jitsbuild-x-leftend [Bukobot 3D Printer Instructions & Docs]

===jit's build:  X left end===

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

{{:wiki:jitsbuild:x_left_kit.png?800|}}

Some of the items shown above may differ slightly from the ones you get in your kit (this is bag 15).

The printed plastic part shown in this image has a significant overhang in the large circular opening (this is the opening on the underside where the UHMW nut, the white object at lower left, will be inserted).  The printing technique used to make this part cannot produce a sharp clean profile with this kind of overhang, so the part must be trimmed before you attach parts to it:

{{:wiki:jitsbuild:cleanup1.png?800}}

{{:wiki:jitsbuild:cleanup2.png?800}}

{{:wiki:jitsbuild:cleanup3.png?800}}


Make sure the UHMW nut goes in straight, and check that there are no protuberances in the channels that will hold the long steel rods.  Get out a steel rod and check that it fits snugly into these channels.  See [[Cleaning up printed parts]].

Also check the two small holes that will hold the screws that attach the Z slides inside the arms of this part.  Widen them enough so that M3 screws can pass through these holes easily.  A 3mm or 1/8" drill bit will work fine.

Sometimes you will find that a screw will not easily fit into a hole in the printed part.  This printing technology cannot produce holes of a precise size, so parts designers try to adjust the sizes of holes so that variations in the printing process are unlikely to produce a part that is unusable.  This means that sometimes you have to widen a hole.  If a screw is intended to be self-tapped into a hole (with no nut on the other side) it is important that the hole not be too wide, so the designer will specify a smaller hole than really needed for that screw.  If you have a lot of trouble self-tapping a screw into a hole, then widen the hole, but not too much.

On the other hand, if a nut is to be used on the screw, the hole can be widened until the screw easily passes through.  Be very careful to determine which holes use nuts and which don't, as it can be a big hassle if you remove too much plastic from a hole that needs it to hold threads.

Sometimes a designer will indicate which holes need nuts by printing a nut-shaped depression at one end of the hole.  In some cases you can press the nut into this depression and it will fit there, and sometimes even stick there.  But if this depression is printed on the bottom of a part, its shape will not be very accurate and the nut may not fit into it.  In this case, it may **//not//** be necessary to adjust the size of that depression to actually fit the nut;  try adding the screw and nut to the part, then check to see if the protruding nut will interfere with anything.  Often there is no potential interference, and no need to do anything else.  Consider the nut-shaped depression to be just a hint that a nut goes on that side of the part, and not an actual required feature of the part.

Note that there are no lock-washers in this design.  Vibration during operation may cause nuts to unscrew.  You can use a dab of threadlocker (the blue removeable type) to hold nuts in place.  Many nuts and screws are left loose throughout much of the build process, so that the position of various parts can be adjusted in later steps;  don't apply threadlocker until these adjustments are made.  If you are worried about nuts working loose during the build, apply a small dab of threadlocker near the end of the screw, far from the nut;  the nut may work itself toward the end of the screw, but it won't leave.

Now get out one stepper motor and one synchromesh pulley and put the pulley on the motor shaft.  Align the setscrew with the flat on the motor shaft and tighten it with your 1.5mm hex driver.

At this point you can use four M3x10mm button-head screws to attach the motor to the printed plastic part.  However, unless you have particularly large hands, this motor can make it harder to attach this assembly to the Z axis later on, so you might want to defer this step until later.  If so, put the motor and its four screws in a bag and set it aside.  The images to follow assume the motor is installed now.

 (bottom view):

{{:wiki:jitsbuild:x-leftend_assembled_bottomview.png?800}}

Note that the two nuts near the bottom of this image are sitting on top of nut-shaped depressions, but don't fit precisely into them.  They don't need to.  There is room on the bottom of this part for the nuts to protrude from the surface.  Threadlocker can be used later to keep these nuts from wandering if you are concerned about it.

(Almost) top view:

{{:wiki:jitsbuild:x-leftend_assembled_topview.png?800}}

The screws with fender washers on them should be quite loose.  The long steel rods will be inserted under the fender washers later.

The wires for the stepper motor have been threaded through the oval hole near the motor.

Next we will install the endstop.  However, you may not want to install yours yet, as it tends to be in the way and the wires can be easily broken.  You may wish to follow these steps to attach the endstop switch to its holder, and wait until final assembly of the printer before attaching this subassembly to the X left end.  Many of the images from this point on will show the endstop already installed.

From the endstops kit:

{{:wiki:jitsbuild:x-endstop-kit.png?800}}

{{:wiki:jitsbuild:x-endstop.png?800}}

Some builders have positioned the switch on the other side of its printed bracket.  It should work either way.  This way places the wires in a more protected position.

Check to make sure stray strands of wire aren't shorting across the switch terminals.

Thread the endstop wires through the same oval hole near the motor, wrap all the wires around the assembly, and set it aside, along with its Z-slide sub-kit.

[[jitsbuild-x-rightend|Next: X right end]]


//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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