any photos of homemade jigs?
in the process of making my first lugged frame. any links or pictures to other related endeavors?
I think jigless makes more sense than home made jig, simply because most of the home made jigs require more stuff to make than the average home has on hand. I think a lot of folks have little idea how limited in application the actual jig is, particularly for lugged building, where it doesnèt actually hold it straight during brazing.
That said, in my mind the best homemades are: the one on Jonnycycles website, Looks like a home made Anvil, the plans Composite pro has been developing for the Frameforum comunity. And I guess the 8020 picture frame.
Most people want the Jig to:
- provide a working environment for the build, and that is mostly done by tables and vises;
- Provide an accurate reference for the assembly. This is difficult because it requires the jig to be far sturdier and more accurate than the bike. That kind of jig requires a lot of tooling to build up to that standard, and only pays back after the first dozen or so frames are made. It also imposes a lot of design limits that most jigs donèt meet: the jig needs to be built in a particular way for the various assemblies to scale off the jig. It has to reflect ideas like BB height, top tube length, etc... Any adjustible jig can be configured in space, but a jig that allows you to translate design specs to 3 d space is like an enourmous, caliper. If it doesnt do that, its partly missing in action.
- Hold the frame in place while it is welded. This is very difficult to do because the metal will move as it wants to. A jig really needs to incorporate helpful features like backpurge that might limit the damage. Many frame building techniques are going to move the tube, which is why we have cold setting rigs. Also the better jigs in this space need to provide access which means either vertical frames or huge amounts of offset from the reference surface.
I think doing the above 2-3 things is relatively practical for forks, but its a big job for frames, and in some senses less necesarry. People have jigs, what exactly they are doing is another mater.
so your recommend against a frame jog for lugged construction? i weld all day long, and know what happens when you start welding anything that isnt secured, but i would think lugs to be far different. Is there fit quite tight? ive got some reading to do, ive already scavenged the web, but fellows link on google got me to some pages i havent been before.
A lot of guys do use jigs for lugged bikes, and it really makes their life easier. I don't know if you are setting up for a business or a personal one-off. But for the jig to really help it needs to fit into the criterion above to some extent.
Lugs are not a tight enough fit to control joint movement, they need a little looseness for the silver, and they aren't all that deep, nor do they necesarally come at the joint from all angles since the designer understands the loads aren't inside the triangle. Look at head tube lugs for instance.
One thing that doesn't work with lugs is coming at the joint from all over at once with the silver. You pick a spot and feed it all in from there, or at least relative to discreet areas. So you get cooling that is uneven, and you can't really tack or pin that totally out. Some minor movement is hard to beat particularly with first efforts.
As you weld all day you know you don't need an expensive fixture to secure your work. you probably don't have a single fixture that holds everything in the final piece, but you may work from subassemblies. That works here too.
Of course I should have mentioned that you should look at anvil for his jigs, lots of picture, and you can adapt his ideas to your work or buy one of his jigs.
You probably already know about pinning, you should search that if you don't.
I was reminded this morning of what the blacksmiths call all those anvils out there that look, and weight like anvils but aren't properly heat treated. They call them anvil shaped objects. Same thing with jigs, there are a lot of jig shaped objects. For them to actually do something, they need to be more than going through the jig shaped objects motions.
Last edited by NoReg; 11-21-07 at 09:02 AM.
thanks again peter. as a side, were you the fellow who helped/and have yourself, made wood fenders?
im going to get some junked or lug bikes and disassemble them and play around. most of my welding is as most ruff industry is concerned, mig. And mostly all i need is a square and ruler. That said, i do have brazing experience somewhere back in time, and have that touch for acetylene/oxy that one gets as if it were riding a bicycle. so hopefully this will help in the instincts department while brazing.
i do not know about pinning and will search it out.
i do realize about making gravity work with this application, letting the silver flow DOWNhill.
I am not going into business, but I am at that winter to be point of finding a hibernative project, as well as wanting a touring frame, one which i cannot find the dimension in any mass produced cycle i've seen.
one more question if you dont mind; silver vs brass. Silver IS stronger i presume, but is its working difficulties for the first timer worth its benefits. moreover, are the properties of silver necessary with the longer body lugs?
oh and one more...supplier wise. Im thinking of going with "nova cycles" for my tubing and lugs, is tis a mistake?
thanks for all the insight.
Nova is a great company to work with. Also there is Henry James. Both great places. Nova has an online store so you can see whats instock and look around (you still have to call in your CC#). Henry James has a pdf of their stock but no pictures.
Originally Posted by joseph senger
Brass is stronger than silver and is used to filler larger gaps. Silver is only applicable if the clearance is fairly tight - less than 5 thousands.
My favorite place to purchase from is Joe Bringheli - bringheli.com His web site kind of sucks but his prices are the best and he is very helpful.
Even people with a frame fixture (jig) don't typically do the brazing with the tubes constrained. The fixture is used during tacking for when pinning (driving in small nails/pins to hold the assembly together). The actual brazing is done freehand with the frame in a stand so it can expand with heat.
"one more question if you dont mind; silver vs brass. Silver IS stronger i presume, but is its working difficulties for the first timer worth its benefits. moreover, are the properties of silver necessary with the longer body lugs?"
I don't actually know which is stronger. You can certainly use a lot less Silver for filet brazing. Tensile strength of brass vs silver isn't the only issue, adhesion also counts, and so does the required heat. I think Silver probably waxes brass on the last two, but not the first?
Cost dictates you will use a whole lot less also. However, there was a very brief discusion on silver fillet brazing on the other forum, and part of the reason folks gave for not doing it any more (seems some of them had done a lot of it at one time) was because it created fillets too small for current tastes. If you look on the Desperado site, you will see what is meant by that - smaller than tig welds. Like you, I come from a non-bike welding background, which is true of some of the name builders also. Bike making tends to be a little narrow on what it accepts. I'm looking for options that aren't being used but make more sense for the home builder. But even that said, some of the big shops use all three products on one bike, TIG, Brass, and Silver.
I just bought 4 pounds of silver off ebay, I like working with it, and think it is easy. It seems about the best choice if you are using straight propane, but that is a bad idea, and I am switching to oxy propane next.
I'm mostly a woodworker, and did make bamboo fenders, still using them, and they are great. I have more ideas for them, and need to get a bike finished so I can try out new fenders.
I'm in the same place you are with touring frames.
what are your thoughts on fillet vs lugs, anyone?
I was tempted to do fillet, because this is where i shine in welding, as to say, it is not always my logical ability to design, which my daily work defines, but an aptitude for the feel/technique of working with metal. However I like the idea of lugs for the inherent clamping and low heat consumption, but also the absolute freedom of fillet.
as well, on the subject of joints , i was presuming id be using an oxy/acetylene, i am correct in this being an ok mix for the desired temps? what type of flame temp are we looking for in a lugged procedure anyway? I read somewhere it is the transcending of ochre color from within the metal when one should begin filling. non of my processes ever really NEED this stage, so although i can recognize it, to maintain it, i am ignorant, and am sure as with all welding, particular temperature can severely help.
I am learning everyday, thanks to this thread, the phreq email service, and hunting, but, as with learning anything new, some aspects seem quite alien, i think im getting some feel for the process down...its the little things that count anyways. I do apologize, and have definitely concluded a practice frame essential. it may make a nice christmas present for someone!
yes peter, the bamboo, right!. I ended up making some oak ones, they by far got the majority of comments touring. I am currently building my snow/winter bike ( a tad late), its called tideland, for most the precipitation/snow on land is in fact, as im sure you know, from the oceans dehydration, as well, the movie tideland I really adore...and i miss the ocean greatly. so...I am going to be making some other "drift wood" parts. So rougher looking bits, seat post and handle bars atleast. any ideas on how to achieve strength with this? I was thinking to maintain the look, any fiberglass is out, so potentially a stiff metal core or just drastically oversize....drawing board time.
Last edited by joseph senger; 11-23-07 at 07:14 PM.
Originally Posted by Peterpan1
Low fuming brass, such as that sold by Gasflux (very popular with the bicycle folks), is rated at 63 ksi tensile strength http://www.gasflux.com/brazing.html
I can't find a similar reference for silver brazing alloys other than Harris states the range of strength is 40 - 70 ksi.
Silver joints must be kept tight, from 1-5 thousands clearance, or the joint strength is compromised. While using silver is standard procedure for braze-ons, including brake bridges which often require a fillet, most builders will not use silver for fillet brazing tubes together. Weld engineers talk about internal shrinkage and micro cracks as reasons for not using silver for fillet brazing. I know some builders thumb their nose at this concerns but most heed the warnings.
I don't know what the actual temps are but for silver brazing the metal should be deep red in order to get the silver to flow really well through a lugged joint. The tubes these days are pretty tough so it's no real worry if more heat is added; as long as the flux does not burn, the heat is no concern.
Regarding fillet vs. lugged, lugged is easier in my opinion. Fillet brazing takes a lot of heat and with heat comes distortion. Making pretty fillets requires more skill than filling a lug as well - my opinion again.
My view of the world of course.
I wouldn't rely on lugs for all that much natural clamping, though pined they hold their own. I use center punch to create a few small dimples to center the tubes in the lugs, that way I get a tight fit and lots of space. I'm very careful about keeping any such dimples out of loaded areas. you can work the lugs any way you want, they are like sheet metal, and I believe originally were. So you can shrink or stretch them to get the fit you want. The only downside with beginers and lugs seems to be knowing that they actually got it filled. though one can practice and cut up some substitutes.
Nessism. That sounds like a good review of the orthodoxy. Because I'm after these home alternative methods I tend to root out some pretty odd sources, and some of the these people have built frighteningly few bikes. On the other hand often welding sources and such are for totally different scales of work.
What interested me about the silver discusion on FF was when Walker came into it, and mentioned he had built a ton of silver fillet bikes and had some more silver and might do more. Not saying it was the best way, or anything, but just added another data point to the idea that it was possible to do. I am not advocating building fillets for large tubes with silver. Just saying it can be strong, and it isn't hard to work. When the heat is right it just girdles the joint.
I find I have to get the tube fairly hot with silver. Paternek in his video is doing it all without much red, and the required heat (this relates to flux effects also) is so much lower that eyewear is UV optional. The heat coming out of the torch is vastly less, and so on. So it must be being worked at a lower temp. The hoter the torch, the cooler the material seems to work, which is a paradox, if a comon one in welding and so forth. I hope to be able to get the heat down with the hoter torch.
I pretty much agree with you on heating tubes, though I notice Bob Brown has collected some ammo on this and finds that time under the torch is more critical which does seem to favour silver. Except I think it comes under the general catagory of "its all good".
OA is the typical torch. I have propane already (BBQ) and it seems to have a lot of advantages over OA, but most people seem to be using OA. I have a woodshop and need to keep it clean so propane is better for that also. OA is probably better for gas welding, but Tinman has some new propane heads that are supposed to make propane welding less insane.
To be honest with you, when brazing I tend to use more heat than some people claim is necessary. Modern steels are very tolerant of high heat and don't loose strength the way old school hardened tubing used to (such as Reynolds 753). When brazing main tubes I use white flux and keep the flame moving so the entire joint comes up to temperature before trying to add any silver. If you keep the flame moving, such that the flux does not burn, I don't think there are any worries about overheating the metal.
Yea, some people use silver to fillet. Moser frames were built that way and a few small builders do it as well. I think if the fillet is large enough the strength issues go away. Not sure though. My opinion is to stick to the tried and true - and for fillets, that means brass. To each their own.
I think it might be the opposite on internal stresses, The less the material the less differential cooling to mitigate, this is totally a guess. But the successful fillets almost seem invisible.
There is a formula for minimum fillet size - something like 3 times the metal thickness or something to this effect. Invisible fillets don't seem like they will have enough metal in them.
Originally Posted by Peterpan1
Depends on the power of your glasses I guess. The fillet formulas I am familiar with for steel tubing would indicate that the brazed and welded joints in comon use are way over the necesarry size. But then again those formulas may be for pipes in a power plant, very few people are really working with our size of stock, so I would be inclined to accept the traditional practices.
By the way, 5 thou, to go back to an earlier point is a big breazy gap. It's about the thickness of a piece of magazine stock. I think most of us would be surprised if our joints where so fat they wouldn't catch a piece of paper, in places. I have a wooden block hand plane I made that will cut shavings of .5 thou, that's one tenth the toterance required, in wood.
On the other end of the spectrum, in the gas welding 4130 DVD, they have huge gaps in the tubing, gas seems to fill holes a lot better, and they are not worried by the gaps, and we are talking airframes.