Framebuilders - lugged apoxy?

what are the real disadvantages of using apoxy on a lugged tube set it the tubes are prepared and mated correctly? frame builders have been using apoxy for all types of applications. is there a super obvious reason i am overlooking?
racking my brain.
xjosh

Are you asking why epoxy isn't used instead of brazing? If so, I'm curious, too. I'm learning a bunch of stuff now in preparation for building my first frame and I've been curious about different materials and why they are or aren't used. I'm used to building RC planes where there are lots of well considered but odd material choices based on local situations.

I'd speculate that the shear forces in the epoxy would be sufficient to make stress fractures over time, but I'd like to hear from someone who knows better than I.

Glue together frames use lugs with much greater surface area than brazed frames. You can not simply use regular lugs and epoxy them together, the joints will fail.

Who makes such lugs? What are they called?

(I'm just curious about this, by the way. If I have access to a frame jig, I have access to an oxyacetylene torch, but I'd like to know all about the various technologies and techniques)

There have been plenty of glue-together frames in the 80's. They are really heavy

What makes them heavy? Do the lugs need to be superbig or something?

I build exxon grafteks using hysol 9320 epoxy gluing graphite to chromed lugs specially designed for the application. This is one of a few epoxys that are strong enough to hold up and very expensive, $200 a quart. Weldind, brazing or soldering is far less expensive. If you need lugs, I have extras

Nessism is dead on. There isn't any reason why epoxy couldn't be used, it just can't be used with lugs designed for metal brazing.

Lugs are a kluge that has developed into an art form. Today if you want to escape brazed lugs with a steel frame the better alternatives are TIG or fillet brazing. The bigger gain there is unlimited geometry in how the tubes fit together.

Nice bike shb!

Yeah, wicked wheels.

You haven't e-mailed me on lugs yet, dpowers@harris.com 321-259-4394 graftek lugs, perfect for epoxy

You haven't e-mailed me on lugs yet, dpowers@harris.com 321-259-4394 graftek lugs, perfect for epoxy

Do u still have lugs? It would be fun to play with those lugs.

thanks

This is a modern day example of beautiful lugwork, with window cutouts.
Carbon fiber lug joined to c/f tube on our custom Zona tandem.
While this is not 'apoxy' it's a space age glue used in the aerospace industry
Joining dissimilar tubes/lugs materials can be problematic.

e-mail me with your address and I;ll send you a set

Check out the lugs on this Alan (http://images.google.co.uk/imgres?imgurl=http://www.classicrendezvous.com/images/Italian/alan/AlanCX1S.jpg&imgrefurl=http://www.classicrendezvous.com/Italy/alan.htm&h=77&w=143&sz=2&hl=en&start=3&um=1&tbnid=tQg6OSIETgPgNM:&tbnh=51&tbnw=94&prev=/images%3Fq%3Dalan%2Bcyclocross%2Bglued%26svnum%3D10%26um%3D1%26hl%3Den) alu cyclo-cross frame.
It uses threaded lugs to improve adhesion and for safety. This was the standard cyco-cross frame of champions for most of the 1970s and 80s.

alan frames were under alot of stress due to the lugs having the same exact angle on the bottom steerer tube to down tube for every size frame so when you went small or large frame sizes, the tubes were bowed and I saw a few crack the tubing, also, they had an internal part of the lug that went into the end of the tubing so it was a 2 piece lug.

e-mail me at dpowers@harris.com and I'll mail out a set of lugs, they need chroming which is on these lugs, expensive

There was a guy who built some awesome recumbent aluminum tadpole trikes without welding or brazing. He epoxied them together. The performance was excellent.

http://www.trimakazi.com/

Epoxy has a tendency called creep. When under constant load it will stretch causing your frame to fail.

Epoxy has a tendency called creep. When under constant load it will stretch causing your frame to fail.

Better not tell all the people riding carbon frames...the carbon cloth material is embedded in epoxy which is what holds it in place. Also, literally hundreds of thousands of frames have been "glued" together with epoxy glue and lugs. Do some research on "Look" and "Trek", both brands use epoxy to hold together their marque frames.

Better not tell all the people riding carbon frames...the carbon cloth material is embedded in epoxy which is what holds it in place. Also, literally hundreds of thousands of frames have been "glued" together with epoxy glue and lugs. Do some research on "Look" and "Trek", both brands use epoxy on their marque frames.


This is probably one of the few times you'll find Nessism and me agreeing, but epoxy doesn't creep to any degree worth mentioning. Not until you surpass it's glass transition temperature, the lowest of which in any epoxy system is about 120 degrees C.

The problem is it's brittleness and much lower shear strength by comparison to other bonding joint systems...

That's not altogether true either. The gougeons have a notch test that is a standard way of comparing the creepiness of different brands of epoxy glue. They will send you a booklet, or perhaps they have it on their website. They are respected testers of epoxy and structures to the extent that one of their more useful tests was adopted by SNAME. The creep, and failure occurs at room temperature, but it does require a constant significant force, which would be unlikely to occur with a frame assembled and at most times not signifcantly loaded. The GTT on WEST is relatively low due to the room temperature cure. Though it can be post cured.

That's not altogether true either. The gougeons have a notch test that is a standard way of comparing the creepiness of different brands of epoxy glue. They will send you a booklet, or perhaps they have it on their website. They are respected testers of epoxy and structures to the extent that one of their more useful tests was adopted by SNAME. The creep, and failure occurs at room temperature, but it does require a constant significant force, which would be unlikely to occur with a frame assembled and at most times not signifcantly loaded. The GTT on WEST is relatively low due to the room temperature cure. Though it can be post cured.

That's the definition of creep, though - constant deformation under constant load. The mechanism of creep may change depending on your materials and the temperature range, but it all falls under that heading.

Very few epoxy-system bonded fibre reinforced polymer structures are under a load that is a significant proportion of that required for measureable creep at ambient temperature. And yes, *all* systems cure at room temperature. Its just that some do it reaaaaaaaaally slowly ;-)

Although its fair to say all polymers are viscoelastic in their behaviour, above *or* below their glass transition temperature, in most stove-cured systems, the actual viscous portion of that behaviour is immeasurable at room temperature. For all intents and purposes they are strong, brittle solids.

i remember hearing years ago that some of those earlier Look frames had problems with the tubes coming apart from the lugs in areas that were close to salt water, ie the ocean. something about the salt eating away at the epoxy causing the failure.

i remember hearing years ago that some of those earlier Look frames had problems with the tubes coming apart from the lugs in areas that were close to salt water, ie the ocean. something about the salt eating away at the epoxy causing the failure.

Some early glue together frames failed due to corrosion in the joints. Fix was to anodize the lugs before gluing to reduce the galvanic reaction between the parts.

I have friends that had some glue together Trek bikes, with carbon tubes, and these people got a reasonable service life out of the bikes. After a few years there was paint bubbling at some of the joints indicating the start of corrosion. Not good. My understanding is that it's common to use a wrap of fiberglass as an insulator of sort these days. Works well or so it seems; failing joints are not very common despite hundreds of thousands of frames on the road.

e-mail me at dpowers@harris.com and I'll mail out a set of lugs, they need chroming which is on these lugs, expensive


i sent you an email and a pm

Excuse my ignorance but is it possible to both braze and epoxy joints or will the heat of brazing destroy the epoxy bond? How about some kind of tig or spot welding along with brazing?

Some early glue together frames failed due to corrosion in the joints. Fix was to anodize the lugs before gluing to reduce the galvanic reaction between the parts.

I have friends that had some glue together Trek bikes, with carbon tubes, and these people got a reasonable service life out of the bikes. After a few years there was paint bubbling at some of the joints indicating the start of corrosion. Not good. My understanding is that it's common to use a wrap of fiberglass as an insulator of sort these days. Works well or so it seems; failing joints are not very common despite hundreds of thousands of frames on the road.

That's interesting, because in the aerospace electronics industry epoxy systems are renowned for their excellent dielectric behaviour. Bearing in mind that there should be a layer of epoxy between the aluminium and the carbon anyway, even if you put bare tube in the hole, as it were, from the epoxy component of the tubing, it seems odd that a wrap of GFRP would make that much different. If the epoxy conducts, it's gonna conduct with or without glass fibre filler......

"Excuse my ignorance but is it possible to both braze and epoxy joints or will the heat of brazing destroy the epoxy bond? How about some kind of tig or spot welding along with brazing?"

It depends on the situation. I can't think of any structure that actually works that way. Brazing occurs at above 800F, which is destructive to most if not all epoxies of small shop variety. Tig welding can be very closely controlled so there probably could be a situation where it could be managed. It would be better to evolve the process so the gluing occurred after the TIG.

I do know of one example, the repair of golf clubs which are socketed together with epoxy. I have seen the extent of the heat occasionally required to separate such joints and it can be spectacular. I had one 3 wood that suffered a broken carbon shaft, and I removed it from the clubhead and reshafted it. It took massive amounts of heat to the point where the residue burn like a roman candle after the shaft was withdrawn. I'm pretty sure on could have tigged in the area of that socket without the shaft failing. That shaft was originally bonded with a post cure phase.

In general, the average shop with the sophistication to do the tig or epoxy work, shouldn't really find itself in this kind of bind...

I work at a large aerospace company that makes just about every satellite dish in space and it's strictly forbidden to bond to anodize aluminium pieces. I also make exxon grafteks and sometimes substitute the steerer tube with black anodize alum. but mask off where I;m bonding.

lugs are on their way, mailed out today

I work at a large aerospace company that makes just about every satellite dish in space and it's strictly forbidden to bond to anodize aluminium pieces. I also make exxon grafteks and sometimes substitute the steerer tube with black anodize alum. but mask off where I;m bonding.

I'm not aware of such restrictions on any of the products for aerospace the company I work for manufactures... I have a feeling it might be a vacuum-aluminium oxide issue.

You have to remember that most expoxy systems are activated with either acid anhydrides/acyl chlorides or strong Lewis acids, all of which are remarkably corrosive to aluminium, such that they tend to eat straight through even a really deep and solid anodised layer. Once it's in space, there's little in the way of half-decent joint inspection that can be done.

Do you anodise or alochrom parts?

We do an epoxy prep that is airbrushed on and then baked, kept in a controled enviroment, then epoxyed. The exxon graftek frames I build have the primer sprayed inside the lugs before bonding. I do use anodized head tubes at times but make sure theres no anodizing where the lugs are. Maybe the clear coating or sealer they do on the anodizing would affect the epoxy joint?

The Raleigh Techniums were Epoxy Bonded and there was a lot of engineering of the lugs and the paint that went into this Technology as can be seen in this phamphlet posted a while ago. see thread Edit - there are 2 thumbnails on the link not scanned in order.
The advent of tig welded Alum frames and low cost killed this program

http://www.bikeforums.net/showthread.php?t=215343

I have an 87 and have put many miles on it withloads and it is still going

The seal to an anodising is nothign more than a boiling water dunk... It just removes the porosity of the aluimina layer by providing more aluminium hydroxide - that decomposes at room temp back to alumina - to seal it all up. I can't see that making much difference.. Admittedly the surface would have less pore, but it's still pretty fractal, with lots of remaining surface area and roughness...

the way I have seen and done anodizing, the first step is to dip in etch, then rinse, then in the anodizing tank with electricity,rinse, then to a color tank, black or other colors, our company uses blue alot, then to a sealer tank which puts a shiny surface on the part. If you skipped the sealer process, it would be very dull looking. What I'm getting to is that the anodizing is before the color and sealer and what experts tell me, the color and sealer is what doesn't work with epoxy.

the way I have seen and done anodizing, the first step is to dip in etch, then rinse, then in the anodizing tank with electricity,rinse, then to a color tank, black or other colors, our company uses blue alot, then to a sealer tank which puts a shiny surface on the part. If you skipped the sealer process, it would be very dull looking. What I'm getting to is that the anodizing is before the color and sealer and what experts tell me, the color and sealer is what doesn't work with epoxy.

Gotcha. I see what you mean. That'd be an organic sealer like the brightening agents they put in tin platings... They're not really freindly to adhesives. no :-)

I wish i worked for an aerospace company you guys are really great cool in fact.

I Was told that one of the issues In which a layer of fiber glass/some sealant help was, Moisture.. That moisture gets in the joints and rapidly acelerates Corosion. This was in regards to an aluminum frame with aluminum Lugs. How this affects Carbon with stainless lugs, I have no idea, As i have recently been shipped a set of exxon Lugs, Anyone have any Tips in building one, I'll be making a thread when i get them to document the whole build, Buy i'm anxious to get started any tips? and do the exxon lugs HAVE to be chromed, other than style points?

Hi, I am the one that sent you the lugs, you can paint the lugs after build, doesn't have to be chromed, although chrome looks really nice, I use hysol 9320 epoxy for gluing, this is what we use to build satellites and space stations. I feel that the moisture problem from years ago is from epoxy shrinkage and that lets moisture in. Todays epoxys don't shrink very much at all so there shouldn't be a problem, especially if you prep the joints well using IPA at the end.

Epoxy?
http://i134.photobucket.com/albums/q119/hotbike/00000024-1.jpg
This bike is made with *polyester resin*, which is more brittle than epoxy. It held together anyway.

Extremely oversized tubing is the key to strength.

I would like to see more bikes like this one. Keep in mind that anything fiberglass can be done in Carbon Fiber.
I used ten layers of fiberglass throughout the construction. Each layer is .030, but I like to say the thickness is a quarter inch.

I am saying that this bike is proof that carbon frame builders are dragging their feet. Composites open up a lot of possibility in design freedom.

But you could wrap steel tubes with fiberglass and in that manner create lugs, and need no welding whatsoever.