Homebrew_PCBs

Well, I've done some tests trying it the easy way, and while it
SHOULD work, it doesn't, at least not consistently. The problem is
that both the carrier and the board are (obviously) much thicker than
paper, and when they hit the drum/transfer roller interface there is
a slight (and variable) delay as first the carrier and then the board
go through. There are also problems in the X axis because the carrier
"grabs" slightly when it hits the drum and has a tendency to get a
little out of parallel to the motion axis. In theory we could wait
till the pcb (or a "header" of equal thickness) is under the drum
before telling it to print. However, this may create problems in the
charging timing since the printer does not expect there to be a board
present at that time. The X axis problem could be handled with a
better and longer carrier guide, but too much friction would create
its own problems.

There is no reason that DLP can't do ds boards, but I'm far from sure
that the mechanics of your typical laser printer can be "bulked up"
enough mechanically to produce consistent results. Probably the best
way to do ds DLP would be to make a flatbed laser system, much as has
been done for inkjets. Print one side, put it in an oven to fix the
toner, flip it and print the other side.

This would also be the way to go for a commercial product - anyone
interested in collaborating?

Mark

As Harvey just said, I think it would be easier to just glue two thin boards together to make a ds board. They don't even have to be the same thickness. If you want to get cute you might even make both pieces from ds stock and leave a lot of copper on the "hidden" side of each. Coat some solder paste on the copper, clamp it and put it in the oven to solder the two boards together. This (and gluing) might be a problem if you reflow the boards, but you might be able get some high temperature epoxy.

Mark


-----Original Message-----

>From: Mark Lerman <mlerman@...>
>Sent: May 23, 2010 11:29 AM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] DLP Double Sided Update
>
>Well, I've done some tests trying it the easy way, and while it
>SHOULD work, it doesn't, at least not consistently. The problem is
>that both the carrier and the board are (obviously) much thicker than
>paper, and when they hit the drum/transfer roller interface there is
>a slight (and variable) delay as first the carrier and then the board
>go through. There are also problems in the X axis because the carrier
>"grabs" slightly when it hits the drum and has a tendency to get a
>little out of parallel to the motion axis. In theory we could wait
>till the pcb (or a "header" of equal thickness) is under the drum
>before telling it to print. However, this may create problems in the
>charging timing since the printer does not expect there to be a board
>present at that time. The X axis problem could be handled with a
>better and longer carrier guide, but too much friction would create
>its own problems.
>
>There is no reason that DLP can't do ds boards, but I'm far from sure
>that the mechanics of your typical laser printer can be "bulked up"
>enough mechanically to produce consistent results. Probably the best
>way to do ds DLP would be to make a flatbed laser system, much as has
>been done for inkjets. Print one side, put it in an oven to fix the
>toner, flip it and print the other side.
>
>This would also be the way to go for a commercial product - anyone
>interested in collaborating?
>
>Mark
>
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Mark, didn't we just make the DS board up of two SS ones stuck
together so we avoid printing on the other side?
Using two DS boards doesn't seem to help with that.
Just a thought.... ;-)


ST

On Sun, May 23, 2010 at 7:08 PM, <mlerman@...> wrote:
> If you want to get cute you might even make both pieces from ds stock and leave a lot of copper on the "hidden" side of each.
> Coat some solder paste on the copper, clamp it and put it in the oven to solder the two boards together.

Of course, but if we use black tape or resist tape or a Sharpie to mask off the outer 1/2 inch or so along the edges of the bottom side of the top board and the top side of the bottom board before etching we will be left with a copper pattern in the hidden layers that can be easily soldered.

Mark


-----Original Message-----

>From: Stefan Trethan <stefan_trethan@...>
>Sent: May 23, 2010 1:13 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] DLP Double Sided Update
>
>Mark, didn't we just make the DS board up of two SS ones stuck
>together so we avoid printing on the other side?
>Using two DS boards doesn't seem to help with that.
>Just a thought.... ;-)
>
>
>ST
>
>On Sun, May 23, 2010 at 7:08 PM, <mlerman@...> wrote:
>> If you want to get cute you might even make both pieces from ds stock and leave a lot of copper on the "hidden" side of each.
>> Coat some solder paste on the copper, clamp it and put it in the oven to solder the two boards together.
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Put the carrier on a rail so it cannot move side to side but still (be
adjusted?) move up n down.
Then have a raised area (maybe a square) to butt the PCB (corner) up
against ... there may be other details that
that need attention ... but this may be a start.
When the PCB/carrier is staged (prior to print) maybe the x and y could
be trimmed.
There would have to be a fiducial mark on each side of the blank PCB.
Jim KI6MZ

Mark Lerman wrote:

> Well, I've done some tests trying it the easy way, and while it
> SHOULD work, it doesn't, at least not consistently. The problem is
> that both the carrier and the board are (obviously) much thicker than
> paper, and when they hit the drum/transfer roller interface there is
> a slight (and variable) delay as first the carrier and then the board
> go through. There are also problems in the X axis because the carrier
> "grabs" slightly when it hits the drum and has a tendency to get a
> little out of parallel to the motion axis. In theory we could wait
> till the pcb (or a "header" of equal thickness) is under the drum
> before telling it to print. However, this may create problems in the
> charging timing since the printer does not expect there to be a board
> present at that time. The X axis problem could be handled with a
> better and longer carrier guide, but too much friction would create
> its own problems.
>
> There is no reason that DLP can't do ds boards, but I'm far from sure
> that the mechanics of your typical laser printer can be "bulked up"
> enough mechanically to produce consistent results. Probably the best
> way to do ds DLP would be to make a flatbed laser system, much as has
> been done for inkjets. Print one side, put it in an oven to fix the
> toner, flip it and print the other side.
>
> This would also be the way to go for a commercial product - anyone
> interested in collaborating?
>
> Mark
>
>
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>
>
>

Hi Jim,

I have a cnc pcb router that registers by 2 holes. What I thought for this was a hole near the top and a slot on the bottom of the blank pcb. I would then print a line down the exact middle of the carrier and drill a hole to mate with the one on the board. The hole wold fix the top and the slot would align the bottom. Put a pin through the holes, align the slot with the line, tape the top and bottom of the pcb to the carrier, remove the pin. Then print the top, remove the pcb and put it in the oven to fix, then flip it over and pin and tape as above to do the bottom as a mirror.

That would work fine if I could be sure the carrier hit the print point at the exact same time each run. However, due to slippage, I can't. The best way I can think of is to get the carrier rolling and have a sensor that triggers the print well after the carrier gets under the drum. This can be done, but I'm not entirely sure it is worth the effort.

Mark
-----Original Message-----

>From: Jim <jhutch17@...>
>Sent: May 23, 2010 3:06 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] DLP Double Sided Update
>
>Put the carrier on a rail so it cannot move side to side but still (be
>adjusted?) move up n down.
>Then have a raised area (maybe a square) to butt the PCB (corner) up
>against ... there may be other details that
>that need attention ... but this may be a start.
>When the PCB/carrier is staged (prior to print) maybe the x and y could
>be trimmed.
>There would have to be a fiducial mark on each side of the blank PCB.
>Jim KI6MZ
>
>Mark Lerman wrote:
>> Well, I've done some tests trying it the easy way, and while it
>> SHOULD work, it doesn't, at least not consistently. The problem is
>> that both the carrier and the board are (obviously) much thicker than
>> paper, and when they hit the drum/transfer roller interface there is
>> a slight (and variable) delay as first the carrier and then the board
>> go through. There are also problems in the X axis because the carrier
>> "grabs" slightly when it hits the drum and has a tendency to get a
>> little out of parallel to the motion axis. In theory we could wait
>> till the pcb (or a "header" of equal thickness) is under the drum
>> before telling it to print. However, this may create problems in the
>> charging timing since the printer does not expect there to be a board
>> present at that time. The X axis problem could be handled with a
>> better and longer carrier guide, but too much friction would create
>> its own problems.
>>
>> There is no reason that DLP can't do ds boards, but I'm far from sure
>> that the mechanics of your typical laser printer can be "bulked up"
>> enough mechanically to produce consistent results. Probably the best
>> way to do ds DLP would be to make a flatbed laser system, much as has
>> been done for inkjets. Print one side, put it in an oven to fix the
>> toner, flip it and print the other side.
>>
>> This would also be the way to go for a commercial product - anyone
>> interested in collaborating?
>>
>> Mark
>>
>>
>>
>>
>>
>> ------------------------------------
>>
>> Be sure to visit the group home and check for new Links, Files, and Photos:
>> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>>
>>
>>
>>
>>
>>
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

The two hole alignment system is a good way to align the PCB in X and Y
to the carrier ... the carrier X location is known with the added sensor
... carrier Y is not yet known or controlled.
I think this is two separate problems 1)locating the PCB relative to the
carrier and 2)locating the carrier relative to the printer.
I don't have the printer modification finished yet. Still scratching my
head on the cutting of the paper platform. I'm leaning toward your way
with the dremel tool. When finished, I will be able to observe the
operation of the carrier/printer. ... I'm sure you will have the problem
solved by then. ... I will cut tomorrow and then re-assemble. (I don't
have a day job to get in my way!)
Jim KI6JMZ

mlerman@... wrote:

> Hi Jim,
>
> I have a cnc pcb router that registers by 2 holes. What I thought for this was a hole near the top and a slot on the bottom of the blank pcb. I would then print a line down the exact middle of the carrier and drill a hole to mate with the one on the board. The hole wold fix the top and the slot would align the bottom. Put a pin through the holes, align the slot with the line, tape the top and bottom of the pcb to the carrier, remove the pin. Then print the top, remove the pcb and put it in the oven to fix, then flip it over and pin and tape as above to do the bottom as a mirror.
>
> That would work fine if I could be sure the carrier hit the print point at the exact same time each run. However, due to slippage, I can't. The best way I can think of is to get the carrier rolling and have a sensor that triggers the print well after the carrier gets under the drum. This can be done, but I'm not entirely sure it is worth the effort.
>
> Mark
> -----Original Message-----
>
>> From: Jim <jhutch17@...>
>> Sent: May 23, 2010 3:06 PM
>> To: Homebrew_PCBs@yahoogroups.com
>> Subject: Re: [Homebrew_PCBs] DLP Double Sided Update
>>
>> Put the carrier on a rail so it cannot move side to side but still (be
>> adjusted?) move up n down.
>> Then have a raised area (maybe a square) to butt the PCB (corner) up
>> against ... there may be other details that
>> that need attention ... but this may be a start.
>> When the PCB/carrier is staged (prior to print) maybe the x and y could
>> be trimmed.
>> There would have to be a fiducial mark on each side of the blank PCB.
>> Jim KI6MZ
>>
>> Mark Lerman wrote:
>>
>>> Well, I've done some tests trying it the easy way, and while it
>>> SHOULD work, it doesn't, at least not consistently. The problem is
>>> that both the carrier and the board are (obviously) much thicker than
>>> paper, and when they hit the drum/transfer roller interface there is
>>> a slight (and variable) delay as first the carrier and then the board
>>> go through. There are also problems in the X axis because the carrier
>>> "grabs" slightly when it hits the drum and has a tendency to get a
>>> little out of parallel to the motion axis. In theory we could wait
>>> till the pcb (or a "header" of equal thickness) is under the drum
>>> before telling it to print. However, this may create problems in the
>>> charging timing since the printer does not expect there to be a board
>>> present at that time. The X axis problem could be handled with a
>>> better and longer carrier guide, but too much friction would create
>>> its own problems.
>>>
>>> There is no reason that DLP can't do ds boards, but I'm far from sure
>>> that the mechanics of your typical laser printer can be "bulked up"
>>> enough mechanically to produce consistent results. Probably the best
>>> way to do ds DLP would be to make a flatbed laser system, much as has
>>> been done for inkjets. Print one side, put it in an oven to fix the
>>> toner, flip it and print the other side.
>>>
>>> This would also be the way to go for a commercial product - anyone
>>> interested in collaborating?
>>>
>>> Mark
>>>
>>>
>>>
>>>
>>>
>>> ------------------------------------
>>>
>>> Be sure to visit the group home and check for new Links, Files, and Photos:
>>> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>> ------------------------------------
>>
>> Be sure to visit the group home and check for new Links, Files, and Photos:
>> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>>
>>
>>
>>
>
>
>
> ------------------------------------
>
> Be sure to visit the group home and check for new Links, Files, and Photos:
> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>
>
>
>

Jim,

The best way to see what's happening is from the bottom, though I haven't really done that myself. Remove the paper tray and suspend the printer while looking from the bottom.


BTW, since the drum is light sensitive I would suggest you leave the paper tray in and perhaps drape something over the rear of the printer when you are not using it. So far I have not had any trouble, but I try to be careful, though I often forget and just leave the printer exposed. Since the fuser is no longer there, you can see the drum from the rear.

Mark

-----Original Message-----

>From: Jim <jhutch17@...>
>Sent: May 23, 2010 8:58 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] DLP Double Sided Update
>
>The two hole alignment system is a good way to align the PCB in X and Y
>to the carrier ... the carrier X location is known with the added sensor
>... carrier Y is not yet known or controlled.
>I think this is two separate problems 1)locating the PCB relative to the
>carrier and 2)locating the carrier relative to the printer.
>I don't have the printer modification finished yet. Still scratching my
>head on the cutting of the paper platform. I'm leaning toward your way
>with the dremel tool. When finished, I will be able to observe the
>operation of the carrier/printer. ... I'm sure you will have the problem
>solved by then. ... I will cut tomorrow and then re-assemble. (I don't
>have a day job to get in my way!)
>Jim KI6JMZ
>
>mlerman@... wrote:
>> Hi Jim,
>>
>> I have a cnc pcb router that registers by 2 holes. What I thought for this was a hole near the top and a slot on the bottom of the blank pcb. I would then print a line down the exact middle of the carrier and drill a hole to mate with the one on the board. The hole wold fix the top and the slot would align the bottom. Put a pin through the holes, align the slot with the line, tape the top and bottom of the pcb to the carrier, remove the pin. Then print the top, remove the pcb and put it in the oven to fix, then flip it over and pin and tape as above to do the bottom as a mirror.
>>
>> That would work fine if I could be sure the carrier hit the print point at the exact same time each run. However, due to slippage, I can't. The best way I can think of is to get the carrier rolling and have a sensor that triggers the print well after the carrier gets under the drum. This can be done, but I'm not entirely sure it is worth the effort.
>>
>> Mark
>> -----Original Message-----
>>
>>> From: Jim <jhutch17@...>
>>> Sent: May 23, 2010 3:06 PM
>>> To: Homebrew_PCBs@yahoogroups.com
>>> Subject: Re: [Homebrew_PCBs] DLP Double Sided Update
>>>
>>> Put the carrier on a rail so it cannot move side to side but still (be
>>> adjusted?) move up n down.
>>> Then have a raised area (maybe a square) to butt the PCB (corner) up
>>> against ... there may be other details that
>>> that need attention ... but this may be a start.
>>> When the PCB/carrier is staged (prior to print) maybe the x and y could
>>> be trimmed.
>>> There would have to be a fiducial mark on each side of the blank PCB.
>>> Jim KI6MZ
>>>
>>> Mark Lerman wrote:
>>>
>>>> Well, I've done some tests trying it the easy way, and while it
>>>> SHOULD work, it doesn't, at least not consistently. The problem is
>>>> that both the carrier and the board are (obviously) much thicker than
>>>> paper, and when they hit the drum/transfer roller interface there is
>>>> a slight (and variable) delay as first the carrier and then the board
>>>> go through. There are also problems in the X axis because the carrier
>>>> "grabs" slightly when it hits the drum and has a tendency to get a
>>>> little out of parallel to the motion axis. In theory we could wait
>>>> till the pcb (or a "header" of equal thickness) is under the drum
>>>> before telling it to print. However, this may create problems in the
>>>> charging timing since the printer does not expect there to be a board
>>>> present at that time. The X axis problem could be handled with a
>>>> better and longer carrier guide, but too much friction would create
>>>> its own problems.
>>>>
>>>> There is no reason that DLP can't do ds boards, but I'm far from sure
>>>> that the mechanics of your typical laser printer can be "bulked up"
>>>> enough mechanically to produce consistent results. Probably the best
>>>> way to do ds DLP would be to make a flatbed laser system, much as has
>>>> been done for inkjets. Print one side, put it in an oven to fix the
>>>> toner, flip it and print the other side.
>>>>
>>>> This would also be the way to go for a commercial product - anyone
>>>> interested in collaborating?
>>>>
>>>> Mark
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ------------------------------------
>>>>
>>>> Be sure to visit the group home and check for new Links, Files, and Photos:
>>>> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>> ------------------------------------
>>>
>>> Be sure to visit the group home and check for new Links, Files, and Photos:
>>> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>>>
>>>
>>>
>>>
>>
>>
>>
>> ------------------------------------
>>
>> Be sure to visit the group home and check for new Links, Files, and Photos:
>> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>>
>>
>>
>>
>>
>>
>
>
>
>
>------------------------------------
>
>Be sure to visit the group home and check for new Links, Files, and Photos:
>http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
>
>
>

Insofar as the Y axis, you could try running the motor for the paper path
rollers though your microcontroller, then you could modulate the speed of
the motor after it has already engaged the board but before the printing has
started, until the correct alignment criteria have been met.

I can't think of much you can do about the X axis other than bulking up the
mechnical rigidness of the printer, and there are limits to that.

It'd be interesting to see a true flatbed implementation of the DLP process,
though I haven't done enough with laser printers to have a good feel for
what would be involved.

-Andrew

On Sun, May 23, 2010 at 11:29 AM, Mark Lerman <mlerman@...> wrote:

>
>
> Well, I've done some tests trying it the easy way, and while it
> SHOULD work, it doesn't, at least not consistently. The problem is
> that both the carrier and the board are (obviously) much thicker than
> paper, and when they hit the drum/transfer roller interface there is
> a slight (and variable) delay as first the carrier and then the board
> go through. There are also problems in the X axis because the carrier
> "grabs" slightly when it hits the drum and has a tendency to get a
> little out of parallel to the motion axis. In theory we could wait
> till the pcb (or a "header" of equal thickness) is under the drum
> before telling it to print. However, this may create problems in the
> charging timing since the printer does not expect there to be a board
> present at that time. The X axis problem could be handled with a
> better and longer carrier guide, but too much friction would create
> its own problems.
>
> There is no reason that DLP can't do ds boards, but I'm far from sure
> that the mechanics of your typical laser printer can be "bulked up"
> enough mechanically to produce consistent results. Probably the best
> way to do ds DLP would be to make a flatbed laser system, much as has
> been done for inkjets. Print one side, put it in an oven to fix the
> toner, flip it and print the other side.
>
> This would also be the way to go for a commercial product - anyone
> interested in collaborating?
>
> Mark
>
>


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

To those who have been following the DLP thread(s):

I have spent the last few weeks experimenting with producing double sided pcbs with my E260 laser printer. What I found is that the hack I have documented is not adequate for DS boards. The repeatability is almost perfect in the X axis, but the Y axis (defined as the axis through the printer) varies a bit, sometimes quite a bit, from run to run.

The problem is that the paper path is not quite straight, which results in some friction and hesitation as the carrier moves, especially as it traverses the space between the input rollers and the transfer roller. Once the carrier enters the printing area it seems to move at a constant rate.

The biggest culprit is the Manual Feed Paper Guide which forces the carrier to actually bend a bit. In fact, if you tape the rear edge of the pcb to the carrier, the top surface of the pcb will touch the 4mm shaft, causing (in the worst case) the timing to be so bad that either the carrier stops moving or the printer errors out.


I have redesigned and redocumented the hack and will be uploading the latest version in the next few days. This only works with the MCU version of the Modification! The changes are:

1 - The input rollers now use a 5 mm shaft and 13 mm rollers instead of the 4 and 10 currently used. I upped the shaft diameter because the 4 mm shaft fits too loosely in the notches. You can still use the 4mm shaft if you already bought it by wrapping 5 or so turns of electrical tape around the ends to bulk them up to about 5mm. The added 3 mm to the roller diameter allows pcbs to easily fit under the shaft as the carrier advances. Both the shaft collars and aluminum spacers (rollers) are now 5mm ID. That said, if you already have the 10mm rollers they will still work, although thick pcbs might be a bit dicey.

2 - The Manual Feed paper Guide is not used and can be discarded.

3 - I have also deleted the Center Bracket. It is not necessary since the corrected paper path now feeds the carrier in a very straight line and does not touch the Center Bracket.

4 - The reflective sensor is not used as the NPIS. Instead we are using the U shaped transmissive sensor that was originally called the Narrow Media Sensor. It is mounted on a small piece of aluminum angle that also acts as a centering guide. This new bracket is mounted on the swing-down Front Cover.

There are a few other changes that make the conversion a bit easier. More details on both the improved hack and double sided boards to come.

Mark

Mark,
Thanks for that, very timely... I am holding all the components for the MCU mod, but will wait for your revised mod and update my inventory; I hope to facilitate suitable DS-DLP for simple boards, without very fine pitch.
Roger

 

To those who have been following the DLP thread(s):

I have spent the last few weeks experimenting with producing double sided pcbs with my E260 laser printer. What I found is that the hack I have documented is not adequate for DS boards. The repeatability is almost perfect in the X axis, but the Y axis (defined as the axis through the printer) varies a bit, sometimes quite a bit, from run to run.

The problem is that the paper path is not quite straight, which results in some friction and hesitation as the carrier moves, especially as it traverses the space between the input rollers and the transfer roller. Once the carrier enters the printing area it seems to move at a constant rate.

The biggest culprit is the Manual Feed Paper Guide which forces the carrier to actually bend a bit. In fact, if you tape the rear edge of the pcb to the carrier, the top surface of the pcb will touch the 4mm shaft, causing (in the worst case) the timing to be so bad that either the carrier stops moving or the printer errors out.


I have redesigned and redocumented the hack and will be uploading the latest version in the next few days. This only works with the MCU version of the Modification! The changes are:

1 - The input rollers now use a 5 mm shaft and 13 mm rollers instead of the 4 and 10 currently used. I upped the shaft diameter because the 4 mm shaft fits too loosely in the notches. You can still use the 4mm shaft if you already bought it by wrapping 5 or so turns of electrical tape around the ends to bulk them up to about 5mm. The added 3 mm to the roller diameter allows pcbs to easily fit under the shaft as the carrier advances. Both the shaft collars and aluminum spacers (rollers) are now 5mm ID. That said, if you already have the 10mm rollers they will still work, although thick pcbs might be a bit dicey.

2 - The Manual Feed paper Guide is not used and can be discarded.

3 - I have also deleted the Center Bracket. It is not necessary since the corrected paper path now feeds the carrier in a very straight line and does not touch the Center Bracket.

4 - The reflective sensor is not used as the NPIS. Instead we are using the U shaped transmissive sensor that was originally called the Narrow Media Sensor. It is mounted on a small piece of aluminum angle that also acts as a centering guide. This new bracket is mounted on the swing-down Front Cover.

There are a few other changes that make the conversion a bit easier. More details on both the improved hack and double sided boards to come.

Mark

--
Dell XPS8700 256GB SSD 2TB HD 24.0 GB RAM Win8.1 64-bit Intel x64 8 Core(TM) i7-4770 CPU@3.40GHz 3.40 GHz

Hi Mark,
First of all I want to say thanks to You and Stefan for pioneering work for DIY prototypes.

I love your processes, development, and sharing of knowledge.

For multilayer boards, I've always been an advocate of printing single-sided thin
PCBs and layering them up as needed. On Ebay you can get the material in 5mil, 8mil and 10mil
 and if only double sided material, you can use the extra side as planes and isolate route or etch them
in an extra step. If my stackup is to thin, say for only 2 sides, I found bare FR4 that I use as a base
to bind the sides to for stiffness.

Alignment fudicials or targets are used for each pattern. Then after etching, I drill fine holes
through which I insert sewing needles or music wire to align during the stackup.

I was using 3M spray adhesive, but it can be unforgiving of misalignment. Someone mentioned a slower thin epoxy solution and that made sense for me. You just have to remove any epoxy 'extrusions' that occur from the holes.

So for me you process is darn near perfect, the added stability you propose is surely a benefit too.

I hope to get some pictures to share of results as time permits.

Best Regards, and sorry if I came across as pompous in the past, I was kidding.
Lee Studley

R. Lee Studley Senior Hardware / Software Engineer
Innovative Control Systems, Inc. (ICS)
10801 N. 24th Ave. Suite 103
Phoenix, AZ 85029

602-861-6984 Main Line
602-588-9440 FAX

www.icsaero.com 

On 26 Aug 2014 11:14:20 -0700, you wrote:

>Hi Mark,
>First of all I want to say thanks to You and Stefan for pioneering work for DIY prototypes.
>
>I love your processes, development, and sharing of knowledge.
>
>For multilayer boards, I've always been an advocate of printing single-sided thin
>PCBs and layering them up as needed. On Ebay you can get the material in 5mil, 8mil and 10mil
> and if only double sided material, you can use the extra side as planes and isolate route or etch them
>in an extra step. If my stackup is to thin, say for only 2 sides, I found bare FR4 that I use as a base
>to bind the sides to for stiffness.
>
>Alignment fudicials or targets are used for each pattern. Then after etching, I drill fine holes
>through which I insert sewing needles or music wire to align during the stackup.
>
>I was using 3M spray adhesive, but it can be unforgiving of misalignment. Someone mentioned a slower thin epoxy solution and that made sense for me. You just have to remove any epoxy 'extrusions' that occur from the holes.

Put a layer of masking tape over the boards when you epoxy them
together, and that keeps epoxy fingerprints from getting all over the
board. I use a "blue" tape simply because the adhesive is less
aggressive, and it's easier to get off.

Harvey

>
>So for me you process is darn near perfect, the added stability you propose is surely a benefit too.
>
>I hope to get some pictures to share of results as time permits.
>
>Best Regards, and sorry if I came across as pompous in the past, I was kidding.
>Lee Studley
>
> R. Lee Studley Senior Hardware / Software Engineer
>Innovative Control Systems, Inc. (ICS)
>10801 N. 24th Ave. Suite 103
>Phoenix, AZ 85029
>
>602-861-6984 Main Line
>602-588-9440 FAX
>
>www.icsaero.com http://www.icsaero.com/

Lee,

I agree that using two boards is pretty easy, but I'm enjoying the challenge! The way I am now doing it (experimental):

1 - Print a "centerline" on the carrier with a cross line near the top.
2 - Mark the approximate center of the pcb, making a pencil mark at the top (leading) edge of the board and the bottom edge.
3 - Use a box cutter to carefully cut a very thin groove through the top and bottom of the pcb, being careful that the cut is as perpendicular to the plane of the board as possible. This marks the center and is visible from both top and bottom surfaces of the board.
4 - Align the board on the carrier with the top "cut" at the cross on the carrier and the bottom cut on the centerline. Tape it in place, top and bottom.
5 - When you draw up the board, make a couple of alignment fiducials on the same place on both top and bottom.
6 - Print the top.
7 - Acetone vapor fix the top.
8 - Drill through the fiducial marks with a very small drill.
9 - Remount the board on the carrier, carefully aligning the "cuts" as in step 4.
10 - Print the bottom side (reverse!).

11 - Check to see if the bottom side fiducials are properly aligned over the holes. If not, just wipe the toner off with a paper towel, make any adjustments necessary in the print dialog to get the location better, then loop to step 10. DO NOT remove the pcb from the carrier to do this. The whole "run" takes just a few seconds.

12 - Once the alignment is true fix the bottom in acetone vapor.

13 - Etch!

Of course, everything depends on the printer being able to print the in the same place every time. I took a pcb and ran it through the printer 5 times, printing only a single dot. All the dots were within about .020 of each other, with most being on top of each other.

Mark




At 02:14 PM 8/26/2014, you wrote:

Hi Mark,
First of all I want to say thanks to You and Stefan for pioneering work for DIY prototypes.

I love your processes, development, and sharing of knowledge.

For multilayer boards, I've always been an advocate of printing single-sided thin
PCBs and layering them up as needed. On Ebay you can get the material in 5mil, 8mil and 10mil
 and if only double sided material, you can use the extra side as planes and isolate route or etch them
in an extra step. If my stackup is to thin, say for only 2 sides, I found bare FR4 that I use as a base
to bind the sides to for stiffness.

Alignment fudicials or targets are used for each pattern. Then after etching, I drill fine holes
through which I insert sewing needles or music wire to align during the stackup.

I was using 3M spray adhesive, but it can be unforgiving of misalignment. Someone mentioned a slower thin epoxy solution and that made sense for me. You just have to remove any epoxy 'extrusions' that occur from the holes.

So for me you process is darn near perfect, the added stability you propose is surely a benefit too.

I hope to get some pictures to share of results as time permits.

Best Regards, and sorry if I came across as pompous in the past, I was kidding.
Lee Studley

R. Lee Studley Senior Hardware / Software Engineer
Innovative Control Systems, Inc. (ICS)
10801 N. 24th Ave. Suite 103
Phoenix, AZ 85029

602-861-6984 Main Line
602-588-9440 FAX

www.icsaero.com

Have you posted your new mods for double sided boards?

Still writing the documentation but should have it up by the weekend.

Mark





At 10:57 AM 8/27/2014, you wrote:

Have you posted your new mods for double sided boards?

On Wed, 27 Aug 2014 06:22:57 -0700, you wrote:

>Couldn't you print two single sided boards on thin material then epoxy them together?
>
> 

I do.

Registration of the boards is critical.

Really critical.

When you do it properly, the boards work very well.

PS: in EAGLE (for instance), you print the bottom without mirrored,
and without upside down. Rotate the board to get the long axis
vertical on the printer.

For the top layer, do as above, but select mirrored and upside down.
This prints each part of the board on the same area of the bottom
board, so that the upper left parts of the board are printed upper
left (say) on the printout, and that holds for top and bottom. If
the printer has distortions due to paper feed, this tends to even them
out between the layers.

Harvey

Roger,

Did you get my email re reprogramming the board?

Mark


At 04:40 PM 8/25/2014, you wrote:

Mark,
Thanks for that, very timely... I am holding all the components for the MCU mod, but will wait for your revised mod and update my inventory; I hope to facilitate suitable DS-DLP for simple boards, without very fine pitch.
Roger

On 8/25/2014 12:41 PM, Mark Lerman mlerman@... [Homebrew_PCBs] wrote:

 


To those who have been following the DLP thread(s):

I have spent the last few weeks experimenting with producing double sided pcbs with my E260 laser printer. What I found is that the hack I have documented is not adequate for DS boards. The repeatability is almost perfect in the X axis, but the Y axis (defined as the axis through the printer) varies a bit, sometimes quite a bit, from run to run.

The problem is that the paper path is not quite straight, which results in some friction and hesitation as the carrier moves, especially as it traverses the space between the input rollers and the transfer roller. Once the carrier enters the printing area it seems to move at a constant rate.

The biggest culprit is the Manual Feed Paper Guide which forces the carrier to actually bend a bit. In fact, if you tape the rear edge of the pcb to the carrier, the top surface of the pcb will touch the 4mm shaft, causing (in the worst case) the timing to be so bad that either the carrier stops moving or the printer errors out.


I have redesigned and redocumented the hack and will be uploading the latest version in the next few days. This only works with the MCU version of the Modification! The changes are:

1 - The input rollers now use a 5 mm shaft and 13 mm rollers instead of the 4 and 10 currently used. I upped the shaft diameter because the 4 mm shaft fits too loosely in the notches. You can still use the 4mm shaft if you already bought it by wrapping 5 or so turns of electrical tape around the ends to bulk them up to about 5mm. The added 3 mm to the roller diameter allows pcbs to easily fit under the shaft as the carrier advances. Both the shaft collars and aluminum spacers (rollers) are now 5mm ID. That said, if you already have the 10mm rollers they will still work, although thick pcbs might be a bit dicey.

2 - The Manual Feed paper Guide is not used and can be discarded.

3 - I have also deleted the Center Bracket. It is not necessary since the corrected paper path now feeds the carrier in a very straight line and does not touch the Center Bracket.

4 - The reflective sensor is not used as the NPIS. Instead we are using the U shaped transmissive sensor that was originally called the Narrow Media Sensor. It is mounted on a small piece of aluminum angle that also acts as a centering guide. This new bracket is mounted on the swing-down Front Cover.

There are a few other changes that make the conversion a bit easier. More details on both the improved hack and double sided boards to come.

Mark

--
Dell XPS8700 256GB SSD 2TB HD 24.0 GB RAM Win8.1 64-bit Intel x64 8 Core(TM) i7-4770 CPU@3.40GHz 3.40 GHz

Mark,
Sorry for my slow response, too many things to do...
I expect to get the board in the mail within a day or two. I have trimmed the board to .95 x 1.55"; I hope that won't affect your holding method for programming. I'm about to review your latest Instructable; I will be updating  my parts inventory, and since I had already cut two sheet pieces to 12", I presume I'll need to include another sheet to meet the 14" callout .
Thanks,
Roger

 

Roger,

Did you get my email re reprogramming the board?

Mark

--

Dell XPS8700 256GB SSD 2TB HD 24.0 GB RAM Win8.1 64-bit Intel x64 8 Core(TM) i7-4770 CPU@3.40GHz 3.40 GHz

Roger,

You can probably make do with the 12". The advantage of the extra 2 inches is that the trailing end of the Carrier will still be in the rollers when the trailing end of a 6" long PCB is being printed. The MCU you have now is actually calibrated for an 11" carrier, but works okay for a 12 inch one. You could try it as is and see how it work for you. Or, send it back and I'll reprogram it for either 12 or 14 inches, your choice.

Mark


At 02:12 PM 9/4/2014, you wrote:

Mark,
Sorry for my slow response, too many things to do...
I expect to get the board in the mail within a day or two. I have trimmed the board to .95 x 1.55"; I hope that won't affect your holding method for programming. I'm about to review your latest Instructable; I will be updating  my parts inventory, and since I had already cut two sheet pieces to 12", I presume I'll need to include another sheet to meet the 14" callout .
Thanks,
Roger

On 9/4/2014 5:47 AM, Mark Lerman mlerman@... [Homebrew_PCBs] wrote:

 

Roger,

Did you get my email re reprogramming the board?

Mark

--
Dell XPS8700 256GB SSD 2TB HD 24.0 GB RAM Win8.1 64-bit Intel x64 8 Core(TM) i7-4770 CPU@3.40GHz 3.40 GHz

Mark,
I mailed the MCU out earlier today...
Many thanks,
Roger

 

Roger,

You can probably make do with the 12". The advantage of the extra 2 inches is that the trailing end of the Carrier will still be in the rollers when the trailing end of a 6" long PCB is being printed. The MCU you have now is actually calibrated for an 11" carrier, but works okay for a 12 inch one. You could try it as is and see how it work for you. Or, send it back and I'll reprogram it for either 12 or 14 inches, your choice.

Mark


At 02:12 PM 9/4/2014, you wrote:

Mark,
Sorry for my slow response, too many things to do...
I expect to get the board in the mail within a day or two. I have trimmed the board to .95 x 1.55"; I hope that won't affect your holding method for programming. I'm about to review your latest Instructable; I will be updating  my parts inventory, and since I had already cut two sheet pieces to 12", I presume I'll need to include another sheet to meet the 14" callout .
Thanks,
Roger

On 9/4/2014 5:47 AM, Mark Lerman mlerman@... [Homebrew_PCBs] wrote:

 

Roger,

Did you get my email re reprogramming the board?

Mark

--
Dell XPS8700 256GB SSD 2TB HD 24.0 GB RAM Win8.1 64-bit Intel x64 8 Core(TM) i7-4770 CPU@3.40GHz 3.40 GHz

--
Dell XPS8700 256GB SSD 2TB HD 24.0 GB RAM Win8.1 64-bit Intel x64 8 Core(TM) i7-4770 CPU@3.40GHz 3.40 GHz