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Old 04-19-2010, 07:39 PM   #1
shagy
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Default brazing question

So, I have the makings of an oil tank, or at least I think I do.

I have two stainless steel halfs previously used as flour or sugar containers, they are about 4.5" in diameter I figure the two of them together will give me about 3.5 qts of oil.

I plan on using stainless or brass nuts for the oil line fittings and reusing the stock sportster oil cap that I have (it's got a thermometer).

Here is the question: I found a brass tube that fits the cap/plug and it is cheaper than finding stainless. How well will a brazed oil tank hold up? And will this look like shit?

Opinions and knowledge welcome.
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Old 04-19-2010, 07:52 PM   #2
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Default Re: brazing question

Never mind if you saw my last post...I F'ed up the ole "rithmatic>.....

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Old 04-19-2010, 07:57 PM   #3
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Default Re: brazing question

not a sphere its a cylinder about 7 in tall 4.5 radius not exact but something like that. I calculated it out just don't have the demensions with me right now.
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Old 04-19-2010, 08:03 PM   #4
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Default Re: brazing question

Yeah I just redid the math...you'll have plenty of volume...sorry...
as for the brazing I have no idea-sorry again-
but I'd like to see pics of the pieces!!!
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Old 04-19-2010, 08:59 PM   #5
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Default Re: brazing question

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Originally Posted by shagy View Post
So, I have the makings of an oil tank, or at least I think I do.

I have two stainless steel halfs previously used as flour or sugar containers, they are about 4.5" in diameter I figure the two of them together will give me about 3.5 qts of oil.

I plan on using stainless or brass nuts for the oil line fittings and reusing the stock sportster oil cap that I have (it's got a thermometer).

Here is the question: I found a brass tube that fits the cap/plug and it is cheaper than finding stainless. How well will a brazed oil tank hold up? And will this look like shit?

Opinions and knowledge welcome.
Not quite sure I understand exactly what you plan to braze, but here are some rules of thumb:

If you're planning to braze the tank itself together, no. Brazing butt-joints, and outside fillets on sheet metal is a no-no. The tank construction needs to be welded.

If you're talking about brazing the bungs on, that's all good. Those are inside fillet joints and will hold up fine.

If you're talking about actually brazing in a brass tube, I wouldn't do that. I think the tube will crack where it's joined.
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Old 04-19-2010, 09:11 PM   #6
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Default Re: brazing question

I brazed bicycle frames and they held much more than the oill tank , are you talking about brass or silver braze?
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Old 04-19-2010, 11:07 PM   #7
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Default Re: brazing question

I'm looking to do something similar. I was at Target and I was looking at those little bathroom cans. The spun aluminum or stainless ones for toothbrushes or other odds and ins, and thought it would work for a tank.
I'll be checking back to see what you come up with!
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Old 04-20-2010, 12:09 AM   #8
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I brazed bicycle frames and they held much more than the oill tank , are you talking about brass or silver braze?
That's inside corner fillet brazing. Remember I said that was fine? You can fillet braze motorcycle frames together too. Rickman frames were brazed, as were most road race frames back in the 60's and 70's. I wasn't talking about the filler material, I was talking about the type of joint.
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Old 04-20-2010, 12:43 AM   #9
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Default Re: brazing question

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Originally Posted by J_F_Byrd View Post
Not quite sure I understand exactly what you plan to braze, but here are some rules of thumb:

If you're planning to braze the tank itself together, no. Brazing butt-joints, and outside fillets on sheet metal is a no-no. The tank construction needs to be welded.

If you're talking about brazing the bungs on, that's all good. Those are inside fillet joints and will hold up fine.

If you're talking about actually brazing in a brass tube, I wouldn't do that. I think the tube will crack where it's joined.
Good answer I didn't know that I couldn't do the butt-joints. I did know that I could braze the bungs and possibly the filler neck but I wasn't sure if it would hold up.

The tube would only be about 1.5 inches if that makes any difference. I had only considered the brass because it is easier to find and cheaper.

Here is what I am working with.... guess I will be buying a spool of stainless wire and some gas.
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Old 04-20-2010, 03:04 AM   #10
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Good answer I didn't know that I couldn't do the butt-joints. I did know that I could braze the bungs and possibly the filler neck but I wasn't sure if it would hold up.

The tube would only be about 1.5 inches if that makes any difference. I had only considered the brass because it is easier to find and cheaper.

Here is what I am working with.... guess I will be buying a spool of stainless wire and some gas.
On thin materials, a brazed joint's strength depends on contact area and bead thickness. So your filler neck would be fine to braze, as would any bungs. But the tank itself, weld it. If you don't have a tig, you can weld the more common stainless (304) with a torch using the right flux.

If you're using a MIG, I hope you're already really experienced at welding leak-proof stainless vessels with it or you're gonna be pulling you hair out chasing pin holes.

Last edited by J_F_Byrd; 04-20-2010 at 03:07 AM.
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Old 04-20-2010, 11:52 AM   #11
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Default Re: brazing question

What is the recomended flux for welding 304 stainless with a torch? I hear a lot of people contradicting each other about this, from one will/won't work to you can't do it at all.
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Old 04-20-2010, 10:18 PM   #12
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Default Re: brazing question

Don't want to hijack, but I do have a similar question about my tank:

I have a copper tank that i'm building, and I butt soldered together the two halves. I used 15% silver solder rod if I remember correctly. I've done something like three passes around the circumfrance to try to build up the area before grinding down.

Does the "no butt weld" thing apply to copper as well? here are some pics:



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Old 04-21-2010, 02:49 AM   #13
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Default Re: brazing question

As Byrd has mentioned the strength of brazing comes form it's contact area. You have to remember there is no melting of your base material, so all your strength comes from the surface area of your fillet. It is suprisingly strong, if done correctly your brazed joint will be stronger than the base material around it. Weekend before last i had a 'brazing seminar' at my garage and flew over Englishman Colin Taylor from Italy who has been doing brazing longer than i've been alive. We made quite a few sets of clip-ons and headlight mounts, which the clip-on handlbar is brazed right to the fork tube clamp...somewhat important. One set is for a Egli Vincent that we are scratch building (Copy as we are making the brazed tube frame to Egli-ish specs) ..anywho I digress, we let all our 'students' pratice and actually braze up som etest pieces for the fun and to show them the strength I took a test piece whcih was a piece of thin wall 35mm ID tube with a piece of flat stock brazed perpendicular to it..by a first time torch user, put it in the vise and started bending the flat stock back and forth. The brazed area did not budge or lift at the edges, but instead the base metal further away form the brazed joint would just start to bend . As Byrd said above a butt joint with 2 sheets end to end is really frowned upon, but it can be done. The problem being it needs to be done from both sides and unless you can get to the inside of your tank after cleaning it REALLY well , you will never know how well it is covered...and you can't grind down the weld because that is your strength. I can try to show a couple pics from the weekend if anyone is interested. I have a Brazed lightweight framed Dresda ,'71 I think, in my shop as well as a '77 Martin framed KZ1000 which is also a brazed contruction tube frame, both have been race bikes for 30+ years, both frames are still perfectly sound ...
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Old 04-21-2010, 03:04 AM   #14
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Default Re: brazing question

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Originally Posted by Bayonet6d View Post
Don't want to hijack, but I do have a similar question about my tank:

I have a copper tank that i'm building, and I butt soldered together the two halves. I used 15% silver solder rod if I remember correctly. I've done something like three passes around the circumfrance to try to build up the area before grinding down.

Does the "no butt weld" thing apply to copper as well? here are some pics:



looks like your actually welding here, melting the base material due to the low melting temp of your base material, depending on the specific alloy your copper is melting aorund 1900F, but with your silver added content, bringing your melting temp down, your filler should be melting much less like 1100 even. . You should be OK, just make sure you clean in between passes very well with Acetone or the like, but I'm not an expert in brazing copper balls.... I would pressure test it for sure.
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Old 04-21-2010, 05:39 AM   #15
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looks like your actually welding here, melting the base material due to the low melting temp of your base material, depending on the specific alloy your copper is melting aorund 1900F, but with your silver added content, bringing your melting temp down, your filler should be melting much less like 1100 even. . You should be OK, just make sure you clean in between passes very well with Acetone or the like, but I'm not an expert in brazing copper balls.... I would pressure test it for sure.
I'm having a hard time telling exactly what he's got going there based on the photo. He says the tank is copper, so either the photo color or my monitor color are way off. Looks like navel brass on my screen. You're right, what appears to be the joint looks almost welded, and concave at that.

Yes, what you said about getting away with brazed butt-joints is right on.

If one has a butt joint in silver-smithing solid silver that's to be silver soldered (technically a brazing operation I suppose) a butt joint is common, but it's got two key differences between soldering brass, or brazing steel: The fusion point of the base metal is within 100 F of the filler metal, and a process called "toothing" (a bunch of little "nicks" made with a jewelers saw) is done to the joint edges, to increase the surface area. Those are done from one side and finished down. I think the joint properties are somewhere between a braze and a weld on that due to a degree of boundary melt or increased interlocking to the surface lattice structure because of the close temps between base and filler.
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Old 04-21-2010, 05:56 AM   #16
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What is the recomended flux for welding 304 stainless with a torch? I hear a lot of people contradicting each other about this, from one will/won't work to you can't do it at all.
Of course you can do it. But as with aluminum, you need to use a *very ****slightly carburizing flame. By slight, I mean a feather less than 1/16 inch beyond the inner cone. Neutral is fine, but you do this to error on the right side of the adjustment. ANY oxidizing properties, and it won't work for you. You base metal must be basically surgically clean.

http://www.tinmantech.com/html/stain...ing_suppli.php

I've personally had the best luck applying the flux liberally to the back of the join only, and on the filler rod, and setting the torch flame as I said. The flux then tends to wick up into the join, and doesn't get scaled up. The torch adjustment can't be the slightest bit oxidizing, even with flux, and obviously you've got to use the right size tip and line pressures for thin gauge materials.

The one thing you'll notice when you've gas welded a stainless joint, is that the weldment won't give you a perfect color match, and is slightly less resistant to corrosion at the joint.
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Old 04-21-2010, 11:10 PM   #17
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Default Re: brazing question

J F Byrd,

The tank material I used was an old Copper Soda acid fire extinguisher. I thought it was brass at first until I cut into it and noticed the color difference in the fresh cut. Certainly not as bright yellow as brass. it really looks just like a penny on a fresh cut.

It is hard to tell where the braze line is, but it's not the one you mentioned above. it's the almost perfectly straight line about a quarter inch below it.
Anyway, thanks for the insight into brazing, etc. I'm gonna try her out after I cleanup that ugly ass seam. Hopefully she holds together...
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Old 04-21-2010, 11:43 PM   #18
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I'll send you pics of my home made tank tomorrow.I welded it first and since there were a few leaky areas,I brazed all the joints...It took care of all the leaks. As for the copper lines,man...they could be messy.My Trumpy vibrates so much that my return line broke right at the flare and leaked oil all over.I installed a small rubber bushing under the flare and also some clear rubber line in the middle of the line to dampen the vibrations.You'll have the pics of my new set up tomorrow.
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Old 04-23-2010, 09:12 AM   #19
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Ok,here it is
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