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Final Fitting of the first Do-Nothing Machine

Picture 1: The end of the last installment

Now that we have the shuttles completed and sliding freely in the base of the Do-Nothing Machine, we are ready to assemble it… or so we hoped. As normal, the way things actually happened, there were more unforeseen difficulties and a few self-created others.  However, working through problems is part of normal procedure.  It is not only designing on paper, but “thinking on your feet” and working past problems that pop up throughout construction.

This is the third of the series on the Construction of the Do-Nothing Machine.  The first two are Routing the Base and Making the Shuttles.  There will be a few more instalments on alternative ways of constructing this and at least one more on mathematical analysis of the machine.

Picture 2: Tools used to drill the holes in the shuttles and handle.

I did not go to the trouble of actually drawing out the design to calculate the length of the shuttles. I thought I would just “cut to fit” and the first assumption on the length was wrong.  I decided to cut the first shuttle into two equal pieces.  I then drilled holes into this to mount a 1″ long 6-32 machine screw.  If I would have had a small pin vise, I would have done all this work manually.   Instead I used a Dremel and very small drills to start the hole.  This probably actually ended up being a good thing because the holes were easy to line up to be perpendicular to the shuttle piece because the length of the Dremel and its cylindrical shape makes this almost fool-proof.  Two accessories for the Dremel used in this job were the small drill set and the set of collets to hold these bits.  The final drill for the machine screw was the 5/64″ drill but I needed to sink the round head of the screw above the bottom of the shuttle and worked up to 15/64″ bit to accomplish that.  When using these larger bits I used the spare chuck as a pin vise for these bits and drilled this larger diameter by hand.  Although this was slower than using an electric drill, it guaranteed that I would not drill too deep.

Picture 3: The initial set of shuttles in the actual machine.

The initial assumption was that I would put a nut on the machine screw and tighten it to firmly hold the screw into the shuttle and then put a washer between the nut and the handle. This ended up being unsatisfactory for several reasons.  First this put the handle higher on the screw making it easier for the handle to twist the shuttle in the groove.  This caused the shuttle to bind in some locations.  Second, sometimes the nut would rub the handle enough to twist and loosen on the shuttle.

Picture 4: A tee nut.

The idea to overcome both of these problems was to use a “tee-nut”. The tee-nut is designed to be driven into a hole on furniture and the barbs on the nut hold it in place and prevent it from turning. Larger sizes of these are often used to mount legs on furniture.   This presented another problem.  The thin shuttle could only accommodate one of the barbs and the others might actually rub on the base and/or split the shuttle.

Picture 5: Breaking off the extra barbs on the tee-nut.

As shown in picture 5, a small pair of vise grip locking pliers was very handy for breaking off the extra barbs. It was necessary to thread a machine screw into the tee-nut while doing this job to provide the extra leverage me to hold the tee-nut while bending the barbs.  I had to drill the top of the hole in the shuttle to 13/64″ diameter to to fit the shoulder of the tee-nut into the hole.

Picture 6: The first assembly of the complete machine

I drilled holes in the handle so that one shuttle was completely extended while the other shuttle was at the center of the crossing of the grooves. At this time I also fitted fitted the knob on the handle. I assembled the machine again and ran headlong into the next set of difficulties. The problems this time were the shuttles are too short to make the operation as enjoyable to watch as it would be if the shuttles barely miss each other. I also had a problem with the screw of the handle hitting the base at the corners of the base.

Picture 7: Initial set-up with the longer (4″) shuttles.

I still had the one 4″ shuttle and shaped another one and drilled the holes as described earlier into the center of these. 4″ turned out to be a very small amount too long so a little was trimmed off each end of the shuttles. A new handle was cut and drilled. Everything worked well this time, except the nuts holding the handle to the shuttles would become tight if the handle was rotated in one direction and loose if the handle was rotated the other direction.

Picture 8: The final version without cutting off the extra long screws. (That will happen after painting)

The 1″ machine screws were replaced with 1 1/2″ screws to allow two nuts to be put on the top of the handle.  The 2nd nut will be a lock nut to bind the nuts to prevent the nut from turning on the screw.  A washer will also be placed between the nut and handle.  The final modification was to add a handle to the bottom of the machine by cutting a section of 1″ dowel rod and counter sinking a flat head screw in the center of the crossing point of the grooves.  The handle was also glued to the base.

This version will be painted for the finish and used in a planned YouTube video.   Meanwhile I will be thinking of further improvements and alternative building methods.

Now that this initial one is completed I will cut one or two more bases using some lower tech methods than the router.   I will also do a post on methods to build these in an increased production method.  (Cutting tools with fixtures).   The biggest hassle in this version has been the fasteners and I will look into alternatives to the screws.  (I am not sure I will have anything to post about on that.)  Another thing I will think over is creating an adjustable one to route ellipses.  Again I will not promise that I will get that accomplished.  Finally, there will be at least one more post that is more mathematical talking about the movement of the shuttles and handle in relation to each other.  Although the mathematical one will be somewhat boring and detailed, it is an exercise we need to go through to work through an example mechanism.

Gary

 

 

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