# Using brazing rod for small parts - good idea? ..and what about the flux?



## VicHobbyGuy (Jun 25, 2022)

I'm new to model building - I  got a lathe just a few months ago.
I've read mentions/suggestions about using brazing rod for parts requiring small diameter brass/bronze rod.
Is this common, or would I be better to just buy brass rod ($$) from a hobby supply place.

And if using brazing rod - what about the flux? Is it easy to remove? Most of the brazing rod I see at PrincessAuto (my local Canadian equivalent of HarborFreight) is coated with flux.

Thanks!


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## lee webster (Jun 25, 2022)

I have no experience of machining anything, yet, but I can tell you that here in the UK I bought from my local DIY superstore a 1M length of 4mm dia brass rod for £6. To me, that makes using anything else a false economy


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## gartof (Jun 25, 2022)

I have used brazing rod for small suff I have (almost gone) some 6mm bare rod works for me
Gary


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## SmithDoor (Jun 25, 2022)

VicHobbyGuy said:


> I'm new to model building - I  got a lathe just a few months ago.
> I've read mentions/suggeations about using brazing rod for parts requiring small diameter brass/bronze rod.
> Is this common, or would I be better to just buy brass rod ($$) from a hobby supply place.
> 
> ...


I buy brazing rod without flux for parts. It is lower in cost


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## VicHobbyGuy (Jun 25, 2022)

Thanks. I'll look around for no-flux rod.


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## krypto (Jun 25, 2022)

Sometimes it's just handy to pick-up a piece of 1/8" brass filler rod and the welding supplies section of the store.  This doesn't have flux.


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## wazrus (Jun 25, 2022)

I've used Tobin bronze as steam chest studs, in 4 and 5mm sizes. TB doesn't usually have flux. In fact, the majority of brazing rods i use do not have flux and in this, i think of the 45% silver I routinely use. I have 45% in both 1.6 and 3.2mm rods. The flux-coated rods have their uses, for sure, but most of my brazing is done without coated rods and that includes welding with TB., for which i usually use a powdered flux.


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## plipoma (Jun 26, 2022)

I've used 1/16" and 1/8" brazing rod for small parts but I think it is not as soft (harder) as 360 brass rod. Can anyone comment or verify?


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## danallen (Jun 26, 2022)

I agree with the post above. You can machine brazing rod but it cuts more like bronze than brass. The flux coating comes off easily - often when you want it to stay on.


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## Bentwings (Jun 27, 2022)

VicHobbyGuy said:


> I'm new to model building - I  got a lathe just a few months ago.
> I've read mentions/suggestions about using brazing rod for parts requiring small diameter brass/bronze rod.
> Is this common, or would I be better to just buy brass rod ($$) from a hobby supply place.
> 
> ...


i haven done stick brazing in many years . Some rod may be bronze rod as that as used to repair cast iron . I generally just purchase what I need on Amazon of from McMaster Carr. Some of this has become very expensive . You should be able to get bronze TIG rod at a welding supply . They often will only have 1/16- 3/32 and 1/8” rods in plain but there may be stick in thicker that you can strip the flux off.  PMResearch steam has some round and flat stock too . They have been very good to deal with they have some small metric taps and dies    As well as scale steam fittings .  If you buy on Amazon check your orders very carefully I’ve received the wrong size several times  it’s usually not worth the trip to send it back unless you are close to a return center.


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## wazrus (Jun 27, 2022)

Bentwings has mentioned sources of very small taps and dies and my experience is that the internet is very hard to beat. Of course, you'll be buying stuff from the land of gleat manuflactures, but I don't have an issue with that when  the prices are right. Just today, I took delivery of five of each 1.4mm and 1.6mm dies, I think for the princely sum of just over US$40 the lot, I think it was.


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## Bentwings (Jun 27, 2022)

wazrus said:


> Bentwings has mentioned sources of very small taps and dies and my experience is that the internet is very hard to beat. Of course, you'll be buying stuff from the land of gleat manuflactures, but I don't have an issue with that when  the prices are right. Just today, I took delivery of five of each 1.4mm and 1.6mm dies, I think for the princely sum of just over US$40 the lot, I think it was.


I too search the internet. And reviews some stuff has poor reviews I try and stay away from or quality . I did have one good experience I wrote a poor review and received a new product that was what I wanted in the first place. At no charge another sent me the correct part and said keep the mistake. So I have a part I’ll probably never use gathering dust  LOL


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## packrat (Jun 27, 2022)

Yes, brazing rod in the 1/4 inch size and larger make good punches and to make small pins for gunsmithing work....


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## krypto (Jun 27, 2022)

The reason 1/8" brass rod is handy is that's the size you need for 5-40 thread.  Not exactly the most common thread form these days, but still a handy size especially if you work on any PM Research kits.


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## wazrus (Jun 27, 2022)

Yeah, your US/UN form threads aren't as common as they once were and a particularly irritating one use is the 4-40 used on DB25 breakout connectors. Gawd, i frittered hours away trying to find screws to suit. i now have some on order - ex internet. I have, in the past, re-fitted those connectors for 3mm metric, but I'd rather not do that. And i haven't found much to grumble about in the quality stakes of taps and dies.


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## Bentwings (Jun 27, 2022)

krypto said:


> The reason 1/8" brass rod is handy is that's the size you need for 5-40 thread.  Not exactly the most common thread form these days, but still a handy size especially if you work on any PM Research kits.


I don’t have much in bronze rod anymore. I have a little iv ordered for small parts but that’s about it bronze is great fit steam stuff over brass. Steam gets after brass after a while especially if very hot


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## krypto (Jun 27, 2022)

If you think 4-40 is hard to source, try finding taps over here for the BA hardware Stuart supplies in their kits. 

I've found it's usually cheaper for me, even with postage, to order the small taps and dies directly from England for some of the more esoteric threads.


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## Toymaker (Jun 27, 2022)

If you copy and paste this phrase "Copper Aluminum Weld Flux Cored Wire Low Temperature" into the eBay search box, or Google, you'll find lots of suppliers.  The sellers call this product "Welding rod" but in truth I believe it's just another brazing rod.  I've seen diameters of 1.5mm to 2mm.  The flux is inside, same as flux cored solder, in fact, at first glance it looks like common solder.   I've been using this product for several years, and although it's sold to "weld" aluminum, I've found that it bonds to mild steel, tool steel, stainless, copper, brass, bronze, and of course aluminum.   The melting point is spec'ed at 360 to 400 centigrade, so a common propane or butane torch can be used.  

It's biggest drawback for me is that the flux is very hard to remove; I usually use sandpaper or a heavy wire bush.


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## Weldsol (Jun 28, 2022)

Be careful what you use re brazing rods as these come in several grades and some may not be suitable for what you want and are not easily identified in the loose bare wire format without the box with the id on it.
the most common ones were Silicon bronze. Manganese bronze. Nickel bronze. Aluminium bronze. all these had different mechanical properties, so some could be ok for making say studs and others not so good.(note these were for oxy fuel brazing using powder flux ) there are quite a few other alloys out there that are used for TIG

Paul


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## Vietti (Jun 28, 2022)

Agree with the comment to be careful about brazing rod for raw material..  Buy a little and try it first!  I bought some 3/16" rod years ago and every once in a while I try to use it and end up cussing it.  It is very hard to turn or thread.


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## awake (Jun 28, 2022)

plipoma said:


> I've used 1/16" and 1/8" brazing rod for small parts but I think it is not as soft (harder) as 360 brass rod. Can anyone comment or verify?


Hmm - perhaps work hardened from the drawing process. Have you tried annealing it?



Bentwings said:


> You should be able to get bronze TIG rod at a welding supply .


Note that TIG brazing rod is a different alloy (silicone bronze) than gas brazing rods and never have flux on them (flux would be counterproductive in the use of TIG). Whether or not the difference in alloy matters when using some as a part in a hobby machinist project ... that is, of course, for the machinist to determine!


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## VicHobbyGuy (Jul 1, 2022)

Update: I bought some brazing rods on clearance and, as reported, the flux is easy to remove. I just soaked the rods in a bucket of water for a few hours and the flux came off with a Scotchbrite pad.


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## Steamchick (Jul 6, 2022)

On the subject of removing fluxes.... many fluxes are in one chemical state when in a powder form, but "activate" when heated to melt/ liquify. Then when they cool, the mixture of un-used flux and chemically changed flux (from taking the oxygen from the oxides) forms a ceramic. Usually, this slag can be either knocked off as it is mechanically brittle, or washed off by soaking in water. Be careful. The shards from brittle slag are hard and sharp like glass. The chemical solution of flux and oxidised flux is corrosive, so can cause chemical burns. Read the safety data sheet before playing around with this stuff. 
Hard to remove slag may be dissolved in acidic wash, such as an acid pickle. I use central heating descaler.... but some slag can take a week of soaking to become loose enough to wash-off. I have never found a slag that won't succumb to pickle solution.
Toymaker, I have not found a specific reference telling us what alloy rods you used for the aluminium joints of your Freon spray bar?? Can you help please?
Ta.
K2


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## Bentwings (Nov 21, 2022)

awake said:


> . I may have been misleading  yes. No flux needed  unused silicone bronze mostly for the copper Rc functioning scale exhausts  also used on some very thin stainless. However I had double regulators so back purging stainless was easier than  just using thin rod I just sold my Lincoln 275 square wave welder plus almost all ofvthe rods I had  considering I leased it to a company I worked at right after I got it then got paid to use it  it didn’t owe me anything. I guess I scored on this one . LOL  one thing that is rarely noted is most TIG welders have a very short higher amount start than you Tink it only lasts a moment but when welding very thin materials this can make poor starts and burned holes . The way to get around this is to have a copper starting block . You start the arc on the copper then quickly move to the area you are welding . Some old timer told me this  even with a pedal start and the welder set on very low power it’s still enough to make a fault in the weld.  I did a lot of aluminum fuel and oil tanked on racers  lots o edge welding.   Another thing this guy showed me was doing just the opposite when tack welding edges start the bump up the power or pre set it . With practice you get so the tacks are in just the right spots so you can  full penetrate weld the seams. He was very good gas welding aluminum . I never did get good with this even with all the best equipment . The TIG welds worked very well but gas  nope don’t bother .   Welding or  silicone brazing copper was tough . Copper soaks up heat like a sponge so you either build in heat sink or have to stop and cool it befor it degrades from excess heat
> Hmm - perhaps work hardened from the drawing process. Have you tried annealing it?
> 
> 
> Note that TIG brazing rod is a different alloy (silicone bronze) than gas brazing rods and never have flux on them (flux would be counterproductive in the use of TIG). Whether or not the difference in alloy matters when using some as a part in a hobby machinist project ... that is, of course, for the machinist to determine!


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