[febikes]

I tried to attach a cable guide with silicon bronze and it turned into a puff of smoke similar to what is described in the following thread.
https://bbs.homeshopmachinist.net/showthread.php?t=40869

I tried doing various things and could not seem to get the bronze to flow in anything approaching a reasonable way. Two things would happen. If it got to hot it would explode in a puff. If it was too cold it would simply not flow, I was never able to get it to the right level.



What do the rest of you TIG guys do for cable guides?

 

[restlessrider]

I think most tig builders use O/A to braze guides on

 

[j-ro]

Are you using C02 for gas? that doesn't look right.
I've welded huge projects with silicon bronze and not had that happen.
You won't ever get it to flow under that guide.
It will always bleed rust if you don't weld all the way around it.
You should be using argon.
Silicon bronze has a lot of stuff in it. that white stuff is the Zinc, just like if you were to weld on somethiing galvanized.
Silverbrazing those cable guides on is really simple; clean both pieces, flux, heat until flux is clear, introduce silver and watch it dissapear underneath and come out the other side.
Silicon bronze has limited use in framebuilding, It works great if you use it on the right things. Not so much if you try to force it. One place it works well is attaching binder bosses, you can build it up, shaping it with the tig torch as you go and then file it to whatever you want. I've used it on bridges as well.
It could work on other brazeons but you need to be able to go all the way around them.

None of this is meant to sound snotty, just trying to troubleshoot that for you.

 

[Cracked Headtube]

Tonight I fired up the TIG torch and had a similar 'blow-out'
I just for got to open up my argon tank. :madman: Check your gas flow.

 

[febikes]

Thanks all!

I was using pure argon 15 CFH with a gas lens but it could be I need to turn up the flow.

I don't yet have an O/A setup but it is on my longer term shopping list. I might simply try using map gas but if I go that route I will need to order some $ilver.

 

[Walt]

O/A is worth every penny

If you don't want to spend the $ on an O/A setup, just tig the guides on with whatever your normal filler is. It's fussy and you'll need to be careful and precise, but it's certainly doable.

-Walt

Thanks all!

I was using pure argon 15 CFH with a gas lens but it could be I need to turn up the flow.

I don't yet have an O/A setup but it is on my longer term shopping list. I might simply try using map gas but if I go that route I will need to order some $ilver.

 

[customfab]

Like Walt said, just weld the damn things on. Only thing I brazed on the last frame I built were the bottle bosses.

 

[D.F.L.]

I tried the TIG Bronze experiment once and was completely unsuccessful. I'd like to hear the process from somebody who's good at it.

 

[Cracked Headtube]

Walt, what disc guides are you using these days? Do i remember you having trouble with powder coat not getting coverage beneath the guide? What was your solution?

 

[febikes]

I tried some more tonight and it was more of the same mess. I remember that when the BREW dude did this it went quick and looked easy. On thing is that he used MIG wire while the guy at the welding store sold me TIG rod so that could be an issue but more then likely I am just getting too hot.

 

[mexi mike]

Make sure the guides are steel
DC-
2% thoriated tungsten (red)
15-20 CFH
somewhere around 30-50 amps

Make sure your torch head isn't leaking, and there are no leaks in your leads.
Ditch the magnet squares on your table, they tend to mess with puddle control.
Try simple stringers with it on scrap.
SiBr is very simple to lay in, doesn't take a complex process, or anything different than steel to steel with steel, just less heat is needed.

 

[Citizen Kane]

Looks like zinc in the rod to me, check the spec on your filler, I've never had that problem with Tig brazing wire.

 

[j-ro]

Make sure the guides are steel
DC-
2% thoriated tungsten (red)
15-20 CFH
somewhere around 30-50 amps

Make sure your torch head isn't leaking, and there are no leaks in your leads.
Ditch the magnet squares on your table, they tend to mess with puddle control.
Try simple stringers with it on scrap.
SiBr is very simple to lay in, doesn't take a complex process, or anything different than steel to steel with steel, just less heat is needed.

Good stuff here, I think part of the problem lies in the guide itself, I believe it a cast guide which is a whole nother can-o-worms. Silicon bronze is great for this too but there is a small learning curve. I'll try a couple this afternoon.

 

[j-ro]

Heres a couple of pics from this morning, the first is a cast guide with silicon bronze welded at 31 amps. No problems but I think from watching the guide as I was welding I could see where a problem could arise. The guide, because it was cast wanted to 'boil' and with more heat it probabally would just cook the top layer off.
The weld could easily be finished with emery cloth but there is still the issue of the inside which is unwelded and would bleed rust after the first drop of sport drink leaked on it.
The second shot is just a miter I had on the bench, it was welded to show that you can use it for bridges and shape it like a fillet. Do not use it for main structural joints. IT WILL FAIL, but you can lay in some shapely welds in tight areas with it.

 

[febikes]

Big thanks j-ro! It looks like your really good with the stuff.

In terms of cable guides it seems that you are not a fan of the technique even though you clearly have the skill. I have a frame built with bronze on the cable guides, it is not leaking rust yet but that could be because it is new and because it is powder coated rather then painted.

I am going to look into getting some silver for the guides.

 

[febikes]

Question for j-ro and/or others, exactly what kind of rod are you using for this? I bought some 1/8" brass rod from Airgas/national welders. The guys in the weld store tell me it is for TIG but no matter what I do it seems to turn into a white powdery mess. The process also involves lots of snap, crackle, popping sounds, smoke, and lots of green color in the arc. I have my argon turned up to 30 cfh and am using a gas lens. I also tried at 20 cfh. I was using 30 amps and really trying to go as cold as possible but nothing would happen until the stuff got hot and at that point unless I pushed things to snap, crackle area it would not change from sold.

I wonder if I bought the wrong stuff.

 

[j-ro]

Question for j-ro and/or others, exactly what kind of rod are you using for this? I bought some 1/8" brass rod from Airgas/national welders. The guys in the weld store tell me it is for TIG but no matter what I do it seems to turn into a white powdery mess. The process also involves lots of snap, crackle, popping sounds, smoke, and lots of green color in the arc. I have my argon turned up to 30 cfh and am using a gas lens. I also tried at 20 cfh. I was using 30 amps and really trying to go as cold as possible but nothing would happen until the stuff got hot and at that point unless I pushed things to snap, crackle area it would not change from sold.

I wonder if I bought the wrong stuff.

The stuff you want is labeled 'Silicon Bronze'. it is a duller than brass color.
I have meant to try regular brass brazing rod with flux and a tig torch and also the prefluxed stuff. Maybe today is the day I give it a shot

 

[j-ro]

OK febikes, i couldn't wait.
Heres four shots, They are all around 70ish amps or so. important to note that this was done on .120 wall tubing

The first is regular old brass from the steel yard brass. you have to foot feather the heat to make it bond, too much heat and it just blows out.

The second is fluxed steel yard brass. This train wreck speaks for itself.

The third shot is weldmold 880t

The fourth is Silicon bronze, same amps on both faces just different speed and feed rate.

I was kind of surprised that I was able to tig with the straight brass but when it comes down to it, it is just simpler to grab a torch and do it right. As far as braze ons are concerned its much simpler to just braze them. There's no shortcuts.

Take care,
jake

 

[j.m.]

Mark, I'll get some flux and let's just try it with your mapp torch.

 

[febikes]

An update triggered by thoughts in a different thread....

In any case, I am still using SiBronze for TIG guides and am getting a little better at it.

The following is a close up of a guide from my latest bike in progress.


I find that doing a bottle mount with TIG is harder then doing cable guide. The follow is an extreme closeup of the a TIGed water bottle guide.


Does anyone else around here TIG their water bottle mounts?