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jit's build: upgrading to v2 extruders

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This page is intended for Bukobot v1 owners who may wish to upgrade their printers to the new v2 extruder and X carriage. It may also be useful for v2 owners who want more details about how their extruders and X carriage go together.


When Deezmaker introduced the Bukobot v2 in mid-2013, one of its primary improvements was the Spitfire extruder. It has many benefits:

  • It can achieve higher temperatures, so it can extrude more kinds of plastic.
  • It heats up faster, and cools down faster.
  • It's a lot easier to remove from the X carriage, and also easier to clean.
  • It's more compact. Because of that, the v2 frame is smaller.

Most v1 owners probably won't want to replace their frame with a smaller one, but the more compact extruder does let them print taller objects. In addition, the single-extruder v1 frame is wide enough to hold a dual-extruder v2 X carriage without reducing the build volume.

Therefore, current owners of single-extruder v1 Bukobots can upgrade to dual-extruder without changing their frames or synchromesh cables. The only things they need are:

  • the dual-extruder v1-to-v2 upgrade package, described below
  • one more extruder motor
  • an Azteeg X3 (some people have already upgraded to this, for various reasons)

But for most people, the big attraction will probably be the ability to print other kinds of plastic. Beyond the usual PLA and ABS, it can print:

  • MABS: methyl methacrylate butadiene styrene
  • Nylon
  • Polycarbonate
  • Laywood: looks like wood, smells like wood, made out of wood
  • PVA: polyvinyl alcohol, water-soluble and used for printing supports
  • HIPS: high impact polystyrene

and probably other stuff too. (Heated bed required of course.)

The upgrade kit

This is the new X carriage:


The plate on the left goes under the linear bearings, and the plate on the right goes on top of the linear bearings. The plates are held together by the screw and nut, clamping them tightly onto the linear bearings. The extruder(s) mount on top of the carriage.

If you buy a v2 Bukobot, each extruder comes fully assembled and already screwed onto the motor, so you just bolt this assembled module onto the top of the carriage. But since v1 owners already have extruder motor(s) and these motors aren't exactly cheap, the upgrade kit includes no motors and comes partially assembled:

Two extruders are shown there. They are assembled as mirror images, to minimize the distance between the hot-end nozzles (this minimizes the width of the v2 frame). If you only have one extruder, it doesn't matter which way you orient it, but most people assemble it as a left-hand extruder, with the nozzle toward the right.

Here, one of the extruders has been disassembled even further, so you can see more of its parts:

The fan is just out of shot, attached to those two long screws visible at the bottom. Also, the heater element is not shown above; it's a small silvery can with two long red wires coming out of it.

The lever assembly contains a small bearing at one end, barely visible in this image. The perimeter of this bearing will bear against the filament and press it against the teeth of the Tatsu drive gear.

There are two red flat aluminum plates with fins around three sides. They are almost identical, but one plate has two countersunk holes and the other plate doesn't. The two short flat-head screws shown at the top go through those two holes to secure this plate against the face of the extruder motor. The short button-head screw goes through a third hole into the motor, and the long black flat-head screw goes through the fourth motor mount hole after passing through more of the assembly.

Here some of the parts have been partially reassembled:

The long black flat-head screw supports the lever assembly. Two washers go on each side of the lever.

Note that the v2 Bukobot has the X axis synchromesh cable in a different location, so you need special spacers to hold the cable in the correct position for the new carriage. These spacers are not shown above. The cable pulleys need to be moved too, and the spacers for that are not shown above either.

Two synchromesh cable spacers are needed, to hold the cable the correct height over the carriage plate. The upgrade kit may come with two laser-cut acrylic pieces to use as spacers. If you don't get those, print them and make sure they fit into the top carriage plate as shown farther down the page (a file and a rubber mallet may be handy).

You also have to reposition both pulleys so that the cable is in the correct position in the Y direction. The pulley on the X stepper motor shaft is easy to relocate, but you'll need spacers to relocate the other pulley. On the printer shown in the images below, one M8 nut and four M8 washers were needed to get the correct spacing, but your mileage may vary, so get a bunch of M8 washers. It was necessary to unscrew the M8x30mm bolt that supports the pulley to such an extent that most of its length was no longer within the plastic pulley support, so it was replaced with a longer M8x50mm button head bolt to insure that the tension of the cable would not cause the bolt to split the support piece.

Preparing for the upgrade

You have to disassemble your old extruders and X carriage before upgrading. It's a really good idea to print anything you might need for the upgrade before doing this. So print the spacers mentioned above if you didn't get them in the kit.

As mentioned above, on this particular printer the following parts were used to relocate the right-hand pulley:

  • one M8x50mm button-head bolt
  • one M8 nut
  • several M8 washers (this printer needed four altogether, yours might need more or less)

If your kit didn't come with these, consider getting some.

Also needed were a number of cable-ties, in various colors and sizes.

Double-check that you have all of the parts shown on this page. Read the entire page carefully before taking anything apart, paying particular attention to the hardware re-configuration problem described near the bottom of the page (and on a separate page).

You will have to disconnect a number of wires during the upgrade, so make sure your wires are marked. On this particular printer, wires going to the left extruder are marked with white cable ties, and those going to the right extruder are marked with red cable ties. (This convention is inherited from the era of stereo: red is right, white is left.) Marking your wires greatly reduces the probability that you will get them crossed; the printer performs rather poorly if the right-hand thermistor is wired up to the left-hand thermistor circuit. Don't forget to mark the four-wire bundles coming out of the motors.

When you disassemble your old carriage and extruders, a lot of small parts will fall off, and you might need some of those for the upgrade. (And if things go wrong with the upgrade, you might need to reassemble your old carriage, so you don't want to lose any of those parts.) So get a big sealable plastic bag (gallon-size at least) to hold the old carriage and all those other parts.

If you cut all of the excess length from your X axis synchromesh cable when you first built the printer, then you may have made a mistake. This cable, as originally supplied, should be long enough for the new X carriage. But the new carriage is narrower than the old dual-extruder carriage, so its cable attachment points are closer together, and more cable is needed to reach those points. Check that your cable has enough extra length hanging out of the carriage; if it doesn't, you might need a new cable. If you have a single-extruder v1, you shouldn't have this problem.

After you have printed everything you need, and made sure you have all the parts you need, remove the filament from the extruder(s).

After removing the filament, you should rotate your extruder motor shaft(s) so that the flat of the motor shaft (and the little set screw that holds the Tatsu drive gear in place) are facing down. Start up your host software, connect to the printer, and instruct each extruder to retract filament until the Tatsu set screw is pointing down. Because the extruder motors won't turn when the hot-ends are cold, issue the M302 command first.

It's also helpful to raise the X axis a bit before starting the upgrade. Raise it far enough so that you can fit the entire length of your 5mm hex driver, plus a few centimeters, under the X axis steel rods (holding the hex driver vertically). This will make it easier to tighten the bolt that will hold the new extruder in place. (If you have a right-angle driver, this probably won't matter so much, but raising the axis half-way will make it easier to reach under, and see under, the axis.)

Take the old carriage apart

Start by unplugging the power supply, and unplugging the USB cable. For now, leave all the wires attached to the Azteeg controller.

You don't have to disassemble the whole X axis; just clip the cable ties holding the linear bearings in their holders, and then you can lift the X carriage off. But first, disconnect the wires from the extruder heater(s), thermistor(s), and fan(s) from the terminal block on the X carriage. For now, leave the terminal block attached to the bundle of cables that goes back to the Azteeg. Loosen the hardware holding the terminal block so that the block can be slid back and away from the carriage plate.

That leaves the extruder motor cable(s) still attached to the Azteeg. Don't disconnect those. Instead, disassemble each extruder far enough so that you can reach all four screw heads that hold the extruder block onto the motor. Remove those four screws and back the motor out of the extruder. Carefully set the motor(s) down on the printing platform.

Finally, detach the synchromesh cable from the X carriage plate, then lift up the X carriage and put it into the plastic bag, along with all that loose hardware. Straighten out the cable and hang it somewhere for a well-deserved rest.

The next couple of images are taken from the back of the printer.

(Those Tatsu drive gears weren't intentionally removed from the motor shafts. They fell off. Apparently these can work themselves loose over time. Remember always to tighten these really well, with the set screw well centered in the flat of the shaft.)

Before installing the new carriage, loosen the screw that holds the Z endstop on the right frame piece and move it down as far as it will go. You will have to reposition it eventually, but you might as well move it now so that the new carriage won't hit it during the upgrade.

Assemble the v2 X carriage

Insert the two synchromesh cable supports into their holes in the top carriage plate if you haven't done this already. See the image below for the correct locations.

If your synchromesh cable has an eyelet attached to one end, you can use it as shown below. Otherwise, you'll need a screw and nut on each side to secure the cable.

Thread the synchromesh cable through various holes in the top carriage plate as shown below (except your plate isn't attached to the linear bearings yet). The first hole is at the lower left in the image below; the hole is located in a narrow slot. The cable goes down through that hole, then up through the hole next to the plastic spacer, and over the spacer. Then under and around the pulley shown, across to the motor pulley, around that pulley, and back to the other side of the carriage plate, over the spacer, down the hole, then up through the other hole that's in a narrow slot. Don't make the cable tight yet; leave it loose enough so that is easy to slip the cable off of the pulleys.

Secure one end of the cable to the plate. If you have the eyelet, secure that end. Take all the slack out of that end and shove the cable up the slot as far as it will go; the slot will hold it firmly in place. If you don't have the eyelet, insert a small screw through that hole and put a nut on it and tighten.

Slip the cable off the pulleys. Hold the plate upside down and let the loop of cable dangle toward the floor, just as you did when you first assembled the printer. It should hang in a plane, as before; if it twists up, untwist it.

Set the new top carriage plate on top of the linear bearings, line the little tabs up with the notches in the linear bearings, put the screw through the hole, hold the bottom plate under the linear bearings, hold the nut under the hole in the bottom plate, line up the screw and the nut and tighten. Look under the bottom plate to make sure the linear bearings are lined up with the tiny tabs in the plate. When everything is lined up and tightened, loop the cable loosely around the pulleys. You will tension the cable later. Now you can slide the new carriage back and forth and enjoy.

Sight along the lower portion of the cable and observe that the pulleys and the cable spacers don't line up. They should line up fairly well in the Z direction, provided you've got the correct spacers, but they need adjustment in the Y direction. The pulley on the motor shaft can be moved easily by loosening its set screw, but the other pulley needs spacers:

Here, a lot of spacers were needed, so one nut and several washers were used. The old M8x30mm bolt was removed and replaced with a longer M8x50mm bolt to protect the plastic block it screws into.

Measure the distance from the lower part of the cable to the nearest steel rod, at both ends of the X axis. Adjust the pulleys so that these distances are equal, and the cable is parallel to the steel rod.

When you've got the spacing pretty close, take most of the slack out of the cable and re-check the cable alignment. Slide the X carriage to both extremes and double-check the alignment, sighting along the length of the cable and measuring too. When the alignment is accurate, take all remaining slack out of the cable. Don't forget the short stretches of cable that run below the top plate. Pull the cable as tight as you can, until you can strum it. Then secure the other end by shoving it up its slot and inserting a screw and nut as described before. If you have a lot of loose cable hanging out, wrap it around the plastic support to use it up and then secure the free end in the narrow slot next to the plastic support.

Slide the carriage back and forth, looking for interferences and alignment issues. Adjust the pulleys again if necessary.

The next several photos are taken from the front of the printer.

Assemble the new extruder(s)

Starting with the left extruder (or the only extruder):

Detach the red plate that has two countersunk holes from the rest of the pieces, and attach it to the left-hand extruder motor:

Note that the Tatsu drive gear shown above will have to be flipped around, and the fan will be rotated so that its wires are close to the big hole at the end of the fan spacer bracket.

Here, the Tatsu drive gear has been turned around, and more parts added:

(view from beneath)

The long black flat-head screw has been screwed into the motor. Its head protrudes. From right to left, this screw passes through:

  • the red plate that doesn't have two of its holes countersunk
  • two washers
  • one white plastic lever section
  • not the bearing (that's an illusion; the bearing is between the camera and the screw, not on the screw)
  • the other white plastic lever section
  • two washers
  • the red plate that has two of its holes countersunk
  • the face of the extruder motor gearbox

The screw that holds one washer and one plastic spacer goes through both red plates, and its nut installed. The screw and nut are not visible in this image.

The Tatsu drive gear is positioned so that its teeth are aligned with the bearing at the end of the lever, and then its set screw tightened. Make sure the set screw is centered in the flat of the shaft and tightened very securely.

Note that the lever assembly has to be positioned correctly before the extruder is assembled, otherwise its bearing will be on the wrong side of the Tatsu drive gear. The bearing at the end of the lever assembly will be positioned over the hole where the filament enters the hot-end assembly.

Next, place the hot-end assembly between the two red plates, with the nozzle oriented toward the right for the left-hand extruder. Put the two long screws through the fan and the fan spacer bracket, then through one red plate, then the hot-end assembly, then the other red plate.

Note the orientation of the fan. The label on the hub of the fan faces toward the motor. There is no direction-of-flow arrow marked on the fan. The corner of the fan where the wires emerge should be next to the big hole in the fan spacer bracket.

Add two nuts to hold this assembly together.

Below, the left-hand extruder assembly is shown lying on its side. Owners of v2 Bukobots get this pre-assembled. Note that the heater has been installed here; it is held in place by tightening a set screw.

Below, two extruders have been assembled and attached to the carriage. Each assembly is held in place by tightening its M6x12mm bolt, underneath the top plate. You can reach the M6 bolt with a 5mm ball-end hex driver if you slide the platform all the way back and slide the X carriage all the way to one side, provided you raised the X axis enough before you started.

Next, install the terminal block onto the top plate, as shown below. Only six positions are needed on the terminal block. (Or will fit.) If you have more wire positions than shown below, cut away the extra ones. The block is held in place with the same hardware used on the v1.

You may want to rearrange the wires that are currently hooked up to it before you attach it. Detach the old heater wires first.

You no longer need the wires formerly used to supply power to the heaters. Anyway, they are too thin to carry the current needed by the new heaters. You will run the meter-long red wires from the heaters all the way down to the Azteeg. Yes, you have to re-do those bundles of wire, but don't do it until you have finished dressing all the wires on top of the X carriage.

Hook up the thermistor(s) and fan(s) to their correct terminals. If you have two fans, they connect in parallel. Fan wires are polarized, red for + and black for -.

Photo taken from the back of the printer:

There will probably be some slack in the wires going from the fans and thermistors to the terminal block. Reach between the motors with a thin hex driver and pull that slack under the motors. (Warning: if you don't have two motors, don't reach between them.)

Take the slack out of the red heater wires where they pass by the motors, and secure all those wires with a medium cable tie around each motor:

Slide the X carriage all the way toward the X endstop and check that the X axis endstop switch touches the edge of the top plate but not any of the wires. Adjust that endstop and/or move wires if necessary. On this particular printer, the endstop didn't need to be adjusted at all.

Finish dressing the wires as shown above. If you have the acrylic piece shown below, you can secure your bundle of wires to it. It can be attached to the bottom of the top X carriage plate using the screw that attaches the terminal block (but the old screw may not be long enough).

Note that the image above is of a v2 Bukobot, and doesn't have the synchromesh cable spacers. As you can see, its cable follows a very different path.

Now you can re-do the bundles of wires that go down to the Azteeg. Remove the old heater wires, and run the new red heater wires all the way down to the heater screw terminals on the Azteeg.

Double-check that the heater wires and the thermistor wires go to the right places. We marked them red and white so that they wouldn't get mixed up.

Make height adjustments

Turn the Z endstop adjustment wheel until it is in the middle of its range. The Z endstop holder should be all the way down on the frame as far as it can go, and loose. Move it down there if it's not there already.

You need to lower your X axis until the nozzle(s) are almost touching the platform. However, because your extruder is now more compact, you may not be able to go down that far before a collision occurs somewhere else.

It is possible that the UHMW nuts supporting the Z carriage might collide with the pieces that join the Z axis motor shafts with the Z axis threaded rod. Or, a collision might occur with some other parts near there. This is to be avoided.

Temporarily remove each extruder from the top of the X carriage and set it down on top of the carriage, with nothing protruding below the X carriage: Use your 5mm hex driver to loosen the M6 bolt, slide the extruder forward, lift it up a bit and slide it back, resting the nozzle tip on the top plate of the X carriage.

Connect the USB cable, power up the printer, and connect your host software. Don't home anything. Don't move anything other than Z.

Use your host software to move Z down, a millimeter at a time, until a collision is about to occur somewhere. When you reach the point of imminent collision, disconnect your host software and power down the printer.

Now try to re-install your extruder(s). If you can install an extruder without hitting the platform with the nozzle, then you will have to move some things around on your printer. Because v1 Bukobots vary, you will have to determine how to reconfigure your particular printer. You need to be able to move the Z carriage down farther, so the nozzle can reach the platform (or perhaps raise the platform?). This may be the most complicated part of this entire upgrade.

This subject is complicated enough to justify its own page. Go there now and then come back here.

Once you have reconfigured the printer, try the above procedure again. If you can lower the Z carriage far enough so that you can't re-install the extruder(s) because the platform gets in the way of the nozzle, then you can proceed to the next steps.

Connect the USB cable, power up the printer, and connect your host software. Don't home anything.

Raise your Z carriage far enough that you can re-install the extruder(s) without a nozzle hitting the platform. Power down, and install the extruder(s).

Slide the platform all the way forward. Slide the X carriage until the nozzle(s) are centered above the rear of the platform.

Once again, connect the USB cable, power up the printer, and connect your host software. Don't home anything.

Put one finger on the Z endstop switch. Be prepared to quickly click that switch twice.

Now you are living dangerously. You will instruct your host software to home the Z axis only, and watch the nozzles descend toward the platform, and click the endstop switch twice right before the collision.

Slide the Z endstop holder up the frame until the switch clicks. Tighten the M5 screw to secure the endstop holder. The endstop holder may try to move around while you're tightening that screw; don't let it.

Tell your host software to move up one centimeter, then home Z again. It should stop just above the platform. Note the distance between the nozzles and the platform.

Move it up again, turn the adjustment wheel enough to raise the endstop switch by half that distance. Home Z again, note the distance. Repeat until it's right.

Software settings

(If you have taken the opportunity to change to a different Azteeg board, remember to tell Slic3r that your printer is different; this is under the Printer tab. Or, download the appropriate Printer profile from and load that. Also tell your host software; it's the dropdown list where you choose the chip type.)

Some of the settings inside your Marlin firmware have to be changed to match the thermal characteristics of the new hot-end(s). Connect your host software and issue these two commands:

M301 P8.29 I0.37 D45.91


Don't heat anything up yet.

Now home your X axis and verify that no part of the X carriage is hitting any part of the printer (if it is, adjust that endstop). Measure from the pointy end of the left (or only) extruder nozzle to the centerline of the platform (or measure to the near edge of the printable area of the platform and add half the width of the platform).

Now go into Slic3r, go to the Printer tab, and the General section. “Print center” might need tweaking because your X carriage is a different width and the nozzle(s) are positioned differently. Enter your measurement from above into the X box:

(As it happened, this setting was unchanged for this particular printer.)

If you have two extruders, measure the distance between the nozzle points. Then go to the Extruder 2 section and tweak the “Extruder offset” settings:

Nominally, the new X carriage is designed for an offset of 30mm for the second extruder. This particular printer measured more like 29.5, so that number was entered.

(These settings may need to be adjusted further if you ever actually try to print with two materials. The usual calibration procedure is followed; print a test pattern, measure any offsets, adjust settings, repeat.)

By convention, Extruder 1 is at offset (0,0).

When you're done changing these settings, click the Save button (looks like a floppy disk!) to save the Printer settings under a new name (your Bukobot deserves a new name, doesn't it?) and use that profile from now on.

Thanks to the Deezmaker guys for providing the upgrade kit and answering questions.

The contents of this page may be re-used under any of the following licenses: The Creative Commons Attribution-ShareAlike 3.0 Unported License (CC BY-SA 3.0), or the GNU Free Documentation License (GFDL, version 1.2 or later).

jitsbuild-v1-to-v2.txt · Last modified: 2013/11/20 23:18 by jit