Enough with the Rosie fer cryin’ out loud…

By popular demand, I’m letting go of the Rosie theme.  I won’t say who demanded it, but there was a foreign accent and threats of mayhem involved…

I’ve been busy the last couple of days, biding my time until my new fender washers arrive.  Three subassemblies are complete (pictures below), and I’ve assembled all three of the Optostop boards.  Its been a long time since I’ve done any soldering so this was fun and didn’t take very long.  Three boards, each with 21 through-hole connections to make.  Someone handy with a soldering iron could probably do it in 15 minutes.  It took me, well, lets just say it took me longer.  The good news is that I tested all three and they all passed.

Oh, and I learned that you don’t press down on the flux pen – the stuff squirts all over and is incredibly sticky.  Isopropyl alcohol on a toothbrush seems to clean it up pretty well, but I think my shirt may no longer be wearable to work.

So the first set of pictures is a continuing buildup of the extruder carriage in the last post:

This view shows the installed motor on the pinchwheel bracket.  If you were to look down next to the motor shaft, you would see that there is a bearing that is used as a pinch roller with the shaft.  The fiber stock feeds through the small hole in the top, between the shaft and the pinch bearing, and down through the heated extruder head (not built yet).  The thin metal flag is used along with an Optostop board to keep the carriage from going too far as it traverses in the X direction.

This picture shows the biggest problem I’ve run into so far.  The recessed cap screw near the upper left hand corner of the motor is actually about 1 cm too short.  The pinch wheel bracket has been redesigned to form an extension on the side, which made the bolt path about a cm longer.  Unfortunately the designers didn’t catch this and call out a longer screw in the BOM.  To get around this and avoid having to wait a few days for a 50 mm long x 4 mm capscrew, I dug out a Forstner bit and drilled a counterbore just larger than the washer and deep enough that the captured nut can fully engage the screw.

This is just a view of the bottom of the carriage.  You can see that the extruder head is missing.  Once these pictures were taken I removed the motor.  It turns out that the part it attaches to is not quite dry and weeps moisture when compressed by the screws.  It will need to take a trip back into the oven before the motor undergoes final installation.

The next set of pictures show the “vertical-bearing 360”

In this picture you can see the round holes to the left and right that grasp the X-axis rails.  The triple bearing sets at top and bottom surround (thus 360) the vertical axis rails.

The small circuit board is an Optostop with three resistors, an LED, an RJ-45 connector, and a difficult-to-see optical sensor.  Behind the board where you can’t see it is another vertical hole.  Inside this hole is a captured 8 mm nut which will thread onto the vertical leadscrew that drives the completed X-axis up and down.  This picture (respectfully stolen from the Reprap website) shows things a bit better:

Finally, the last assembly I have completed is the leadscrew nut assembly from the other end of the X-axis:

Again, you can see one of the round holes that grab the X-axis rails (on the top surface at bottom left), but this time you can see the leadscrew passage on the right vertical face which also contains a captured 8 mm nut to ride on the second leadscrew.  The Optoswitch flag for the vertical motion (Z-axis) is also clearly visible.

Finally, one last bit of progress:  the three new gears are complete and have been fitted to their motors.  The arbor holes were still a little small because of the STL faceting, but a small rattail file took care of that in a few minutes and a solid press fit was achieved.

The next step is to create a couple more X-axis subassemblies, and then assemble them all into the final X-axis.  Hopefully, I’ll be able to get to work on that tomorrow, assuming the new fender washers arrive 🙂


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