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Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

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Old 11-05-09, 05:05 PM   #1
Airburst
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Glued frames

Has anyone ever heard of a non-lugged frame made from tubes glued together with epoxy resin or something similar? If not, does it sound like it would work?

I know that there were some aluminium and carbon frames that were made with tubing glued into lugs, and I've seen some information on bamboo frames built in the same way, but would it work without the lugs? I'm thinking something like fillet brazing, only with some sort of resin or glue
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Old 11-05-09, 05:23 PM   #2
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I'm not a framebuilder, or a scientist, or even particularly bright.
But no.
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Old 11-05-09, 05:35 PM   #3
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The epoxy (3M ScotchWeld) I use on my bamboo frames would not hold up without the lugs.
Even after it fully cures it has some flex (which I like because it helps to buffer the wood from grinding).

The strength of the frame's construction comes from the lugs, the epoxy just holds the tubes in place.
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Old 11-05-09, 06:45 PM   #4
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Early 90's Treks were bonded (glued) aluminum. I have a 1000 myself (well, I bought it for the gf). Here's a thread about one (not mine): Mystery Alloy frame roadbike, what is it?

She really doesn't ride/abuse it much, so I can't speak to its durability. Nice looking frame for being a lower end model though!
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Old 11-05-09, 08:45 PM   #5
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You might could build a frame similar to the way Scott did with the CR1, fit the tubes and then wrap them with carbon fiber and of course resin. I have never played with carbon fiber at all but I believe carbon-tubed frames with lugs or wrapped with carbon fiber ride far better than a monocoque frame, Look frames were the best riding frame that I ever rode and if I wasn't riding my own frame I would be riding a 595.

As to the Trek 1000, what type of bonding agent or glue did they use to glue aluminum tubes together, must have been super-glue. I have seen a few of those frames but never knew they were glued, its a trip that they hold up. Gluing my frames together sure would save me a lot of time, had I known this I never would've started fillet-brazing.
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Old 11-05-09, 09:36 PM   #6
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Those Trek frames have internal lugs which hold the frames together. It's not as simple as butt joining the tubes together.
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Old 11-06-09, 06:37 AM   #7
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Now it makes sense.
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Old 11-06-09, 10:43 PM   #8
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Originally Posted by meech151 View Post
As to the Trek 1000, what type of bonding agent or glue did they use to glue aluminum tubes together, must have been super-glue. I have seen a few of those frames but never knew they were glued, its a trip that they hold up. Gluing my frames together sure would save me a lot of time, had I known this I never would've started fillet-brazing.
Those Treks used epoxy to hold the frame together. They are internally lugged to provide sufficient contact area in the joints for the epoxy to bond with.
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Old 11-16-09, 07:07 PM   #9
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Quote:
Originally Posted by Airburst View Post
Has anyone ever heard of a non-lugged frame made from tubes glued together with epoxy resin or something similar? If not, does it sound like it would work?

I know that there were some aluminium and carbon frames that were made with tubing glued into lugs, and I've seen some information on bamboo frames built in the same way, but would it work without the lugs? I'm thinking something like fillet brazing, only with some sort of resin or glue
Yes, it is called " tube to tube construction". Some carbon frames are made like this WITHOUT lugs. They are literally glued together, sanded and then either painted, cleared or both. There are advantages/disadvantages to each type of construction method.
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Old 11-16-09, 07:45 PM   #10
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Yes, it is called " tube to tube construction". Some carbon frames are made like this WITHOUT lugs. They are literally glued together, sanded and then either painted, cleared or both. There are advantages/disadvantages to each type of construction method.
Interesting. I know Nick Crumpton uses "tube-to-tube" CF frame construction, but after bonding the joints he uses prepreg carbon cloth layers at each tube junction and the junctions are vacuum bagged and cured in an oven, so it's not quite as simple as just gluing the mitered tubes together.

From a June, 2008 article in Road Bike Action magazine:

Tube-to-tube construction (the way Crumpton assembles his frames) was not known to anyone in the bike industry at the time. Later, Crumpton would discover that shortly after he worked it out, another brilliant mind had begun to perfect the process in Germany. His name is Peter Denk—the mastermind behind Scott USA’s groundbreaking tube-to-tube CR1. Presently, tube-to-tube construction is largely accepted as the lightest method to build carbon fiber frames. The process is simple in theory, says Crumpton:

“I take premade carbon tubes, miter the joints and fit them into a frame fixture the same way I would build a steel frame,” Crumpton explains. “The tubes are bonded together and, essentially, the frame is complete. Then prepreg [carbon cloth that has been preimpregnated with epoxy resin] carbon reinforcements are layered at each tube junction. I vacuum-bag the frame junctions and cure them in an oven. The vacuum puts even pressure on the carbon layers regardless of the shape of the joint, so there is even compaction. After that, there is a lot of sanding and finishing—much the same as a metal frame.”


Can you cite an example of tubes just bonded together without reinforcing lugs or layers of CF cloth?
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Old 11-16-09, 08:23 PM   #11
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I would be interested in building a frame in this manner but have a couple of questions. First, what are these vacuum bags that he is using, where do you get them and how do they work exactly? Second, what type of oven do you need? Also, I am sure this is not a big issue but what about cable guides? I take it someone sells plastic braze-ons? I was curious what would happen if you glued carbon tubes into steel lugs, anyone have any info on this?
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Old 11-16-09, 09:07 PM   #12
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Meech,

This link has a fairly decent primmer on vacuum bagging.

For materials look through this link.
Order this pamphlet, it's well worth the five bucks.
When you are ready to start working with composites order this practice kit and a roll of carbon cloth or TOW line.
You will also need some couplers, hoses, vacuum generator, and stuff from this page

YouTube- West SystemŽ Vacuum Bag Demonstration

West Systems has some good videos on composite basics.

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Old 11-17-09, 07:15 AM   #13
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Thanks for all the info, I appreciate it. Do you have any thoughts about the gluing carbon tubes into steel lugs idea, good idea, bad idea, workable? Just curious. Thanks again.
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Old 11-17-09, 01:12 PM   #14
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Columbus makes carbon rear triangles for metal bikes.
It was in fashion a few years ago, not so much now.
I'm using one for a bamboo bike.

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Old 11-17-09, 04:28 PM   #15
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I would be interested in building a frame in this manner but have a couple of questions. First, what are these vacuum bags that he is using, where do you get them and how do they work exactly? Second, what type of oven do you need? Also, I am sure this is not a big issue but what about cable guides? I take it someone sells plastic braze-ons? I was curious what would happen if you glued carbon tubes into steel lugs, anyone have any info on this?
I don't know much about them, but I've heard of bikes made with carbon tubes glued into aluminium lugs, and I'm sure I read something on the web about titanium lugs and carbon tubes. Given that those two both work, I shouldn't imagine steel lugs would be a problem. After the advice on this thread, I'm considering it myself, as my original idea of glue and no lugs seems to be fundamentally flawed.
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Old 11-17-09, 04:56 PM   #16
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I spoke with West Epoxy Company today and they said carbon w/steel lugs is no problem. Only concern is the same as every other bonding situation, make sure the parts are well sanded and clean. He told me they have parts that were glued to steel over 40 years old. I did have a customer who built his own carbon fiber frame from scratch and said gluing carbon to aluminum isn't the best case scenario however I have owned about 3 or 4 Look frames that had aluminum lugs and never had a problem, its probably all in the prep work. As far as manufacturing a carbon frame out of tubes, I believe the tube-to-tube method that the other members have spoke of is the way to go but it is gonna take a fair amount of practice like everything else. I am gonna start with building a frame using steel lugs with carbon tubes and just gain experience as I go. I imagine you can gain a ton of experience just learning how to make a carbon tube correctly. Anyway, ever onward. Chao.
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Old 11-17-09, 08:37 PM   #17
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Meech, if you don't want to go the vacuum bag route you can also use tape.
http://www.bmeres.com/carbonframe1.htm
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Old 11-19-09, 11:59 AM   #18
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Originally Posted by Scooper View Post
Interesting. I know Nick Crumpton uses "tube-to-tube" CF frame construction, but after bonding the joints he uses prepreg carbon cloth layers at each tube junction and the junctions are vacuum bagged and cured in an oven, so it's not quite as simple as just gluing the mitered tubes together.

From a June, 2008 article in Road Bike Action magazine:

Tube-to-tube construction (the way Crumpton assembles his frames) was not known to anyone in the bike industry at the time. Later, Crumpton would discover that shortly after he worked it out, another brilliant mind had begun to perfect the process in Germany. His name is Peter Denk—the mastermind behind Scott USA’s groundbreaking tube-to-tube CR1. Presently, tube-to-tube construction is largely accepted as the lightest method to build carbon fiber frames. The process is simple in theory, says Crumpton:

“I take premade carbon tubes, miter the joints and fit them into a frame fixture the same way I would build a steel frame,” Crumpton explains. “The tubes are bonded together and, essentially, the frame is complete. Then prepreg [carbon cloth that has been preimpregnated with epoxy resin] carbon reinforcements are layered at each tube junction. I vacuum-bag the frame junctions and cure them in an oven. The vacuum puts even pressure on the carbon layers regardless of the shape of the joint, so there is even compaction. After that, there is a lot of sanding and finishing—much the same as a metal frame.”


Can you cite an example of tubes just bonded together without reinforcing lugs or layers of CF cloth?
I could but I'd rather not. Suffice to say, the frames we use for our top of the line Series 7 carbon bikes use "tube to tube construction", no lugs and no wrap other than athsetics (a UD finish). However, there is a wrap of unidirectional carbon over the outside portion of the tubes, but this does not cover the joints. You can CLEARLY see that the joints are visible and not covered. It is a bit annoying to look at (in bare form) but it is a mute issue since our frames are fully painted before being built. The only bare carbon visible on our frames are a large portion of the seat stays. With no clear coat or paint on the frame, you can just barely feel the joints. The frames we use are sub 900 grams for the smaller sizes so I agree that tube to tube construction is ONE of the prefered construction methods for lightness. There are at least a DOZEN different ways to lay up carbon (and other composites). Each has it's strengths and weaknesses. We ended up choosing this particular frame because it is very light, but also very stiff but compliant, BB30 and visually appealing.
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Old 11-19-09, 02:24 PM   #19
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Where can I view one of these frames? When I google Raptor Custom Bicycles I can't find the right site.
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Old 11-19-09, 02:51 PM   #20
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I'd also be interested in some photos of the Series 7 Raptor. I didn't have any luck with Google either.
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Old 11-19-09, 03:26 PM   #21
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As far as using epoxy to fillet a frame, it probably isn't practical, but it is done with boats all the time. The problem is mostly in sizing the fillets correctly, and the correct size is really large. Even if you could tolerate the size, materials like wood and epoxy composites are more stable when filleted, because they have similar expansion ratios, or are otherwise docile. Metal sometimes shucks epoxies if it expands or contract outside of their elastic limit. On my trimaran some metal parts are bolted to beefed up glass/wood structures, but in some case the metal fasteners are just bonded into a little pot of epoxy. These make very strong connections. Let's say with bikes that you could attach a threaded stud to the head tube, and it doesn't need to be carefully aligned, then you meet a tube over it and fill the last inch or so of the tube with epoxy. That would probably be strong enough for our purposes, but it isn't a fillet or light.

One problem with filleting on bikes is that the sides are very shear, and there isn't much room to build up fillet mass. With metal that is ok because the material is very strong, but with epoxy it would be a serious problem. Think of where the top tube meets the seat tube. The side of that joint may allow only a paper thin covering.

To some extent the question isn't fair. If bikes had always been glued with epoxy, and brazing was a recently introduced technology, brazing would probably not catch on because the existing frames would look so different from what we currently expect that brazing would not seem a reasonable solution.
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Old 11-20-09, 11:31 AM   #22
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Where can I view one of these frames? When I google Raptor Custom Bicycles I can't find the right site.
That is because we are not quite up and flying yet!

I'm still in the process of getting frames back from my painter. I've been very fustrated by the amount of time it has taken to get these first few bikes painted, built and finalized (albeit on a very limited budget as well). Everything was put on hold for almost two months just in the design, artwork and set up for the frame/fork decals. Once we've built the first couple of bikes, we will take MANY pictures. I was told that they would be painted and ready for assembly by 11/18/09 but that has come to pass and they are still not finished yet. I will be getting an update sometime today. Suffice to say, I don't mind waiting a little longer (for the painting) because my painter does phenominal work. He's painted for several mainstream bicycle manufacturers and comes highly recommended by lots of folks. I especially like the fact that he can replicate paint and color schemes accurately from frame to frame. It's also super nice that his shop is less than 10 miles away.

I've set up a temporary Myspace page in regards to specifications, geometry, color combinations etc. http://www.myspace.com/raptorbicycles

You will probably need a myspace account to view it. Or Maybe not, I'm not sure.

A more formal website is in the works but I need product to promote first.

I'm hoping to have at least the first 2-3 bikes built by the end of next week at the latest. At least one SRAM Red Series 7 (frame/fork colors: pearl white w/black accents) and one Shimano Dura-Ace 7900 (Black Mica Pearl w/red accents). I'm hoping (keeping my fingers crossed) that I will have pictures of the painted frames and forks within the next 48-72 hours. At any rate we are getting close.
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Old 11-23-09, 05:07 PM   #23
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http://link.brightcove.com/services/...id=29739780001

^^^
Two good primers on composite lay-ups.
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