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

===jit's build:  X carriage===

(Go back up to [[jitsbuild]])
 
{{wiki:jitsbuild:x-carriage-duo-kit.jpg?800}}

This kit is for the X carriage of the dual-extruder model.  The kit for the single-extruder models is the same, except the lower five parts shown on the parts list are each quantity three instead of quantity four. (This is bag 17 plus a metal plate from the flat-pack in the currently shipping kit)

The parts for each linear bearing are:

{{wiki:jitsbuild:linear-bearing-subassembly1.jpg?800}}

The printed plastic part may need trimming before assembly.  Place the nut into its hexagonal hole in the printed part, and make sure it fits flat against the bottom of its hole:

{{wiki:jitsbuild:linear-bearing-subassembly2.jpg?800}}

Snap the bearing into the printed part, and verify that it fits well, and that the two parts are parallel. The bearing should be seated all the way into the printed part so that the inner shaft of the bearing is just above the lip of the printed part. A fully assembled bearing is shown below. But before you do the final assembly with the nut and zip tie, make sure all the bearings fit into their printed parts well. 

{{:bearing-fit2.jpg?500|}}

Do this with all of the linear bearings and holders, and compare them;  they should look the same.

A good way of checking the bearing holders is to insert bearings into all of them and then put a piece of your precision steel rod through them:

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

Here, the second one from the right isn't lining up with the rest.  You can also see a printing defect in this part, where one layer looks different.  This part is usable;  it just needs to be trimmed a bit.

Where needed, trim the part (remove the bearing first!).  See [[Cleaning up printed parts]].  

Remove the bearing from the printed part, if you haven't done it yet.  (If you can't get a good grip on it, insert your 5mm hex driver through the middle of the bearing and carefully pry it out.)  Now insert the screw into the hole in the printed part.  Does it slip in easily?  If not, you have a choice:  widen the hole, or thread the hole.

This screw fits into a nut, so it is safe to widen the hole.  (Some other holes in the machine will be getting a screw but no nut, so those holes must not be widened too much or the screw threads won't hold.)

Alternatively, you can thread the hole.  Since a nut will be applied, it is important that the threads you make in the hole line up with the threads in the nut, otherwise the nut will float above the bottom of its hole.

To properly thread the hole, insert the nut into the hexagonal hole in the printed part and thread the screw through the nut and into the printed part;  some force will probably be required to turn the screw, but with a screw this large it shouldn't be too difficult.

{{wiki:jitsbuild:threading-a-printed-part.jpg}}

Then, remove the screw, being very careful not to let the nut fall out of its hole.  Move the screw to the other end of the hole and screw it in, making sure to get it into the threads you just cut into the printed part.  As long as the nut remains in the same position as before, lying flat against the bottom of its hole, its threads should line up with the screw as it emerges from the plastic.  Screw the screw through the nut.

That was just for demonstration.  As it turns out, the holes in the linear bearing holders shouldn't be threaded;  later steps will be easier if the screw slips through the hole easily.  If necessary, widen the holes in all your linear bearing holders (you have seven or eight of them altogether).  Then insert the screw and nut and tighten.

Insert the bearing into the holder, make sure it is centered and parallel, and wrap one cable tie around the subassembly to secure the bearing into the holder:

{{wiki:jitsbuild:linear-bearing-subassembly3.jpg}}

Make sure the head of the cable tie isn't on top of the flat surface of the holder;  position it next to the bearing.  Make it tight, and then cut off the loose end of the cable tie.

Repeat the above for all of the bearings needed for the X carriage (three or four of them).

To complete the X carriage, you will need one or three flat metal parts. Remove the screws from the printed parts, and screw the bearing assemblies onto the metal parts as shown.

For the single-extruder models (bottom view):

{{wiki:jitsbuild:x-carriage-singleextruder-bottomview.jpg?800}}

For the dual-extruder model (top view):

{{wiki:jitsbuild:x-carriage-duo-topview.png?800}}

Note the two screws in the middle of the dual-extruder assembly.  Screws and nuts applied here will increase the stiffness and stability of the X carriage, but you may not have these optional parts in your kit.  Any short screw that fits will do, as long as it doesn't collide with the steel rods that will pass through the linear bearings.  We are using use a pair of M5x8mm screws and nuts in this build.

For the dual-extruder model (bottom view):

{{wiki:jitsbuild:x-carriage-duo-bottomview.png?800}}

Add a few more parts:

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

Also add a terminal block (six positions per extruder) and M2.5x16mm socket-head screw and nut (one set per extruder):

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

Position the terminal block(s) so that they won't interfere with the X tensioner or the matching slot on the far side where the synchromesh cable will be attached.

The loose screw shown above will be used later to attach the synchromesh cable to the X tensioner.  Put this screw back in the X tensioner bag for now.

Now set the X carriage aside.


[[jitsbuild-x-leftend|Next:  X left end]]



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