Testing The Theory of Where Seat Irons Go | Engels Coach Shop 

Hi Dave. I just wanted to say that doing a test like this shows a tremendous amount or respect to your viewers! You could have only stated your response, or no response, to the questions posed. Going the extra step to provide data resulting from a real time test is excellent. warm regards vic

The old masters built the seats like that because their experience proved to them that it was the best way! Any time we try to out guess them, we fail! Reminds me of a story I heard Roy Underhill (PBS - The Woodwrights Shop) relate. During his time at Williamsburg, Va., he found himself beside a master sharpener as he meticulously sharpened various tools. Using one of those massive stone wheels that somehow had water applied to cool the steel, Roy noted that the direction of rotation was the opposite of todays modern bench grinders which have the top of the wheel rotating toward the operator. Wondering to himself what the benefit of that was, could it be more accurate, did it affect the structure of the steel less?, he got up the courage to ask what he thought would be a very astute question with an equally astute response! The man, still grinding, paused for a second, then said “if it turns the other way, it throws water all over me”!

This test and reasoning is now documented for future generations. Thanks.

This is teaching you a trade. This was how I was taught my trade. Understanding the design and proper use. Then testing your theories. Once you understand why it worked or didn’t, you gained a ton of knowledge. Thanks Dave. Another great teaching moment.

I’m 74 yrs old and been watching ye doing various tasks and a good amount of demonstration and explanation. Struck me a while back that a wainwright/wheelwright with 2-3 hrs. a day in schools, teaching how you do, he younguns’ d learn working math, economics, sociology, business and a few good trades to get into. Plus a teacher using the Holy Bible to teach reading, social Studies, spelling, grammar and literature. Talk about turning out some intelligent and respectful citizens…

Thanks, Diane and Dave for devoting your time to educating today's "Engineers" on how physics works in construction. Well done. Cheers

Dave you nailed it! Those old timers knew a thing or two about mechanical advantage and materials science. Unlike people today they had to do more with less. ✌🏻❤️🇺🇸

Dave, I've got to hand it to you. You are a very patient man. You're a great teacher and thanks for the explanation. Stay safe.

Thank you for that Mr Engels. The hundreds of years of experience that has gone into coach building and wagon building designs shows that there are always very good reasons for any particular design. Of course builders can and do have different approaches but the underlying reasons are based on fact and experience.

I appreciate the effort you took to explain to the couch carpenters why things are as they are. In watching you do the build, it explained itself. The toe bevel, the carriage bolt physics pretty much explained themselves as to the way things were designed. Well done Dave for doing the "seat build 101 for city folk".

Nice demonstration, your time and explanation are priceless. I also thought about passengers moving in and out between the seats, and the possibility of snagging skin or clothing if the stays were on the back side. Thanks Dave😊

Dave: Thanks for spending a lot of your valuable time explaining the how and why you do the same thing you have been building for 40 years.

And that viewers is how a craftsman knows when things are right!

There are lots of analyzing and evaluating all this old construction methods. I really enjoyed it.!!!

You may comment as much as you wish, but keep in mind Dave is a real craftsman with a ton of experience over the years learning from his own mistakes, he would not build something without thinking first if it is really the correct way to do so! Thanks, Dave, I liked this explanation very much!

Kudo's to Dianę for remarkable video editing with text insertions. I will nominate her for the RU-vidy Award in that category. Seriously, this was an exceptionally fun and educational video to watch.

I'm impressed that you tightened the nuts so they were square to the irons as if it were the finished wagon seat!

When you move the irons, you change the "hinge" point where the upright part wants to rotate back due to the force. You could imagine the joint opening up or the back edge under compression vs in tension. However; I did not anticipate the seat bottom bending like it did. Nothing like building a model and see how all the parts react to the stresses. Again, well done.

From time to time I post the same comment: horse drawn vehicles really are a symphony of forces. Their desing is amazing.

Thanks, Dave for the full explanation. You have again confirmed that 1. You respect your audience, 2. You know what you're doing, and 3. your understand why things are done as they are. I once read that American horse-drawn vehicles, at least the passenger vehicles, tend to be lighter in construction than comparable European vehicles of the same era, and that this was partly due to the longer distances that American horses needed to be able to cover. Designers fine-tuned the structures, mating wood and iron to achieve the best weight to strength ratios, which allowed coaches to carry more paying passengers, or allowed for more speed and comfort on the way. I would be interested to know if others have heard similar or conflicting ideas.

The old setup used the strength of each material. Steel under tension and wood under compression. Basic engineering. Great 'shop made' test that shows it so clearly.

Mr. Davie and Mrs Diane, today I felt like a big idiot, but at the age of 68 I always saw the irons from the outside, now I'm sure they would have to be from the inside where there is greater anchorage, greater strength, greater support. thank you so much for proving me wrong. A video like this is very rare. Thank you very much. Tenho muiiiito respeito pelo Senhor e pelo seu trabalho.

Thank you for a very complete answer to a logical solution to a question that was not thought out. Your patience knows no bounds! May you continue with these excellent presentations.

THANK YOU FOR THE VIDEO. I WOULD NEVER QUESTION YOUR FOUR PLUS DECADES OF EXPERIENCE. BEST WISHES TO YOU AND DIANE.

Ol fart carpenter here Framing Square: wide tang is 2", narrow tang is 1=1/2" i love your wagon work!

I'm always impressed by the engineering of these wagons. The seats, the hubs, the connection of live animals to a fixed machine. People easily forget that people a hundred years ago were just as smart as us, they just had different materials. Thanks for the fun demonstration, now back to work haha.

Dave, if the RU-vid channel Project Farm existed in 1750, this is the sort of content he'd be making. Excellent stuff. LOVE your channel ❤

Look, I'm just gonna confess it. I never made the connection between "carriage bolt" and "carriage." This was a real lesson for me. Thanks!

I promise I've never felt the need to teach you how to build coaches. Good video and a well designed experiment.

Good Questions. Good Answers. Thanks Diane and Dave. I think you get a kick out of the testing of "normal" coach building. Hence the wagon is the teacher.

It is commendable that you answer questions in such detail. Many are just genuinely curious, while others are annoying armchair warriors that “think” they know better. Kudos to handling both!

As a structural engineer it is immediately obvious to me that it is stronger with irons on the inside. When one leans back on the seat back the irons go into tension and the wood into compression. The joint gets compressed. Since the wood is loaded cross grain it has more strength in compression than in tension. As an aside in modern steel construction washers are used under nuts because the washer is hardened and therefore harder than the base steel and will prevent the nut from digging in. Nice test. I spent a career doing structural testing and you did as clean a test as I've seen done.

People have been building carriages for a thousand years. Some things are tried-and- true. After watching your last video I asked myself the same question and arrived to the same conclusion you just demonstrated. Been following your channel for many years

Thanks for taking the time out from the actual build to address this question ... highly interesting!

Thank you for the very well spoken explanation for the use of the hardware. I did not realize you are going to cover the seats. After your testing I have no doubt that you have the irons in the correct location.

Dave as one of those people who made the comment about how it looked wrong to have the irons on the inside for a comfort sake, but did not mean it was wrong I wanna say thank you for doing this video with the test. Especially since I use to run into carriage bolts with square nuts on things a lot when I was a kid, I saw something in this that made me also think about the comfort and safety of the other passenger's that tells me the irons are in the correct place. And that is how the nuts protrude from the back which could ruin one's clothing and possibly rip a hole in one's flesh, which would not be good if one ripped a whole in their expensive dress or a man's trousers especially if such thing cost a pretty penny. Which if the carriage bolt head was on the inside, to prevent anyone being hurt by the carriage bolt and nut facing the back would mean having a counter sunk hole and washer to hid the square nut so no one got hurt. And my apologies Dian, for the long post.

I believe you are recreating the seats as they were originally built. I think the people that were commenting on strength of where the irons go were probably saying that the method with the bolt heads on the the back of the seat wood there is significantly less surface area supporting all of the load on the seat back as opposed to the surface area of the irons if they were on the back. The only analogy I can think of is if you were building stairs you wouldn’t put the stringers on top of the treads with screws holding the treads to the bottom of the stringers from underneath. I don’t think anyone would challenge your research ability. You show is one of the best of any genre. Thanks for effort and time for producing them.

Great explanation and demonstration. I agree that the compression of joints would be the superior method. Thanks for taking the time to do this. I appreciate it .

*- Thanks for the work of presenting the compression test, Dave.* *- The wood on the outside of the iron's bend added stiffness or strength to the iron equal to something like adding a 1/16" or more of thickness to the iron bar.* *- I get the usefulness of having the back side of the wooden back be clean without nuts to catch or rip passengers clothing, or have someone tinker with and loosen.* *- I guess the wood is tough enough to prevent carriage bolts from breaking through the back boards or getting loose * *- Covering the inside like you reminded us about makes it all possible.*

I was a mechanical engineer for 40 years and specified fasteners regularly. Yet I never realized that carriage bolts were named after the vehicles that utilized them!

I hope your local school district has invited you to judge their Science Fair projects. You are a great resource for your community!

when I started plumbing 25 years ago the guy I worked with would have told me to watch and learn. lol❤ I love this stuff!

You proved it to me. Thank you for sharing. Have a great day and stay safe.🙂🙂

Great demonstration Dave. It is fitting that you would go to such lengths to demonstrate rather than just state the answer since you are compiling a wheelwright and wainwright video library. Love this channel!

Thank you for that demonstration and explanation. I used to be in the "outside" camp, but watching the joints flex showed me the error of my thinking.

Wow! Thank you for the amazing Physics video! I have to admit that I was one of the "boneheads" who asked about the outside iron placement, also not realizing about padding. I thought the stripped down mud wagon would be bare bones, literally! I also compared it to a basic park bench in structure, with metal supporting the back. But once seeing the seat bench extending past the back, and that actually puts the whole area into compression not just the joint. Thus spreading the torquing force over the back half of the seat. I can see this design being much more durable over the constantly bouncing that travellers would have to endure. Also with the irons on the outside would cause the screws to rip out quickly, as the constant flexing with small screw head and threads can only end badly. So thank you again for learning me today!

Great video AND history lesson. If anyone knows how wagons were built, it’s YOU.

Great experiment Dave, some small detail questions arose while testing, but your `simple` experiment was well thought through and you adressed all my little doubts during the tests and explanations. I love it! Thank you for sharing strength as an extra thing to do the inside ironwork. I managed to come up with the upholstery whilst i saw your build video, and thougth smart people in the time. But it also being stronger dove totally under my radar.

Brilliant. What a demonstration! I too wondered at the time, but concluded that original carriage builders like current airplane designers were/are way smarter than me. I have worked with timber since age 5 (now 75) when a school extension caused a clever first grade teacher to bring over the builders to our class seated on the bitumen playground. They scattered offcuts, nails and hammers before us. I watched other kids bang nails in. Don’t know why but I rummaged till I found two 1x6 by 8” pieces then placing a third piece across the upstanding original 2 equal pieces I nailed up a stool. No bracing of course my mind was not quite clever enough and we didn’t have RU-vid in 1953. And mister Engels was so far away from New Zealand.

Hearing you echo over yourself was hilarious. And it makes sense that you would rather have the iron in tension rather than the wood.

Agreed with Vic, respect for the person asking the question. Surprised by how much more flex the outside iron showed. Thinking that would become a failure of the screw/ glue joint faster. Very quick test but accurate.

Hi Dave thanks for taking the time to explain and show . 😎.

It is refreshing and gives confidence that the development work has all been done so long ago most likely proved in the day by how strong this arrangement was and inspite of all our modern beliefs that we can do everything better we just might have to be happy that we can’t, thanks Dave for educating us all. In the same time period if you needed a 1/4 inch bolt the masters used a 1/2 inch bolt and the job never came back because the bolt failed. Something to think about.

I love the way you explain your work and questions about alternative methods. I am all thumbs and will never use traditional wood working but I love learning. Thanks.

Dave, really good explanation, but you know that any of us that have been watching for any amount would never question your vast amount of knowledge of blacksmithing, woodworking or western carriages. You are a Renaissance Man !!!

Very interesting. I'm convinced, of course. And very nice editing, especially of the simultaneous action replays at the end there. Thanks.

What a brilliant explanation, Dave. Thank you!

Watch this video..it's physics. 😁 Explanation at the end was solid.

Dear Mr. Engels, I usually like the videos where you create something rather than the ones where you reason or explain something. But this video is absolutely brilliant! As a man with an engineering degree, who studied the discipline called Sopromat (strength of materials) - the result was clear to me from the very beginning. In the first case, almost all of the load was on the iron, but in the second case -- a significant part of the load was also transferred to the seat board. And I also can't stop humbled by people who sincerely believe that we are smarter than our ancestors just because we have iPhones in our pockets and can look something up on Wikipedia at any time, whereas our ancestors couldn't. In this regard, I highly recommend them to reread the ancient novel "The Mysterious Island" by Jules Verne. Guys, especially those with an engineering background -- how many of you are capable of what a 19th century American engineer with the rare name of Smith was doing there? :)

Well, I too, thought the irons should be on the outside. But, then, I realized the seats will be upholstered and the head of the carriage bolt is a lot easier on the passengers knees than a bolt head. I never even considered the compression of the wood added strength. Great demonstration, Sir.

Excellent demo and explanation. Thank you for all your time.

Thank you Diane for Wednesday's video. I got a good look at Dave's 'wrecking tool.'

I thought about everything you tested last video and came to all the same conclusions. The bolts on the inside do look like they could be uncomfortable, but the seat pads could remove any discomfort. You are a very good builder.

Before you even started your testing I put my money on placing the irons on the inside. Thanks for your efforts.

Thank you for the lesson. You are a heck of a teacher,!

You are a good teacher!!! Thank you!

No doubt about it Dave was right in his work. Great job Dave and a great job of SHOW N TELL !!! Stay safe around there and keep up the great videos. Incase you are still wondering, spring has arrived in some parts of the USA. Had to turn the heat on for a little while here in DEEP EAST TEXAS today and it felt good. Fred.

Thank you, Dave, well done, I did also look at that this with the nuts on the inside but believe it or not I did pause the video and visualize that exact problem they would cause on the outside.

thank you Professor Dave.

The length you go to prove, why people build THIS mud wagon the way they did is simply fascinating! Once again thanks for explaining in detail, why they did it this way. Who would have thought people had so much knowledge from push and pull forces? My guess is a lot of trial and error and collecting experience through mistakes!?

My guess on the washers on the carriage bolts was because the wood was weather deteriorated at the time of the repair and the person doing the repair opted for a larger bearing area so that the carriage bolts didn’t pull through the wood. I actually did this to my little red wooden stake side wagon when I was a little kid. The original holes had wallowed out.

Got it! I think I’m ready for the test on Friday. Excellent experiment and explanation.

An excellent example of the scientific method.

I hadn't thought of it in a strength basis, just aesthetics. However, as soon as you mentioned strength, it was obvious without much thought it would be stronger inside. It was nice to see my first thoughts validated.... if they had not been, I still would have learned something. Learning is not always comfortable but I have learned to be thankful even when what I have learned has been uncomfortable and forced me to rethink my assumptions. Thank you for taking the time to demonstrate this.

Haha. Genius! The seat back goes into compression. I’m sure I would never have thought about that. I will now. 😉

wonderful teaching moment thank you! Happy Easter!

Simplistic? Yes. Does it prove where the iron should be? Yes. Right where you built it. Thanks for the test.

Thanks for the explanation of the irons not being in the back. Mine was more a general question rather one to this particular mud wagon original design. I can also see now that the with the irons on the inside the joint where the seat back wood meets the seat bottom wood also adds strength. It goes to show why I am not a coach builder. 👍 I have learned a lot over the past years watching your videos.

What a great science class.

Excellent video. I had very similar questions regarding the carriage bolts and iron placement and how they were installed in last weeks video. At least I wasn't the only person who was confused and appreciate the explanation.

Dave Thank you for the explanation and demonstration

Yes I wondered about the irons then My thought was oh there will be some type of covering. Thanks for a great instructional video.

I'm 1 who had asked that question about the direction of putting the bolts in, I should have figured it out on my own, and this video makes it so clear as to why. As always, nice work!

Thanks for conducting the test and posting the results. I know you are following the original builders plans and I'm perfectly fine with that. As far as the strength of the seat with the irons in front vs in the back, my thought is the steel is equally strong either way. However, my gut feeling is that over time (50 - 60 years) the wood will become the weak point of concern, not the steel. With the steel in back the wood would have more support as it ages/deteriorates. That being said, you're doing a fantastic job, the seat will last for lots of years to come and I support you 100%.

Hello again. Been watching all these years and still my favorite sub. Remember, I was a finish carpenter for a long time (about as long as my long winded comments) L0L. I must say, throughout all the chats we've shared over the years about love of millworks and work ethic, I'd say this particular video may be the best reminder for me of why I love it so much. The math and creations are one thing but the subtle natural physics you have to consider in every design and solution you pursue is a part I've never really been able to explain. How these not so obvious issues really get into the marrow of the joy that comes w/ accomplishing a worthy product for someone else that you can stand by. I love understanding what ppl have come up before me and the rare times I may find a solution I can be proud of. You make it seem so interested in a very inspiring. Good job sir. Thank you for your continued sharing, Sincerely .................... Steph (Louisiana)

Thank you for such a detailed explanation. Charles

Excellent wrap up explanation of the science

Lovely bit of science, well done.

Nice explanation, the old guys new what they were doing.

Thanks for the science side trip!

Yes , Yes, Yes , This is correct Sir Dave , you know your business, can we see more of your wonderful Diane? I'm shy too don't let it hold you back❤ Mike and Jane

Very good test and it got your point across. And you have seen this in other work you have done in the past. Love the videos learning the past they way they made things work and last with what they had at the time. Thank you

And, the side irons are bent with the wood on the outside. Great installation and explanation as long as you understand the mechanics of a carriage bolt and the square shoulder of the head digging into the wood. Thank you Dave, and Diane!

Logic says the seats would need to be padded, because of the primitive suspension, and the condition of the "roads" back in the day. As usual, your explanation if fully comprehensive. Cheers from Australia.

I had assumed irons on the inside as correct with my thinking that the iron will not stretch whereas the fibers of the wood could separate if the irons were on the outside. Also, as a carpenter, having the extra wood on the back side makes it less prone to breaking off or splitting open seat bottom. Great demonstration, even though I was not one of those that had to see it to believe it.

Mr. Engles, thank your efforts. Don't listen to these idiots. Thank you for your explanation. You are the man!!

Great demonstration! Thanks for taking the time to show this.

Good job of explaining how things work! and why!

Good video. As a (60 year old) carpenter, I am unsurprised at seeing such a demonstration. The same principle applies to corners of concrete retaining walls, as commonly seen in basements. The horizontal reinforcing steel that is bent to go around a corner is far more critical in internal corners, because it stops the two sides from pulling apart.

Thank you for the explanation. I was wondering the same thing about the bolts, but figured there was a going to be upholstery on the seats.