This version is now obsolete. The current version is located Here.
For the latest changes, additions and errata see step 13
This is the second version of my E260 modification. It uses an ATtiny13 MCU to control the timing of the printer and make it possible to print double sided PCBs at home.
As an electronic hobbyist and inventor I often need to make printed circuit boards (PCBs) in single or small quantities. Usually these are relatively simple circuits, an MCU, some input conditioning circuitry, some output circuitry, and usually they are single sided or perhaps double sided, with just a few vias. And usually I want them right now!
Toner Transfer (TT) has become the method of choice for most hobbyists. A laser printer is used to print an image of the PCB on special “transfer paper” which is then placed on the bare copperclad board and either ironed on or run through a modified laminator to transfer the image to the copper. When the PCB is etched, the toner acts as a resist, preserving the copper below it while the rest of the copper surface is etched away.
While TT works, it does have some problems. The process involves several steps, all of which are critical to success. Often there is pitting of large planes, and in many cases parts of the image don’t transfer, leaving gaps that have to be hand edited or completely redone. Trace widths under 10 mil, while achievable, are unreliable.
Since we know that laser printer toner is a great resist for making printed circuit boards, I have long wondered why we use Toner Transfer, rather than printing directly on PCBs with a laser printer. After all, if the boards produced by transferring toner first to paper and then to PCBs works well, then putting the toner directly on the PCB should be even better!
The main arguments against the viability of the process, aside from the mechanics of getting a thick board through a paper-thin path, seem to be (a) the drum is too fragile and will quickly be damaged by the boards, and (b) the copper will dissipate the static electricity charge needed to transfer the toner to the board.
Over the last four years I have been experimenting with Direct Laser Printing (DLP), and it works! I have run hundreds of boards through my modified Lexmark E260 printer, and not only can I print on copperclad boards, I can print on aluminum sheets and other metals as well. Using Muriatic Acid/Hydrogen Peroxide etchant I can now make a PCB in under 15 minutes!
I am still experimenting with the process, but trace widths down to 4-5 mil (.004-.005) seem to be readily accomplished. Mechanical registration of the PCBs seems adequate to make simple double sided boards, though I have not made a serious effort to investigate this.
After trying several brands and models of laser printer, the printer I have settled on is the Lexmark E260. I use it because:
1 – It has an excellent Local Printer Utility that allows almost every printing parameter to be adjusted.
2 – It is readily and reasonably available on Ebay or Craig’s List. I paid $45 for each of the last two I bought on Ebay, including shipping.
3 – The drum is separate from the toner cartridge and is relatively inexpensive (<$30), so it can be replaced if it does become damaged.
4 – The printer has a manual feed slot in front so the paper path can be “flattened” with reasonable effort to pass PCBs.
5 – The charge on the drum seems to provide for essentially perfect transfer of toner to grounded metal sheets.
Step 1: Parts and Tools
E260 Laser Printer - This can be a E260, E260d, E260dn. Ebay
1 x 4mm Stainless Steel Rod x 12" (1272T34)
6 x 4mm Shaft Collar (57485K64)
2 x 10mm OD x 4mm ID x 16mm long Aluminum Spacer (94669A814)
1 x 20" Extension Spring .187" OD .026" Wire (9665K15)
2x Adjustable Aluminum Spacer, .335ODx.260IDx.5 long (93441A215)
1x1x.062 Aluminum Angle x 12 inches (8982K39)
6"x24"x.016 Aluminum Sheet (89015K115)
Copper Tape with Conductive Adhesive .250" x 18' (76555A711)
2.7K ohm resistor various sources
MCU Board see text
E260 Service Manual
.9 mm hex key (McMaster 7289A32)
Nibbling Tool (optional) see photo
Dremel or similar rotary tool (optional)
Standard workshop tools - screwdrivers, wire cutters, small saw, soldering iron, etc.
The table above has a parts and tool list for this project. Most of the parts are available at McMaster-Carr, but many can also be found at local hardware stores.
You will need the E260 Service Manual for this conversion. For convenience, I have appended it below.
Step 2: Testing the Printer
Step 3: Stripping Down the Printer
To successfully complete this project you will need to have and use the Service Manual (SM) for the printer. Steps that are thoroughly covered in the SM (Section 4:Repair Information, Removal) will not be detailed here. I will add (SM) to those steps covered in the Service Manual. For the location of parts on the bottom of the Paper Platform see photos.
In this step you will be opening up the printer and exposing the Paper Platform for cutting. As you remove each part be sure to keep track of which screws were removed. You might want to tape the screws to the part or label them. Removal of some of the subsections below may require removal of other subsections or parts, so pay attention to the SM. To replace a subsection or part, reverse the removal steps. Using the SM as a guide do the following:
Remove the Right Cover (SM). It is the side with the access door.
Remove the Left Cover (SM)
Remove the Lower Front Cover (SM)
Open the Front Door.
Remove the Paper Feed Guide with the 6 small rollers. It is held in place by 2 screws on each side, not by the 8 screws on top. Discard it.
Remove the Manual Feed Paper Guide [Photo] and save it and its 2 screws. You will use it later.
Remove the Transfer Roller (SM). Be sure to remove and save the small spring under the right bearing clip and save it. The spring on the left side is attached to the transfer roller cable and should not be removed. The left bearing can slide off the transfer roller, so remove it and put it safely aside with the spring. Note that the clips on the bearing are oriented to the outside of the shaft. Also note that the bronze bearing can slide out of the clip and get lost if you are not careful.
Close the Front Door and remove and discard the pivoting beige Paper Holder.
Remove the Rear Door and Cover (SM).
Remove the Top Cover Assembly (SM).
Remove the Rear Exit Guide Assembly (SM) – Note that the longer screws are at the top.
Remove the Fuser (SM). The only part we need from the Fuser assembly is the connector and cable to the Exit Sensor. Cut the cable where it enters the Fuser, save the cable and discard the Fuser.
Locate the Thermistor cable on the Controller Board at J-12. Cut the cable leaving about 1.5 inches of wire. Remove the connector and solder a 2.7K resistor across the two wires. This resistor makes the printer think it has a Fuser heated to 200 C still attached. Without this resistor the printer will error out when booting. The resistor can be covered with tape or heat shrink. Replace the connector with its resistor at J-12 [Photo].
Remove the top rear 2 screws on the Rear Exit Guide assembly (save them) and remove the top section with the Narrow Media Sensor. Take the bottom section and remove the rollers and the reversal solenoid. Remove all the gears and small rollers. You will not be using the gears, rollers, or solenoid. Remove the Narrow Media Sensor and its flag from the top piece. Remove the piece of tape with its attached "bristles" and remove the 4 black plastic holders. You should now just be left with two bare green plastic pieces [Photo]. Replace the top section on the large lower section and screw them together with the two screws you saved [Photo]. Save the Narrow Media Sensor and its cable – you will be using it later!
Replace the stripped down Rear Exit Guide assembly using only the 4 upper screws (SM). Be sure to put the longer ones in the top holes.
Replace the top cover Assembly(SM).
Turn the printer upside down.
Remove the LVPS/HVPS (power supply) (SM). Remove and discard the thick 2 wire cable to the Fuser power supply. When removing the power supply note that one screw is different than the other 3 – that one screws into the plastic. Make special note of where the power supply tabs go under that screw. As you are removing the power supply, note which cable goes where and their orientation. Remove the Transfer Roller cable connector first using long nose pliers to pull it sideways out of its slot. Note its orientation. Press the connector tab to remove the two and three pin connectors. The multipin connector just pulls out.
Remove the 3 screws holding the power supply shield and remove the shield.
Remove the Duplex Assembly (SM) and discard it.
Remove the Main Motor Gear Drive Assembly (SM). Be careful detaching the motor cable. Since removing the door link (fuser link) will allow the door to "hang" open, disconnect the Operator Panel cable connector (J5) to avoid tension on the connector. You can also remove the door at this time to provide easier access to the Paper Platform.
Remove the Media Feed Clutch (SM) and discard it.
Remove the Media ACM ASM Feeder Mechanism (SM) [Photo]. All of these parts can be discarded, so it does not matter if you damage them in removal.
Remove and discard the pivoting plastic piece and spring that sits just behind the paper drive shaft and rollers [Photo].
Remove the Toner Patch Sensor [Photo]. It is held in place by 2 screws in the bottom of the paper platform, near the Media Feed Mechanism. Also remove the spring loaded sliding plastic window located just behind the Toner Patch Sensor These parts, too, can be discarded.
Remove the screws holding the Paper In Sensor (PIS) and the Duplex Sensor in place [Photo 02]. Each is held by one screw. Remove the wires to these sensors from the wire guides. Cut the wires to the Duplex Sensor close to the connector (J27). Be sure you are cutting the correct wires (Red/Black/White).
Remove the wires going to the Manual Clutch Solenoid from the same wire guide and weave it into the wire guide for the Main Motor cable [Photo].
Remove the screw holding the Manual Feed Paper Sensor (MFPS) in place [Photo]. Cut the cable near the sensor and pull the cable back into the controller compartment. You will not need the sensor but you will need the cable and connector.
Step 4: Cutting the Paper Platform
We are now going to cut a piece out of the Paper Platform. This is necessary to allow the carrier and pcb to easily pass through the printer without hitting the bottom of the toner cartridge. I used a Dremel [Photo] with a router bit, but you can also use a small saw. The most important precautions in cutting this platform are protecting the laser openings and removing all the plastic chips!
The openings to the laser mechanism must be covered. I used strips of two inch painter’s tape to cover all the openings. I also covered any areas where chips could lodge and cause trouble later on while printing [Photo].
We are going to remove an approximately 7.375 inch wide piece of the Paper Platform extending from just inside the Transfer Roller gutter up to and through the front of the printer. The right and left guides are the first and last "ridges" in the Paper Platform. The yellow lines in the photo outlines the area to be removed [Photo]. Photos above show the finished inside of the printer after the Center Platform and Input Rollers are installed.
It is easiest to cut the left and right sides from the top, following the ridges in the platform. Be careful cutting the areas around the rollers – you don’t want to damage the shaft or rollers. Then turn the printer over and make the back cut, being sure the back cut includes the front edge of the Transfer Roller gutter [Photos].
Once the cut is done remove the section of plastic and smooth all the burrs. If you used the Dremel there will be pieces of melted plastic along the edges of the cut that can easily be removed with a screwdriver or your fingers. If necessary, use a file or sandpaper to smooth the edges.
Then clean up all the chips! Use a vacuum to suck up all the chips, then canned air to clean anything you missed. It is vital to prevent chips getting into the laser mechanism. It is also vital to keep chips from scratching the drum, so clean, blow and vacuum! Do a final cleanup of plastic chips, then remove the protective covering from over the laser openings
Step 5: PCB Feeder Assembly
While the original Manual Paper Feed Assembly in the E260 can successfully feed PCBs into the printer, it was designed to move paper, not PCBs and will eventually start slipping. In this step we will be converting the Manual Feed Input Rollers into a robust mechanism by adding a spring loaded set of passive aluminum rollers above the rubber drive rollers. See the photos and the description below.
Since the carrier we will be using is 6 inches wide we need to first move the two outer rubber rollers on each side of the shaft till they are touching and located with the outer edges 6 inches from the other pair. The rubber rollers are held tightly to the shaft by friction, but they will move with finger pressure and some "wiggle". To find the center you can temporarily put on the Manual Feed Paper Guide [Photo] and sight a line to the middle "rib" at the back of the Paper Platform cutout. You can move it later if it isn't perfect.
Using needle nose pliers or a screwdriver spread the edges of the adjustable spacers just wide enough to “snap” over the 6 mm steel rubber roller shaft and place one spacer on each outer side of the two drive rollers [photo]. These spacers will keep the springs from rubbing on the shaft. Close the gap in the spacers carefully to keep the spacer as round as possible. They should turn freely on the shaft.
To add the new rollers cut a 10.75 inch piece of 4mm stainless steel shaft. This shaft will fit into the slot located directly over the 6 mm input shaft. Then slide on two 4 mm shaft collars, a 4mm x 13 mm diameter x 16 mm long aluminum spacer, followed by two more shaft collars, a second spacer and two more shaft collars.
Position the aluminum rollers over the outer pairs of rubber ones with the inner edges lined up and tighten the shaft collars on each side with a .9mm hex key to hold them in place. Since the upper shaft does not rotate, the shaft collars should be loose enough to allow easy rotation of the rollers [Photos]. Position the outermost shaft collars about .25 inches from the next one in. This forms a groove between the shaft collars to hold the spring in place. Leave them loose for now.
Put the new roller assembly in place, the press the ends firmly down into the slots [Photo]. The aluminum rollers should be able to rotate against the rubber rollers below with essentially no space between them. When you add the springs in the next step it will pull the aluminum rollers tightly against the rubber rollers below.
Cut 2 pieces of extension spring, each about 1.75 inches long [Photo]. Use a wire cutter to gently separate the last two turns on each end from the body of the spring, creating “eyelets” to hook the ends of the spring together in a loop around the 2 shafts.
Take a 10 inch length of steel wire and run it through one of the spring eyelets, then under the two shafts and through the eyelet on the other end of the spring. Grip both ends of the steel wire and pull the two ends of the spring together. Twist the ends of the wire together several times to secure the spring in a loop. Rotate the spring so that the wire is on the bottom resting on the adjustable spacer and cut off the excess wire. The photos show how to do this. Now position and tighten the outermost shaft collars to form a groove for the spring.
Step 6: Replace Some Things
Replace the power supply shield.
Replace the LVPS/HVPS (power supply) (SM). Replace the 3 internal connectors first, being careful to replace the cables in the correct connectors and in proper orientation. Replace the Transfer Roller connector using long nose pliers. See the photos and directions in the SM. The power supply should slip easily into place - it should not need to be forced.
Replace the Right Rear Foot by its 2 screws.
Replace the Main Motor Gear Drive Assembly (SM). The large gear with the large helical spring can be removed and discarded. It was used to drive the fuser and is not needed. Be careful to attach the motor cable. The Fuser Link goes through the slot in the front of the printer. It will later be attached to the door. You may have to "wiggle" it a bit to get the gears to mesh, but the assembly should slip easily into place. Do not force it!
Replace the Transfer Roller.
Replace the door. Be sure to reconnect the Fuser Link and the electrical connector (J-5)
Replace the Left Side Door.
Replace the Paper Tray.
Replace the Rear Door.
The Rear Door Cover is designed to swing open to guide media that is too stiff to bend well, out the back of the printer. For our purposes we will leave it closed, but we need to make a cutout to allow the PCB on its carrier to pass [Photos]. Using a Dremel or a saw, cut a rectangle from the bottom of the cover using the horizontal "shelf" [Photo 38] on the inside as a guide. Smooth the edges [Photo] and replace the Rear Door Cover.
Step 7: Carrier Guide and New PIS
We are now going to make and mount the new Carrier Guide (CG) and the New Paper In Sensor (NPIS) [Photos].
Cut a 4.5 inch piece of 1x1 inch angle aluminum. Drill two .125 inch holes in one leg of the angle, centered on the face and 1.75 inches apart. Place the angle on the inside of the Front Cover aligned with the plastic “ridge” as shown in [Photos], and mark the location of the holes. Drill .125 inch holes and use 4-40 hardware to attach the Carrier Guide to the Front Cover. Align the Carrier Guide with the ridge on the Front Cover as shown in [Photo].
Replace the Front Cover.
The Narrow Media Sensor will be used as the NPIS. This is a U shaped sensor with a phototransistor (PT) in one leg and an IR led in the other. A thin slit in the plastic housing allows a beam of IR light to go from led to PT. The output is normally low, but when the beam is interrupted it goes high. We will be drilling a small hole in the edge of the Carrier to trigger the NPIS.
Cut the 6 inch wide x .016 aluminum sheet to 14 inches. Place it against the Carrier Guide (CG), resting on the Front Cover with the front edge at the interface of the Input Rollers. Push the leading edge of the carrier into the roller interface. As shown in the photos] use a pencil to mark the path of the carrier across the CG, then remove the carrier.
Remove the CG from the Front Cover. Hold the NPIS against the CG aligned so that the bottom of the pencil line is centered in the U and the NPIS is perpendicular to the pencil line. Make sure you are forward enough on the CG that the mounting lug of the NPIS will fit in the angle, then draw a line on the CG along both sides of the NPIS. See photos.
We are now going to cut a slot in the CG for the NPIS [Photo]. The easiest tool to use is a Nibbler as shown in [Photo], but you can also use a small saw and a file. The exact size is not critical. Now use a tin snip to cut a small piece of the .016 thick aluminum sheet to make the mounting plate for the NPIS as shown in [Photos]. The location of the three .125 holes are not critical, just be sure to leave enough room between them to fit the nuts. The mounting plate allows the inside of the U to be flush with the surface of the CG.
Mount the NPIS to the CG, then mount this assembly back on the inside of the Front Cover. Run the wires from the NPIS through the same opening as the Operator Panel cable and leave them in the Controller Compartment to be connected to the MCU.
The mechanical modification is now complete.
Step 8: The MCU Controller Board
The E260 uses 3 sensors to monitor the path through the printer. The first, the Manual Feed Paper Sensor (MFPS) detects the presence of an object at the Manual Feed Rollers. When it gets hit, the input rollers run for a second or so to pull the PCB into the rollers. After “Print” is clicked on the computer, the second sensor, the Paper In Sensor (PIS), goes low when the PCB reaches it. This sensor starts the actual print cycle. The final sensor, the Exit Sensor (ES), goes low when the PCB exits the printer. If these sensors are not hit and released at the correct times the printer will “jam” and flash an error light.
In this hack we will be using a MCU to monitor the sensors and provide the correct timing to the printer. We will be using the Cancel (X) button on the Operator Panel as our new MFPS (NMFPS), and the new sensor mounted to the Front Cover as our new PIS (NPIS). The ES will be emulated by the MCU and will not be a physical sensor.
The MCU I am using is an 8 pin Atmel ATtiny13. The circuit is very simple. I designed a small single sided PCB and (of course) printed and etched it [Photo]. The Schematic and Parts Placement files are appended below.
I have mounted the MCU Controller board to the inside of the Right Side Cover Access Door because I wanted to have easy access in case I need to reprogram the MCU. To do this I had to add extensions to several of the wires attached to the board, most notably those from the NPIS and Cover Open Switch. If you don't care where the board is, no extensions are necessary and you can just cover the board with insulating tape and let it sit anywhere in the Controller Compartment.
Cut the leads from the Cover Open switch [Photo] at the switch body and remove the connector at J7 from the printer board. The black wire, pin 3 is ground and the red center wire is 5 volts. Pin 1 must be also connected to the 5 volt supply, otherwise the printer will think the door is open.
Follow the diagram and connect the leads from J14-2, J23-2, and J27-5, i.e. the MFPS, PIS and ES. Note that the pins on each of the connectors are numbered from right to left.
Since we are using the Cancel (X) button as our new MFPS, we have to connect our controller to J5, pin 5. To do this first disconnect the door cable at J5. Carefully cut back the insulating covering of the cable so you have enough cable exposed to easily get to the individual wires. Isolate pin 5 and CAREFULLY scrape away the insulation to expose the copper [Photo]. Make sure you are far enough from the connector so that if you accidentally cut the wire you have enough room to solder it back together! Solder a 10 inch length of wire to pin 5 then use electrical tape to cover the connection as shown in the photo [Photo]. Finally solder the wire to the indicated pad on the controller board. Note that the signal on this pin is 3.3 volts, not 5 volts, but it works fine for this application.
Bring the 3 wires from the NPIS to the controller board and solder them to the designated terminals. The black lead goes to ground. The voltage to the IR led can either be supplied via a 200 ohm resistor on the MCU board or by connecting J14, pin 1 to the red sensor wire to use the built in 200 ohm resistor on the Printer Controller. The blue sensor lead goes to the MCU Controller board as indicated. It has a 4.99K resistor pull up to the 5 volt line.
If you are not concerned re the location of the MCU Controller board, just wrap it in electrical tape and leave it in the Controller Compartment. Replace the Right Side Cover. Make sure the MCU board comes through the access door. Using double sided foam tape mount the MCU board to the inside of the access door [Photos].
Step 9: Software
I have written the controller software in Assembly Language for the Atmel ATtiny13 MCU. The Source File is appended. Since I am "self taught", I might (probably) use some conventions and notation that are not standard. If anyone wants to write a more "professional" version, I would be happy to include it, giving proper credit. Likewise, if anyone wants to write an Arduino version or a C version, I would be happy to include those as well.
The Source File is appended below.
Here is the program in pseudocode:
MFPS = Printer input from original MFPS (MCU output)
PIS = Printer input from original PIS (MCU output)
ES = Printer input from original ES (MCU output)
NMFPS = X button on Operator Panel (MCU input)
NPIS = New sensor on Center Bracket (MCU input)
1 - Loop here till X pressed and released.
2 - One second delay. Necessary because X delivers several pulses when released.
3 - Clear printer MFPS line - rollers grab carrier and pull it in.
4 - Loop here till either X pressed and released again or NPIS goes low (printing).
If X pressed and released again, reset MFPS and go to 2 else continue to 5.
5 - Clear PIS.
6 - Delay 1.825 seconds.
7 - Clear ES ;all three sensors now low
8 - Delay .950 seconds.
9 - Reset MFPS.
10 - Delay .825 seconds.
11 - Reset PIS.
12 - Delay 1.875 seconds.
13 - Reset ES.
14 - Done, so loop back to 1 to do again.
Step 10: Making the Carrier
Make a 6x14 carrier by cutting a 14” piece of the 6 inch wide x .016 thick aluminum sheet, then beveling all 4 corners and filing all edges smooth. Place a piece of either vinyl electrical tape or Kapton tape over the leading edge of the carrier, folding it so half is on each side of the carrier. Kapton tape is thinner than the vinyl, making insertion into the rollers a bit easier, but the vinyl works quite well. Cut the tape around the beveled corners. This protects the printer drum from getting gouged as the carrier enters [Photos]. Using a 6" carrier the maximum PCB width is about 5 inches, but I usually use 4 inch wide PCBs.
Slide the carrier through the slot of the NPIS with the leading edge at the interface of the input rollers. Holding the Carrier against the Carrier Guide, mark the carrier 2.5 inches from the center of the NPIS. Now drill a small hole 4mm from the edge of the Carrier. I used a .026 inch drill, but anything in that range or a bit larger should work just as well. See [Photos].
This hole is the "trigger" for the NPIS. As the carrier moves into the printer, the NPIS is blocked by the opaque metal carrier. However when the hole arrives in the center of the NPIS, the IR from the led hits the phototransistor and the output of the sensor goes from high to low for a very short time (6.7 msec for a .026 inch hole). The MCU recognizes this transition and starts the timing for the print.
Step 11: Making a Print
Replace the Toner Cartridge and Drum. I suggest that you get a brand new Toner Cartridge and Drum for PCB printing. This will give you maximum toner density on your PCBs and should last a very long time. You might want to keep a used spare to experiment with and keep the new one only for prints that you actually want to etch.
It is important to note that the PCBs you run through the printer must be FLAT! Significant warping of the board, especially in thicker boards, will result in bare areas. Thinner boards are able to be flattened as they pass under the Drum, but .062 boards must be flat to work reliably. It is also a good idea to lightly sand the edges of the boards to eliminate sharp edges that might damage the Drum.
The surface of the PCB must be grounded for the process to work! The carrier is grounded via the rollers. To ground the surface of the PCB use a small length of .25 inch (or .5 inch) wide copper foil tape [Photo]. Make sure that the tape you use has conductive adhesive!
Place the PCB centered left to right on the carrier and about 1 inch from the leading edge. Put a piece of the copper foil tape on the leading edge of the pcb, connecting the pcb to the carrier. Then place a length of .75 inch wide electrical tape over the leading edge of the PCB, covering the copper tape, and securing the pcb to the carrier [Photos]. Lightly clean the surface of the pcb using a Scotch Brite or other pad, then wipe the PCB with acetone [Photo] and allow it to dry. We are now ready to print!
The Local Printer Settings Utility allows you to change most of the settings of the printer. I have not tried all the various combinations of settings, but I usually use Paper Source=Manual Paper, 1200 x 1200 dpi, Toner Density=10. After making changes you must click on Action and Apply Settings to make the changes permanent.
Slide the Carrier through the NPIS holding it firmly against the Carrier Guide and hold the leading edge at the interface of the input rollers. Press and release the Cancel (X) button on the Operator Panel. A second after you release the button the rollers will “grab” the carrier and pull it in. If it doesn’t, simply press and release the X button again. You can also gently push the carrier in as the rollers grab. Just be sure you don’t push the carrier in to the point where it triggers the NPIS as this will cause an error. Note that if you remove the Carrier from the NPIS after you have pressed the button it will also cause an error. If that happens reinsert the Carrier then press the Continue button on the Operator Panel.
Once the carrier is in the printer, select the correct printer and click on “print”. The printer will pull the carrier in and print the image on the PCB. As the print emerges from the rear of the printer you can either slide it all the way out or leave it suspended in the exit opening.
Shown above are prints I made using this printer. You can see in the close up how dense the solid areas are and how solid the 10 mil traces are.
When it leaves the printer the toner is stuck tightly to the PCB by static electricity. You can tap it, blow on it and even drop it on the floor and it will stay put. However, all it takes is a light rub of your finger to wipe the toner off! To use toner as a resist in an etching bath, the toner needs to first be "fixed" to the copper.
Jim Hutchinson, a fellow DLP enthusiast, discovered that the easiest way to fix the toner is by immersing it in acetone vapor. Place a few tablespoons of acetone in a container. Suspend the PCB above the liquid (use some spacers), cover the container and let it sit for at least 2-3 minutes. Then remove the PCB and let it "air out" for a minute or so. The toner will now be hardened and bonded to the copper. You are now ready to etch and use your new PCB.
I am now recommending that the PCB be in the acetone vapor for a full 20-30 minutes. This melts the toner and actually allows it to "heal" over any pits or defects making for more solid traces and, especially, large planes.
Step 12: Conclusion
DLP works, is reliable, and is very fast. Using Muriatic Acid/Hydrogen Peroxide high speed etchant I can go from design to ready-to-use PCB in less than 15 minutes!
Double sided PCBs are next. Using just the Carrier Guide, the E260 can achieve registration that should allow double sided boards of some complexity to be made. Now that the basic DLP process is stable and repeatable, I will be continuing experimenting and hope to publish an Instructable on double sided printing in the near future.
Step 13: Errata and Changes
Change #1: In step 10, 2nd paragraph, the hole should be 4mm from the edge, not 5mm.
Change #2: In step 5, do not put tape or heat shrink on the ends of the added shaft. leave them bare.
Change #3: In step 5 the springs should be a little looser. Either cut them to 1.75 inches instead of 1.5 inches or stretch them out a bit to that length before mounting.
Change #4: In step 11 the acetone works much better if the pcb is left for 20 minutes or even longer. This "melts" the toner, which "heals" over any pitting or defects.
Change #5: In step 8 the parts placement pdf showed a 27K resistor. It should actually be 4.99K or 5K. This has been corrected.