Tandem Tom

So I think I might be getting dangerously close to dipping my toe into this pool!
So please be gentle as I make some inquiries!😀
I have ordered from the library Paterek's book and loo forward to spending time with it. But have just 2 questions this morning.
I know that OA torches are the norm. But for doing lugged frames will oxy-propane work?
Also I am intrigued with stainless steel racks. If I decided to play around with SS tubing would the above torch still be able to get the job done?
Thanks!!

Andrew R Stewart 

Short answer, yes OP will work for brazing a frame.
This topic has been extremely well covered in the second link, below, to Velocipede Salon. The first link is about O concentrators, another worthy consideration.

https://www.velocipedesalon.com/foru...ors-40262.html
https://www.velocipedesalon.com/foru...ane-30480.html

SS will take the same temps as 4130 to braze, the temp is controlled by the filler/flux, not the base metal. But how that base metal shows and distributes the heat will be different. My advice for starting to play with SS and silver (50N will retain it's color in use and not tarnish like 56% does) is to watch the flux for it's hints of correct temp. Andy

Doug Fattic 

Like Andy already said, yes using propane with oxygen for brazing works great! It is way cheaper and easier to buy and doesn’t come with acetylene’s restrictions. While acetylene equipment works kind of okay with propane, mixers and tips designed specifically for propane work much better.

Here is the short version of what propane equipment I recommend. Most framebuilders like to use a lightweight torch handle instead of the heavy duty kind sold in complete units with cutting attachments. The most popular are the Smith AW1A or the Victor J-28. The Victor compatible Uniweld 71 is the biggest, lightest and cheapest of these 3 units. Smith makes the AT-61 and Victor the UN-J mixer/elbows specifically for propane that screw onto the torch handle. On the other end of these mixer/elbows are threads to receive screw on tips that come in various orifice sizes. Victor’s TEN series of tips are for propane and work well. The Smith series of screw on tips work poorly with propane and are not recommended. But the best propane tips in my opinion are made by the Paige Tools Company for the jewelry trade. These are multi-port tips that surround a sharp center flame with stabilizing little side flames. This makes the flame much less likely to blow out that easily happens when using acetylene equipment with propane.

Just recently Paige Tools listened to pleas from bicycle frame makers and made adaptors so their tips can fit on the threadings of either the Victor and Smith elbows. In my framebuilding classes, I have both oxyacetylene and oxypropane equipment for students to try out. Almost always they choose propane even if they already have oxyacetylene equipment.

Tandem Tom

I could not have asked for 2 better responders!!
Thanks!

calstar 

From the Paige website: Home note: this is not a secure site(at least my computer says that)

Tandem Tom

Yesterday I was close to an Airhead store so I took some time to check it out. The counter fellow was very friendly and took quite a bit of time. In his spare time he fabricated roll cages, heat exchangers and more. So when I told him what I was thinking of pursuing and that I was considering OP he said it was a "dirty" setup. It would leave dirty welds. He was all for OA only.

Andrew R Stewart 

Tom- Are you welding or brazing? I ask because the counter guy seemed to reference welding. And, perhaps when welding it does result in a weld other then desired. But then nearly no one who welds bike stuff uses a flame of any source. But in all the posts and examples I've seen there's been no mention of "dirty" results (excepting burned flux, as usual). Andy

unterhausen

sounds like received wisdom to me. It works fine for brazing, and I expect it works fine for welding too. OP is used nearly exclusively in glasswork, you would think if it was dirty they wouldn't use it

Still haven't tracked down an oxygen concentrator, or I would be using it.

calstar 

Propane cannot be used for Gas Welding. When acetylene burns in oxygen, it creates a reducing zone that cleans the steel surface. Propane does not have a reducing zone like acetylene and can hence not be used for Gas Welding.

source: ​​​​​​https://www.wilhelmsen.com/marine-pr...ne-vs-propane/

regards, Brian

the entire page below, interesting pic of the max flame heat zone of propane and acet



Facts

• The flame temperature when burning Propane in Oxygen is 2800 degree C
• The flame temperature when burning Acetylene in Oxygen is 3100 degree C

Propane (also called LPG—liquefied petroleum gas—or LP gas) is a widely used fuel. It is transported an stored as a very cold liquid, and can cause a “freeze burn” or frostbite if in contact with the skin. The liquid propane is turned into a gas inside a tank or a cylinder. In its natural form, propane is colourless and odourless. To make propane easier to detect in the event of a leak or spill, manufacturers add a chemical compound to give it a distinctive smell.
Welding

Firstly: Propane cannot be used for Gas Welding. When acetylene burns in oxygen, it creates a reducing zone that cleans the steel surface. Propane do not have a reducing zone like acetylene and can hence not be used for Gas Welding.
Brazing

Propane can like acetylene be used for Brazing. For capillary brazing (silver brazing) equal result. For Braze “welding” (thick flowing brazing alloys) acetylene will be an advantage
Cutting

Propane can like acetylene be used for cutting. If you cut with acetylene, you normally put the tip of the inner flame cone on the metal (1mm from the plate surface). If you do the same with propane, you will be waiting for a long time. If you raise the torch so that the outer flame cone is used the preheat process is started faster. Propane releases only a small proportion of heat in the inner flame cone (less than 10%), so most of the heat in the flame is located in the outer cone. Acetylene releases almost 40% of its heat in the inner flame cone.
Therefore, acetylene is better for cutting than propane. While temperature wise acetylene is hotter than propane the fact is that people are using propane for cutting incorrectly. The mistake they make is that they are cutting with propane as they would cut with acetylene. Where the heat is in the propane preheat flame is not where it is with acetylene. In short, it takes a different technique to use propane for cutting and in general, acetylene preheats faster. The Ship breaking/ ship demolition yards and scrapyards are often using propane for cutting because cutting quality is of no concern.
Heating

…is a different matter. To say propane gives off less heat it is not correct (plain wrong actually). Acetylene is hotter but gives off less heat. The majority of preheating is done with Oxygen / Propane. This is a fact. The available heat from propane is higher.
Equipment

Cutting require different cutting attachments and cutting nozzles

Economy

Propane has greater stoichiometric oxygen requirements than acetylene. For the maximum flame temperature in oxygen, the ratio of the volume of oxygen to fuel gas are 1,2 to 1 for acetylene and 4.3 to 1 for propane. So, there is far more oxygen being consumed when using Propane. Despite Propane being less expensive than acetylene, this is counteracted by the higher oxygen consumption.


Download Technical update - Gas Welding - Acetylene vs propane

unterhausen

I would like to see that from a more authoritative source. Everything I have seen so far looks like received wisdom (which is a PC way of saying old wive's tale). You can have a reducing flame with propane. The other thing I have seen is that acetylene produces a co2 layer. But I have seen references to industrial welding with oxy/propane.

This is a bit of a side issue, because oxy/propane is widely used in brazing. Very few framebuilders use gas welding.

Doug Fattic 

Tom, propane and oxygen work perfectly for brazing bicycle frames as long as you use propane specific equipment. I switched from acetylene about 17 years ago. The reason I have done a lot of research on using propane is because many of my framebuilding class students find propane a better fuel source when they live in bigger cities. Local welding supply stores will not sell or ship acetylene to non-business addresses nor will they allow the transport of it in private vehicles. In addition local ordinances and/or insurance policies prevent its use. Politicians have been wise not to try and regulate a popular BBQing fuel.

In addition propane has other advantages like not giving off a lot soot like acetylene does if you don’t turn up the oxygen quickly enough. It is way cheaper to use and it is sold and exchanged in many more locations at much longer business hours. The fact to keep in mind is that it can be fussy to light and keep lite if you are not using the best propane specific equipment like an UN-J or AT-61 mixer/elbow and multi-port tips. The Victor series of TEN tips work well too. It requires a higher oxygen ratio but because I use an oxygen concentrator I don’t have any oxygen expenses except for electricity and maintenance.

Part of the learning curve of a beginner is to learn whose advice to follow. One of the best things that ever happened to me was that I was trained by a master. I give constant thanks for that advantage because I could start right out doing things properly without the confusion of mistakes that come from trail and error.

calstar 

I'm a curious guy, thats the only reason I searched oxy/propane welding in response to the earlier comments in this thread. I searched for more info on the subject and found lots of info on forums and industrial sites that say welding with propane is a no go, didn't find any that say oxy/propane welding is a standard procedure. There is tons of info on cutting with propane, its favored by many for economic/availability reasons.

Always open to learning, regards,

Brian

unterhausen

But information like that gets widely spread without any research backing it up. I'm sure there is authoritative data available, I'll have to check when I get on a university system.

I found one reference on a forum to a factory doing propane/oxy welding. Also not authoritative.

Oxy propane is colder so welding with it is probably pretty annoying. When I was out looking, I saw a video comparing OP cutting with OA cutting and the difference was ridiculous. Good thing we all do brazing and not welding or cutting. I do some gas welding and it's horrible with my setup. Bad enough I have thought about getting a MIG or a TIG.