Banjo Hangout Logo
Banjo Hangout Logo

Premier Sponsors

573
Banjo Lovers Online


Want to hide these Google ads? Join the Players Union!
Jan 28, 2020 - 2:08:49 PM

Brett

USA

2029 posts since 11/29/2005

Anyone here ever cut down a 11” brass tension hoop to a smaller size and brazed it? What type rod did you use to braze? Could you do it with your yellow MAPP gas bottle, or does it absolutely require oxy/ac rig? I don’t have a “real mans” torch setup.
I need to cut an 11” down to 10 & 3/4”.

Jan 28, 2020 - 3:11:02 PM
likes this

2765 posts since 2/18/2009

I routinely join brass tension hoops and tone rings using Harris Stay-Silv rods and flux and a Bernzomatic torch with MAPP gas. I can heat the joint in a 1/8x1/2" hoop to red in about 2 minutes or less, but a 3/16"x5/8" takes a long time. I have an oxy-acetylene torch but it's a pain to bring into the shop since it has many feet of hose and gets tangled up in everything, and I'm not nearly as accustomed to using it. Someday I would like to get myself organized and practice using it for banjo parts. At a guess I would say a tank of MAPP lasts for maybe 30-40 jobs, so it's not the cheapest but I can get it in town at the hardware store, whereas it's 30 miles to where I can get acetylene or oxygen bottles exchanged.
Zach

Jan 28, 2020 - 4:15:04 PM
like this
Players Union Member

rudy

USA

14949 posts since 3/27/2004

I join all my rims with 4 stainless steel button head screws and a 1/16" thick joining strap.

Jan 28, 2020 - 7:11:42 PM

104 posts since 2/20/2004

Silver solder

Jan 28, 2020 - 9:33:44 PM
Players Union Member

Helix

USA

12207 posts since 8/30/2006

Jan 28, 2020 - 9:41:03 PM

PaulRF

Australia

3067 posts since 2/1/2012

quote:
Originally posted by rudy

I join all my rims with 4 stainless steel button head screws and a 1/16" thick joining strap.


That's a great of completing the task if you don't wish to braze or lack the equipment.  Looks good as well.

Paul

Jan 29, 2020 - 1:02:03 AM
Players Union Member

Helix

USA

12207 posts since 8/30/2006

google.com/shopping/product/1/...2Cmvi%3A0

Or take a look at what I used to join rolled brass for a 10" rim.

Jan 29, 2020 - 6:12:11 AM
likes this

12600 posts since 6/29/2005

It can be done with a Mapp gas torch with a little patience.  A good silver brazed joint in brass can be stronger than the metal it joins.

 


If the hoop is nickel plated, it's going to get blackened and discolored around the joint, so better to make the joint under the tailpiece.   Plain brass can be cleaned up so the joint is practically invisible with the right brazing alloy.

 If you have a notched  tension hoop and you are going to reduce it from an 11" head to a 10 3/4", the notches will be different and the space If under the tailpiece will be reduced.

Jan 29, 2020 - 3:15:47 PM

Brett

USA

2029 posts since 11/29/2005

A buddy at work loaned me his Lincoln Electric “flux coated bronze” brazing rod pack, telling me use all I want. I have a yellow mapp small tank with the built in ignition button. The tension hoop is cheap brass import that is merely round, no notches, no groove. I’d buy one used, but a lot of folks can’t tell if they have 10 & 3/4” and a 10 & 15/16” is too large. So, going to cut down a fleabay 11” $15 special brass tension hoop.

Jan 29, 2020 - 3:29:24 PM

12600 posts since 6/29/2005

quote:
Originally posted by Brett

A buddy at work loaned me his Lincoln Electric “flux coated bronze” brazing rod pack, telling me use all I want. I have a yellow mapp small tank with the built in ignition button. The tension hoop is cheap brass import that is merely round, no notches, no groove. I’d buy one used, but a lot of folks can’t tell if they have 10 & 3/4” and a 10 & 15/16” is too large. So, going to cut down a fleabay 11” $15 special brass tension hoop.


You should check what the soldius and liquidus temps of the Lincoln Electric “flux coated bronze” brazing rod is.  You will not get the tension hoop joint above 1200 degrees with mapp gas. 

Jan 29, 2020 - 4:24:53 PM

Brett

USA

2029 posts since 11/29/2005

1680 Fahrenheit, glad you said, glad I just checked. So I need to use something posted above.

Jan 29, 2020 - 4:36:14 PM

Brett

USA

2029 posts since 11/29/2005

Wow, I’m glad Helix posted that, I didn’t know they made a rig that small and likely reasonably priced. I could use that a lot on old cars to bust loose rusted fasteners.

Jan 29, 2020 - 6:11:57 PM
likes this
Players Union Member

rudy

USA

14949 posts since 3/27/2004

quote:
Originally posted by Brett

Wow, I’m glad Helix posted that, I didn’t know they made a rig that small and likely reasonably priced. I could use that a lot on old cars to bust loose rusted fasteners.


I have one of the Mapp - Oxygen torch setups that Helix linked and I will warn you that it is fairly expensive to keep oxy tanks on it.

If I was going to do a lot of torch work I'd opt for just going with a small oxygen - acetylene torch rig.

Jan 30, 2020 - 2:13:53 AM
Players Union Member

Helix

USA

12207 posts since 8/30/2006

Brett Helix welded in the shipyards. I've seen a lot of different things from the old days. The old guys showed us how to stay out of trouble with Sched. 80 8" pipe in 40' sections. We learned from those cats.

Coat Hangers are mild steel. They make great welding rods. Some of us welded our own pedi-cab frames to tow people to and from the big arena games in Phoenix and Tempe. I mitered my corners and we made pockets full of money. 21 speeds and a garden tractor tie rod end attached to the seat post.

When I am done using my little torch, I disconnect the bottles, that makes them last longer. I don't have the room, nor interest in having a large bottle around. I always get the right temp quickly. I moved enough big bottles out of clamshell buckets in the snow up high above the Willamette River on Ross Island.

The flame gives a little "hiss" that you learn to listen for.

In the factory, we had a guy standing around talking while holding an unlit torch, when he struck the striker, he blew his overalls off. Dude.

Jan 30, 2020 - 2:07:11 PM

Brett

USA

2029 posts since 11/29/2005

I can mig weld and have a Hobart, as I tinker on antique cars, but I don’t believe I can mig brass. First, I’ve got to see if the fleabay brass 11” even makes it here. Given where it’s coming from, and what’s going on over there with quarantines, they may have shut down production and/or may not have workers to load seavans.

Jan 30, 2020 - 6:36:07 PM

DSmoke

USA

799 posts since 11/30/2015

quote:
Originally posted by Brett

I can mig weld and have a Hobart, as I tinker on antique cars, but I don’t believe I can mig brass. First, I’ve got to see if the fleabay brass 11” even makes it here. Given where it’s coming from, and what’s going on over there with quarantines, they may have shut down production and/or may not have workers to load seavans.


You could of bought a cheap steel one from Ebay and mig it, been there done that.  But that was after I went down the same road as you and when I cut it, I realized it wasn't brass after all.

Jan 30, 2020 - 7:27:43 PM

Brett

USA

2029 posts since 11/29/2005

That’s good to hear too.

Jan 30, 2020 - 7:34:49 PM

Brett

USA

2029 posts since 11/29/2005

I think I’ll split an old 10.5” split tension band I have and spread it out 1/4” with a plate like Rudy showed. Then turn mig down low and try to fill gap with weld also. That should be strong. And use flat hooks.

Jan 30, 2020 - 9:46:44 PM

88 posts since 9/30/2009

Harris 56% silver brazing alloy and a MAPP gas torch will do this easily. Use plenty of flux. I like the Harris Stay-Silv flux but any white borax type flux will do. Once you discover silver brazing, there is no end to the things you can do with it. I repair old banjo hooks that have cracked from over tensioning and you can't tell once they've been cleaned up. Good luck!

Jan 31, 2020 - 7:14:45 AM

12600 posts since 6/29/2005

I wouldn't say it's "easy—many people just can't do it, like hearing a banjo head note.  I know this from way back in art school where we all had to learn—even with instructors and proper equipment, some people can't master it.

Having said that, the Harris 56 is by far the "easiest "of the alloys to use—it has a low temp and flows exceptionally well.  Jewelers normally use three kinds of silver solder; "easy", "medium", and "hard".  The reason for this is that they want to make two joints close to one another, often joining a new piece onto another already joined assembly and they don't want the first joint to come apart when they heat the piece up to join the second.  Jewelry is much smaller scale and much less of a heat sink than a  banjo tension hoop, the mass of which tends to pull heat away from the joint.  Some small jewelry pieces can be silver soldered with propane.

Here are the three basic grades of silver solder that jewelers use—you will notice the liquidus range goes from 1325F to 1420F:  Getting the temperature of a piece up 100 degrees can be very difficult with a low-temp torch, and too high temp can melt the metal if you are not careful.

In my experience, you would have a very very difficult time joining even 1325 with mapp gas on something heavy like a tension hoop.

Harris Safety silv 56 has a liquidus of 1205F, and that's why it will work with a mapp gas torch.  It has a silver color great for stainless steel and nickel silver, and is actually NSF rated for repairing restaurant equipment.  If you want to match brass better, you have to use other alloys, which normally have higher temperatures.

Finding the right ones can be a quest.  In the production of a banjo, I use 3, sometimes 4 different kinds, and use the safety silv 56 very sparingly because it's the most expensive kind.  They call it "safety silv" because it has no cadmium—something to be wary of when looking for brazing alloys.

Edited by - Ken LeVan on 01/31/2020 07:17:29

Jan 31, 2020 - 9:24:38 AM

3722 posts since 5/12/2010

Had been wondering about the "safety" part of the name, now it makes sense. I try not to breath the fumes no matter what kind of solder I use.

The Harris 56 seems to work very well with my MAP torch, though I am thinking of upgrading to an acetylene torch which is cheaper and I could use for other things as well. 

Jan 31, 2020 - 9:54:53 AM

2765 posts since 2/18/2009

The only rod I've ever used since I began to learn is Harris Stay-Silv 15, and it has worked fine for me with MAPP. I've made (at an estimate) somewhere around 150 joins with it over the last few years. If I make a good tight fitting joint it can be hard to find it after sanding the hoop. I have to use a bright light and hold the hoop quite close to my face. Some of my joints are not as tight and there will be a silver line on the inside or the outside, but I put that part under the tailpiece anyway. When I first started out I did some tests where I joined two short pieces together and then twisted the joint to see if it would break. Maybe when this lot of rods runs out I should try the 56, it looks like it's a little cooler and that would save on fuel.
Zach

Jan 31, 2020 - 10:20:53 AM

mbanza

USA

2170 posts since 9/16/2007

I've been using "Super Sil-Flo" (Catalog No. 48571) with "Sta-Silv" flux. It works quite well and is usually stocked at decent hardware stores.

Jan 31, 2020 - 10:36:37 AM

950 posts since 1/26/2012

I really like soldering paste as opposed to using rods. You put it where you want it, and heat it up until it flows. Super simple I've used THIS soldering paste for many brass things, including a tension hoop. It works fine with a regular propane torch for small jewelry sized pieces (I just soldered some things this morning with it), but I use MAPP for thicker pieces like making ball shoes or tension hoops.

Hangout Network Help

View All Topics  |  View Categories

0.3125