Or anyone else with pertinent information ... Did I see you post something a while back about brazing carbide ? I have some brazed boring bars (for my boring head) that are chewed up , and a stash of high quality solid carbide router bits ... I have regular brazing rod with and without flux , regular brazing flux , and phosphor bronze TIG filler .
It wasn't me. At least not in a meaningful or useful way. I thought you were the one talking about brazing carbide for a glass blower or something like that a while back. Now I am all confused.
The toughest thing I ever brazed was refrigeration lines with self fluxing silvphos15. I did it with OA and kept blowing out lines in place. In the end I made the assembly on the welding table and connected it in with flair fittings. More recently a refrigeration tech said he has better luck with a turbo torch with just air instead of OA.
Sorry that's all I got.
It sounds like the OA torch did not have the needed total BTUs per second to get the assembly up to brazing temperature. The OA may also have been too hot in one place. From what I've read, for OA, one would use a rosebud torch. I always used acetylene-air or propane-air. Sometimes I build a muffle from stacked fire bricks.
Joe Gwinn
When I've used Silphos rod for brazing copper I've just used the likes of a Benzomatic/Rotherberger propane/MAPP torch and no problem at all getting it to the right temperature even for larger tube like 15mm plumbing tube. I tried to instruct someone else and she was like a deer in the headlight lights and overheated it even with one of those as she was concentrating all the heat in one spot, got it done in the end though once she got used to it. I have in the past used OA for soft soldering as it gave me better control but you need to know how to move the torch to control and get the heat where required.
I was easily able to do it on the bench. Out of position on the compressor I kept blowing it out. Drove me bonkers. I was using a welding tip. Using a rosebud never occurred to me. About the only time I use the rosebud is either for a quick forging job, or for welding preheat.
I've done a lot of brazing using the prefluxed brazing rod and silphos. I have 2 OA torch setups, a Victor Journeyman and a Uniweld. For both I use a "0" welding tip with 5# oxy and 5# acetylene. I prefer neutral flame color. For copper to copper and copper to brass I use the silphos moving the flametip slowly along the weld path. When it gets red and not yet cherry I start dippin and movin. I haven't burned through I think due to the fact I don't stay in one place with the flame tip. For steel to steel or steel to anything else I use the prefluxed brazing rod. I don't know the composition but it looks like brass or brass alloy. I get a spot almost yellow before I dip the rod. If you get the temp right you can lay the rod down in the path of the tip and it will flow nicely. I've had good luck with these methods. YMMV
Steve
Gee , thanks guys for all the responses ... I guess I should have been more specific on the information I was seeking . I was looking for information on filler rod composition and type of flux to use .
I was making glass bead mandrels , TIG welding TIG electrode pieces to SS handles with Invar42 nickel/iron filler . She doesn't call me any more . I think she found out about my conservative leanings ... she's friends with the libs at the (dead)end of our road , might have seen my Trump flags <grin> .
I was making glass bead mandrels , TIG welding TIG electrode pieces to SS handles with Invar42 nickel/iron filler . She doesn't call me any more . I think she found out about my conservative leanings ... she's friends with the libs at the (dead)end of our road , might have seen my Trump flags <grin> . Snag
--------------------
They preach tolerance, but only for their own beliefs.
The method I used ~40 years when I did this on a semi-regular basis on large lathe bits used for roughing forgings:
Heat end of tool to melt braze. I used O/A back then but today I would use my turbo-torch with a 5 or 6 tip, and flip out the old insert. Allow to cool, coat the insert socket with brazing flux, place ~.002" brass shim stock cut to fit, coat insert with flux and place on shim stock, heat slowly to dry out and melt flux then heat rapidly from the bottom of the tool not directly on carbide until brass melts and flows.
This worked really well using 3/4" square ~3/16" thick inserts made for use in brazed tools, not sure if it will work with all grades of carbide.
Glen
On the subject of flux I was told regarding silver soldering inserts to use a more active flux intended for stainless steel rather than one intended for steel.
That makes sense since the chromium oxide layer is less reactive than the iron.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.