamps) mounted 90 degrees apart
> and pointed toward the drill tip. As the drill tip approaches the board,
> the shadows will converge on the target.
>
> Bruce
>
> 



[Non-text portions of this message have been removed]

Do you have a picture of the setup?

 

  _____  

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Charles R. Patton
Sent: Thursday, June 09, 2011 6:33 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Precision Drilling of PCBs

 

  

I have an old small miniature precision drill press. I drilled a 3/8" 
hole on centerline with the drill bit and cut a pocket in the underside 
of the base plate and put a piece of 1/8" thick plastic in the pocket. 
The plastic also has a 3/8" hole in line with the baseplate. I lined 
the hole in the plastic with 3 white SMT LEDs cocked to throw their 
light up through the hole. Next I took a cheap ($10) webcam that has a 
lens that can be hand adjusted to focus at about 1/2" (Just keep 
screwing it out until it focuses on a board placed on the top side of 
the base.and pressure loaded it into place with a spring loaded clamp 
(made from 1/2 of a small desk fan clip-on clamp.) There is still a 
problem in that the "boresight" will be likely be twisted in relation 
to the flat of the lens. I.e., when you look at the drill come down 
toward the lens, it will look like it is coming from one side or 
another. The solution I arrived at to circumvent that (as I tried to 
physically adjust it, and it was just too much of a pain) is take a 
vacuum formed transparent carton of about 0.010" thick sheet such as 
sold in the grocery store that contains fruit like tomatoes, cherries, 
strawberries, etc. Cut out a clear, un-molded portion (typically in 
the lid) and preferably about twice as big as the board you want to 
drill. Tape it on the top side of the baseplate with a clear section 
over the 3/8" hole the camera is looking up through. Set the drill to 
down stop just after drilling through this plastic (so you don't hit the 
lens below) and drill a hole with your smallest intended drill. Now, 
although the drill moves through the image, the hole in the plastic is 
fixed and exactly where the drill will be. Put your PCB with the traces 
face down on the baseplate and center a spot you want to drill in the 
center of that hole. Drill. You' can easily drill within 0.005" or 
even better if you want to take the time, with no problem. The 3/8" 
view allows you to see traces around the hole and allow you to know 
where you are on the PCB.

The particular web cam I used was a"Gear Head" unit that comes with 
AmCap software. It is fairly low resolution, and noisy, but it has in 
addition to the screw lens with enough throw to focus close, the 
capability of having the left-right, up-down reversed in the AmCap 
software. So when I slide the PCB left, the image moves left. This 
definitely makes like easier.

Regards,
Charles R. Patton

. On 6/9/2011 1:16 PM, Bruce Parham wrote:
>
>
> > Hello Group
> >
> > I have a quick question about precision drilling of home made PCBs.
> >
> > Because of poor eyesight, I use a CCD microscope next to my Dremel
> > Model 300 drill press stand. Although this set up is a big improvement
> > over doing thing solely 'by eye', there is a parallax error introduced
> > between the location of the retracted drill tip and where it 
> eventually comes in contact with the PCB. Once I saw a milling machine 
> where one
> > was able to sight straight down into a bulls eye. Is there a way to
> > rig mirrors to do this?
> >
> > P.S. Sincle sided boards are no problem, as I can hold them up to
> > strong light and position a hand held rotary tool with good enough
> > accuracy.
> >
> > Any suggestions would be appreciated.
> >
> > Cheers
> >
> > Chris
> >
> Hi Chris,
>
> You might try to find a metallic first surface mirror that you can
> drill a small hole into on a 45 degree angle
> and mount onto your drill stand with the drill bit going through the
> hole. Position the camera so it looks into
> the mirror from the side and down the drill via the mirror.
>
> A less elegant method is to use two point source lights (small halogen
> desk lamps) mounted 90 degrees apart
> and pointed toward the drill tip. As the drill tip approaches the board,
> the shadows will converge on the target.
>
> Bruce
>
> 

[Non-text portions of this message have been removed]





[Non-text portions of this message have been removed]

On Thu, 09 Jun 2011 17:30:26 -0000, you wrote:

>Hello Group
>
>I have a quick question about precision drilling of home made PCBs.
>
>Because of poor eyesight, I use a CCD microscope next to my Dremel
>Model 300 drill press stand.  Although this set up is a big improvement
>over doing thing solely 'by eye', there is a parallax error introduced
>between the location of the retracted drill tip and where it eventually comes in contact with the PCB.  Once I saw a milling machine where one
>was able to sight straight down into a bulls eye.  Is there a way to 
>rig mirrors to do this?  

Drill from the bottom up.  Use your CCD microscope to focus on the
hole.  Put red tape or the like on the screen to indicate the location
of the hole as you drill with a blank board.  That locates the hole on
the screen.

Harvey

>
>P.S. Sincle sided boards are no problem, as I can hold them up to
>strong light and position a hand held rotary tool with good enough 
>accuracy.  
>
>Any suggestions would be appreciated.
>
>Cheers
>
>Chris 
>
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

If you have a motorized XY table (such as a CNC sherline mill), you could
mount the camera with some cross hairs and have a drill button that will
offset correctly automatically and drill.

Alternatively you could use a manual XY table with a digital readout and
again offset the known distance.  You could even do it manually.  Your work
flow would be see hole in crosshairs, move known XY offset, drill, move back
known XY, repeat.

Henry

On Thu, Jun 9, 2011 at 3:09 PM, Lawrence Kincheloe <lokimail@...>wrote:

>
>
> If I understand the problem correctly...
>
> An easier solution might be to map out the distortion using something like
> grid paper and use a clear stencil for "cross-hair" like grid lines.
>
>
> On Thu, Jun 9, 2011 at 4:30 PM, Leon Heller <leon355@...>
> wrote:
>
> >
> >
> > On 09/06/2011 20:51, Boman33 wrote:
> > > A very long time ago commercial hand drilling was done with the drill
> > > mounted under a table and a microscope with cross hairs was used on the
> > top.
> > > The drill was on an air cylinder so when things were lined up a
> > footswitch
> > > was pushed. No parallax. A similar rig was also used to create a NC
> paper
> > > tape so additional boards could be drill automatically.
> >
> > They had one of those at a French university where a friend of mine
> > works. I tried it out when I was working there, and it works very well.
> > They got rid of it when they closed down their in-house PCB fabrication
> > facility. It was made by Excellon, who invented the drill file format
> > that we still use. Someone in the UK actually offered me one of those
> > machines three or four years ago, but I wouldn't be able to get it up
> > the stairs here.
> >
> > Leon
> > --
> > Leon Heller
> > G1HSM
> >
> >
> >
>
> [Non-text portions of this message have been removed]
>
>  
>


[Non-text portions of this message have been removed]

Hi,

I've logged way more hours than I care to remember on a Exelon bottom drill
and it was hands down the best way to drill accurate holes in PCB
prototypes. The largest board I did as I recall had about 4,500 holes. Only
broken drills were when I did something stupid like not set the feed
correctly. We normally drilled boards 5 up. I had replaced the original pure
optical targeting with a B&W CCTV camera (it was the mid 70's). The
alignment was easy. Turn-on the camera and monitor, let them warm-up for an
hour. Then we drilled a single hole in a waste area with the board clamped
in position, taped a large target to center the hole. A .030 hole was about
5 inches across, you would be amazed at how accurate the human hand is with
good visual feedback. The nice thing about the bottom drill was all the
waste was on the bottom so the optics stayed clean.

Anyway I've moved on from the PCB business after the EPA started closing
down the small PCB houses. Now working at Microsoft as a SAN engineer and
doing hobby CNC systems in my spare time. The point is I use a very nice
software package called CentreCam for optical alignment/edge finding and
measurement on my CNC. 

I have no association with them just like and use their product. With it you
can overlay several different types of targets on a webcam image. In the
link provided just click on the Software Download button. You do need to
provide Email, Name and Country I've never gotten any spam from them.

http://www.miketreth.mistral.co.uk/centrecam.htm


Thanks,

Ron Cody
KF7MKY

"Good decisions come from experience, experience comes from bad decisions."

-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
On Behalf Of Henry Liu
Sent: June 09, 2011 11:22 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Precision Drilling of PCBs

If you have a motorized XY table (such as a CNC sherline mill), you could
mount the camera with some cross hairs and have a drill button that will
offset correctly automatically and drill.

Alternatively you could use a manual XY table with a digital readout and
again offset the known distance.  You could even do it manually.  Your work
flow would be see hole in crosshairs, move known XY offset, drill, move back
known XY, repeat.

Henry

On Thu, Jun 9, 2011 at 3:09 PM, Lawrence Kincheloe
<lokimail@...>wrote:

>
>
> If I understand the problem correctly...
>
> An easier solution might be to map out the distortion using something like
> grid paper and use a clear stencil for "cross-hair" like grid lines.
>
>
> On Thu, Jun 9, 2011 at 4:30 PM, Leon Heller <leon355@...>
> wrote:
>
> >
> >
> > On 09/06/2011 20:51, Boman33 wrote:
> > > A very long time ago commercial hand drilling was done with the drill
> > > mounted under a table and a microscope with cross hairs was used on
the
> > top.
> > > The drill was on an air cylinder so when things were lined up a
> > footswitch
> > > was pushed. No parallax. A similar rig was also used to create a NC
> paper
> > > tape so additional boards could be drill automatically.
> >
> > They had one of those at a French university where a friend of mine
> > works. I tried it out when I was working there, and it works very well.
> > They got rid of it when they closed down their in-house PCB fabrication
> > facility. It was made by Excellon, who invented the drill file format
> > that we still use. Someone in the UK actually offered me one of those
> > machines three or four years ago, but I wouldn't be able to get it up
> > the stairs here.
> >
> > Leon
> > --
> > Leon Heller
> > G1HSM
> >
> >
> >
>
> [Non-text portions of this message have been removed]
>
>  
>


[Non-text portions of this message have been removed]



------------------------------------

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

On 11/06/2011 02:16, Ronald Cody wrote:
> Hi,
>
> I've logged way more hours than I care to remember on a Exelon bottom drill
> and it was hands down the best way to drill accurate holes in PCB
> prototypes.

I liked the clamp mechanism that secured the board when the pedal was 
pressed.

Leon
-- 
Leon Heller
G1HSM

Hello Group 

I have received many great suggestions.  Thanks very much!

It seems like all of them would work.  Although bottom drilling seems
like the most accurate 'manual' method, it would be impractical with my Dremel drill press stand.  Likewise, placing a front surface mirror around the drill bit would be mechanically cumberrsome.  After thinking about it for a while, I have decided to place an angled FS mirror and CCD camera beneath the drill platform.  This setup would have the additional advantage of keeping all elements aligned and would be very easy to calibrate.  Although there may be a problem with lighting the underside of the drill platform, my CCD has led illumination.  Hopefully, the mirror should serve the dual function of conveying the image and illuminating it.  

Yesterday, I mail ordered an FS mirror, got some wood and built the contraption.  Hopefully, the contraption should work after the mirror arrives!

Thanks again for all your sage advice!

Cheers

Chris (W1EH)
--- In Homebrew_PCBs@yahoogroups.com, "schenckcharles" <schenckcharles@...> wrote:

>
> Hello Group
> 
> I have a quick question about precision drilling of home made PCBs.
> 
> Because of poor eyesight, I use a CCD microscope next to my Dremel
> Model 300 drill press stand.  Although this set up is a big improvement
> over doing thing solely 'by eye', there is a parallax error introduced
> between the location of the retracted drill tip and where it eventually comes in contact with the PCB.  Once I saw a milling machine where one
> was able to sight straight down into a bulls eye.  Is there a way to 
> rig mirrors to do this?  
> 
> P.S. Sincle sided boards are no problem, as I can hold them up to
> strong light and position a hand held rotary tool with good enough 
> accuracy.  
> 
> Any suggestions would be appreciated.
> 
> Cheers
> 
> Chris
>

One possible problem with using a front surface mirror is that due to 
the size of your camera, you may find the the distance from the lens to 
the board surface is longer than if you can mount the camera somewhat 
more in the vein of my previous suggestion of directly underneath.  The 
downside side of mounting with a longer optical path is that the image 
magnification will thereby be lessened and with low resolution webcams, 
this can significantly affect your ability to resolve where your drill 
will hit.  This factor is why I tried to make the lighting very thin and 
get the lens front as close as I reasonable could from the underside.  
As a side note:  By the use of the clear plastic with the drilled hole 
on the top side, even though I'm drilling with the camera underneath, I 
have surprisingly little drill dust coming down on the lens.  Apparently 
the drill acts as a pump and draws the dust up and away.

Another observation: About the technique of putting a marker on the 
screen.  I tried this early on and found that there was significant 
error having to do with the parallax error due to the thickness of the 
glass on an LCD screen.  In my case, I have a thicker than normal glass 
as I have added anti-reflection coated museum quality glass (such as 
used for photo and  painting) mountings. But I also noticed that the 
point seemed to drift -- probably because of camera thermal mechanical 
instabilities.    This thermal mechanism will be worse with the front 
surface mirror due to extra mechanical "stuff"  and that coupled with 
the smaller image of the pads may be something to watch out for.

And a final warning as I mentioned in  a previous post on this subject.  
Watch out when drilling.  As you concentrate on the screen, you can't 
see where your hands are in relation to the drill.  I started drilling 
my thumb -- not a good thing to do.  Now I'm definitely more careful to 
look out and take care that as I move the PCB, that I haven't placed a 
finger in the drill path.

(Also someone requested photos of my setup -- I'll try to get take some 
next week -- I'm tied up with a consulting project right now.)

Regards,
Charles R. Patton

On 6/12/2011 10:08 AM, schenckcharles wrote:
>
>
> Hello Group
>
> I have received many great suggestions. Thanks very much!
>
> It seems like all of them would work. Although bottom drilling seems
> like the most accurate 'manual' method, it would be impractical with 
> my Dremel drill press stand. Likewise, placing a front surface mirror 
> around the drill bit would be mechanically cumberrsome. After thinking 
> about it for a while, I have decided to place an angled FS mirror and 
> CCD camera beneath the drill platform. This setup would have the 
> additional advantage of keeping all elements aligned and would be very 
> easy to calibrate. Although there may be a problem with lighting the 
> underside of the drill platform, my CCD has led illumination. 
> Hopefully, the mirror should serve the dual function of conveying the 
> image and illuminating it.
>
> Yesterday, I mail ordered an FS mirror, got some wood and built the 
> contraption. Hopefully, the contraption should work after the mirror 
> arrives!
>
> Thanks again for all your sage advice!
>
> Cheers
>
> Chris (W1EH)
> --- In Homebrew_PCBs@yahoogroups.com 
> <mailto:Homebrew_PCBs%40yahoogroups.com>, "schenckcharles" 
> <schenckcharles@...> wrote:
> >
> > Hello Group
> >
> > I have a quick question about precision drilling of home made PCBs.
> >
> > Because of poor eyesight, I use a CCD microscope next to my Dremel
> > Model 300 drill press stand. Although this set up is a big improvement
> > over doing thing solely 'by eye', there is a parallax error introduced
> > between the location of the retracted drill tip and where it 
> eventually comes in contact with the PCB. Once I saw a milling machine 
> where one
> > was able to sight straight down into a bulls eye. Is there a way to
> > rig mirrors to do this?
> >
> > P.S. Sincle sided boards are no problem, as I can hold them up to
> > strong light and position a hand held rotary tool with good enough
> > accuracy.
> >
> > Any suggestions would be appreciated.
> >
> > Cheers
> >
> > Chris
> >
>
> 
> Reply to sender 
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