Oxyacetylene Tank Sizes?

[cheeseman]

Hello, I have looked all over the place but can't find a site that helps you determine or even gives you a baseline of how long various tank sizes will burn for. I know that for every 1 cylinder of acetylene used you will use 2 oxygen cylinders of the same size. I also know that cutting uses up more fuel than welding. I guess I want a second hand opinion on some of the cylynder sizes you guys use for custom bike builds and how long they last you. I also see these little kits all over the place that come with a torch kit, a 10 cf acetylene tank and a 20 cf oxygen tank for around $300 and many different brands sell them. Anyone have any experiance with these kits? Thanks.

 

[darwin]

For cutting stock nothing can beat a band saw, as far as a welder a decent mig welder would work just right. Then theres the old grinder for cleaning up the edges. Youll find these 3 tools in the long run to be far cheaper to operate and more versatile for your needs to fabricate then an acetylene rig. Just my thoughts. Buying these tools used should be fairly simple since theres a gazillion out there.

 

[stude13]

hey cheese; i agree with darwin. you are right about fairly low cost gas rigs it a specialty tool, maybe later. you can find the tools darwin talked about and many others at pawn shops, take your dad. mitch

 

[lennyharp]

The advantage of oxy acetylin is that you can low temp braze. This is a very friendly way to build a bicycle frame. Cro moly 4130 steel tubing is the standard that has been best for bikes for a long time. Basically it is a spring steel that is very repairable and light weight and strong. At welding temperatures the 4130 steel crystallizes and becomes brittle and can lead to failures. If you can work a fillet on a joint you are working the heat below that critical temperature. That gives a good reason to get the tool you want.

Low temp rod is about 1600 F + and regular brazing rod is 1800 F + degree melting point. Welding is well over 2000 degrees. 1850 is the critical heat for 4130 cromium molybnium steel. Welded steel just needs more thickness at the weld than is needed for the brazed joint. It is a trade off for double butted steel tubing as the added thickness is put there for modern welded frames.

I would not use the torch to cut this type of steel for the same heat reasons. I also hate wasting gas or in cutting you use a ton of Oxygen as that is what feeds the burning steel. I have tanks that are about 2 feet tall and there are 2 sizes larger. For Frame building this will last for at least 5 frames. I use a 00, 0 & 1 size tips for the majority of my work and these are all small tips by a welders standards. But I don't weld, I braze at low temperatures.

 

[crazeehorse]

I also see these little kits all over the place that come with a torch kit, a 10 cf acetylene tank and a 20 cf oxygen tank for around $300 and many different brands sell them. Anyone have any experiance with these kits? Thanks.

yes, i have used the small oxy acetylin units you are talking about for 20 yrs. they work great, i keep 2 sets of tanks, so when one runs out, i have time to gat a refill, saves a lot of cussing, & such. how long will it last, i honestly could'nt say, it depends what you do with it. i mostly used mine to sweat copper lines with sil-phos 15% silver for strong joints.mine would last much longer than a cutting job or the like the small kits are fine i use (uniweld) brand, it has a cutting head, & you can buy many different tips for most any job. the unit i have now is about 8 yrs old. to be honest my old unit was in good shape, i just wanted to get a new one, cause i liked the new carrier better.

 

[DougC]

I have a 10/20 kit also.
And I agree--it's tough to say how much weld time you get, because that depends on the flame size, material thickness, and so on. "An hour of welding" is about 59 minutes of fitting parts, and about 60 seconds of actual torch time.

Where I go, the tank exchanges are about $30 for both. A lot of people get hung up on the danger factor of storing pressurized fuel tanks around the house, but how many people do you know that have a propane grill?

I think that if a person only has $300 to spend, you're a lot better off with an oxy-acetylene torch than any cheap 110V wire-feed setup.
~

 

[cheeseman]

Electric welding is great but you can not braze using bronze with a mig welder. For my project I would be using thicker tubing than you would find on a normal bicycle so welding would be more appropriate. However I would like to be able to braze if I want to do a build using thinner tubing. Not to mention I do not have high-amperage outlets. Only 15 amp outlets exist so that would mean having 20 amp outlets put in to weld anything reasonably thick for a bicycle. So my question is then for the begenning welder which one do you think is easier to learn. Gas or electric?

 

[lennyharp]

frame build 101

http://en.wikipedia.org/wiki/Bicycle_frame is a great start for information on the Bicycle frame. You are right to add some thickness to a standard bicycle frame to get more strength for a motored bike. If you are to use 4130 below is a table from Nova Cycles Supply for one of their Mountain bike tube sets.

DIA(MM) WALL(MM) LENGTH(MM)
DT 31.7 0.8/0.5/0.8 650
TT 28.6 0.8/0.5/0.8 600
ST 28.6 1.2/0.6/0.9 520
CS 24 0.9 425
SS 16 0.6 560
HT 36 1.1 200

For example the DT is the down tube from head tube to bottom bracket is the largest tube and takes the most stress in standard bicycle riding. It is less than 1 milllimeter on each end and only .5 mm for most of it's length.
1 millimeter = 0.0393700787 inch
This should give you an idea of the great strength the Cro Moly tubing has, and why a mountain bike can weigh 25 to 30 pounds and still be strong. If you double the wall thickness you would be overbuilding for a motored bike with say a 5 hp 20 lb motor. Brazing works great with .049 inch or even .065 inch wall thickness tubing. Welding works great too but for my money I would braze a well mitered tube with a filit radius that holds and is very repairable. Mike Rother has a great article on old Schwinns and filit brazing.