jitsbuild-extruder [Bukobot 3D Printer Instructions & Docs]

===jit's build:  Extruder===

(Go back up to [[jitsbuild|jit's build]])

Get out the extruder kit:

{{wiki:jitsbuild:extruder-kit.png?800}}

The small circular object at the top is a bearing.  At left is the gearbox/motor and the Tatsu drive gear.  The hot end is at lower right.

(If you were one of the people who got their Bukobot before the bulk of the Kickstarter orders started shipping, then you may have a different extruder design.)

Examine the extruder lever (bottom view and top view):

{{wiki:jitsbuild:extruder-lever-bothviews.png}}

All of the thin structures on this part must be removed.  A good tool for this is:

{{wiki:jitsbuild:extruder-lever-trimming.png?800}}

Also widen the screw hole that's nearest the bottom end of the lever in this view, so that an M3 screw can slide freely through it:

{{wiki:jitsbuild:extruder-lever.png}}

But don't widen the other hole.  It will eventually hold a self-tapped M3x16mm button head screw, with no nut.

Clean up this part with a file.  Blow away all the tiny fragments of plastic before inserting the bearing.

The bearing goes in here:

{{wiki:jitsbuild:extruder-bearing.png?800}}

Now clean up the other printed part.  None of the holes in this part will need to hold threads, so check that the screws will pass through them freely.  The two holes in the base of this part (not the middle hole!) will need a 4mm or 5/32" drill bit.  You will probably have to unblock the lower end of the channel that will hold the 60mm long screw.  Also clean up the mounting surface for the gearbox;  the gearbox should lie flat against it.

Pay special attention to the small hole in the middle, where the filament will eventually pass through.  Clean up the conical approach to this hole, without widening the hole itself.  There shouldn't be any protuberances that will snag the filament as you try to push it through.

Before you install anything on the extruder block, get out the extruder mount kit and the hot end.  Make sure the M4 mounting screws can pass freely through the two holes in the hot end;  widen them if necessary, with a 4mm or 5/32" drill bit.  Then bolt the parts together like this:

{{wiki:jitsbuild:hot-end-block-align.png?800}}

Note how the parts are oriented.  The aluminum heater block at the left end of the hot end is pointing toward the camera.

Look down the throat of the extruder block, and check that the passage into the top of the hot end is lined up.  If it doesn't quite line up, or if you had trouble getting the two screws lined up, you should widen the two mounting holes in the plastic part a bit more, using a slightly larger drill bit, then reassemble this and see if you can get things to line up better.

Now take this assembly apart.

Put the Tatsu drive gear on the gearbox shaft, and tighten the setscrew against the flat of the shaft.  Grab the drive gear and twist the gearbox shaft around until the setscrew is pointing in the opposite direction from the way the wires are coming out of the motor.  The motor will be mounted with the wires pointing down, and the setscrew pointing up.  The gearbox gears the motor down quite a bit, so it may take some effort to turn that gear.

Before you install the gearbox/motor on the extruder block, install a screw and washer and nut from the extruder mount kit into this hole in the base of the extruder block, but not the matching hole on the other side:

{{wiki:jitsbuild:extruder-block-1screw.png}}

Install the gearbox/motor onto the extruder block, with the wires pointing down.  One of the long screws goes through the hinge hole in the extruder lever:

{{wiki:jitsbuild:tatsu-align.png?800}}

Close the extruder lever and look down through the hole in the lever at the Tatsu gear and the bearing.  They should be aligned.  If they're not, open the lever and adjust the position of the Tatsu gear on the shaft.

Take the nut off the mounting screw, insert the second mounting screw, and attach the hot end in the proper orientation, adding the two nuts to hold everything together:

{{wiki:jitsbuild:extruder1.png?800}}

Double check that everything is oriented as shown above.

Add the remaining hardware:

{{wiki:jitsbuild:extruder2.png?800}}

This assembly is ready to add to the X carriage.  However, you may need to raise the X axis first, otherwise the hot end may hit the platform.  If you used the soup can leveling method earlier, then you may not need to raise anything, but you should still go through the steps below to make sure the hot end clears every part of the platform.

If you have a dual-extruder model, you don't need to raise the X axis before installing the first extruder.  If you are installing the left extruder, just move the X carriage all the way to the left and the extruder will clear the left edge of the platform.  You may still have to raise the X axis before you move the extruder back to the right.  The following assumes you have a single-extruder model and have to raise the X axis before installing the extruder.

Hold the extruder assembly next to the X carriage and see how much the carriage has to be raised before the hot end clears the platform when the extruder is installed.  Keep in mind that some parts of the platform may be sticking up higher than other parts, as you haven't leveled the platform yet.

Move the X carriage and the platform until the big hole with slots, where the extruder will be mounted, is above the rear support screw in the middle of the back end of the platform.

Raise the X axis by rotating the Z axis couplers.  You need to turn them clockwise, as viewed from above.  Rotate the two couplers a couple of rotations at a time, keeping them in step.  Occasionally check to see if you have enough clearance to install the extruder.

Once you have enough clearance, install the extruder.  Don't move the X carriage or the platform during the following.

Lower the extruder through its hole, hot end first.  The four wires from the hot end fit through a slot next to the extruder:

{{wiki:jitsbuild:extruder-from-above.png?800}}

{{wiki:jitsbuild:hot-end-wires.png}}

Make sure you put the mounting screws through the correct slots.  It goes on at an angle, so the extruder motor points straight back.  After checking for interferences, put the nuts on the underside of the carriage and tighten the mounting screws.

{{wiki:jitsbuild:extruder-from-front.png?800}}

Now it's time for the initial leveling of the platform.  We will do this again, more precisely, later.

Place the extruder wires somewhere where they won't hang up on the synchromesh cable or anything else.  Watch the hot end and slowly move the X carriage to the right.  If the hot end gets closer to the platform, then the platform height adjuster on the right needs to be turned.  Turn it anti-clockwise, as viewed from above, to lower that side of the platform.

When you get to the right back corner of the platform, slowly move the platform back so that the right front corner of the platform moves toward the hot end.  If needed, adjust that wheel to keep the platform from colliding with the hot end.

Once you get to the front right corner, slowly move the hot end to the left.  If it gets near the platform, lower the left front corner of the platform by turning that wheel the same way as before.  Once you get to the left front corner, it should be safe to move the hot end to any part of the platform.  Check that, slowly.  If you have any hardware protruding from the top of the platform, such as the wire connections on the heated platform, don't hit them with the hot end.

If you have a second extruder, do that one too.  Carefully check platform clearance, as the second extruder might hang farther down than the first.  If they hang at different heights, you may have to shim with thin washers.  But first, check to make sure the extruders aren't hung up somewhere on their mounts.  Also check that an imaginary line drawn between the two extruder nozzles is exactly parallel with the horizontal steel rods;  if not, adjust the position of one or both extruders until it is.

Note that the lower portion of the hot end should be thermally insulated for best results.  Polyimide tape is provided for this purpose.  This is not covered here, but look [[hot-end-thermal-management|here]].

You should now have everything set up so that you won't get a collision between the extruder(s) and the platform, no matter where you move either axis.  At this point you should move the Z axis endstop up until its switch is fully depressed.  Loosen its 5mm screw (the one holding it onto the right frame piece) and move it up, then tighten that screw.  You will re-adjust the endstop later.

[[jitsbuild-wires|Next:  Wires]]

//The contents of this page may be re-used under any of the following licenses:  The [[http://creativecommons.org/licenses/by-sa/3.0/|Creative Commons Attribution-ShareAlike 3.0 Unported License (CC BY-SA 3.0)]], or the [[http://www.gnu.org/copyleft/fdl.html|GNU Free Documentation License (GFDL, version 1.2 or later)]].//
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