Introduction: Coconut Cracker

I had inadvertently found a great way to open a coconut, one where the meat falls away from the shell and you do not have to dig it out or cut it apart. Now I'm trying to recreate it in better ways...

Step 1: The Evolution of an Idea...

If you are not interested in the brief story of how this
project came to be the please feel free to skip ahead to step 5.

About 2 years ago I was wondering around the produce section of my local not quite the warehouse grocery store and stumbled upon a whole array of not from around here foods. And there they were the big box of magnificent mature coconuts… I hadn’t had one in years, so I paid my $3 and left happy. OK so I had to come immediately back since I had forgotten about the rest of the groceries. Shortly I was headed back home for some much needed relaxation.

I remember from my childhood that my father used a screwdriver to drain the water then whacked the coconut with a hammer before using a spoon to dig out the meat, so I followed suit. Stab, whack, scoop and enjoy. Well in theory. So the draining went well and the anticipation built. The hammer was next and a couple of smallish hits later and nothing, so I decided to bam it up a notch. Nice hard swing and whack! Everywhere it went except for the parts that were mashed beneath the 32 oz framing hammer. After getting it cleaned up I was now at the digging phase. I used a knife, spoon and wood chisel to scrape and dig. That took the fun out of the process and the coconut for some reason did not taste as sweet as I remember.

The whole ordeal took the better part of an hour and I was left thinking that there had to be a better way.

First of all I love coconut and the thought of whacking something that I love with a hammer seems quite wrong. The same goes for the stabbing it to get the water. The simple act of opening a coconut was horribly barbaric and needlessly violent.I certainly didn't want that kind of energy in my snack!

I went back to walking past the big box at the grocery store, occasionally getting one but I did however modify one step, I now had a hand drill to carefully auger out the top for draining the water.

One day I thought to hold the coconut in my bench vise while i drill it out when I tightened it too much and there was a rather satisfying snapping sound as the coconut split just off center. More importantly the meat seemed to come out a lot easier. Plus the whole opening and hulling the coconut took significantly less than 5 minutes. I now was using to vise to open my coconuts.

Sadly or Luckily, the coconuts for sale were not always the smaller kind so several years and many missed opportunities to enjoy the coconut later, I finally got around to doing something about it.

Step 2: The Donut

In order to save space I thought that a simple press would do the trick, so I tried a c-clamp. This met with limited success so I decided to cast my own specialized clamp from aluminum since I had been itching to make something in a foundry that I just built. Several hours starting with quick prep, gathering scrap aluminum and melting it to the right consistency making a foam donut with assumed dimensions… I cast the aluminum donut and drilled then tapped a hole to take the screw from an old clamp and assembled the beefy chunk of metal. Proud of my creation I grabbed a coconut and I just wouldn’t fit…

Step 3: Build a Better Donut

Fast forward a couple of months and I’m itching to try again. Frustrated with my earlier design flaw, set out to make it right this time.

With careful planning and measurements I refined my donut and made a larger more elegant shape from foam in order to do some more sand casting. Taking great care I set out to cast this one right, All went smoothly and I patiently waited for it to cool. The excitement of the reveal was intense. From the sand it came… pre-broken. Bad casting… More work gone and I was starting to rethink the design.

Step 4: Finally Got It to Work

From the ashes… I gathered up some scrap pieced of 1 inch square
steel tube and angle cut the ends. I drilled a 5/8 inch hole through the center of one piece then welded a ½ inch nut to the inside hole. I completed the frame and welded the tube to a scrap piece of steel plate. Next I carefully welded and 3 sided force spreader with a spike on the downward side. I also made a t handle for a section of ½ inch threaded rod from a piece of 1 inch conduit. This was welded together. I assembled the frame and handle. This was then all cleaned up and assembled.

Time to try it… I grabbed my coconut and drained the water. Placed it on the base place and gradually tightened the screw. The coconut groaned and made little snapping sounds I turned the handle some more with the same result. Looks good so I kept going. More turns that the coconut was visibly deforming then then was a satisfying snap that the coconut literally broke in half and the meat fell out whole with not one piece of shell on it! NOW WE ARE GETTING SOMEWHERE!

I used this design for the better part of a year before the screw bent and the tip broke.

Step 5: Build a Better Press

I had stumbled upon the best way to open a coconut now I
just needed a way to give it controlled slow pressure until it falls apart.

I set about making a light duty arbor press. Since this was just a proof of concept I will be adding form to the function in the next version. Sadly this one is made from the worst kind of material for this sort of thing. Seriously don’t use wood for the moving parts. While mine does work, it will certainly not last very long.

Step 6: The Moving Parts

Since this whole machine is made from wood I did make the
moving parts larger than they would need to be if made from metal.

I have included templates for those that would be wanting to go down this road...

I began with using a gear template and made a spur and rack gear of arbitrary size. To be honest I guessed on this one and wound up getting it ok, not great but easy to work with.

I cut 2 gears from the plywood and at the same time cut 2 racks from 2 inch wide strips of plywood.

The cutting was done with a scroll saw and I am starting love that thing…

Both the spurs and racks were glued and clamped together then sanded smooth on all sides. The gears need to mesh but not bind.

Step 7: The 4 Pieces of the Base

I built the base around the moving parts. I just went for it
and measured very little.

There are however a couple critical dimensions to work with. The first is the opening for the coconut. I made this one a circle of 8 inches in diameter. This should be large enough to accommodate even the largest of coconuts.

The gear location is also critical it is above and to the rear of the big opening.

I used craft paper to get a rough idea of the size and shape based on the dimension requirements. Yes it sort of looks like and arbor press. The gear is placed offset to the back and above the opening. The final shape is sketched out and the template is cut from the craft paper.

This template is then cut from plywood. I used 4 equal shapes. The center of the gear location is marked on all 4 pieces.

Step 8: Prepare the Inner Base

Next, 2 of the base pieces have to have the gear location cut out
and the front 2 inches in front of the gear removed, this is measured from the tooth base not tip. The gear teeth will stick out past the front of the piece.

These pieces are then glued together and clamped until dry.

The assembly is sanded and the gears are dry fit into place to check for clearance.

Step 9: The Outer Base

The 2 remaining base pieces need to have some cutouts where
the gears go. I used a 2 1/8 inch hole saw for this. It was done with a drill press to get the holes even. The cutouts from the holes are kept for late and 2 additional are cut from some scrap plywood.

One by one the outside pieces are glued and clamped in place until dry. The last side must have the big hole lined up with the first. It too is glued and clamped until dry.

The whole assembly is the sanded on all sides and edges to give the impression that it is just one massively thick piece of plywood.

Step 10: Bearing Surface

Since a hole-saw was used to make the gear cutout holes the center pieces will have some spacing. I wanted this since I was going to use a bearing surface made from some copper tube. The tube was cut about a half an inch wide then a 1 inch section was removed. It was then forced to fit into the cutouts on the side pieces of the base. From here the cutouts will fit with a bearing surface.

Step 11: The Drive Gear

I used the gear template to make a big tooth small gear the size of 2 of the cutouts. I used the scroll saw to cut these little gears then they were glued and clamped together. All sides were sanded once the glue was dry. I then countersunk one side of this gear assembly to house a ¼ 20 nut.

Step 12: The Spur

The main gear was then put into place and the two side pieces were attached to it using a long ¼ 20 bolt. The small gear was then glued and tightened to the right hand outside of the gear assembly.

I also measured and used 3 long deck screws to hold the outside gear firmly to the inside gear.

Step 13: The Rack

The rack was then positioned into the slot in front of the main gear. The sides were measured and sanded to have very little clearance along the front.

I piece of plywood was measured and cut to act as a front cover and rack support. This was measured, drilled and screwed in place using 8 2 inch drywall screws.

The rack was then tested to make sure it moved freely without wobble or binding. I had to sand the sides to get it slightly tighter.

Step 14: The Handle

I chose to use a big tooth gear for the handle attachment. Yes it is probably unnecessary but it will prevent a metal wrench from being used. And it is removed when not in use.

The handle is a little crude and I used the gear template to make a cutout then kind of hand cut and formed the shape of the handle. It was then all sanded smooth and test for fit.

The whole thing wanted to tip so I added a cross brace to the front for stability. Again this was sanded drilled and fastened in place with dry wall screws.

Step 15: Next Steps...

Yes it crushes cans too.

I will be using my findings from this to build an aesthetically pleasing metal and wood version that will be allowed in the house...

Comments

author
shivanib9 made it!(author)2017-06-01

i just loved this method of cracking coconut..can u just share the dimensions and other calculations to be used...m having project on this topic...i would be grateful if u do that for me...

author
tyler+roberts made it!(author)2017-03-19

now I have little use for a coconut cracker, but a small arbor press is something I could make use of.

author
throbscottle made it!(author)2016-08-03

I think this has just become my favourite instructable. Just love it.

Of course, whilst your dad was smashing coconuts, your mum really ought to have been telling you that you can crack them by putting them in a low oven for a while. Not as much fun though...

author
Random_Canadian made it!(author)2016-08-04

I'm intrigued... I've not heard of that method.

author
throbscottle made it!(author)2016-08-04

Only done it once or twice, worked a treat, you just wait for the crack sound. Was a gas oven, setting 1/2 or 1/4 - don't know what that is deg F or C

author
ClenseYourPallet made it!(author)2016-08-03

Fantastic job. I think this is extremely cool. Thanks for sharing

author
Random_Canadian made it!(author)2016-08-04

Thanks! glad you like it.

author
rbclima made it!(author)2016-08-02

Really nice build! Just a little overkill hehehe i always open dry coconuts with a few hits of a tiny hammer. It splits in half with 3 or 4 hits on the right spot

author
Random_Canadian made it!(author)2016-08-04

Thanks. The tiny hammer may have been a better way at the beginning but I misjudged the strength of the shell.

author
ThomasK19 made it!(author)2016-08-02

Brilliant! We don't have coconuts around here. But I guess you can stun your friends by breaking walnuts with this device xD

author
Random_Canadian made it!(author)2016-08-04

Funny that you should mention that...

author
joshcube made it!(author)2016-08-02

This hits every category for a great instructable:

1. Born of a simple but salient need.

2. Prototyping with discussion of failures.

3. Over engineered for the task.

4. Built a tool out of plywood that essentially could be bought.

5. Built with basic garage tools, not cut on a $15,000 laser cutter.

Bravo. This is a truly "best of" post. Can't wait to see your spouse-friendly version. :)

author
Random_Canadian made it!(author)2016-08-04

Thank you! and the home version is in the works.

About This Instructable

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Bio: Bit of a background in various electrical and mechanical fields, obscure sense of humour and typically willing to help...
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