dbrandow Posted November 26, 2010 Share Posted November 26, 2010 I'm in the process of designing a chair I'd like to build, but I'm having difficulty settling on the material size to use for the supports. I'm pretty new to blacksmithing, couple of years, and I've never made anything that was intended to bear the weight of anything other than plants. I've seen one set of plans that uses 1/2" by 1&1/2" square for a bench, although presumably that would be overkill for a chair based on the number of people sitting on it. Would anybody with some experience let me know what works best? Quote Link to comment Share on other sites More sharing options...
NRunals Posted November 26, 2010 Share Posted November 26, 2010 I feel like it's not so much about the size of the material , it's more about the distribution of weight. Think of toothpick bridges, they hold a lot of weight with just toothpicks and wood glue. I bet you could go as small as 1/4 inch, but that might get tricky. If it was me I think I'd use at least 1/2 inch or 3/4. Quote Link to comment Share on other sites More sharing options...
jimbob Posted November 26, 2010 Share Posted November 26, 2010 most of the lawn and garden chairs I've see or owned were either 3/8 or 1/2 depending on where you bought it most seem to use expanded metal for the seat and back . the old ice cream parlor chairs were made of 1/4 stock Quote Link to comment Share on other sites More sharing options...
bigfootnampa Posted November 26, 2010 Share Posted November 26, 2010 There is no simple way to answer your question. Tubing can be quite thin if it is of reasonable diameter and has strong enough joins. Lots of manufactured chairs use lightweight tubing for strength. Rod or square bar is generally stronger than flat bar... but depending on the exact application this may be reversed in some designs. Wider flat bar is also stronger for a given thickness. Thicker flat bar is stronger for a given width. These are the absolute basics. Triangular assemblies resist racking and generally have great strength for the amount of material used to make them. The LONG list of variables is quite impossible to cover in anything less than book length. Trial and error (more positively expressed as EXPERIENCE) is the truest method for design development. You cannot expect to make a one off design that is optimal or even anywhere NEAR that unless you have both broad and deep experience at similar designs. The normal process is to make one the best that you can imagine it and then test and improve and retest and improve again until you have a really refined design. Quote Link to comment Share on other sites More sharing options...
JNewman Posted November 26, 2010 Share Posted November 26, 2010 Perhaps if you put up some sketches of your design others could give you some better input. Do you plan on electric welding it together or do you plan on collars, rivets, or mortise and tenon. Often if you design with bracing you can get away with much thinner materials. But heavier stock differentiates hand made work from mass produced imported chairs. Tapering from heavy to thin is also something that can make your work look different and higher quality. Quote Link to comment Share on other sites More sharing options...
dbrandow Posted November 27, 2010 Author Share Posted November 27, 2010 Perhaps if you put up some sketches of your design others could give you some better input. Do you plan on electric welding it together or do you plan on collars, rivets, or mortise and tenon. Often if you design with bracing you can get away with much thinner materials. But heavier stock differentiates hand made work from mass produced imported chairs. Tapering from heavy to thin is also something that can make your work look different and higher quality. Hmmm...I can understand how a sketch would help convey the design better, but unfortunately my ability to sketch died of natural causes somewhere in the 3rd grade. :-) I've put up what I can come up with on short notice, hopefully it'll make some sense. The proportions are wrong, and I've intentionally left off the embellishments, seat and chair back so as to make it somewhat understandable. Also, keep in mind I'm an amateur, and a new one at that. Given how poorly I weld (to be fair, I've had a grand total of 10 minutes instruction), I'm going with sizeable rivets to attach the arm/front leg sections to the back leg sections and mortise and tenon joints when attaching the cross pieces holding the sides and upon which the seat and back rest pieces attach to. I can certainly agree with the notion of using heavier than strictly necessary stock, but I'm trying to balance that with a concern about ending up with too stocky a design. I like the idea of tapering from heavy to thin, I was certainly thinking of doing that on the arms so you could have a nice wide, downward curving section to grab in the palm of your hand. Quote Link to comment Share on other sites More sharing options...
Frank Turley Posted December 20, 2010 Share Posted December 20, 2010 I would be tempted to use 3/4" square at a minimum. This will give you heaalthy tenons, 3/8"D or larger. If the tenons are round in section, you can make cold chisel marks around the hole before peening them over. This helps keep them from twisting after installation. The marks will be covered by the peened head. My "ice cream parlor" chairs were made in Mexico as "saloon or cantina" chairs. They are of 5/16" round MS and below the sheet metal seat, each leg is of two 5/16" rods parallel for about 4" and then twisted. Each foot opens into a U-bend, about a 2" spread. The stretcher (brace) is a horizontal square joining the four legs, again of 5/16" round stock. Without this bracing, you'd be in trouble. It is important not to underbuild. I made a coffee table once with legs that were too slender. Even with the stretcher, the table vibrated like mad, if bumped. I started over. http://www.turleyforge.com Granddaddy of Blacksmith Schools Quote Link to comment Share on other sites More sharing options...
nuge Posted December 20, 2010 Share Posted December 20, 2010 Hmmm...I can understand how a sketch would help convey the design better, but unfortunately my ability to sketch died of natural causes somewhere in the 3rd grade. Looks like a sketch to me pal. The joint where the arms hit the back is not the greatest. The rivets are susceptible to shear which isn't too horrible in furniture but not the greatest form, if ya know what I mean. After a little while of some big guy plopping down in the seat they will loosen up. Might want to redesign that joint. I rented some shop space from a master timber framer a while back and learned a lot about stout. Making triangles in your design is the easiest way to get there. Quote Link to comment Share on other sites More sharing options...
ianinsa Posted December 20, 2010 Share Posted December 20, 2010 Aside from the strength of the joint(very important) proportions are paramount to get a comfy chair! From our experience and we have produced thousands the angle /ratio of depth of seat to angle of repose(seat back angle) changes the way in wich a chair works. Also bear in mind the primary use lounging, eating, reading, sitting and playing boardgames etc. all of wich require a slightly different sitting position. Rather that make/try and adjust it is easier to find a mass produced plastic chair that feels right(for your aplication) and then copy the proportions ie.width & length of seat does the seat slope? height of front of seat and height of armrest etc. I have seen numerous chairs made by suposedly experienced guys that are sturdy and look good but would have been great tools for the Spanish inquisition. Usually the companies that make plastic chairs have spent fortunes in R & D so choose carefully and use their R & D work to your benefit. Just my &0.02 worth. Good luck on those chairs. Ian Quote Link to comment Share on other sites More sharing options...
divermike Posted December 20, 2010 Share Posted December 20, 2010 I took a class with Jay Burnham Kidwell, we built chairs out of 5/8ths I think, it worked very well, and because it's bigger stock, somewhat more forgiving. Quote Link to comment Share on other sites More sharing options...
dbrandow Posted January 14, 2011 Author Share Posted January 14, 2011 Thanks to everyone for your feedback, its been very helpful. I've decided to go with 3/4" square, the chair will end up weighing about 100 pounds, which is bordering on absurd, but better too heavy than too light. I also made a few modifications to the design, specifically at the joint. I'm going to overlap them vertically and drift out a reasonably large hole (5/8" round is the current plan) for the mortise and tenon joint. Its still in its early stages, but in case anybody is curious, here (hopefully) is a picture of what it looks like when assembled. Note that the angles have gotten distorted by all the drifts I've been putting in the seat, and I've only got cross pieces for holes 5 and 7, I think it was, in that picture, and there's a rather obvious blank section where the ornate back will someday bee. Thankfully I have another several months before I need to finish it, as I may need them. :-) Quote Link to comment Share on other sites More sharing options...
Adam2519 Posted January 14, 2011 Share Posted January 14, 2011 Mate! That is shaping up very well indeed. Like the twists running up the back supports and your overall design. Any chance of a sketch of the ornate back you plan to put in there? Can't wait to see more progress shots. Adam Quote Link to comment Share on other sites More sharing options...
dbrandow Posted January 17, 2011 Author Share Posted January 17, 2011 Mate! That is shaping up very well indeed. Like the twists running up the back supports and your overall design. Any chance of a sketch of the ornate back you plan to put in there? Can't wait to see more progress shots. Adam Its getting there, although I'm not very good, so the progress is pretty slow. I've gotten all the slots drifted now, I ended up with 10 per side, and I've gotten the curve of both side of the seat adjusted, getting them to match reasonably close was arduous. I was originally planning on putting that same twist in other places as well, but its a lot of painstaking work, even with a treadle hammer, so I might opt for something simpler instead. As for a sketch of the ornate back, I'd have to respond by asking which version you want. :-) I've designed and redesigned the back so many times I can't begin to describe it, and I haven't yet settled on what I'm actually going to go with. At this point I've still got a long way to go before I need to commit, but once I do have a better idea of what I'll go with, I'll be sure to post it up here. Thanks for encouragement! Quote Link to comment Share on other sites More sharing options...
dbrandow Posted February 2, 2011 Author Share Posted February 2, 2011 Quick update, still looks pretty terrible and there's a huge amount of work still to be done, particularly embellishments, but here's where I am so far. No welds of any kind, 3/4" square stock for the most part. Front view of the chair (note that three of the cross pieces for the seat don't currently fit, the top bar isn't visible in this picture, the back hasn't been finished yet, and the angles of the legs and arms are a bit wonky still): Side view of the seat (drifting those holes took 20-45 minutes each, riveting not yet finished, just loosely assembled at the moment so I can check alignments): Side view of how the seat/arms attach to the back (this part has been riveted together, although the back decorative part hasn't): Two pictures showing the beginnings of what the back will eventually look like. I ended up settling on something that isn't particularly artistic, but I think should be pretty neat. Picture a three-by-three grid with the bars going in and out of each other, something that can't be accomplished without some tricky in-place bending and so forth: If you feel the need to criticize, be gentle, I've only been blacksmithing for a couple years and I'm well aware that I'm not very good, this is about fun, not talent. :-) Quote Link to comment Share on other sites More sharing options...
JNewman Posted February 2, 2011 Share Posted February 2, 2011 Looking good David. That chair looks like a very challenging piece. I assume you are aiming to get it done for Caniron this summer. One thing you might consider is drawing the front of the legs down a little so they are the same width as where you put the mortices. An alternative might be to use heavier bars for the seat cross pieces and tenoning them and then monkeying them. After you rivet them over that will add a lot of visual width to the legs, where the mortices are. If you decide to go with the heavy cross pieces, you can bring the butchered cross pieces to the OABA meeting at my shop in April. We could knock the tenons down quickly on the power hammer. We could even do some monkeying with the chipping hammer. Let me know if you want to do that and I will make sure I have the right sized stoppers made up for the hammer and a monkey tool for the chipping hammer. Quote Link to comment Share on other sites More sharing options...
dbrandow Posted February 3, 2011 Author Share Posted February 3, 2011 Looking good David. That chair looks like a very challenging piece. I assume you are aiming to get it done for Caniron this summer. One thing you might consider is drawing the front of the legs down a little so they are the same width as where you put the mortices. An alternative might be to use heavier bars for the seat cross pieces and tenoning them and then monkeying them. After you rivet them over that will add a lot of visual width to the legs, where the mortices are. If you decide to go with the heavy cross pieces, you can bring the butchered cross pieces to the OABA meeting at my shop in April. We could knock the tenons down quickly on the power hammer. We could even do some monkeying with the chipping hammer. Let me know if you want to do that and I will make sure I have the right sized stoppers made up for the hammer and a monkey tool for the chipping hammer. Well, it probably wouldn't be that challenging for most blacksmiths, but its challenging for me, anyway. :-) And yes, the goal was CanIron, it'd be fun to say I've had something in a gallery, and I wanted to try something significant enough to justify it being there. I certainly have been puzzling over what to do with the front legs. My tentative plan had been to do another twist, either a two-rope twist like the back legs, or perhaps something simpler like a pineapple twist, in the hopes that the twist would disguise the difference in size. However, you've given me pause for thought, that's something I hadn't considered, that would help balance it out. Let me get back to you on that one, and thanks in advance both for the idea and the offer. Quote Link to comment Share on other sites More sharing options...
dbrandow Posted March 20, 2011 Author Share Posted March 20, 2011 Another update, primarily so that I can log this for future purposes. Its not going particularly well, as you'll see, I think is project is just a little too far outside my skill set, but I'll keep plugging away at it. Front view: Side view: Closeup of the leg: What the back will look like, although its missing a lot of the "wires": Quote Link to comment Share on other sites More sharing options...
jeremy k Posted March 20, 2011 Share Posted March 20, 2011 David - It looks as it is in your range - by that, I mean you have been working a larger stock and doing the forging, mortice and tenons fine. As we all have to do at times, things just need to be tweaked during the assembly. As you have found out, you just don't make a chair like that in a few hours as a one off piece. Just think of how much insite you have learned during the whole process so far - that's worth doing it alone. This also gives you more confidence so you can do more and complex items in the future. - JK Quote Link to comment Share on other sites More sharing options...
Dillon Sculpture Posted March 20, 2011 Share Posted March 20, 2011 I would like to see more up and down movement in the arms and the back shaped as well in both planes, that is definitely an ambitious project, never tried a chair myself. Quote Link to comment Share on other sites More sharing options...
Mainely,Bob Posted March 20, 2011 Share Posted March 20, 2011 I agree with Danger.Hardly any flat planes in the human body and that`s what you`re going to put in it. I usually prefer organic over mechanical look in things like chairs.That means curves like the ones you have in the front legs and seat being echoed in most of the other parts even if the curves are slight they still turn a dead flat piece into something more flowing and organic. All this is easy for me to say as I`m not the one making it and you are. Quote Link to comment Share on other sites More sharing options...
dbrandow Posted March 21, 2011 Author Share Posted March 21, 2011 I agree with Danger.Hardly any flat planes in the human body and that`s what you`re going to put in it. I usually prefer organic over mechanical look in things like chairs.That means curves like the ones you have in the front legs and seat being echoed in most of the other parts even if the curves are slight they still turn a dead flat piece into something more flowing and organic. Its a good point, and I agree with it, I may tinker with the arms and back if I get ambitious. I'm going to focus on getting it closer to completion and then we'll see, of course. The only caveat with the arms is that the forearm resting on it is straight, but I can definitely see your point, even more so about the back. All this is easy for me to say as I`m not the one making it and you are. No worries, I always really appreciate getting advice, even when I don't take it. :-) Quote Link to comment Share on other sites More sharing options...
dbrandow Posted June 23, 2011 Author Share Posted June 23, 2011 Latest pictures... (as you can tell, picture composition is not my strong suit) I think I've pretty much given up, oops, finished, I meant finished (other than the wire brushing, sanding, applying vinegar paste, cleaning off vinegar paste, applying three coats of primer, applying three coats of paint, ...). If nothing else, this was an excellent learning experience on a number of fronts. Quote Link to comment Share on other sites More sharing options...
freeman Posted June 23, 2011 Share Posted June 23, 2011 Looks like a wide range of techniques and a ton of work went into that project. Way to stick with it! I especially appreciate your taking photos along the way so we can see your progress. Quote Link to comment Share on other sites More sharing options...
dbrandow Posted June 25, 2011 Author Share Posted June 25, 2011 Looks like a wide range of techniques and a ton of work went into that project. Way to stick with it! I especially appreciate your taking photos along the way so we can see your progress. Definitely a ton of work and a lot of different techniques. A lot of the jointery techniques I'd never put into play on anything like that scale before, nor had I tried to construct anything that awkward before. I definitely built up some more muscles hoisting that thing up to the forge table to get heated up and then back down again to get hammered on, that's for sure. My best guess is that it was in the neighbourhood of 85 pounds or so. Makes me think I should break down and get a torch one of these days. Some day when I'm less bitter, , I might put up another post on this thread on how the process unfolded so others can learn from my mistakes. :P Quote Link to comment Share on other sites More sharing options...
freeman Posted June 25, 2011 Share Posted June 25, 2011 Why bitter? It looks like you've got a perfectly functional chair there. What are you dissatisfied with? Quote Link to comment Share on other sites More sharing options...
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