This time I will show you how to build a simple but sturdy nutcracker from things one can find in every household. The first picture shows (most of) the things you will need.
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Step 1: Mark Where to Drill Support Pillar Bolt Holes
The two diving chamber windows will be bolted together, with the three vacuum cleaner pipes as supporting pillars. Since I plan to bolt the pillars into snug seats in the acrylic slabs, I tried to mark the position of the bolt holes as accurately as I could. (It helped to think about the LIGO facility when doing it.)
Step 2: Set-up of the Acrylic Slabs in the Drill Press
I quickly realised that the pressure chamber windows were a bit large, and had a less than optimal shape for allowing for a simple set-up in my drill press. The first two pictures shows my first effort. After one or two holes, I realised that it was, just barely, possible to squeeze the wise in. The last two pictures show that set-up.
It may not be possible to see this in the pictures, but on one side of the windows, I had marked the centre. The window is adjusted with the help of the square, until this centremark is straight below the mark on the perimeter, (see previous step).
Step 3: Drill Holes for the Pillar Screws
Drilling this deep in solid plastic was a new experince for me. I had heard that one really needs special drills with a different geometry at the tip, but decided it should be possible to cheat with drills for wood and metal, given some care.
The name of the game seems to be to have a lot of patience. If too much pressure is applied, or too high speeds, too much heat will accumulate and the acrylic will melt. If it does, the hole will deform an look really bad. Literally!
Apart from the visual beauty of the end result, I also had some concerns about the subsequent gear tapping. Overzealous drilling can result in oversized holes, leaving little or no material for the threads.
I used water as cutting fluid. It may not provide optimal lubrication or cutting performance, but was practical for a couple of reasons.
- It does not leave any residues.
- It does not harm the plastic.
- It can absorb a lot of heat.
- It is easy to spot when it reaches 100 °C
I think I could drill 4–5 mm at a time. (Drill, withdraw, clean drill, add water, repeat, ...)
Step 4: Tapping the Threads
Originally, I had decided to use as long screws as possible in order to spred the load on as much surface as possible. I wanted to avoid the risk of stripping the thread from the holes due to a few seconds of abscent-mindedness and over-tightening. When I tapped the threads, I was really grateful for the entry of the holes, the section which shouldn't have any threads. They helped me align the tap properly, avoiding the classic mistake of starting off at an incorrectable angle.
The tapping had to be subdivided into about 4 stages. There was no way for the cuttings to find their way out of the hole on their own.
Due to the taper of the tap, the holes were drilled somewhat deeper than the length of the screws.
Step 5: Cut and Drill Support Pillars
Care was taken to
- cut the pillars squarely,
- mark a straight line along the pillar, so that the top holes were perfectly aligned with those at the bottom, and
- position the top holes at the same distance from the bottom holes, on all pillars.
2 was accomplished by clamping the pillars to a flat table, and using the device shown in the second picture.
The third objective could be realised by using the first pillar as a tool for marking the holes on the remaining pillars (see the three last pictures).
Step 6: Manufacture Load Distribution Pads
The machine screws will push on these pads, positioned inside the support pillars.
Since the hammock crossbeam stick is slightly thinner than the inner diameter of the vacuum cleaner tubes, I took the chance to add pieces of bicycle inner tube. This not only makes the fit snugger, the layer of rubber will also help to some flex to the structure. This should help loads to distribute more evenly between neighbour screws, and reduce the risk that anything is overloaded.
Step 7: Cut Out Support Pillar Seats
In order to aim the hole saw at the right spot of the acrylic windows, I prepared a drawing of the geometry. This drawing was printed and carefully positioned at the table of the press drill.
It quickly turned out, however, that my hobby drill press was too flexible for the task thrown at it. Fortunately, I hade a third window which could be sacrificed; If both sides of the hole saw are biting into equal amounts of material, the tangential forces will balance, and the hole will end up in the intended position (see last picture).
Step 8: Drill Nut Stamp Guide Hole
The central hole for the engine valve stem was drilled last, since I did not want to lose the centre mark prematurely.
(The picture only shows the pilot hole drill. I have no picture from when the actual, full diameter hole was drilled.)
Step 9: Trim Excess Washers and Rubber
The washers have to be cut slightly, so that they do not leave marks on every table on which the nutcracker is used.
Step 10: Add Felt Feet
The edges of the pillars may be flush with the bottom of the acrylic base plate, but felt feet were added for some piece of mind. I also hope that they will reduce some of the inevitable racket that this machine will make when used.
Step 11: Assemble
After all the pieces ar bolted together, a piece of ventilation hose can be added as eye and hand protection. It stays in position thanks to the snug fit between the pillars. The engine valve actually fits with some margin inside, so the device can be operated with the protective hose in place. The hose also makes the nutcracker delightfully ugly.
Step 12: Try to Control Your Impulses
The picture shows what is left of a hazelnut after the engine valve had been released from the height of a handful of centimetres. Spaghetti western overkill comes to mind.
About two centimetre drop height appears to be adequate for hazelnuts.
If potential energy alone does not finish the job, one could always whack the end of the engine valve stem with a sledgehammer...
Step 13: Epilogue: a Precursor
The nutcracker "Impulse Control Disorder" has a precursor (see picture). Its personality is quite different from its younger brother. Instead of violent impulsive assaults on the nuts, it uses exact doses of force.
Step 14: Addendum
The appended document contains a couple of notes and sketches I have scanned. They may or may not make any sense to everybody.
I will no doubt insult the intelligence of the regular instructablites with the following remark, but I add it anyway due to the minute risk that this page might be viewed by normal people. The ICD nutcracker is not just a nutcracker, it serves as the backbone of a mindblowing culinary system of destruction, no part of which is dishwasher safe. With the appropriate accessory, you can for instance press orange juice, chop onions, put loose stroopwafeln back in shape, as well as carry out the Heimlich manoeuvre on Easter bunnies.
All details will be revealed as soon as all accessories have been certified by the BIPM.