Putting the X axis together

After a few days concentrated work, I seemed, at last,  to have all the mechanical parts ready for final assembly.  The frame had already been assembled, but I had to take it apart to correct a few small defects.  Rather than just put it together again, it seemed more organised to follow the reprap wiki
construction notes systematically, finishing things definitively at each stage.

First on the list was mounting the extruder on the carriage.  Here I had to improvise a bit because the nuts on the carriage conflict with the baseplate of the extruder, and also the large driver cog conflicts with the fixing block on the side of the carriage.  Recesses cut in the baseplate fixed the first problem.  For the second, I cut of the original fixing block and replaced it with a brass wire hook assisted by two locating pins set into the face of the carriage which mate with chamfered holes in the extruder.  I was pleased with the convenience of this arrangement until I replaced the gearwheel and found that it make the hook rather inaccessible.

Upper carriage, unmodified

Lower carriage

Detail of joints

Cutouts and matching nuts

Neat, convenient fixing

Inconvenience restored

This was not in fact the final assembly of the carriage,  as I had forgotten the plate for the fixing belt on the lower carriage.  I made and fixed this, reassembled the carriage and adjusted the positions of the bearings to perfection.  Then I noted that the trapped nut in the upper carriage for fixing the extruder had escaped, so I had to take the carriage apart again.  This time I used epoxy glue rather that rely on friction,

An awkward cut

As I prepared to assemble the bearing plates I found that I had forgotten part of the shaping work.  To make the final cut safely, I screwed them temporarily to a carrier so as to cut accurately while keeping my fingers well clear of the blade

The wood grain in the x-180-z-bearing-plates has to be vertical, so that the flexible pillar is strong enough, but this leaves the tunnels for the x-axis rods a bit weak.  To counteract this I glued an inset piece of wood with the grain at right angles.  The end of this piece is just visible in the picture.  Note that the reinforcement has to be higher than the tunnel and thicker that the central hole to be effective.

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 When I assembled the 180 bearings onto the x-axis idler, I put the flexible pillars both on the same side of the z-axis.  This is a departure from the diagram in the instructions which has them on opposite sides.  I seemed to me that the original arrangement would tend to rotate the structure as the bearings were tightened into contact with the  z-axis, and this problem would be avoided if they were in the same side.

X-axis idler / 180 bearing

X-axis bar clamp

... much time passes ...
It is now 2016, and I have just found this post languishing in the drafts folder, so I am publishing it as is.