Has anyone used glue to joint steel lugged frames?
 

Back in the 80's, there were a slew of bikes made from aluminum glued to aluminum lugs, carbon tubing to aluminum lugs, steel tubing to aluminum lugs, aluminum tubing to steel lugs, titanium to aluminum lugs, and in the 90's we had carbon tubing glued to steel tubing and carbon tubes glued to titanium. Aside from galvanic corrosion issues, it seems like all of these glued together bikes held up just fine.
So how come nobody has tried to just glue steel tubing into the usual steel lugs, instead of brazing them together? This would allow practically anyone to build frames.

because it does not work and stay bonded or people would be using it. you know people have tried

glue bonds need a certain about of surface area, and the amount with a lug is pretty small...extending the lug would impact how a frame works in terms of stiffness

beyond that lugs and tubes are not the precise super accurate fit a glue bond needs to be strong, while the brass or silver used in brazing can fill the slightly less than super perfect fit

you would get a better technical set of replies if this were in frame builder section

FIAT is now basically gluing together steel cars. So, the technology is either here, or nearly here.

I think some of the aluminum bikes had a type of interference or swaged joint that was not glued, although a glueless joint may not work well with steel bicycle lugs as undoubtedly it would collect moisture, and begin to rust which could cause expansion and loosening of the tubing.

As to whether gluing together steel bikes would open bike building to more bike builders, perhaps, although bike building involves making good joints and getting the tubes all aligned properly which shouldn't be underestimated especially when gluing.

There are frame building companies that sell uncut steel lugs that would help if you wished to do a glue joint as it would increase the surface area for gluing.

I think a couple of companies have attempted to sell bamboo kit bikes. That might be a direction to try if you wish to do a home built glued frame.

Renovo makes some very high quality wooden bikes. So, if you can build with wood, you could build a bicycle. Yet, it isn't something that would be for the feint of heart. To keep the weight down, those bikes use hollow tubes.

As Squirtdad points out, standard steel lugs do not have enough surface area for a suitable bond. Lugs could certainly be designed for bonding steel frames, but there is a bit more to building a frame than gluing it together.

Because there are tried and true methods to join similar materials

If a person has the ability and skill to cut tubing to the proper length and join them together in any manner, then they should be able to learn how to braze. I've seen some steel parts brazed together with and put through stress tests and the material itself failed before the brazed joint failed. Steel doesn't require as much skill to weld or braze as does aluminum along with all the considerations you have to make for its particular characteristics for handling loads.

And I think visually there are more clues when a braze isn't correct than when a glued joint isn't correct.

I’d give duct tape a try.

Dan

the technology is here - has been here

auto makers / body shops have been gluing panels for years ... quarter panels ... door skins .. etc ...

the aircraft industry has also been using adhesives for years

A brazed joint can be stronger than a glued joint, and brazing technology is known, proven, reliable, and inexpensive. What would be the advantage of a glued steel frame? IIRC, some of the Raleigh USA "Technium" frames used glued Reynolds 753 tubes to get around Reynolds' 753 brazing certification requirement.

Maybe, just maybe - there is a reason all those mixed frame material bicycles used to be made, but no longer are offered. Most people expect a bicycle to last a lifetime, at least the frame.

Nobody makes a car with a glued frame. Nobody makes steel airplanes.

In the late 1980's Raleigh made glue bonded aluminum frames with the name Techium. I still occasionally see them in use. The best glue for steel is brazing rod. Think of it as hot glue for steel.

They even used glue to attach heat-shield tiles to the space shuttle.

The advantage would be that it can be done by somebody without brazing equipment. ie. me.
Was that steel to steel, or steel to aluminum lug?

Yes. And if you ever handled a heat shield tile, you'd instantly know why. That material is fragile -- it would never hold up to a fastener.

That's the point of the post. I don't know if anyone has tried it. Has anyone tried it?

this is exactly right, that shuttle tile material was lighter than styrofoam.

while I agree that adhesives do exist that have the bond strength sufficient to hold frame tubes together, the process used to effectuate a bond of that strength is more complicated than squeezing some goop out of a tube and pushing the parts together. Surface prep, autoclaving and curing all have to be done "exactly right"

I have a bike (Serotta Ottrott) that is bonded together with carbon tubes and titanium lugs. Kaman Aerospace (maker of helicopter blades) licensed the technology for this frame to Serotta.

The bike is 22 years old now. It seems fine. But the "lugs" are more like sockets - much bigger than conventional steel lugs for additional surface area.

/markp

https://cimg9.ibsrv.net/gimg/bikefor...0a9dff14ff.jpg

apples and oranges one does not equal the other
large flat areas with lots of surface area for adhesives is different a tube in a lug with in a socket.

also the forces in action are very different between a flat panel and bike frame where you movement in every vector

of course some one has tried it... human nature

the fact that you don't see this type of building option means
1) is it so good that the company has been in stealth mode for 20 or 30 years to absolutely perfect it
2) the person who tried it received a Darwin Award after a highspeed downhill first ride test
3) It sort of works but ROI and benefit is not there compared to brazing
4) it works so poorly that there is no reason to spend time and money on it

one thing that could change this in the future might be printed lugs that can be made for greater surface area and precise fit

And here I thought this was going to be a Larry Sellerz thread!

You mean the tiles that fell off mid-flight, to the point they added inspection cameras to the shuttles to see if any tiles were missing?

not quite.

the tiles were generally pretty reliable - until a chunk of ice came off the big cryogenic fuel tank and put a gash in the wing leading edge

which exposed the aluminum / magnesium structure underneath to the searing heat of re-entry plasma

that was not a failure of the adhesive

/markp

Lots of cars (sedans) are unibody construction and use a lot of specialty adhesives to connect all the panels that make up the unibody structure; I've seen a stripped-out BMW sedan and it uses a LOT of adhesive. That can be done due to surface area (lots!) and the expected use of the vehicles (on asphalt roads, maybe a little bit of graded and potholed roadways, light towing). But you want welding/brazing for applications that will see more demanding forces on a vehicle, like off-roading or heavy towing. I don't know if it would work with the small connection areas on a bicycle frame. Does anyone have any experience with those early carbon-fiber frames that were carbon fiber tubes with metal lugs? I've seen a few, and some still show up occasionally, but I've never heard reviews of them, nor do I see any new ones for sale these days.

I rode one to work this morning. Its a Look KG96 from ~1989 with carbon tubes glued into aluminum sockets. The ride is very comfortable despite it being designed as an out and out race bike.

Weren't those designed with threading so that the tubes screwed into the sockets as well as being glued? Or am I thinking of a different bike?

The modern cars are unibody, and the glued parts may well be structural.

As far as planes, most of the bicycle tubing was developed for the aircraft industry including chromoly. Many vintage planes have steel frames, and I wouldn't be surprised if even some modern ones use a cloth or aluminum covering over steel.

For the bike, there are uncut lugs available that may work.

https://framebuildersupply.com/produ...und-chainstays

https://framebuildersupply.com/colle...-top-tube-73-5

https://framebuildersupply.com/colle...-4-top-tube-75

(check the tubing sizes before purchase).

https://cdn.shopify.com/s/files/1/03..._1800x1800.JPG

https://cdn.shopify.com/s/files/1/03..._1800x1800.jpg

https://cdn.shopify.com/s/files/1/03..._1800x1800.JPG

It wouldn't necessarily be my choice for construction.

You still have the lugs that have less gluing surface, but are critical for your frame.

https://cdn.shopify.com/s/files/1/03..._1800x1800.JPG

A number of other parts have to go in such as brake bridges, and cable stops. Some things like cable guides can be clamp on, perhaps from 1950's and 1960's vintage bikes.

You'll likely end up with a issue that parts are designed to be brazed, silver soldered, or welded, but may not have enough surface area for other adhesives.

You don't want your brakes to fall off mid ride in an emergency stop.

Ultimately you'll end up with quite a kludged together frame.

I'd still encourage getting the right tools for the job.