Big Screw Nutcracker

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About: Emeritus Professor of Mathematics.

This is a nutcracker design that is easy and satisfying to use. It will break open tough nuts with a smooth turning action and offers exquisite control. Inspired by the Over Engineered Nutcracker, this design is a combination of wood and metal construction. It can be held in one hand with the nut in place, while the other hand turns in the screw. It is very convenient and pleasant to use. This Instructable describes the main construction details involved in making this style of nutcracker.

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Step 1: Materials

You will need a big screw and a small chunk of strong wood. Clear maple was rescued from the firewood supply in the author's case. The nutcrackers shown here have big stainless steel 3/8-16 Allen head cap screws 3" long. The pressure pad for the end of the screw was made on a lathe from 3/4" diameter stainless steel bar stock, and 3/4" diameter brass rod for the threaded bushing.

Step 2: Forming the Body

The rectangular body of the nutcracker measures about 3-1/2" by 3" by 1-1/2". The nut pocket was hollowed out with a 2-1/8" diameter Forstner bit to a depth of 1-1/4"; this left a 1/4" thick wall behind the cavity adding needed strength to the cracker. The round shaped cracker started from a slightly wider chunk of wood to leave a slightly thicker wall around the nut pocket; after boring out the cavity, the blank was cut and sanded to the round outline. This shape fits the palm of the hand very nicely. The hole for the brass bushing is centered so that axis of the screw is in the center (i.e. front-to-back and side-to-side) of the nut pocket. The threaded bushings are shown in the photo.

Step 3: Machining the Big Screw

The end of the screw was turned down to the minor thread diameter for a short length as can be seen in the photograph. These particular screws have very finely finished smooth and almost polished threads, which makes for smooth operation of the nutcracker. The pressure pad is turned from 303 stainless steel. The concave conical end helps capture and keep the nut in place as the screw is turned. The other end is shouldered and bored to fit the screw end; upon final assembly it is secured to the screw with retaining compound.

Step 4: Handle

The handle for cranking the screw is a 2" length of 1" diameter birch dowel bored to accept the head of the screw. The ends are rounded and sanded smooth for a comfortable grip. The handle is secured to the screw with a generous application of clear epoxy.

Step 5: Beeswax Finish

A good finish for items used with food is a mixture of beeswax and pure mineral oil. In use, this compound is slightly warmed until very soft and almost liquid, then wiped on and rubbed in. After a time, the piece is buffed off with a soft cloth. If the wood is sanded nice and smooth, this Beeswax finish leaves a pleasant velvety feel to the piece.

Step 6: Final Assembly

The threaded bushing is held in place with a light coat of epoxy. Note that the flange of the bushing is on the inside of the cavity so that it takes on the heavy thrust of nutcracking. After turning in the screw halfway, the pressure pad is permanently attached with a strong retaining compound such as Loctite 609. After that, there is no taking the nutcracker apart !

Step 7: Two Completed Nutcrackers

The author actually made four like these and gave three as Christmas gifts - with a supply of nuts to crack.

Step 8: A Joy to Use !

The rectangular nutcracker is my favorite !

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    13 Discussions

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    natantus

    Question 11 months ago

    Where did you source the brass bushings from? I'd love to attempt this but all I've found are threaded brass wood inserts from the local hardware store. Also, did you consider using any off-the-shelf hardware for the pressure pad? I wish I had a metal lathe but I do not so I'm trying to improvise.

    3 answers
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    TinkerJimnatantus

    Answer 11 months ago

    The brass bushings were machined from solid rod. First, the stepped outside was turned, then cut off, reversed in the chuck, and drilled and tapped for the screw.

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    natantusTinkerJim

    Reply 11 months ago

    I thought that might be the case. Impressive work and thanks for the reply.

    I've decided to go ahead and start on this project. I don't yet have a good answer to the pressure pad but I'm sure I'll figure something out. I'll try to post my version when it's complete. Thanks for the inspiration!

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    natantusnatantus

    Reply 9 months ago

    I was able to complete this project with 5/16-18 hardware. You can get brass wood inserts that have the same thread at any hardware store. And for the pressure pad I am using a flange nut which I'll secure with a second hex nut pressed against it and some CA glue.

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    scimsabre

    Question 11 months ago

    Great instructable, I will be making several of these as gifts. How did you cut the recess in the nut pocket for the threaded bush flange?

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    TinkerJimscimsabre

    Answer 10 months ago

    Very astute of you to notice that detail ! Ideally, the flange of the bushing should bear evenly against the wood to spread the loading against the wood and thus help prevent the start of a crack. I really do not know how important that is especially if the wood is good and strong. Be that as it may, a flat seating for the flange was cut with a jury rigged backface cutter in the mill ; this was done right after boring the hole for the bushing with the nutcracker body still in the vise. An easier alternative would be to apply enough epoxy under the flange upon assembly to fill in the otherwise void regions between the flange and the wood.

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    JohnC430

    11 months ago

    a very much easier way to crack walnuts... take two in your hand and squeeze them together and voila.... both nuts crushed!!!
    However I need to crack open apricots, peaches, plums and nectarines.... those are too hard to crack by hand. The usual plier type nut crackers also cant do the job. It takes some effort to break them even with a hammer.

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    TinkerJimJohnC430

    Reply 11 months ago

    Yes, I’ve cracked nuts by hand one against the other when I was younger. My grip was easily up to the task then, but now I am thankful for a good deal of mechanical advantage!

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    kariswg1

    11 months ago

    Simple, nice, functional...great progression of steps...wish I had the tools to make this...

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    JohnC430kariswg1

    Reply 11 months ago

    a Forstenet of that size would cost about $15 and of course a hand drill. if u dont have a hand drill, save up a little each month until u have the money to buy a 1/2" drill. dont go for the 3/8". You can file the ends of the bolts. You dont need a lathe for that....
    Haaah!!!!!!! I just thought of it... just buy a good strong steel clamp and it has all the parts in it to do this without even modifying it....put the nut in the clamp and turn the handle... LOL... Ohh of course you will not have a pretty piece of art work to put on your table. But I am sure your friends will get a kick out of it when you put a bag full of nuts on the table and a few clamps to go around... hahahahahaha
    Heyyy, maybe even my big vice will do the job of breaking harder nuts like peaches etc.

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    SylvanB

    11 months ago

    Very nice. Have you considered selling these?

    I suspect aligning the screw with the grain of the wood might be important to avoid cracking the block, especially with hard nuts.

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    Lorddrake

    11 months ago

    beautiful work.

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    attosa

    11 months ago

    Neat! Lately my father is having issues with coordination, even with cracking walnuts. He'd love this.