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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 10/27/2018 :  15:26:39  Show Profile  Reply with Quote
I'm taking the plunge. We'll see if I know enough to get it done, or just enough to end up with an expensive pile of abandoned parts, materials, and swear words.

I'm documenting it at CGOAB just because it's a lot simpler to put photos in and write a simple page.

http://www.crazyguyonabike.com/doc/21502

Nothing too interesting there yet. Still waiting on the rest of the main tubes. Working on the seat, wheel build is next. Now that I've got the fork, I can take measurements and finalize the design a bit more.

--SpiderMonkey

SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 11/08/2018 :  19:42:02  Show Profile  Reply with Quote
Well, the last of the Chinese carbon fiber tubes have arrived, so now I need to get going on the rest of the bike. I learned a few good lessons on process while getting the seat wrapped up, so I think I'm equipped to start the real work.

I'm refining the design, still using a lousy 3d-builder program for ease of editing. I'll draw up a couple full-scale drawings once I get things more finalized.

I had planned to do the bike with a 2-bend frame, but sketched a 3-bend version as well. I'd have one more join to wrap, so it would probably add some weight. On the other hand, it might make setting the head tube easier (as it would be a 90 degree hole through a main tube, rather than something else).



--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 11/12/2018 :  07:47:38  Show Profile  Reply with Quote
The chainstays I've got planned are CF tube 25mm, 1.5mm wall. (I've got 28mm 1.5mm wall available, but I think 25 should be stiff enough.) I'm wondering if the overlap here looks good. The main tube's 50mm. The overlap (diagonal) measures about 70mm in this sketch.



--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 11/19/2018 :  19:23:25  Show Profile  Reply with Quote
Got the seat frame pretty much done. Weighs 332 grams before the M5 bolts, so probably just under 340 with bolts and polyurethane. Mesh will hopefully add less than 150g, but I'm not sure. It feels really strong. I learned a few good lessons making it. I give myself a B on this effort.

















--SpiderMonkey
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warren
human power expert

USA
6424 Posts

Posted - 11/20/2018 :  12:53:22  Show Profile  Visit warren's Homepage  Reply with Quote
Looks good! Wow if you are going full weight weenie on this small a bike it should weigh under 20 lb easy!
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 11/20/2018 :  19:25:54  Show Profile  Reply with Quote
It definitely would be, however, I'm not going that route, much to my chagrin, at times. This seat will, I think, come in around 500-550g with the mesh on. (A straight mesh sling design might have been lighter and not needed the pad, for a total weight savings of probably 700g.)

But the kiddo's had some issues with recumbutt on sling, so I wanted to try this route. Guess I could always make a sling one as well -- it'd have fewer joins and I'll have leftover mesh anyway.

Since it's my first build, I'm over-building. (Many of these joins are probably 2x or more what they need to be.) In this, case, I probably could have cut the weight on this design for the frame maybe 50 g or so.

Making it adjustable for a pretty big range of growth (perhaps from now until adult sized) is adding some weight, as are some decisions I made like going with disc brakes. (She like's 'em, I prefer them for maintenance, as I'll have like 8 bikes all on the same BB7s!) It's going to (I still think) have an inner sleeve and pinch assembly in the main section for separability, as well as a boom. I went with Deore XT hubs and 32 spoke sun rims, though I could have saved about half a pound with some bitex hubs and 24-spoke velocity rims, it would have added $200 to the wheel budget.

The 2mm wall main tubes are overkill for her weight, but I like that they'll be pretty crush-proof. I could also have gotten away with 45mm instead of 50mm main tube.

I have a pretty detailed weight spreadsheet, and I think the bike will come in around 22.5 pounds before fenders and mirror and pedals, which I still think is decent given that it's going to be a pretty robust touring machine. It'll also be 7 or more pounds lighter than her current recumbent.

I definitely think a weight-weenied version could be 17 pounds.


--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 11/27/2018 :  19:33:44  Show Profile  Reply with Quote
I reminded of the guy I met once who was in charge of designing and building a submarine for the Navy (or a large portion thereof). I said, "That sounds complex." He replied, "Well, it's just like paving a driveway every day for a long time. There's a lot of steps."

I fishmouthed a 25x22 carbon fiber tube for part of the tiller/mast. It's going to nest into a 28 further down, which will have a pinch bolt to lock it in place.

My first time fishmouthing CF tubing this way with the Dremel. I used to do a lot of dental lab work, and I think my grinding skills remain.



Took my time and measured 10x to try to get the correct angle and make sure the T portion of the bars was square. I ended up jamming a little cube of steel square bar (after checking with my square to make sure the square was really square. One angle was...) into one of the armpits and then taped it up with masking tape then dribbled a few drops of superglue into the joints for a preliminary tack. That's been my new procedure before doing the JB qwik tack. Superglue's better than trying to hold things still for 8 minutes, even with little jig bits to help out. I can get a nice firm preliminary preliminary in a few seconds.



I couldn't for the life of me figure out how to get the measurement right for the angle below. It's the rotation away from parallel from my Azub tiller (the model for this tiller) and I like the feel, so I tried to duplicate it. I couldn't do much better than eyeball a bunch of times with my angle finder, but I think I'm close.



These 1.5mm wall carbon fiber tubes (the 25s and 28s I've got) seem insanely stiff for the weight. They're also really beefy radially. The feel like overkill for this part of the bike, but I think the 25s will make pretty good chainstays. I was thinking of going with the 28s, but I think that would really be overkill.

--SpiderMonkey
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alevand
human power expert

USA
3432 Posts

Posted - 11/28/2018 :  07:39:12  Show Profile  Visit alevand's Homepage  Reply with Quote
How strong are the joints?

C:
Tony Levand
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 11/28/2018 :  16:22:15  Show Profile  Reply with Quote
So far, stronger than they need to be. I haven't made anything mission-critical for the bike frame yet, but everything I've joined for the seat and handlebars seems really strong, as in I can't get it to flex much (if at all) given any reasonable facsimile of the stresses that these pieces would get in use or abuse.

But today, since I had a spare, reject seat brace, I decided to reef on it to see what it would take to break it.



This brace was only wrapped at the angles, because it was simply a brace that wouldn't get much stress at all. (Braces that were going to get other stresses, I beefed up by sleeving them and/or running unidirectional tape and tow along the lines where they would get tensile loads.)

I subjected this, then, to a very unfair test, yanking the sides apart until I broke it. That means all there was to resist the pulling force was the adhesion between the wrapped fibers. There was no carbon fiber laid with the axis along the line I pulled.

Still, this took all the strength I had to pull apart, and it took a while, cracking to let me know what was up. This is 17mm tube, 1mm wall, with only about 0.5mm of wrapped tow at the point where this failed. Handlebar-suitable aluminum tubing bent in this shape (or even EMC that some use for a similar clone seat, I bet) would have bent with this treatment.

The surface of the break makes me suspect that I didn't get good epoxy penetration in this wrap either. I've modified my layup process since I made this one to address that.




Anyway, I plan to do more fabric (with crossing angles) on the big joins that matter, with tow wrapping coming in at different angles to give strength in multiple directions. (Tow around a 150-degree bend can't really accomplish that.)

I'll probably clean these up then lay them up with extra material next week with an eye to resisting the pulling I did this time around. Then, I'll try to break the joins again.

--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 11/29/2018 :  18:58:57  Show Profile  Reply with Quote
I was having trouble finding a bottom bracket shell I liked. Titanium was light but pricey. Steel, cheap but heavy(ish) and prone to rust. Stainless, heavy and expensive. Aluminum? I couldn't find many, and the ones I could find were designed for welded builds, so they were very thick wall, way more than I'd need.

Then I stumbled across these, from Calfee.



They're nice and light, very thin, but then they're supposed to have a bunch of layers of composite build up around them. They're nice and knurled up so that saves a bunch of work. Just need to sleeve it in a glass sleeve then build the CF on top from there.

Also, the price was good. I bought 4 (so now I really have bike projects backed up) and paid about $32 total including shipping.

https://calfeedesign.com/product/bottom-bracket-sleeve-english/

--SpiderMonkey
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warren
human power expert

USA
6424 Posts

Posted - 11/30/2018 :  08:17:12  Show Profile  Visit warren's Homepage  Reply with Quote
Sweet!
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/02/2018 :  14:41:22  Show Profile  Reply with Quote
Work on the boom progressed today. Or at least it seems that way. You never know for sure until you unwrap the next morning I guess.

https://www.crazyguyonabike.com/doc/page/?o=1mr&page_id=565567&v=n



--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/03/2018 :  08:06:07  Show Profile  Reply with Quote
I got the BB shell mounted in the boom. I think it's pretty darn strong. I used 2 plies of 11oz unidirectional, 2" wide, at the edges of the shell, so they're overlapped in the center about 40-45cm. Should be about 2mm + of uni all the way around the front of the BB shell and back onto the boom. Ends of shell were wound with a bit of tow to get them about = in thickness. I'll sand this smooth and to a final layer of 5 oz weave over it. I got a little bit of epoxy inside the shell where it cured in the threads (it snuck past my compressed plates) but since I'd expected that and I had greased the threads, it popped off with a quick flick from a pen cap's pocket holder prong.




--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/05/2018 :  13:54:10  Show Profile  Reply with Quote
Wheels done. Just over 1700g for the set including skewers and rim strips. Couple false starts, including putting the long spokes in the drive side of the rear TWO FREAGIN TIMES.

Second truing went a lot quicker. My hands are sore from cutting and threading and bending spokes, and if I EVER say I'm going to paint rims again you'll know I've had a brain aneurism and memory loss.



--SpiderMonkey
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warren
human power expert

USA
6424 Posts

Posted - 12/05/2018 :  18:22:51  Show Profile  Visit warren's Homepage  Reply with Quote
Very nice!
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/10/2018 :  08:30:49  Show Profile  Reply with Quote
I decided the 1/4" CF plate I bought might be too much for the use I've got in mind (though it's still lighter than the aluminum 1/4") so I throught I'd try making some CF plate myself of more like 3-4mm in thickness, rather than the 6+mm. I measured out 8 plies of a 12k weave, 4 right angle, 4 at 45 degrees, and 2 3k weaves for the outside faces. These were 10.5" x 5.5" I set up some 6" x 12" 1/4" plates of aluminum with waxed paper under breather under release film, laid up the plies with about 80 grams of epoxy, wetting each thoroughly with a foam brush. Kind of a PITA, but kind of fun. Then, I mashed them with 4 big C clamps.




The plate came out pretty well, but not as thick as I wanted. Alas, I'd consulted both the retailer's specs for the main fabric for thickness (claimed 0.5mm) and my own digital calipers (0.4mm or so measures) plus the two layers of 3k on the outside, I figured I'd be around 3.25mm. Turned out to be about 2.7mm thickness.



The plate surface was intersting, slightly pebbled, probably a result of maybe the breather as well as the fairly rough nature of the porous 12k fabric that was the majority of the build.



I decided to add some plies to this plate since I wouldn't use it as it was. I know that won't be as strong as if I'd built the entire thing in one go, but the alternative was probably not using the plate at all. (Costs here were minimal, maybe $5 worth of epoxy and $12 worth of fabric, since the fabric I'm using was on clearance.)

I sanded up the plate and put 3 more plies on one side, 4 more on the other, then pressed the heck out of it with clamps again. We'll see how thick it comes out, I guess.


--SpiderMonkey
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Terry
New Member

Canada
57 Posts

Posted - 12/10/2018 :  11:39:40  Show Profile  Reply with Quote
Spider monkey.
I am following your project with much interest. Several of these tasks I have / will try.
Not knowing what these plates are to be used for, but they seem to me overly strong!
Does 6 to 8 layers of cloth not give you enough strength?

Are you wetting out each layer then stacking them? I would wet out the first layer then lay the next on dry and continue wetting each layer.

I found using a foam brush very much a PITA! I prefer a squeegee (credit cards)
Much easier to control the excess epoxy.

Thanks for posting all your work!
Terry
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/10/2018 :  14:17:05  Show Profile  Reply with Quote
I did wet each layer, then place a dry, then wet, building that way. The loose weave 12k didn't like being squeegeed (I tried) so I went with the brush. This plate (or the stuff I bought pre-made) are intended to be bonded to the chainstays as transition to a nice, even, parallel flat for the aluminum dropouts, which will be attached by a couple M6 screws. That's how things are done on our NoComs. Purple plate above is the spot.

The 2.7mm original thickness might have been fine, but I feel better at the current thickness, which is 4.5mm. The plate's not fully cured, and I can still flex it with my hands, but barely. Given a smaller stick (like the one to get used in the bike) and I don't think I could budge it.

--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/10/2018 :  20:10:13  Show Profile  Reply with Quote
The thickened plate came out pretty strong, and it's still got more curing to do. Dremel abrasive wheel won't cut it. Even my diamond wheels want to bog down now. About 4.25mm thick. I think it'll do the job, and now I have enough to do 3-4 bikes' worth of chainstay ends.



--SpiderMonkey
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warren
human power expert

USA
6424 Posts

Posted - 12/10/2018 :  20:26:54  Show Profile  Visit warren's Homepage  Reply with Quote
Wow! Those will be some heavy duty dropouts!

Edited by - warren on 12/10/2018 20:28:49
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/11/2018 :  14:11:02  Show Profile  Reply with Quote
Well the dropouts are still slated to be aluminum. This is the transition plate from tube to dropout. Still probably overbuilt!

I measured the thickness at the back end of the nocom for comparison. The chainstays are about 2mm thick, but they thicken up to about 6mm right where the 6mm aluminum dropout is held on by M6 screws. Maybe because those M6s are running perpendicular to the plane of the plate? I don't know enough to know if there's much, for my lack of a better term, a tearing sort of situation with the M6 screw in the CF at that point. It's kind of why I took mine from 2.7mm up to 4+, because it just seemed like I wanted more meat there for those screws.

--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/11/2018 :  19:10:51  Show Profile  Reply with Quote
So my 12mm hex key arrived. What a behemoth. I was able to take the freehub off the new XT rear hub, but I couldn't figure a way to get the seal off safely to douse it with more Phil's tenacious, my go-to method of silencing the shimano hubs. Hit it with the heat gun to get things moving and ended up just peeling the seal aside and dripping more lube in. Quieter, but not the nearly silent I can get on the Deore LXs. Oh well.

The cones were too tight, as they always are straight from the factory for some reason. These felt OK, but didn't have that tiny bit of play when not clamped in a dropout. Managed to hold 3 wrenches at once to tighten the locknuts and get it set perfectly.

Might seem like an exercise in OCD, but the LX hub on my Catrike was ruined after only a couple thousand miles because they didn't adjust it at the shop when they assembled it (and because I didn't double-check their work on the cones).

--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/15/2018 :  20:40:34  Show Profile  Reply with Quote
The past few days for me have been mostly trying to figure out how to jig up the frame. Not having access to a welder, and wanting to have something adjustable, metal, fairly accurate, and reusable, I decided to try to work with aluminum extrusion. I got this 45mm T-slotted stuff from McMaster-Carr, and it was a little pricey, but it's nice and straight, cut perfectly square, and the main brackets that will hold it together slide well and are also perfectly square. The slots in each side are perfect for a piece of 3/4" x 1/8" aluminum, so using bar stock, you can drill and tap any number of accessories to slide up and down in the slots. I plan on just using the single rail and mounting dummy axles (5/16" threaded rod) on either end, then these tube holding uprights.





I spent more time than I'd like to admit building these little guys. I wanted to have angle brackets to hold the tubes, and I wanted them adjustable by angle. I built these by using the 3/4" bar I mentioned, some aluminum tubing trimmed down to exactly 23mm (I needed to stick it in my drill press and run it over a flat file to get it to length and perfectly square.) and then I very carefully drilled each tube in the middle to tap a 3mm screw coming in from the angle iron above.



The tubes are tapped M5 on each side so a button head M5 screw can lock them into place.



They came out square and even enough for me to get them "calibrated" using a tube to check, and there's just enough wiggle with the slotted alminum bar, etc., to get things lined up, then tighten for lockdown.



The slight space there is because the tubes aren't actually cut square. (I'm not joining lengths like this anyway for this project.)



Since I'm only using the jig to hold tubes for epoxy tacking, I'll likely using nothing fancier to hold things in place than strips of masking tape, like so.






I never could have built this without the examples and resources on this site. I think this is going to work well, and I'm pretty excited to have it nearly done, because I think it's going to make the bike frame build process much simpler than I thought it would be.

Building the jig has also been a lot of good practice for me using a few new tools and perfecting my technique with my lousy drill press, etc. The process of working out how to get truly square tapped holes, squaring up the drill press, and making lots of small, low-impact mistakes has set me up for a lot less frustration doing the bike parts over the next weeks (I hope).

--SpiderMonkey
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warren
human power expert

USA
6424 Posts

Posted - 12/16/2018 :  09:52:27  Show Profile  Visit warren's Homepage  Reply with Quote
I think 15 layers is about right for dropouts.

Cudos on the jig. It looks great. Yeah the hardest part is getting it all straight. Even with a jig I have a tough time keeping things straight. I usually ending up doing a ton of measuring and eyeballing after putting it in the jig.
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/16/2018 :  14:53:40  Show Profile  Reply with Quote
Yeah this is hardly a slide, tighten, and assume it's straight jig. However, with my digital level (which I can zero on the jig then measure relative to that) and ye olde' eyeballs, I at least can get things square, parallel, and so on.

--SpiderMonkey
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SpiderMonkey
recumbent enthusiast

USA
473 Posts

Posted - 12/18/2018 :  19:01:05  Show Profile  Reply with Quote
Boom is now finished (except for cutting it to length and adding a derailleur tube up front). 273 grams here at the full 500mm length. That's about 35 grams of composite layup and 38 grams for the aluminum BB shell. For the kid bike, she'll only be using half the tube, so -100g, plus whatever the dr tube and layup will add, probably about 60 grams, so a 243g boom assembly? Sounds OK to me.



This is a 45mm OD, 41mm ID tube. Layup was 2 layers of 12 oz unidirectional in a U around the end/shell and back, with several layers of 5 oz 3k over that, plus tow around the ends of the shell to sort of reinforce them circumferentially and make the ends more regular. Some glass sphere paste in the armpits of the T to smooth it out as well. Took me many steps. Hopefully I can do it a bit more efficiently the next couple times.

--SpiderMonkey

Edited by - SpiderMonkey on 12/18/2018 19:08:25
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