Strength Testing Bow Tie Keys - Woodworking

[@GunflintDesigns]

What shape keys do you you like to use?

[@atuttle]

I haven't had the pleasure yet, but those asymmetric angular keys in the barn door look so cool! That's got to be my favorite. 😍

[@BruceAUlrich]

@@atuttle Thanks, Adam! For whatever reason, I like them asymmetric like that.

[@GunflintDesigns]

That's awesome! My brain runs on symmetry so those ones hurt my brain!

[@GunflintDesigns]

You're just more artistic than me!

[@sebmstudio1697]

Hey Gunflint Designs, I would like know what bit you used on your X- Carve. The cuts look really neat!

[@karl_alan]

Actually glad you ended up having to kerf the bottom of them. Seems like a more accurate test, since bowties are used to stabilize a crack, to actually have a crack through the board in the tests.

[@GunflintDesigns]

I started this process thinking that straight grain pine would be so weak it's as good as cracked. But you're right, I ended up with a better test in the end.

[@matthiaswandel]

Nice work on the testing!

[@GunflintDesigns]

Well thank you Matthias, that means a lot coming from you! I was really wishing I had an engineer standing with me to help explain my findings a little more coherently.

[@Jack-es9xq]

Whoa, a visit from Matthias!!

[@luismartinez6421]

Just to add couple of comments from a mechanical engineer who spent a master degree analyzing fiber reinforced materials: 1. Your test method is as good as many I've seen in labs. The method and the way you prepared the parts are consistent all over the experiment, so feel freely to call it scientific. Before anyone starts saying anything about the comparison with the lab tests, just keep in mind the objective of the experiment: just to determine how strong are they, he is not trying the determine the exact force (technically it would be the stress) value compared to a specific physic law. 2. If you dig deeper into the fiber material topic, you'll end finding that "fiber oriented" and "cross-fiber" stresses required to break the parts are significantly different. Any fiber reinforced material is stronger when the force (stress) is applied along the fiber and weaker when the force is applied perpendicular to the fibers. The recommendation about cutting the bowties with the fiber at any specific angle will result in a weaker tie. 3. There is a huge difference between a "broken part" and "debonded part", most of the failure modes on wood are more related to debonding on the fibers rather than broken ones. This is relevant if you are using any glue... Check the parts in detail, if the fibers are still glued together, having a "better" glue won't change anything. 4. Do you want to find the perfect shape for the ties... Well, you can get the answer without further testing. From all the shapes you tested, only one failed having most of the fibers intact: the straight one. Then, you get the shape which had the better performance: the classic bowtie. The best solution is right in between: add a straight section to the classic bowtie. This will remove the stress concentration, exactly where the two angles meet. Want to improve even more? Add some radii. What's the best length - width proportion? Just look for the standard probe material testing, that shape is bullet-proof when it comes to stress concentration removal. I'm sorry for the long comment, but this video reminded my first month at the Master (you know, the part of setting up the test, prepare the samples, calibrating the equipment, make tons of testing, collect the data, finding out that you screw up several things, etc). It is very refreshing to see people that still have a genuine interest to fully understand what they are doing and trying to improve their craft by expanding their knowledge. (Btw... English is not first language, I apologise in advance for any spelling or grammar error up there)

[@Scritley]

Thank you so much for taking the time to do this right and gather real scientific data. Most importantly, thanks for selflessly sharing this info with the rest of us!

[@petehafner1659]

I really appreciate the work you did to get these results. Good to know its the long fiber strength and not so much the shape. Thanks

[@immacul8perceptions]

This answered alotnof the questions i had about the strength vs the cosmetic appeal of these. Awesome work

[@SpecificLove7]

Very well done. I wondered if it would really benefit the structure. Thanks

[@jennieanddavis]

You dropped this: 👑

[@GunflintDesigns]

Oh thanks I've been looking for that thing.

[@livinlawki639]

Putting a towel, jacket or blanket on the cables and straps between you and the boards will help keep you from getting fd up.

[@williambrecht4501]

I'm glad you spent the time doing this research, I know more now. I'm thinking of a two stage Butterfly, longer but wider at the very end....

[@YouCanMakeThisToo]

Thanks for doing this, I’ve often wondered how much difference they make

[@GunflintDesigns]

Happy to help! Seems like the bottom line is just pick something you like the looks of!

[@RestorationEndeavours]

Love it. For a small scale proof of concept, this is awesome. I was looking to test the shear strength of some wood keys for beefing up an old chair, and your data will be super useful.

[@paigearnold6673]

Nice work! It’s helpful for me as I begin planning to add bow ties to some of my projects.

[@FishersShop]

Interesting! So it's basically the internal grain structure of the bowtie and the length of the fibers that dictate the effectiveness. At first glance I want to say that the shape has a lot to do with it, but according to this, it really doesn't. That was a great experiment!

[@GunflintDesigns]

Yep! The bottom line is anything is better than nothing. But if you really need to go for maximum strength, there are a few rules to follow.

[@101411726]

Glad to hear these really do help. I have a large slab of cherry wood I plan to use bow ties in to keep a surface crack stable. The slab is then going to act as a mantle/shelf. I thought your results were very interesting too. Thanks for the video!

[@edmondthompson1523]

An option would be to put the small scale on one leg of a simple pulley and multiply by 2.

[@adamtheroofer3659]

In future test there a just a few modifications you can make to make things safer. Use chains as they do not spring near as much as the straps. Add a loose cable like a 1/4” cable / chain/ rope to the ends of the strap and connect them. That way when the break happens the cable will prevent the two ends from flying back toward you and the other direction. I used to test life safety anchors for window washers and there are some things that help with the safety part of pull testing. Only problem is that it doesn’t look as cool when it breaks and a long strap and piece of wood go flying across the yard.

[@paulscott2502]

Interesting experiment! I really like the novelty tie keys, I think it adds more flair to them.

[@GunflintDesigns]

I think so too!

[@WoodInn]

Nice work on this test. Good to see some numbers put to them.

[@mrdg]

A fascinating little study indeed. Thanks for doing it.

[@GunflintDesigns]

I'm glad you enjoyed it!

[@IsaKocoglu]

Excellent experiment! Thank you for biting the bullet for the rest of us 🥰👍

[@tylersmith1029]

First it's #unnecessarywalnut but now its #scientificwalnut really cool to see how much strength these add, while also reinforcing just how strong modern wood glue is. Great video!

[@GunflintDesigns]

Thanks Tyler, I'm glad you liked it!

[@damianainscough]

Great video. Learned a lot and loved the science based testing.

[@FirewoodDesigns]

Great video Mark. Was filmed really well and easy to follow. Keep up the good work

[@Lee-qp6gf]

Very interesting and thanks for your time. I believe most, if not all, are strong enough to do the job on dry wood.

[@GunflintDesigns]

That is exactly the conclusion I came to, but wasn't entirely sure how to articulate it. The real question is what is Strong Enough? I believe they are all capable of doing the job they are designed for.

[@chadb3100]

WOW that was super cool and great info. Keep up the great work

[@deltamase]

Great job my friend. Haven’t had to use these yet but I feel a little more knowledgeable now.

[@GunflintDesigns]

Thanks Chris! That's exactly what I was hoping to get out of this.

[@billnoe8728]

That was a worthwhile test in my book. I actually thought the traditional shape was not going to be the strongest but you proved to me that is was one of the best ways to go. Thanks for doing this test...

[@GunflintDesigns]

Hey Bill, thanks for the feedback! I'm glad you got something valuable out of this!

[@poutineitup9510]

Well done on the test. Thanks for making the video.

[@saimon174666]

Repeatable, with control. Great job!

[@Thom4123]

Very interesting and gives you and all of us a great base line to start with. Thank you for sharing and Take Care

[@TheLukemcdaniel]

I might have tossed together a quick plywood wall to crouch behind, and probably one for the assistant to stand behind

[@TheLukemcdaniel]

@Nate Higgers I like keeping my eyesight, and detest digging splinters our of my ass for weeks but your have fun however you want

[@zandertate184]

Incredible work this is super Interetesting

[@Holzy09]

this was such a great video man! you did a great job of making it as comprehensive and meaningful a test as possible given the limited sample size. and you explanation of how it seems to have failed and what that means was great! thanks for making this, i feel a lot more informed now!

[@GunflintDesigns]

I really appreciate the feedback and I am glad it was useful for you!

[@kosinskiarek]

This is really amazing work friend!

[@GunflintDesigns]

Well thank you very much!

[@daveporter2555]

Great video idea. I really enjoyed it. Thanks, Dave.

[@willybaetens4648]

Hi, Thank you for this remarkable research. I too am wiser than before. Thanks for sharing. Keep it safe. Willy from Belgium. 😷😷😷

[@GunflintDesigns]

You are very welcome Willy! I am glad you found it useful.

[@formerartstudent]

You could've used a very simple pulley system to increase the capacity of you yesterday equipment. Solid experiment all the same.

[@JukeboxJake]

That's what I thought too

[@dredbud9272]

His scale maxed out not the come along

[@formerartstudent]

@@dredbud9272 Exactly. If he set up a pulley system, say 3-to-1, then the scale will read 1/3 of the actual force. Then multiply by 3 to get the correct value.

[@tungsten_carbide]

Thanks so much for doing this 👍👍👍👍 Like you I am totally blown away by the performance of the straight tie! Although I have high trust in well-done glue joints the amount of strength it added - without being canted to the angle of strain - is mucho impressive. This will be super useful in future where I know I can trust those, which I think have a nice aesthetic that suits certain projects perfectly (not that I don't like classic butterflies).

[@richardhogben3776]

Really interesting, thank you for your hard work

[@trevthetruckie7184]

Brilliant research thanks for doing that i enjoyed watching this !

[@JkCanvas]

Great review and learned a lot. Thank you for sharing.

[@GunflintDesigns]

Glad it was helpful Will!

[@3108Home]

Very, very informative. I would have bet otherwise. Thank you for the lesson. Brock

[@GunflintDesigns]

Glad it was helpful!

[@jodytho]

LOVED this!!! you have great presentation style, you're thorough and explain your methods well. And you're funny.... It would be interesting to know how your glue affected your results. I have heard that titebond 3 can cause failures with walnut....

[@DenisJava]

Great demonstration! I like the aesthetics of the whale, turkey leg, and butterfly the best, but that has to do with them being interesting and different. I'm eager to see the dining table project.

[@blevit4354]

Great video! Thanks for sharing!

[@user-ui3es1zs9h]

Thanks for doing this! Your tests are very useful!

[@cransky666]

Great video! It would be really interesting to see what the strongest design you can come up with would be!

[@thedevilinthecircuit1414]

Good info! Next time you use a strap to pull anything, place a jacket, blanket, etc., over each end. if/when the strap lets go, the jacket acts like a drag chute and prevents the strap from flying.

[@johnritchie3889]

very interesting. I’m a structural engineer, and you did the testing exactly as it should be done.

[@johnritchie3889]

@Nate Higgers What? I was praising the job you did. Why the snarky reply?

[@johnbodenchuk514]

I wonder how the strength of woods other than walnut would be, such as mesquite?

[@SecondSonWoodworks]

Love this video! Thanks for sharing. So happy to hear that these joints work :)

[@woowooNeedsFaith]

7:00 - With your setup, it definitely was good thing to do. Otherwise you probably would have ended up in emergency room.

[@reginag4053]

Next time he should prop a mattress or something in front of himself for protection.

[@wolfwoodworkingcreations4321]

You just answered many questions I have always wanted to know. Thanks

[@ptabz3112]

Nice work! Very informative. Can you please tell me what bit you used for surfacing slabs? Thanks

[@mhaz49]

Interesting and a good set of tests. I think the tensile strength of pine vs. walnut (bow ties) has a greater influence than you think. Shape of bow tie is another factor as well as percentage of bow tie material on each side of test slab. There are a gazillion factors of influence, so for a simple test of sizes and shapes, these are decent results. They show the benefit of using bow ties and the additional strength of it PLUS glue add to the structure.

[@metalmorphosis]

Subbed... enjoyed the delivery and the content!

[@torinhalsey6313]

Thanks for going to all that trouble. Very interesting.

[@johnwurst6691]

Great experiment! I like the combination of workshop skills and science! Just to determine if the materials used for keys plays a significant role I'd like to see just the strongest designs repeated with pine keys.

[@petercollin5670]

Quick tip - you can throw a rug, blanket, or towel over the strap to keep it from sproinging back at you. It's a safety trick when winching with a cable. You're lucky you did cut the boards thinner. Imagine the energy that strap would have come flying back at you with.

[@John-NeverStopLearning]

Thank you for the video. So, what were the results? What patterns broke at what tension?

[@Travelingman724]

I was just watching someone using bow ties earlier and I was wondering if they actually add anything to it. The timing of your video showing up was awesome. The next question I have is could you squeeze a split back together, add bow ties, and would it hold?

[@MadduxWoodworks]

That sweatshirt when you’re assembling the pieces 😂 Nice work on the test!

[@GunflintDesigns]

Haha, did I tell you that story? My buddy still hates that shirt, but I think it's one of the best designs I've ever made!

[@MadduxWoodworks]

Gunflint Designs I’m gonna need to request a remake. Support “The Legend” in the south 😂

[@lauracooks4926]

Appreciate the scientific method

[@larrytellman3490]

Very informative results

[@souzarios1]

very good. congratulations

[@bclarkca9113]

Cool experiment!

[@RetiredRhetoricalWarhorse]

I have that same mitre saw. That brush like thing you have behind the blade for dust collection, is that an aftermarket add on or did you build it yourself?

[@thompoz7114]

Awesome video!

[@stonehenge_mach391]

Loved it. Great experiment. Can you replicate with down force on a length of wood, to test the bow tie key.

[@NomadMakes]

Great video! Both fun and informative. Oh, and for future scientific videos, a crazy wig and lab coat would complete the experience :D Thanks for sharing.

[@capitalv8062]

You should try this with walnut burl. I wonder how the fiber of burl would stand up in the test.

[@reginag4053]

Not a woodworker. I think I always had the idea that the key went through the entire thickness of the piece it was holding together. Learn something new every day. I'd be curious to know if a quarter thickness vs. half thickness vs. full thickness makes a difference.

[@guyh.4553]

A great at home scientific non-scientific experiment. Fun project! The only problem that I see with your hypothesis is that you're not taking into the combined strength of the wood, the glue, and bow tie. How fun, great explanation, and great home experiment. Km subscribing due to this video.

[@jebowlin3879]

As you said not very scientific but still very usable information, this stuff is cool no matter what anyone says, would like to see more very fascinating, keep up the good work :D

[@GunflintDesigns]

Thank you! I'm glad that seems to be the consensus - possibly incomplete information, but useful information none-the-less.

[@BronkBuilt]

When you cut the kerf I was thinking to myself the numbers would come out roughly the same as now you are just testing how much does it take to pull a walnet block a part. Then I see the results and I see I was wrong as most of the bow ties didn't break and it was the pine that broke. Thanks for the demonstration.

[@zhookeeper]

Very interesting! Well done.

[@GunflintDesigns]

Thanks Jason!

[@felixfromnebraska8648]

Mark, Great project and interesting data my friend! It blows me away about how much strength a simple bow-tie key can add to a project. You just proved it. Thanks for sharing your project with us, Keep on being safe. Felix 1 other thought or question really: Do you think the strength would double if 2 bow-tie keys side by side were used, or would it be exponential in its strength. Maybe you could do another test or in all of your free time. LOL Thanks again.

[@GunflintDesigns]

Thanks Felix! I really think there is a lot more room for experimentation here, but I think I have all the answers I really need out of it. I'll leave the door open to someone else to keep testing.

[@MurcuryEntertainment]

Bonus round, a key made of plywood. You wouldn't have that plane of shear failure.

[@johnperez3212]

Hey man i luv this pull test now could u do a weight on test

[@GunflintDesigns]

I think this topic is wide open for someone else to explore much more deeply, but for my purposes I think I learned everything I wanted to know.

[@nafitron]

Very very cool!!

[@nickcosta3004]

If you ever go about repeating this type of experiment, I think that if you put some blankets over the straps, it would stop the whiplash earlier, and be a little more protection. similar to what people do when winching 4x4's that are stuck.

[@GunflintDesigns]

That's a good idea. My wife has plenty of blankets around the house, I'm sure she wouldn't miss one!

[@tomim7187]

That was a great test. Yes, not totally scientific but, the results are still eye opening. Not sure I would have done 20 of each piece and spent a couple of days testing them either especially after a heavy piece of steel hit me in the ankle. 😁 Thanks for sharing!

[@denispogodin1585]

to tell you a secret - scientists do the same with mouse /rabit bones or tooth samples to measure shear and bond strength of prosthetic devices and bone grafts/implants, and their sample size starts from 20 in each group... because the fibers in each tissue (including wood) vary significantly... anyway, nice pilot study, thank you kindly for the time you spent and for the work you did, little drops fill the ocean, and even small scientific-like efforts make the whole humanity smarter. Good luck in your next projects.

[@GunflintDesigns]

Man Denis, that's some great info and really nice of you to say. Thanks!

[@Rick-nj2pi]

Still a very interesting test. Never did a bow tie key but what about angle of the hole if possible? Making the slant not only on the bow tie (2D) but on the depth? This would increase the surface area glued and add more strength from the glue itself which you found to be very consequential. May be easier to test using the X-Carve CNC, just a query.

[@GunflintDesigns]

Man that's an interesting possibility! What I failed to express very well was that I think there is a point of "strong enough." Your idea seems very likely to be ever stronger, but it's probably not necessary.

[@StephenGoggin]

What kind of glue did you use? Do you think a different type of glue would change the results? Because I'd be interested to know if CA glue is better/worse...

[@GunflintDesigns]

This was Titebond II. I'm sure this test could be conducted in a bunch of different ways to test all sorts of variables. I'f I was taking an educated guess, I think CA glue would hold a little less, but it would be fun to find out for sure!

[@IrishAnonymous01]

Yeah I'd say that the CA glue would just crack under tension where wood glue gives a little and stretches

[@bekar_au]

Check out Wood By Wright's channel for some strength comparisons of glues.

[@jamesthebrooks]

Curious if a traditional bowie shape would hold any better or worse if the grain follows one of the sides rather than being directly across... In your example, the grain is 90° perpendicular to the short ends of the bowtie, but what if they were skewed slightly to match the angle of the long side?

[@gordroberts53]

Excellent study! Like and sub for you today. Thanks for sharing!!

[@kevinshumaker3753]

How about rotating the grain of the bow tie 15-30 degrees from perpendicular to the split?

[@GunflintDesigns]

That's an interesting idea. Conventional thinking says it has to be 90 degrees, but knowing that the long fibers are actually the failure point, that little extra rotation might make a difference. At some point, they are also decoration - and I'm not sure if it would look odd to have them slightly rotated.

[@kevinshumaker3753]

@@GunflintDesigns How about the non-'standard' (like the whale) designs? I think some more 'artistic' ties might be cool, especially if the strength was as high or higher due to the slight rotation.

[@JulianSammy]

It might be worth thinking about a compound tie if your grain is going to be angled. I'm thinking a 3" long and ½" wide bar set at a 15° diagonal, with smaller triangles set at 15° the other way at each end to make up the bulk of the bow tie shape. If you wanted to be fancy, drill a hole through the whole thing to set a dowel in from triangle to triangle... or easier, cut to ½ thickness at the bandsaw, rotate the two pieces, and glue them together in a laminate.

[@BaldyMacbeard]

Thing is: glue might fail over time, while a mechanical lock won't.

[@dredbud9272]

Glue wont fail in your lifetime

[@MOREENGINEERING]

About 15 years ago I mounted a 600x400(mm)x18 quality ply board to a brick wall with 5 large walnuts of Liquid Nails. I mounted a number of tools to that (shadow) board. and for almost 10 years it worked perfectly. It just hung on and did its bit. Then I walked into my shop one morning and stood there while I figured what was missing! As it turned out it(the board and tools) had fallen straight down(vertically) and lay on the ground(edge) and was wedged between some timber that I had stored. On the back of the Plywood board was 5 flattened does of Liquid nail, all 100% in tact. All about 3-4mm thick. On the brick was was nothing.....NOTHING. Absolutely no sign of the LIQUID NAILS. The bricks were a moulded type(smooth face) not a wire cut brick. It lasted 10 years plus or minus. No extreme heat or cold(around the time of the separation) just normal type conditions. No water or moisture(double brick wall). The tools that I hung from it a few days after the glue had dried were the same ones(more or less) that were there the day it fell. Give me a mechanical device any day. Thanks for the video, very interesting.

[@oldbearnews]

I was thinking about the grains - will the bowtie (with grain going across instead of along) be stronger / weaker or no difference at all? I would also assume that if you had an actual crack (or two pieces joined) to cover - the butterfly would rip out earlier and out of the pieces you want secured?! Cheers

[@BruceAUlrich]

Really cool experiment! That was a really good idea to take a little time to setup the stop block on the bandsaw and not have to draw out all of the relief cuts. That was funny when you were talking about dodging debris when I heard you in the background say, "That one hit me in the butt!" The one that surprised me was the straight bar. That was interesting. Thanks for the shoutout too!

[@GunflintDesigns]

Thanks Bruce! Your footage really helped to sell the definition of a bow tie.

[@maryblaylock6545]

The one that interested me was the butterfly. How did it do compared to the standard bowtie? Was it close?

[@GunflintDesigns]

That one was really strong. It had the mechanical advantage as well as a lot of surface area for glue to hold onto. It broke at 621 - which is about 600 pounds more than the control. It also appeared to do the most damage to the pine (ripped it apart) when it finally tore loose. That tells me the pine was maybe more of the failure in that test.

[@ColdFlame23]

@@GunflintDesigns 500 pounds more than the control... :)

[@MrMarkraffaele]

we need more Katie

[@GunflintDesigns]

Isn't that the truth!?

[@jnix112]

I think it’s creepy that this popped up after I came in from my first attempts at laying out bow ties 😂😂😂. Got to know how strong they are! Hope mine end up being tight!

[@akbychoice]

I think the strongest bow tie key would be two pieces with grain structures crossing each other in a slight angle, then laminated as one. A two player ply if you will.

[@curtismoats3549]

Very informative, however I wonder about the shear value of a key shaped like an armadillo?

[@tysonschroeter9431]

Interesting thanks for sharing this

[@03n]

diamond is worse than a bar because of angle at which force is applied to the glued surface.