# Design Student Lounge Chair



## mcmahobn (May 9, 2012)

Hello everyone,

I just signed up, and was looking for some input on a design project i'm working on. My name is Brian and I'm a product design student at the University of Cincinnati. Our school does this chair project every year, so I doubt I'm the first to seek expertise here. 

The design is for a very reclined lounge/leisure chair. My goal was to make a piece of furniture that was extremely comfortable and visually intriguing.









Some basic info on the chair:
The two wooden "frames" are 1.5"
Steel tubing is 0.75" 

I have woodworking experience and am very handy, but I have never done furniture jointing, and I am fairly lost. I know mortise and tenon joints are the strongest, but I am unsure of how to use them here with my odd angles and lengths.

Here are some shots of my model without the fillets and cushions and nonsense.

























I'd love to hear any and all thoughts, I know I'm missing a lot but I didnt want a huge first post, but more of a discussion.
Thanks!


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## WillemJM (Aug 18, 2011)

You can use M&T joints.

Where the steel tubing goes through the wood, will be a weak point. Not enough width to leave any strength in the wood grain.

Whose software product are you using, looks like Solidworks?


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## vursenbach (Apr 11, 2012)

This is what I see, not to be a party pooper, but to give you something to think about. The first thing I thought was where the back metal rod makes contact with the floor, unless there is some type of foot on the bottom, the chair would scratch a hard surface floor. The left and right arm are only connected by the front of the seat and back of the backrest, which will take a lot of stress when used and could break. There is a metal rods connecting these two spots but they are anchored into the wood and to do so you have to remove wood without strengthening it with more wood causing a weak spot. It sounds odd, but the joint could be made stronger to make these two rods out of wood shave them down with the grain. The last thing that I saw was the fat foam on a thin frame. It just looks off balanced to me. Maybe a thinner and narrower seat, just wide enough for a 300 pound man without extra room. 

Let me also say, I do like the chair and thought it would be a fun project for a weekend. It does look like some of the chairs I've sat in from the 60s with the exception of the little jot in the back of each arm. Good job. I give you a "A" for the project; however, I have not seen the rubric. 

Thanks for sharing.

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## tc65 (Jan 9, 2012)

Here's some more constructive criticism. I like the look of the chair. It's got a newer style with a sort of retro look with the large block cushion (which I like BTW). Some comments on structure: Is the back just supported (and pivot on) the rear metal bar? If that is the case, I think it would be awkward and weak. If you could tie it in to the back of the arms in some way it would help to strengthen the whole chair. 

I don't like the metal bars extending through the rear of the arms. I see myself constantly banging my elbows or catching my shirt on them. I also agree that you need some sort of foot on the two bars in the rear of the chair to prevent floor damage. A suggestion for the rear vertical bars: rather than extending them through the rear of the arms, have them terminate no more than half way through the height of the arm. This would add back some of the wood strength lost if you bored all the way through. You could do the same with the bottom and have the bars terminate in a horizontal wood runner across the back. If the material for the rear bars is meant to be some type of pipe, you will need to have them capped to prevent them from boring into the wood (if you have them terminate in wood).

Keep us updated with your progress and be sure to post some pics of the final project. Is part of the project an actual build, or is it design only?


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## woodnthings (Jan 24, 2009)

*along those line*

The metal rods seem redundant. An all wood chair would be structurally sound. The rods will get in the way, add weight, very little if any to strength,possibly weaken the point where they attach...one or the other, wood or metal. :yes: bill


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## knotscott (Nov 8, 2007)

I like the overall look of the chair, but also have concerns about the metal rods. The top protrusion is sure to become a "poke-point" eventually...at the very least I'd hide it below the surface of the wood. I'm also concerned that the rods will collapse at the bottom given enough pressure because the angle will cause a lot of horizontal pressure where they exit the wood. 

M&T is the way I'd go for the joints.


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## cabinetman (Jul 5, 2007)

I like the chair, but as suggested, might look better done in all wood. Substituting the metal rods with wood, and ending any protrusion through the arms.

I also suggest that you edit your post, and resize your photos to 750 px wide or less. It's difficult to see the whole photo, and it's necessary to scroll back and forth with a wide photo.








 







.


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## mcmahobn (May 9, 2012)

Thanks for all the feedback guys. Please don't hesitate on providing feedback that you may consider "mean or harsh," I am a student and I came to learn.

Some quick points:
a) One of the criteria of the project is that there has to be 3 different materials, which is why the bars are metal. I did reduce the size to 5/8 diameter to give more grain on either side of the wood. I was told this should be enough.
b) The metal coming through the top of the wood is purely a design choice. They are really far back relative to where the elbows sit. We had to do anthropometric studies to see how different sized people would fit, and each percentile had ample clearance. I can post it if there is interest. 
c) im working on inlayed 1/4in steel plate brackets to weld to joints where the bar intersects the wood to reinforce things. They aren't shown anywhere here.
d) when I grab some time, ill edit my first post. I agree its rough to read. The other forum i used to post on resized images automatically. Bad habits.
e) Yes, I'm using solidworks for almost all the modelling. 

Everyones feedback has been super helpful. I have made some adjustments and put a lot of thought into jointing. I'm planning on using standard M&T joints on the main frame, though the joint on the bottom right worries me. Thoughts?









The once piece I am really struggling on is the bottom bar. I was planning on making it out of one larger piece of wood, but I was told that the diagonal section of it would be extremely weak, and would fail within the first few times someone sat on it. Im assuming ill have to use three pieces and join them together, but I would greatly appreciate the best way to do that. 









I forgot to take a picture, but here is the functional prototype I had to make for the last checkpoint. I have gotten the foam for the seat and back since then. I'll try to remember to grab a picture tomorrow.


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## vursenbach (Apr 11, 2012)

I forgot to take a picture, but here is the functional prototype I had to make for the last checkpoint. I have gotten the foam for the seat and back since then. I'll try to remember to grab a picture tomorrow.
[/QUOTE]

I notice that the wood split in the back. Did you figure out why it happened?

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## Treeoflifestairs.com (Jan 9, 2012)

I think some of the responses have been overly cautious. What kind of wood are you planning on using for the frame? There are some very strong woods out there. Ipe looks good and is very strong but it is heavy and you can't use regular wood glue on it. As far as the metal goes. I think some of these guys are just wood workers at heart and don't like it as a medium. I think 3/4" stainless steel rods are a good choice. If you go with a strong wood then you don't have to worry about where it passes through the wood and you still have the look of the larger rod. In my opinion the original picture looks great the way it is you just need to use materials that can handle it.


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## tymann09 (Mar 4, 2011)

hey brian, I too am a design student (attending RIT). I'm going for woodworking specifically though. A couple suggestions about the joints. Mortise and tenon is indeed the way to go, however. from what you've drawn, you've got angled tenons. This creates a weak joint. whenever doing angled mortise and tenon joints, the tenon should always be as close to parallel with the rest of its' body (the shoulders won't be square though). The mortise should usually contain all of the angle that's required to accommodate the tenon. The reason for this is because wood is much stronger when using straight grain, angling the tenon will no longer have straight grain, weakening the joint. Does this make sense? You said you were worried about that lower right hand joint. I'm assuming because it's so close to the end. you could fix this by moving the tenon up, so that the top face is flush with the rest of its' member, thus making it a 3 shoulder tenon, if that makes sense. You would need to cut a very clean mortise though if you did that. This would give you a good half an inch or so from the bottom of the vertical member, which is sufficient. Also, i really like the metal, and think it proves to be a nice aesthetic point, as well as structural. one thing that does worry me is the angle of the back metal leg. normally in chairs, the back leg is opposite the angle you have. The reason for this is so that when someone sits down, the force is drawn down and back, a chair with an angled leg is perpendicular to that force and can take that abuse. with the setup you've got here, I'd be worried about a heavy person sitting down rather quickly and the 45 degree joint in the middle of the bottom exploding due to pressure. hope this all makes sense. I do agree that some responses have been possibly overly cautious, but some of these suggestions should be looked at. Just my opinion.


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