Removing Hose/Cable Guides from a Steel Frame with a Brazing Torch?

Got a custom 4130 steel frame here that is still raw & unpainted.

Looking to remove the brazed-on hose guides/cable guides under the toptube and seatstays.

2 methods are available to me:
a brazing torch vs files, needle files, masking tape, wet&dry sandpaper.

Wondering what are your thoughts about using a brazing torch at a low temperature to melt the silver braze away to release the braze-ons from the seatstays and toptube? (see attached example)

Are there any reasons not to remove braze-ons using a torch?

Any help or advice is appreciated!

Thanks

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You’ll still need to do some filling and sanding if you de-braze them.

If you are very heavy handed it’s possible to deform the tube. Or so I hear 🙄 lol.

Cheers for the heads up dude!

Ahh I hadn't considered that filing & sanding would be necessary after de-brazing. Thought I could just get away with melting the silver 'til the braze-ons fall off and the silver melts flat against the tubing profile.

So since filing & sanding is gonna be an inevitable part of the process whether I use a brazing torch or not, I'm thinking it might just be better to take off the braze-ons purely via filing & sanding.

Suppose one advantage of not using the brazing torch is that I wouldn't be risking warping or deforming the tubes from the heat.

I’ll generally do them with the torch. It’s a bit less elbow grease and the filing/sanding is quite easy going as you’re removing silver which is much softer than steel.

I also have a few different ‘surface preparation’ discs that go on my drill (or grinder) which are a kind of a plasticky polymery abrasive thing. They will remove silver much faster than they remove steel so you can kinda blast over it and get a lot off pretty quickly but used incorrectly they will definitely remove steel so it does take some finessing. I don’t use them in the grinder much as with the higher rpm it’s a lot easier to over do it.

I’d say that I’ve made the mistake of cutting too close to the tube with a hacksaw and nicking it more often than I’ve gotten the heat in the wrong place and pulled too hard and deformed anything doing it with the torch.

Thanks, that's very reassuring to hear that you generally use a torch to remove them!

Yeah I definitely would be concerned about nicking the tube with a hacksaw. Was thinking if I removed the braze-ons without a torch then I'd cover the tube with multiple layers of masking tape as a safety net incase of an unlucky hacksaw or file stroke gone off-course.

Main concern with using a torch is I'd rather avoid a situation where the frame gets distorted and it needs re-aligning/re-straightening. If doing it this way I'd definitely want to do it under the guidance of an experienced framebuilder.

I wouldn't mind leaving the melted silver leftovers on the tube so long as the silver is relatively flat and no sharp edges anywhere. Gives the tube a bit of character and an excuse to not have to use any files or sandpaper haha

If your heat control is half decent you should be able to concentrate most of the heat into the braze on and leave the tube unaffected.

When I said it was possible to deform the tube I was really meaning locally like putting a little dimple or pulling a bit higher as you manipulate the braze on of the tube rather than alignment type stuff.

I'd probably use a grinder with a grinding disc, not a cutting disc, to take the bulk off but switch to files when getting close to the tube and I'd aim to get it flat rather than focus on removing all of the silver. Heat is quicker but you'll need to flux it and I CBA with the cleanup.
Putting heat into the frame should be minimised. Not just for alignment but also for the structure of the steel, making it brittle locally and can be a source of future cracks although it's very unlikely for a small spot like a braze on and if you use a fine torch flame with all the heat in the braze on as MV says.

Probably the heat effect on steel is exaggerated by those who mention it though to be fair. I worked for a framebuilder who was comfortable quickly using a small torch to remove or adjust any brazing

Heat is quicker but you'll need to flux it

You say “need”, I’d say… should!

Right yeah. It's still gonna liquid. Maybe helps wet it out though so makes for less filing flat.
But mostly it prevents oxidisation of the base metal.

Probably the heat effect on steel is exaggerated by those who mention it though to be fair

I’d never noticed brazing braze ons affecting frame alignment until I put 3 little cable guides on a toptube that had an S&S coupler in it and all of a sudden when I undid the coupler for the first time after doing the guides, the frame ‘sprung’ a little bit.

You can rip off small braze on parts with pliers. Just twist them off.