Engineering Principles for Makers Part One; The Problem. #066

I've designed and built quite a large number of machines as well as space-saving devices in fact I've got yet another project that I've been working on which is effectively a dual workbench with the permanent work surface on the bottom you can retract that guy down everything stays perpendicular to the floor and then you have yet another work surface on top or gluing or whatever you want to do but then I thought while this guy was at the prototype stage this would be a good opportunity to show you how I think through these problems and come up with these designs and you guys can also give me some feedback on this one I ended up calling this the dr. farm method I'm gonna show you the first thing you have to do is define the problem so let me show you my problem first and then we'll actually define it in writing what you're looking at is a space as approximately six feet wide by about three or four feet deep and the workbench you just saw a second ago was in this space very comfortably it could slide left and right and that bench has wheels that would allow me to roll it away as you can see now I want to be able to increase my assembly space without increasing the footprint in the shop and that's the challenge now right now some of you have already scrolled down you've pictured in your mind solution as you've seen before like benches that are on the wall and they flop down with legs and things like that but before we go there I want you to just freeze that for a moment don't type that comment just yet let's carefully define the problem and then see how that changes the solution you come up with you got to start by being as specific as possible without constraining yourself to any particular solution one of my favorite examples comes from one of the books that I'm going to put in the description so be sure to check that I've got some references there that I want you guys to check out but one of those books gave an example of cutting grass and they said you could define the problem is I need to design and more efficient lawn mower well you could also say I need to shorten so many acres of grass in so many minutes one definition is going to constrain you to one type of solution while the other one is going to open up all kinds of possibilities to how you might approach the problem the same thing you wanted with your design try not to think about the solution too early because that's gonna force you into thinking about the problem in a way that it fits the solution you already come up with the second thing you need to consider is any constraints that you have for example I've got space constraints I need this thing to be movable so I've got weight constraints things like that so you want to think about manufacturability if you're gonna be making it yourself it needs to be something you can actually manufacture that includes tolerances materials being used for me it needs to be mostly woodworking in nature otherwise it's gonna significantly drive up the cost for me so let me show you the list I came up with all right so my goal is to double my working surface without increasing my floor footprint that's the goal and here are the constraints that I have number one it's got to fit in the same space as the current workbench number two I want it to cost less than $200 in materials and any other purchased components that I may need to give I'm not actually worried about labor as far as I'm concerned the labor price is unlimited I love doing this so I don't care how much time I spend doing it number three it needs to be manufactured with woodworking tools as I mentioned earlier number four the surface must be flat since I'm gonna be using this surface as a reference for being square and flat for many of the things that I'm gonna be making I need to surface itself to be both square and flat it needs to be durable enough to withstand typical woodworking so it needs to be withstand hammering and things like that number six I need to have accessible edges because I'm primarily going to be using this for an assembly table which means I'll be gluing and clamping things together on it and number seven it must be movable I want everything in my shop to be able to either have retracting casters or permanent casters so that it can be moved around now that you know how about to find the problem and I'll put those things on the screen for you think about possible solutions you might come up with oh wait okay I want to actually make you wait but you can pause the video if you need to there's one other constraint that I have it's more of a mental constraint but it's worth mentioning and that's the cool factor I mean it's got to be interesting to me right I love all things mechanical and if it doesn't have some kind of mechanical component to it I'm not gonna be nearly as interested in it and I might be more willing to lean towards a purchase solution the next step in our dr. Farr method is research absolutely you got to do your homework don't just start don't go straight to CAD and start making something you got to do your homework first there's a very very high probability that someone already has a solution to your problem and if I could find a workbench that was within my two hundred dollar budget that I could purchase off the shelf that's an option I at least want to consider but research research research search to well try not to just focus on things that fit within the mold that you're thinking about I jump right into my research and I spent quite a bit of time looking at space-saving devices for whatever reason I felt like that was gonna be the the right topic to search for and what do you know I came across this bed desk combination and the thing that was most appealing to me was the linkage on the side it's got the cool factor right at least for me but what I liked about the linkage is adjusting that linkage would allow me to put that second workbench at whatever height I want it using that linkage on the side would allow me to bring that second workbench up to exactly the same height as the first one it was just about using the right length of the lever and so my design was kicked off into full gear now that we've done our research the last four steps occur just about simultaneously you generally are interchanging them together so the first letter is F and that stands for function how does your machine actually solve the problem what how does it provide a solution in my case I'm using linkages which will allow me to hide my temporary work surface and bring to the same height my working surface my primary working surface when I need access everything here stays in place I can lower it down and present a secondary surface for items that just maybe need to sit and be or whatever without disturbing the things underneath now a is for appearance or you might say geometry as well it's probably a more appropriate term because I'm not just thinking about how it actually looks I'm thinking about the shape of it the shape is what determines how your device your machine is going to handle the stress that's put on it now we'll talk more about stress in the next video but just briefly I like to think about stress as water flowing through my structure so I think about where the force is going to be applied and then how does that get all the way to the floor and in this case I've got these triangular shaped gussets here on the side which is going to help feed the stress down through the pins and then that's going to work his way through the legs and down through the base of my structure here the third letter is our a for risk now at this point you don't want to be too married to your design even if you've already made a prototype this is your chance to totally rip it apart in fact there's another era for you there rip apart your design try to find every possible failure point that you can in fact I'd like to assume it actually has failed and then try to reverse diagnose the problem so I would say okay this guy broke what went wrong and by forcing myself to answer that question I think about all the possible weaknesses in the design before I got to this point I had several weaknesses that I evaluate it and came up with some solutions so I'll share a couple of those with you number one I was concerned about the structure racking like this and I decided to compensate for that by covering the bottom now this is not going to be the final shape but for the prototype I just glued on a square piece in order to keep these legs from being able to rack in the front another possible failure point is the wood around the pins because they're going to be subjected to the greatest amount of stress those holes can wear out over time and possibly become potential binding points or worse the wood the wood might fail completely and my structure fall apart so I'm going to use some kind of bushing or bearing there in order to have a hard surface to rub against and reduce the potential wear point there one other risk I want to mention is the amount of effort it takes to actually lift this guy so based on my 3d model at the top surface as it's designed now with one and a half inch thick top sides and so on it's going to be approximately 60 pounds and the one on the bottom it's gonna be about 50 pounds and this workbench across here is a little over five feet wide that of course doesn't include whatever items might be on this bottom surface that I intend to leave there for you know an extended period of time I've got a couple of ideas about how I wanna approach this it might be as simple as attaching a counterweight here in the back or some kind of spring mechanism to like a spring assist so that is one concern that I have that I am working through and it's not shown here in this scale model there are a couple other things that I've also tried to mitigate but you guys are welcome to offer some suggestions if you see things that you think are potential failure points in this design the last one is model and in this case I made both a 3d modeling CAD as well as an actual three-dimensional prototype and this is a critical step for me in fact all my projects that have mechanical components like this I will often make a prototype so sometimes I make scale prototypes like this where it's 1/4 scale which is very intentional by the way because that way I could make this top three-eighths of an inch or about 10 millimeters that was the smallest surface I felt I could put screws into the side of so all of this I was thinking about as I was scaling this down even to make the prototype as realistic as possible so anyway for example this is 3/8 of an inch but in real life it's one and a half inches in the full-scale model in fact right behind me I have a prototype this is an idea that I've been thinking about for a while I decided you know what I'm really struggling with how it's gonna play out in my mind so I went ahead and just made the prototype it took me a weekend to make that I made it out of scrap pieces of wood it's actually functioning really great so now I'm ready to push my design to the next level remove the flaws that I find in this one and make a more permanent table saw fence this is another prototype that I made it's actually one of the first youtube videos I ever published so basically it have my little bench top bandsaw on one side and then the router on the other side I actually made this prototype out of cardboard first my lathe which is over here to my left just outside of your view was another full-scale prototype that I've built and I actually made several different versions but there's a whole series of videos on that so if you interested in that you can click on the link and see more about my shop male 8 when I made this guy I was very intentional to follow the same assembly process that I would when I make the full-scale model because again this is an opportunity to learn everything I can about my design before I spend too much money and make the full size the full-size workbench and I actually discovered several things number one I left the pin out of my design there's supposed to be a pin here to lock this guy at the top and what do you know it was in my head but I never actually put it in the 3d model another mistake that I made is I glued this in the wrong spot and this is a mistake that I think I would have actually made on a full-scale model if I wasn't paying very close attention so this pin which is just a quarter-inch bolt at this point and it's actually a one inch bolt in real life so again scale true to size from one inch to a quarter inch but this surface is supposed to be flush with this I wanted this whole surface to be flush and I didn't want these pins to stick out over the workbench so this is glued at the wrong level there should be a gap underneath so that there will be cross members on the bottom of this surface here providing more support the last thing I want to mention is that this was designed to be built with dimensional lumber so a lot of this is made out of two by fours two by sixes two by eights things like that that's gonna lead to the easiest manufacturing process once I start thinking about how much stress is gonna be applied to different areas then I might decide I can make it lighter by milling those guys down or I need to beef some areas up by gluing more pieces together but that gives you a good starting point you say okay is it worth the additional work to glue on more or is it worth the weight savings to shave off more material in order to make the design as efficient as you can anyway I'd love to hear what you guys think about this particular design give me any feedback you want to give in the comments let me know what you think and in the next video hopefully we'll be building this guy thanks for watching I just realized I didn't give you guys a very good look at the table saw fence so the idea is there's a click locking pin there it's very snug it only takes about a quarter turn to go from completely loose to completely tight this part is designed to tilt so that I don't have to lower the blade I can just lift it up and tilt it over and one more cool thing if you look at this side you'll see that there's a block of plastic that I have here this is actually melted down hard hats which are made of HDPE one of you sent me a whole box full of hard hats and in thinking about what to do with it I thought maybe will be great if these guys were just used as sliders and this actually works fantastic in this application hope you like that little bonus footage thanks for watching

Channel: Jeremy Fielding

Views: 627,255

Keywords: Jeremy Fielding, Machine design, space saving workbench, dual workbench, making prototypes, mechancial engineering basics

Id: FHhXbz1K0k0

Length: 15min 9sec (909 seconds)

Published: Tue Oct 23 2018