Compact Grappling Hook

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Introduction: Compact Grappling Hook

About: Awesome Gear I've designed myself.

When I was a kid I made little grappling hooks out of paper clips. No G.I. JOE was complete without one! Now that I'm all grown I've graduated from paper clips. Last year I made my son a Katana Letter Opener for Christmas. This year I made him a grappling hook. It screws apart for compact storage and even has an N52 Neodymium magnet. It's tied to 50' of paracord.

Step 1: Gather Materials

Everything you need is at the hardware store.

1, 3/4" bolt

1, 3/4" nut

5/16" steel rod

Neodymium magnet.

Over all it all cost about $11.00.

Step 2: Turn the Body

All the work is done on a Harbor Freight Mini Lathe. To start I machined a flat face on the head of the bolt. This allowed it to sit square against the chuck when I flipped it around. Next I drilled a hole in the end so I would have a place for the live center (a live center is a support that spins along with your work piece while supporting it).

I machined the threads off leaving just enough for the width of the nut. I followed by machining in a cool shape.

Step 3: Finish the Head

Taking the head of the bolt from six sides to a circle takes some patience. It helps to use gear oil to keep things cutting smooth. I turned all the sides round and used a file to bevel the edge.

Since the magnet is 1/2" x1/4" I used a 1/2" drill bit to drill a hole that was just shy of 1/4".

Step 4: Prep the Nut

I used a ruler to mark the center of the nut and drilled a pilot hole. I followed that with a 5/16" bit.

Step 5: Form the Eye Bolt

Every grappling hook has to have a way to tie off. I took a section of 3/16" steel rod and wrapped it around the 5/16" rod. This made a spiral which I could cut down to one loop. I inserted the eye bolt into the same hole that supported the live center. I then cross drilled a hole and hammered in a pin to keep it in place.

Step 6: Making the Tines

This is not the sanctioned way to use a pipe cutter but I do it all the time and it works great. I cut out 3 sections of equal length from the 5/16" rod. I set my lathe to 10 degrees and machined a point onto each tine. Next I used a piece of wire to help determine the final shape.

Step 7: Bend and Weld

I put each tine into a vise and bent them to shape with the help of a pipe. I welded them into the holes I drilled for the nut. I cleaned up the welds with a deburring tool.

Step 8: Powder Coat

I powder coated the everything and baked it in an old toaster oven. I glued in the magnet with super glue and and finally tied it off with paracord. Thanks for reading.

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85 Discussions

Wow, nice ibble!!

Very cool project and excellent directions! Thanks for sharing! Might just be my first ever lathe project...after Christmas?

This is absolutely scary. We aren't making this as a toy , I hope.

Using low grade bolt and rod, (A36) (36000 yield) for this is really scary.

I could show the load calculations, but suffice it to say, do NOT use this "for real"

This is only a "toy"

5 replies

You asked "We aren't making this as a toy" and then said DO NOT use this for real. I believe the correct would be that you are advising that in fact it is just for show and yes you are correct, NOT for real use due to the load strength, etc.

Can you give an example of a "high grade" bolt? If its low grade, is it because of the type of material that its made of? Do you know of a resource to find the yields of different bolts?? Thanks

A classic reference for that sort of info used to be Mark's Handbook for Mechanical Engineers. Most fastener manufacturers have yield and failure strengths on their website (as spec sheets). Low grade is lower strength and related to many things - alloy used, and heat treatment primarily.

All fasteners (bolts, screws, nails, and the like) have ratings for the engineer types. That way they can apply those values in their calculations. Part of why hot rivets fell out of favor, since no two rivets are alike. Bolt grades are also important to pay attention to in mechanical work too. An engine is usually held together with high tensile strength bolts. Replace these bolts with bolts of a lower tensile strength and the likelihood of catastrophic failure becomes a very real possibility. Here is one place to find stuff about fastener grading.

http://www.k-tbolt.com/bolt_chart.html

Be safe out there people.

The paracord is likely to be the weak point unless you think the hooks are going to have huge bending loads on them.

Anyway to make something like without having a lathe, welder and such?

ok, im planning to make this for metalwork for school, but i need ti know will it be able to take my weight? im about 70kg so not quite sure

1 reply
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Lanvi

3 years ago

This is the best grappling hook-tutorial I've seen this far. I am even thinking about using this as project for some of my students, since it includes so many different methods of metalworking.
You did great work on the slides of this how-to and your video is just awesome. Compact as the grappling hook and as entertaining as using it :)

IMG_20150119_142111.jpg
2 replies

Just in case: I do know that this isn't suitable for actual climbing in any circumstance. Also, when I used the grappling hook and the schematics I made, to introduce my student to technical drawing, I told them about the weak points etc. But the paracord did hold my weight (around 78kg or 172 pounds). But it did stretch quite a bit at the strain...

I'm sorry for the problems that imbedded controls that possibly were in the body of text when I copied and pasted from a Word document. They apparently affected the text formatting.

Please
do not take what you are about to read as a condemnation. It is definitely not.
I only want to present to you and your readers some considerations that may, or
not be, important to safety.

I’m
really sorry for opening this bolt grade discussion. There is more to it,
mechanical design, than what I stated concerning bolts.

One
must have the technical knowledge “engineering knowledge” and/or experience to
even attempt to design an item that has safety requirements. Even then there
are degrees of safety that come in to play. What I was attempting to say, and
failed miserably, is there is more to designing and constructing an item than
just going down to the hardware store and buying a component.

One
commenter stated that the rope would probably break prior to claw failure. Yes,
that could be true. However, if the user is injured or killed, it doesn’t
matter which component failed. An item as this where the user is at risk there
needs to be a factor of safety applied. Yes, there still may still be a
failure. If an individual was harmed, or killed, because of the failure then it
is the designer’s/engineer’s reputation that is at risk, let alone the possible
grief, monetary penalty and possible incarceration of said individual. As to
any design, there is a need for a factor of safety. Some of the considerations
that affect the safety facture, are: possible unknowns of the design and the that
of the use this design will “see” in the field, the user’s safety, component
variations, manufacturing variations, etc.

During
my early engineering days right out of the University of Washington, I had the
opportunity to work for a mechanical engineering consultant that had an innate
ability in mechanical designs.

One
particular event, I like to remember, was a failure of a component in a piece
of heavy equipment at a nearby company. The consulting engineer was testifying
as to the mode of failure. It was a failure that could have killed someone. The
bolts on a very large turntable component had failed and the upper structure
came crashing to the ground. The consulting engineer had me take several
pictures of the counterbore for the bolts that held the upper structure to the
turntable bearing. The problem was that the counter bores had become pseudo
countersinks. Someone had taken it upon themselves to modify the counterbore by
simply drilling the counterbores. This had the unfavorable effect in
significantly changing the bolt stresses where the head geometry meets the
shank geometry. This is an example of someone not knowledgeable in the design
making what they felt was not significant. I realize that this moves away from
the discussion of bolt grades. However it does show why some technical
knowledge and experience is needed where personnel safety could be jeopardized.

Please
do not ask me to divulge any further than this. I was only pointing out the
ramifications of modifying a specification.

The reply you received comparing rivets to bolts is ludicrous. To say that
engines use high grade bolts is also a poor argument.

The automotive industry utilizes bolt quality as needed. High grade bolts
for connecting rods, cylinder heads. Lower grade bolts for an oil pan. The
reason for this is that a lower grade bolt would have to be significantly
larger to handle the loading. This requires that the item has to be
proportionately larger. One example of this can be seen in comparing a design
of, say, 80 years ago to a similar design of today. Then, mechanical designs
and fastening components were much bulkier than similar designs decades later.

Another example, I like to reflect on, is a situation that occurred when my
journeyman auto mechanic father and I were rebuilding the engine on my ’68
Toyota. Dad had me torque a flywheel bolt on my 68 Toyota as if it was Detroit
iron. The bolt head sheared right off! Why, the Japanese manufacturer was using
a lower grade bolt for this situation than was being used on, say, a U.S made
vehicle. What am I trying to explain here is that please use components and
installation procedures spec’d by the manufacturer. They have used their
experience and technical knowledge to accomplish a particular design. Varying
from the spec’s, could be annoying, if not deadly.

In summation, please be careful and consider the affect that your design my
have, especially where an individual’s safety, and even life, is at risk.

And also, please consider the unsolicited comments, as mine, that may be
made.

This not only is meant for this individual, but others, as well.

Oh, one other thought, when I brought up the use of higher strength bolts,
there is another consideration I failed to mention. When higher grade bolts are
utilized, alloy (high carbon) steel, is utilized, one must consider the
detrimental effect that the welding process has on the integrity of the bolt.
Another process needs to be incorporated into the design to help reduce the
harmful effect of the welding. I do not want to go there, for that is another
story.

Thanks! I've learned a whole lot since I started posting on Instructables. I don't know how fast I would have improved if I didn't know others would be looking at my work.