brass on brass
 

A fella I do work for once in a while brought me a project. It's a brass "X" frame that supports thin legs on a heavy wood cabinet of some type. It's made from (approx) 1/2X 1.5 rect. bar with 35mmX1.5MM rings that slip over each wood leg. The X connection is cut as slots 1/2 way through each member with a small machine screw holding the bars together where they cross. I think each bar is 6' long. The plan was to just silver the rings on the end but there is a lot of the ring touching the tooling which is aluminum.

The guy is an impressive fabricator but something went wrong and one, if not both of bars are a bit too short. The one I looked closely is about 3mm short (we are talking overall length, the way that matters). He asked me if I could use weld to make it longer. I am also doubting it will be able to support itself not welded (silver brazed) in the middle. I didn't have time to measure for sagging.

He brought it to me offset about 2" from an high density wood particle sheet on turned "offsets" under the end rings.


Anyway, what are my chances when it comes to surfacing the end of the brass bar? I know TIG won't work. It seems like it's going to be very difficult to do that much build up on the end of the brass bar with a torch. Making thicker/larger OD rings is off the table.

oh, and the legs are already on the piece which is not even in the same state as the brass.

I have a few days before again speaking to the decision maker and I hope that those in the know might share some info and shorten my journey to customer satisfaction. I have several gas torch sets and I have nice nickle bronze alloy rod and some generic yellow brass filler (with flux on).

The bars are brass, not silicon bronze

Thanks, Frank

Frank

Since the yield strength of brass is around the same value as that of "silver" brazing rod but the melting point is higher, I'd think your best bet is to braze in a 3 mm shim cut from the same 1.5" x 0.5" bar.

I had trouble following your description, so this may be pointless, but I made a small plane by "welding" brass together. It was a pain, but it worked.
You can see some of the lines. It's 4 pieces of brass, 2 sides, the sole, and the bed for the blade. The problems are similar to making a large fillet, it's possible for the whole assembly to sag. If it is possible, I might add solid brass by welding it to the other pieces. I'm not a big fan of silver and brass combos.

http://i251.photobucket.com/albums/g...en/00004-1.jpg

Unter...: Not pointing, picking or say'in, but the plane looks like it would not to too difficult to cast in a sand or plaster mold? I keep a coffee can nearby to collect left over bits of brazing rod for some future use or to recycle...usually my daughter just steals it to make folk jewelry out of... I am now thinking I would like a little plane... hum?

Frank - My first reaction was "wow man, need to take a picture of it and get it to Frank the Welder. He'll know how to do it..." Then it sank in! Apologies in advance.

So my only second though revolved around an table with one short leg. If it applies here, would it be freasible to just cut off the long ones to match the short ones? Just thinking and sometimes that is not a good thing for me to do...so fwiw - /K

I wasn't so happy with the outcome that I would do it again, I just posted that to show that welding brass is possible. Actually, that plane was the first brazing I had done in many years, I'm sure I would do a bit better job now. It's very solid though, and works pretty well. I dabbled in making carved top wood instruments, that was the reason for that plane.

I have too many unfinished projects already, so I am studiously ignoring the possibility of sand casting things. In my experience, it's tricky to cast things without porosity ruining your finish.

Ill get some pics but the "thin slice" sounds better than welding.

One's own problems are always the hardest to solve! LOL.

The plane looks pretty cool. I have some pretty old wood working tools. They are fun to look at but I don't touch them!


Here ya go

http://farm9.staticflickr.com/8373/8...6019046b95.jpg
30 110 by frankthewelder, on Flickr

http://farm9.staticflickr.com/8515/8...984f7caa3f.jpg
30 112 by frankthewelder, on Flickr

If the wall thickness of the brass rings isn't critical I'd just turn some new ones to take up the gap. For that matter, how critical is the OAL of the legs?

I would shim that and then weld it :)
Probably could just fill it with a big bead of weld

If silver was going to hold it in the original scheme, then silver will hold the shim to the end of the bar and also the tube to the shim. You want very tight clearances with silver in order to keep the strength up. This will also help the appearance.

The guy cut some shims of the bar and brought them over for me to silver to the end of the long bars. This is starting to feel like a hack-job and making me angry.

I can see sticking the shim on the end of the bar, then it slipping when I go to silver the ring on. I really love being the guy to fix a $50,000 piece of wood furniture with a torch.

may be Ill get some pics or delete the thread and lay-low for a while. :crash:

Pin it.

Use brass pins through the shim, brazed in place. Not going anywhere.

You could also pin the collars and grind off the part of the pin that protrudes past the ID (after brazing).

don't envy you. Deleting the thread may be the way to go
you need some variation of the frankenfixture

http://bikeforums.net/attachment.php...hmentid=301279

The shim and pin thing is out. I can't have the extra silver line. I need to add 3.5mm or so on one of the bars so I found some brass filler of the same color and I am going to weld it. I tried it yesterday on one of the pieces I had and it seemed to work. I used brazing flux. I wasn't sure if the flux was for brass or for steel.

I think a fat bevel on each edge of the end of the bar with a bead down the sides to build up the length. I am getting hungry every 30 mins while my brain runs WFO.

I chickened out yesterday. Today is the day.

I am sure if I had that frankenfixture in my shop I would have the confidence to do anything.

I have a friend who is a master brass/bronze sculptor/fabricator. I talked to him on the phone today and he is bringing something I will need. He has a french accent so I am not sure what he is bringing. It might be some type of acid wash or something to eat. I will know later since I don't understand french.

the thing that would worry me is the tube distorting. I copied the EVT dishing tool using fillet brazing and the center tube just went all over the place. Probably should have used heat sinks. All I can say is heat the backside of the tube.

I really struggled with this yesterday. I came to the conclusion as some point that the metal is not "yellow" brass. I was able to add LFB on the end of the bar with no problem. The conditions seemed to improve as I added more LFB. The thing I didn't pick up on is the LFB was pure and clean looking, the bar not so much.

I machined the bar to the correct size and polished the surfaces. The color matched and there was only a little porosity. I fit everything up nice and clean, fluxed, added heat when the flux was ready the brass wouldn't take the silver (commercial 45%).

I went up and down with the heat a little and things didn't improve. The flux when cooled turned a solid grey colored with balls of solid black. The metal, whatever it is has been all over the place and was originally purchased from an online source. I think it is type 360 and not weldable.