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warren
human power expert

USA
6118 Posts

Posted - 04/02/2015 :  08:23:38  Show Profile  Visit warren's Homepage  Reply with Quote
Wow, I'm glad it's you doing the math coding and not me!
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/02/2015 :  09:09:03  Show Profile  Reply with Quote
Warren: lol. Pretty glad the niece has needed help so I could buff up a bit on math.

So far I like the result. Amazingly enough the total stretch was 3/8ths of an inch! ...and it looks soooo much better to me. In essence this slightly violates the NASA airfoil curve but we all know those lines of flow slip down or up along the sides a bit, they don't stay straight (the vertical wires of a bird cage run "straight").

[URL=http://s1372.photobucket.com/user/shooky56/media/Rib%20problem%205_zpshwa0irj8.png.html]
[/URL]

Getting pretty close to being ready for the CNC codes. I have the shape outline into points ready to convert but not the alignment holes. I'll have to "flag" the points that belong to the holes with something I'll recognize with my CNC conversion code. Then replace those flags with proper lift codes (whatever those are, possibly just a Z transition).

Sort of:

point1 for rib edge
point2 for rib edge
....
(-1,-1,-1) dummy flag to encode a tool lift blank move and plunge
pointN for alignment hole1
....
(-1,-1,-1) dummy flag to encode a tool lift blank move and plunge
pointN for alignment hole2
....


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Grant-53
recumbent guru

USA
544 Posts

Posted - 04/02/2015 :  19:10:51  Show Profile  Reply with Quote
Wow, does that ever look familiar! We have been sketching shapes for motorcycle fairings to minimize crosswind effects very much like this.
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/04/2015 :  15:16:05  Show Profile  Reply with Quote
<cough> ...well before all-ya-all get too famboozled with the math a couple strange things happened. The first run of this looked pretty good and I was ready to move and do CNC, then I decided to try a couple other shells and wow did it ever go awry. My math had an error, I'd forgotten my ellipse should have used the general form (which added another couple variables). To make a long story short, I was purely lucky that it worked the first time. As the general form of the ellipse equations takes 5 equations with 5 unknowns (algebraically unwieldy w/o matrices) it became "point prohibitive" by the time I get 5 points away from center, it is no longer an ellipse.

Doh! So I opted for another method, which I like pretty well. MicroSoft's smoothing does make some very gentle interior curves in the tail ribs (only one in my tests) but the tail section doesn't particularly concern me.

Then bro worked with me to produce a tool path. I paid... $3500?? for Aspire 8 years ago and it cost me about $400/hr so far because I haven't used it much. Bro bought a copy not long after and has more experience. He imported the life-sized bitmaps into Aspire.

Apparently Aspire's picture importer does antialiasing which makes my single pixel width curves disappear in places. Wait!, could fill them in solid brb!!! Yep that worked. Aspire roughed up the curves a bit but it's good within 1/10th of an inch. The girls are dragging us out the door by our ankles again tonight but hopefully we'll cut something soon.

BTW that doesn't stop me from producing the G-codes myself, but it's a sanity shortcut to check the shape.
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/06/2015 :  07:11:49  Show Profile  Reply with Quote
The PC hooked to Bro's CNC lost its harddrive. We messed around with it for half a day hoping to get a successful boot to transfer everything to "something", perhaps even ghost it for a new HD. Never got there. Packed up and drove home. Doesn't stop the work but, unfortunately I have no easy way to confirm my CNC codes work when I get that far.

As far as the CNC codes go, studied them some and the movement ones are easy. The tool codes weren't "obvious" to me but at least I have a sample for mach2/3 for a 1/2" end mill. Wanted to select a 1/2" straight flute (edge profiler) but it wasn't in the tool selections. You can design your own but the end mill produces the same codes. We told the software it could cut 1/2" per cut, using 1/2" plywood it did a one-pass cut.

At any rate got a bit of things to catch up on then I'll be back writing in a few days to give a release. At the very worst the printer output method will give the jig saw guys something.

Maybe some kind soul with a CNC router could work with me.

In the interim, bro has put the CNC fix "on the list". As I recall (we haven't looked up anything recent), the controller guys came up with something to liaison the non-interrupt USB ports with the "we gotta have an interrupt feedback" controllers called a "smooth stepper" (probably one product name among several). He also has a couple old XP machines he could throw out there.
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Grant-53
recumbent guru

USA
544 Posts

Posted - 04/06/2015 :  19:29:31  Show Profile  Reply with Quote
The ellipse can be approximated by a series of circular arcs. The holes are done as you said by a Z up, rapid move to the point, and running a circular subroutine. Some of us will use horizontal ribs at the edge for spacing the bulkheads. We appreciate the effort. I have some experience with G codes and cutting plywood using an industrial size router.
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/07/2015 :  11:47:14  Show Profile  Reply with Quote
Thanks Grant. I think you can do my email off the membership thing, not sure. That's an email I don't use really but will check it. Lemme know if you're interested in direct contact here or, if Warren doesn't care, email him and he can forward to the email I really do use.

As far as testing the CNC output. All I'd ask is to tape a felt marker to the tool and let it draw the shape on brown wrapping paper (just an example, the methods are what anybody chooses to do). Just to make sure they are coming out OK. As for me I'm fine with a jig saw but got a bit hooked on the CNC thing and had my head set on it till bro's machine quit. He hadn't fired it up since last fall.

If you have access to a CNC and would be willing to run a few tests. No need to do a rib set. I'm guessing we'd end up with a one rib at a time thing, if it goofs, you tell me what was wrong and I try to fix it until we either get tired, get it working or you tell me to go fly a kit.

Shopping for a CNC myself while bro repairs his, would have bought a Stinger except they upped the price all since my last check from $4K to $6.5K.

Really would like to take my 120oz-in stepper and control system and make it "removable" for multiple tools so I have the control system for my unfinished 12x8x4 foot 3D foam carver.

Mind you I haven't lost a bit of interest in this but real life is banging at the door a bit. Probably could just work on a release. There are a couple bugs (unrelated to the CNC output). Noticed my rider's head did not stay resized on a file load and there is a "focus" problem. A prior focus fix caused all the rider size boxes to lose focus after every character (lol that's a real PITA)... stuff like that, probably dozens of things I didn't catch myself too but it DOES work.

BTW the curve repairer was edited since my last comments on it and the output looks really good now. No interior curves anywhere.

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Speedy
recumbent guru

USA
883 Posts

Posted - 04/07/2015 :  14:51:15  Show Profile  Reply with Quote
http://www.gryphoncnc.com/

Steve Delaire

http://molten3d.blogspot.com
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Grant-53
recumbent guru

USA
544 Posts

Posted - 04/07/2015 :  17:24:38  Show Profile  Reply with Quote
I can check with the folks at Corning Community College about proofing the G codes. The company I worked for moved to another part of the state.
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/08/2015 :  15:34:26  Show Profile  Reply with Quote
Thanks Grant. Don't go through the trouble, at least not yet. Steve sent a link, one of several I'm exploring to purchase one myself.



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txusic
recumbent enthusiast

Spain
125 Posts

Posted - 04/09/2015 :  09:01:46  Show Profile  Reply with Quote
Shooky if you need some graphics, consider me in.. congratulations!
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Upright Mike
human power expert

USA
3803 Posts

Posted - 04/09/2015 :  16:02:26  Show Profile  Reply with Quote
Speaking of CNC and foam cutting, you might look if there is a TechShop location near you. There are DIY Do It Yourself places that are sprouting up across the country. I was a member at the Detroit location. For a small fee, you become a member, take an instructional course then can use their state of the art stuff.
They have what's called ShopBot 3D that can carve 4 x 8 foot and I think 4 to 6 inch deep sections. I have been dreaming of carving out blocks of foam there!
http://www.techshop.ws/
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/12/2015 :  15:35:33  Show Profile  Reply with Quote
Thanks everyone!

Just a quick update. I haven't worked on the CNC output and not much on the software. Stupid Spring and "promises" (lol). Got about another week ahead of me give or take before I get back to the code heavy.

What I have done is clean up a few of the prior mentioned bugs in preparation to make a release. CNC output will probably be in it but as mentioned prior "untested".

As for the foam carver, I've put it on my bucket list to make my own HUGE (by our standards). The original design was to cut foam car bodies, heapum plenty big enough for our shells.



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shooky56
recumbent guru

USA
545 Posts

Posted - 04/16/2015 :  23:03:41  Show Profile  Reply with Quote
Most of the side distractions are behind me and I'm starting to get a few hours on the code daily. Fixed most of the worst bugs I knew of over the last week. Now adding the CNC conversion. Much of my time has been creating visuals to check the output. Looking pretty good.

Release shouldn't be too long.

Concerned that the bit path for the CNC looked rough (it's pixel rounding errors) I painted a translucent yellow 1/16" stripe over the pixels to check. Doesn't look so bad under that light. Mathematically the error in this case should be no worse that +/- 1/72" which means it should stay pretty close to the center of the yellow stripe. That was about the worst section I could find, most of it looks much better.

[URL=http://s1372.photobucket.com/user/shooky56/media/CNC%20tracing%20error_zpsuhgheif3.png.html]
[/URL]

Some pictures of the software at work: Trike is to scale although I didn't put a frame on it. The position of the critical parts is very close (wheels, crank, seat, rider).
[URL=http://s1372.photobucket.com/user/shooky56/media/My%20Trike%201_zpsedihpuf8.png.html]
[/URL]

[URL=http://s1372.photobucket.com/user/shooky56/media/My%20Trike%202_zpsona8anvu.png.html]
[/URL]

[URL=http://s1372.photobucket.com/user/shooky56/media/My%20Trike%203_zpsocyqnexr.png.html]
[/URL]
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/17/2015 :  22:06:15  Show Profile  Reply with Quote
First run at CNC codes. Looks good but it'll need some testing. Remembering back to our first CNC runs, you had to be careful not to slam the tool down to ... or through the bench.

Still a few details about the CNC output that needs clearing up which I may not do before a release. A release is next on my list.

Some of the output problems:
Hard coded a 1/2" end mill but treat it like a 1/2" flute. The code plunges 1/2 inch and cuts the 1/2" plywood in one pass rather than two.

A few things about the rider designer; the pelvis width isn't honored although I don't think the pelvis width would normally be the part that limited the shell (could be wrong about that). Height is finicky, my attempts tended to leave me a couple inches short.
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Grant-53
recumbent guru

USA
544 Posts

Posted - 04/18/2015 :  09:44:40  Show Profile  Reply with Quote
I find my shoulder dimension is about 20 inches and my hips are 18 inches wide. We cut our panels which were aluminum skinned plywood with a 1/4 " end mill at high rpm. Heat build up was a problem. A base form with relief cuts under the tool path were used and the work pieces were secured by air hole suction. I will likely use some of my 0.355" honeycomb aluminum for bulkheads. Thick plywood may be heavier than needed; still a good starting point as some will want to use foam.

Edited by - Grant-53 on 04/18/2015 09:54:09
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/19/2015 :  06:38:55  Show Profile  Reply with Quote
Working on a release. Took all day to get it to work on a "blank PC" but finally got all 200 support files included in the package and it runs.

Going to clean up a few more details, maybe add some instruction videos, then have Warren post the files. As a test to make sure non-recumbent looking bikes actually worked, I dropped Warren (6-4) on my 53 cm Cervelo and threw a shell on him... btw he swallowed up that frame. If the seat post was actually in the seat tube he'd be eating knees.

[URL=http://s1372.photobucket.com/user/shooky56/media/Upright%20shell_zpsiublyktd.png.html]
[/URL]
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Grant-53
recumbent guru

USA
544 Posts

Posted - 04/19/2015 :  20:11:32  Show Profile  Reply with Quote
Looks very good. The proportions 3:1, L:W seem right. There should be enough room for steering motion with aero bars. I would expect the bottom to cover to just below the knee at full extension. We can add the cowling for the helmet if need be or simply use an aero helmet. Some of the nose may have to be transparent. A sturdy bulkhead right behind the seat would allow something to push against.
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/20/2015 :  07:29:31  Show Profile  Reply with Quote
3:1, had no idea just played until it looked good. Nice warm fuzzy to hear your approval.

Was thinking along very similar lines. Lexan, pita to blow but blow a lexan nose, fasten it to the head tube (so it doesn't load the steering of course). Either have it beyond the bars so they don't interfere or, if it extends downward to cover the knees a bit, it may clear the bars. Sure would be nice to maintain the hard aero as far as possible before the soft shell starts.

Tail, no idea and no idea what is being used for stiffeners for the lycra either. Sure you already know.

What worried me was the inevitable crash. Lycra cut to the face/eye area was a primary concern, probably could edge the lexan with one of several options (anywhere from tubing with a slit to auto door edge protector, that kind of stuff). That comment is probably a "no duh" to you builders, just the old grandpa in me worrying is all.

Couple things about the head. Head toward the road would probably stay inside the shape. May even be able to "check ahead" by scrunching down and just peering through the Lexan and or pushing the Lycra upwards enough to get a good view while the eyes actually look through the Lexan. May even be able to see through the Lycra well enough to "stay on the road". ... and then theres a possibility of a mirror on the head tube to see forward. Of course such idiocy wouldn't be good for training or group racing but for Battle Mountain...

I'm sure you know what works and what doesn't... it's just me wondering out loud.
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Grant-53
recumbent guru

USA
544 Posts

Posted - 04/20/2015 :  11:07:07  Show Profile  Reply with Quote
There will be details to work out with sight lines in the front. I plan to use slit tubing around the hard openings near my neck (of which I am very fond). Aluminum or coroplast honeycomb bulkheads and 1/2" OD PVC flex tubing for ribs as needed. My favorite skin material is 1" hex mesh wire bonded between layers of 0.005" tarp plastic. Other folks will have different preferences. With your permission I'd like to post this to the Ecomodder.com forum as we are having lively discussions on the aerodynamics of bicycles and motorcycles. I appreciate the your efforts.
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/20/2015 :  13:46:54  Show Profile  Reply with Quote
Posting: Totally OK with me.

Other stuff: Roger all that!

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shooky56
recumbent guru

USA
545 Posts

Posted - 04/20/2015 :  13:48:26  Show Profile  Reply with Quote
correction on prior post lycra cut, meant Lexan cut (lol). Got to watch that deadly sharp lycra...

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doc777
Starting Member

USA
6 Posts

Posted - 04/21/2015 :  16:47:09  Show Profile  Reply with Quote
Nice work Shooky. Is it possible to have a grid across the sections or perhaps a few more circles or 2x4s to make it easier to line up when I sandwich them together.
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shooky56
recumbent guru

USA
545 Posts

Posted - 04/22/2015 :  06:36:51  Show Profile  Reply with Quote
2x4: It is possible Doc and somebody else mentioned 2x4's to me. For the conduit holes I calc the CNC on the fly. Also I'd expect conduit to be pretty true, more so than 2x4's. It would take me a bit for the 2x4 holes since they really need a "gouge in the corners" because the nominal tool diameters would be too big for the radius of a 2x4 corner. Only have to calculate that once or hijack the codes from my Vectric software and patch the codes in where the 2x4's need to go.

Grid: Going to make a guess. Do you mean for the printed version intended for jig saws. The grids all line up so X=0 and Y=0 on each rib is in line with all the others?

Release is looking pretty good. Couple odd things that have me concerned. (1) I'm not sure I'm correctly sizing the rider when exporting it to the shell designer. A correctly sized rider is important to correctly size the shell so I need to do a few checks there. (2) not too critical but some of the tail shapes look goofy. I believe it comes from only half a dozen points being used to define that shape (sort of a sliver). By the time we get down to 3x6 inch rib free handing is as likely as good as anything I'm generating (on the tail cross sections) so that doesn't worry me much.

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doc777
Starting Member

USA
6 Posts

Posted - 04/22/2015 :  17:54:50  Show Profile  Reply with Quote
Conduit sounds great. I was shopping for PVC tubing for a project, had that in my head. Scratch the 2x4 :(
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