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T O P I C R E V I E W
Adam C	Posted - 11/01/2011 : 12:10:49 How do you design your HPV's? Pencil and paper or CAD software? If you use CAD software which one do you use?
25 L A T E S T R E P L I E S (Newest First)
raymondg	Posted - 01/25/2013 : 07:58:11 quote: Originally posted by warren No lugs needed. Just fishmouth the tubes so they meet together at whatever angle you need and have a good fit, then braze them together. -Warren. And build jigs with MDF, plywood, clamped angle iron, or whatever you can get your hands on and/or are comfortable with. Alternatly, if you don't want to braze or weld, you can overwrap the joints with epoxy and ~~hemp, cotton, kevlar, glass, CNT,~~ carbon fiber. -Raymond
warren	Posted - 01/25/2013 : 06:04:20 No lugs needed. Just fishmouth the tubes so they meet together at whatever angle you need and have a good fit, then braze them together. -Warren.
Steven Challenge	Posted - 01/25/2013 : 02:04:41 Wouldn't you have to have lugs that go in the right directions? Where do I get the lugs?
warren	Posted - 01/24/2013 : 09:12:05 Have you looked into a MAPP gas torch? You can use that to braze with standard brazing rod. You will go through several tanks of gas but it is a cheap way to get started. That plus a hacksaw, a drill, and a couple files is all you need to convert old useless boring upright bikes into exciting and ergonomic recumbent vehicles. -Warren.
Steven Challenge	Posted - 01/24/2013 : 07:32:42 I’ve got limited resources and tools, just a garage, basic toolbox, no welder, no grinder. If I would have to make a custom recumbent, I would probably go for a (ply)wooden frame. The tools I’ve got and know are more for carpenting. I would start with making a jig out of scaffolding bars (Cheap and easy to manipulate). I would use the bottom part of a stationary bicycle for the pedals. That way the rider can try out the dimensions, rather than just a static test fit. Perhaps a physio therapist friend could have a look at the riders position and come to the ultimate riding position. The stationary bicycle can also provide me info about the riders power, this I can translate to the gear ratio. (and probably also the maximum weight). Although I have access to Autocad, I wouldn’t go for digital designing. Without aditional programs for material dimensions, strengh and airodynamic calculation, I don’t see the point in digitalising. I would trace the former aquired dimensions on a big cardboard and put the bicycle components into place. Because I don’t have the tools to do metal work, I would use a donor bicycle. Probably another recumbent bike but a child size road bike might work to. I’ve made plywood bikes before using the same technique. Using the donor bike’s dimensions and frame for parts that matter. Rear triangle for mounting wheel, gears and brakes. Head tube and fork for mounting front wheel. Crankshaft for… you get the idea. With my previous upright bike I put the donor bike frame parts about 3 inches into the plywood. Plywood sheets glued with PE construction glue. After glueing and sanding it’s time for a test fit. Ajust where wanted. Next I could go for a coat of resin/fiberglass. I don’t know if it would add to the structure or if I could make the plywood frame thinner. I could do a rough bending and breaking test with a surplus plywood beam, before I start fabricating. The more I´m thinking about it, the more it makes me want to make my own plywood recumbent bicycle. Sadly, I pormissed TOWMBO I´d clean up the garage first and do a couple of odd jobs around the house.
Adam C	Posted - 01/16/2013 : 12:40:23 We started with a sketch of the fairing profile, then have our rider sit next to the profile, then begin with a very rudimentary frame "design" sketch. Were are still doing sketch iterations of the frame.
purplepeopledesign	Posted - 01/16/2013 : 10:03:37 On my third build, I had a friend trace my side profile on pieces of overlapping cardboard. By flexing joints, we were able to reliably estimate and place pivots. After cutting it out, I had a "dummy" that could be used with components and tubes for simple mock-ups. After enough builds, I really just rely on memory for my various measurements and preferred positions. If there was need for a fully custom fit bike for another person, I would probably build a jig with a seat and pedals. Angles for the seat back and seat platform would be fully adjustable. The bottom bracket would be adjustable for both X-seam and height relative to the seat. :)ensen. Those who claim to be making history are often the same ones repeating it. Video of my trike http://www.youtube.com/watch?v=MdSLRD_2vzc Photos of my trike http://www.flickr.com/photos/purplepeople/
Steven Challenge	Posted - 01/16/2013 : 03:02:04 Ah I see, so it's not just a drawing program you are using, but also plug-ins for calculations. Now, one more step back: As a novice with common sence I would start with the rider position. Where does the handle bar, seat and pedals go. Some kind of jig where you can change the various positions to the optimal positions for that peticulair rider. Do you guys do that?
purplepeopledesign	Posted - 01/15/2013 : 20:36:46 Whether it's bikes or anything else, I almost always start with a hand-drawn sketch. As the design becomes more (ahem) solid, CAD enters the picture. This usually happens long before the final design is ready, for several reasons. First, CAD deals with interference very well, both at the macro scale and more importantly, when elements start to get tightly placed. Second, CAD makes pretty pictures that can close a deal, even at the preliminary stage. For this, I tend to use a non-photorealistic approach to prevent a client from making assumptions regarding the delivery schedule. Finally, regardless of the reason, if changes become necessary, they are easy to make, evaluate and re-submit to the client. It may not be obvious, but when the design is my own personal bike, that "client" is often more demanding than most, especially since he tends to be extremely budget-conscious AND still expects a result that shows improvement over existing designs. :)ensen. Those who claim to be making history are often the same ones repeating it. Video of my trike http://www.youtube.com/watch?v=MdSLRD_2vzc Photos of my trike http://www.flickr.com/photos/purplepeople/
Adam C	Posted - 01/15/2013 : 12:11:35 Structual/aerodynamic/thermal analysis can be performed on CAD models. I work for an aerospace company. We use Pro/ENGINEER. The structural analysis group performs analysis using the Pro/E models directly.
Steven Challenge	Posted - 01/15/2013 : 04:13:50 I have designed and made two upright bicycles using a huge piece of paper and pencil. The bicycles where mainly aesteticly, not made for speed. I copied the dimensions from an existing bike to design my own bike. I could as well used my own body dimensions to get the right sizes and positions. Although I work dayly with Autocad (I'm a draftsman), I can't see why one would design with a CAD program. Unless you have access to a 3d library to model your bike. Using CAD to operate a CNC machine might also be a reason, but does anyone use CAD programs for other reasons? Does anyone uses CAD to do strength calculations or airodynamic computing? So, some of you use some CAD program, but how do you start your design?
Adam C	Posted - 01/10/2013 : 14:44:27 Yesterday, I came across this CAD program called SpaceClaim. One of the founders of SpaceClaim, Blake Courter, also founded PTC (Pro/ENGINEER) and SolidWorks. SapceClaim has been around since 2007 and has released various versions of their CAD program. http://www.spaceclaim.com/en/
Grant-53	Posted - 03/19/2012 : 07:39:01 Coroplast and any other bendable sheet material would work. This could be much lighter and easier than making fiberglass forms. Cut and fold methods for honeycomb materials could be adapted as well.
Speedbiker	Posted - 03/18/2012 : 18:33:28 Pepakura creates ridges that could go perpendicular to the airflow. Very bad for aerodynamics. There might be a way around it, whereby great coroplast liners coyld be designed.
Grant-53	Posted - 03/18/2012 : 17:40:47 If you are pressed for cash I have used spreadsheets to do some things. A 3D graph function could create something of a surface model.
Patrick Bateman	Posted - 02/29/2012 : 21:26:27 There's a program called "Pepakura" which seems ideal for making bicycles with. It basically takes your 3d object, tesselates it, then prints it on your printer. People use Pepakura to make paper models, but it would be trivial to 'glass' the model with carbon fiber or fiberglass. Or even cut the pieces out of aluminum, and make a composite model. The greatest thing about Pepakura is that we could have 'open source' bike designs. One person could create the model, then any of use could print it out on our printers and build an exact replicate. Pepakura works with Autocad, Blender, Google Sketchup, Rhino, etc.
purplepeopledesign	Posted - 02/10/2012 : 15:17:29 An update to the Rhino vs Sketchup comparison. Had to download Sketchup 8 to read some files sent me for an upright cargo bike so I had a chance to evaluate it again since version 2. Much better than before but there are still issues with the both the free and (from what I can tell) the pro version. First, the push-pull tool is so much better that I can see why so many beginners like it. Second, the push-pull tool is so simple that I can see why many pros don't like it. But that's not my beef with it. To get booleans, and a small but useful set of import/export formats, you have to buy it for $500. Even so, you have to hunt around for any number of plug-ins to get fillets, lofts and any number of "basic" modeling tools. The student price for Rhino is $200 and that includes everything but an advanced render engine and a Sketchup import/export filter. For a student, the better deal is obvious. The best street price I've seen for Rhino pro is $800. Considering what you get for the difference, Rhino is still the better choice. :)ensen. Those who claim to be making history are often the same ones repeating it. Video of my trike http://www.youtube.com/watch?v=MdSLRD_2vzc Photos of my trike http://www.flickr.com/photos/purplepeople/
jamesl	Posted - 02/10/2012 : 09:54:48 quote: sketch up is useful to a point ... the free version I was playing with a couple years ago wouldn't output a file extension that could be used in a CNC .stl , .dxf or such The new free version of Sketchup can export to stl & dxf with a free plugin.
Adam C	Posted - 01/19/2012 : 21:48:04 quote: Originally posted by Dreamer I like your quote Adam C. I hope we get to watch your vehicle and team at Battle Mountain 2012. If you wait to built until you've perfected all the elements of design you'll either never start building or you'll never finish. Dreamer Thanks Dreamer. We acquired two sets of fairing molds recently. Our plan is to build bikes for those fairings and just have some fun at BM. Then we'll design a pure speed bike for 2013.
Dreamer	Posted - 01/19/2012 : 19:52:59 I like your quote Adam C. I hope we get to watch your vehicle and team at Battle Mountain 2012. If you wait to built until you've perfected all the elements of design you'll either never start building or you'll never finish. Dreamer
Adam C	Posted - 01/19/2012 : 16:25:51 My female rider is a college student so I guess we buy Rhino through her.
purplepeopledesign	Posted - 01/19/2012 : 15:16:04 Before you spend the money, install the trial.... it's a full version that stops saving and printing after some set number of saves, but all other functions continue to run so you can actually practice with it. That said, you should also consider whether or not you can get the student discount, which is a substantial amount and is also an unlimited commercial licence. Finally, I believe there is a free Mac version that is well past beta but still only for release to people willing to test and return commentary. If you already have access to CAM systems, find out if they can import some of the Rhino export files. If so, then no need to get any plug-ins. Many people use Rhino as stand-alone beside their other systems. In my case, I only use the Penguin plug-in because I like the output and there are no other softwares like that anywhere. :)ensen. Those who claim to be making history are often the same ones repeating it. Video of my trike http://www.youtube.com/watch?v=MdSLRD_2vzc Photos of my trike http://www.flickr.com/photos/purplepeople/
Adam C	Posted - 01/18/2012 : 13:30:17 quote: Originally posted by purplepeopledesign Yes, but they're not considered "parts." Rather, you build a model, then save it. When you start the assembly file, you can either import the the model as a block or paste it as part of the actual file. If you import it, the assembly file only contains positional and textural data for the block. You can put any "material" or texture on it, even differing from the original file, but I tend to not bother with rendering details, preferring to use the Penguin plug-in to get sketch-like output with lines that go past the corners. Here's the thing... unlike SW, Rhino files are all the same. Any file can be used as a block, including assemblies. It get's complex, but AFAIK, you can have assemblies of assemblies or paste stuff together to make one big component. Even better, not everything has to be a "closed" solid. You can add stuff that has microscopic anomalies at the seams. So, even though it's not physically possible for the object to exists, you can still stitch it together if you want, especially if you don't want to take the time to model something perfectly but need to see what the gist of a shape will look like. An example would be putting last years fenders on a new car design for a marketing evaluation. And even so, this situation rarely exists since Rhino has an internal calculation resolution of (at last count) 15 decimal places. I've sent stuff that supposedly had artifacts in the .0001 mm range to plastics suppliers that had no problems milling out an injection mold. The other nice thing about Rhino is that because it uses NURBS geometry, it is very fast and can still run on older Athlon and P3 processors, so it helps to save resources there also. :)ensen. Those who claim to be making history are often the same ones repeating it. Video of my trike http://www.youtube.com/watch?v=MdSLRD_2vzc Photos of my trike http://www.flickr.com/photos/purplepeople/ Ahhh...I see. I think I just may plop down the $995 for the program then. i'm also interested in the some of the CAM add-ons to machine a female mold at some point. Thanks for the info, purplepeopledesign!
purplepeopledesign	Posted - 01/18/2012 : 12:49:09 Yes, but they're not considered "parts." Rather, you build a model, then save it. When you start the assembly file, you can either import the the model as a block or paste it as part of the actual file. If you import it, the assembly file only contains positional and textural data for the block. You can put any "material" or texture on it, even differing from the original file, but I tend to not bother with rendering details, preferring to use the Penguin plug-in to get sketch-like output with lines that go past the corners. Here's the thing... unlike SW, Rhino files are all the same. Any file can be used as a block, including assemblies. It get's complex, but AFAIK, you can have assemblies of assemblies or paste stuff together to make one big component. Even better, not everything has to be a "closed" solid. You can add stuff that has microscopic anomalies at the seams. So, even though it's not physically possible for the object to exists, you can still stitch it together if you want, especially if you don't want to take the time to model something perfectly but need to see what the gist of a shape will look like. An example would be putting last years fenders on a new car design for a marketing evaluation. And even so, this situation rarely exists since Rhino has an internal calculation resolution of (at last count) 15 decimal places. I've sent stuff that supposedly had artifacts in the .0001 mm range to plastics suppliers that had no problems milling out an injection mold. The other nice thing about Rhino is that because it uses NURBS geometry, it is very fast and can still run on older Athlon and P3 processors, so it helps to save resources there also. :)ensen. Those who claim to be making history are often the same ones repeating it. Video of my trike http://www.youtube.com/watch?v=MdSLRD_2vzc Photos of my trike http://www.flickr.com/photos/purplepeople/
Adam C	Posted - 01/18/2012 : 12:19:31 quote: Originally posted by purplepeopledesign Rhino is in use mostly by industrial designers. It does not do "solid" models, but it does 3D surface models. The question to ask is what is the difference? As far as I can tell, the only advantage of a solid model file format is when you have an assembly of multiple parts comprised of different materials. With that, FEA can do it's job on the whole assembly. For CFD, the software only needs to know the surface geometry and for that Rhino excels. If I could afford it, I would also have Solidworks with the associated CFD and FEA. I would model in Rhino and import to SW for assembly and analysis. Instead, I tend to build with a "solid" strength factor built in... at the cost of weight instead of money. :)ensen. Those who claim to be making history are often the same ones repeating it. Video of my trike http://www.youtube.com/watch?v=MdSLRD_2vzc Photos of my trike http://www.flickr.com/photos/purplepeople/ Ok, I think I understand it more. Can you build assemblies in Rhino 3D like you can in typical 3D mechanical CAD programs?

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