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Please help shrt Q. on soldering brass


Chofo
09-12-2011, 02:51 PM
Hi:

Would apprecciate help. First time working wuth brass or soldering anything. This is to make parts for the 1/24 Ferrari 250 GTO.

I'm trying to solder a couple of brass rods with a 25 w soldering iron.

It melts the solder when I tin the tapered surface, but when I touch this tapered surface near the joint to be soldered, IT DOES NOT MELT THE SOLDER AS IT IS SUPPOSED TO DO...

Should I buy a 40 w soldering iron? Is that the big difference? Or am I doing somethig else wrong?

Thank You

R.

gionc
09-12-2011, 03:02 PM
Mmm this is not the right way with one iron: it is supposed to be a right way (put a small piece of soldering wire paste -0.5 mm any 10 mm of seamed line- and warm up the two brass section with a FLAME soldering tool until the paste melt.

With a iron you have to:

-1: check the "tapered" bit: it have to be done by brass or copper: if it is chromed iron the stuff is too cheap to work decently... you may fill a new one on a lathe or ask a friend to do so....

-2: you have to use a flux liquid: it is a acid solution that clean and de-oxide the parts, ans also limit the work area, brush the flux with a thin brush (wash it than) when you need to seam

-3: using the iron collect a drop of solder melting the soldering paste (wire, better the thin one (0.5 mm diam) without paste inside...., when you move the tapered bit very near the area supposed to be soldered you'll see the drop going to the flux..... I guess without the flux with the iron you do nothig, if not big balls of solder or cold seams.....

-4: it need practice: muuuch practice, to do clean invisible strong seams, but anyone may do it.

-5: it si cool and fun... so it's easy do muuuch experience and screw up ton of rods....

-6: the work area must be quite clean

good job...

Chofo
09-12-2011, 08:09 PM
Thank You very much! I'll try to find the right materials and then practice a lot!
Chofo

MidMazar
09-13-2011, 01:19 PM
One key aspect of soldering any material is to use the proper flux (paste). Good luck.

CFarias
09-13-2011, 06:30 PM
Everything mentioned above is great advice and should be followed.

In addition to that it could be the result that, as you put the pieces together to be soldered, you have now increased the amount of heat absorbing mass that the soldering iron has to overcome. For example, if you double the amount of brass being soldered then the brass will take twice as long to heat up.

Also, long pieces of brass such as rod or tubing, owing to their shape, can reject the heat to the air quickly which will also exacerbate the situation.

And, if you are soldering directly on a fire brick or some other massive object, the heat from the iron could be going right though the brass and directly to it. I use a marble tile piece and it can absorb a good amount of heat from my pen torch.

Finally solder, once melted and cooled, will need a higher temperature to remelt.

Normally these wouldn't really be a serious problem but I don't know if a 25W soldering iron wouldn't be affected by them. If there is anyone out there who uses a 25W'ter please chime in on your experience! 40W would naturally be better.

I use a resistance-type soldering system but those are very expensive, however, I also use a small, affordable, pen-type soldering torch with very good results.

Also, pick up some copper braided line at you local electronics store like Radio Shack (you can get the pen torch there, too). Sometimes when you are working a joint you can accidentally remelt a previous joint nearby because of the heat. Wrapping the copper around the brass just upstream of the older joint keeps the heat from reaching it. The heat will go down the copper and not the brass; so, be careful as the copper will be very hot. If you can't find the copper braid, strips or thin rods might also work.

Hope this helps.

CFarias
09-13-2011, 06:35 PM
P.S.: How big is your soldering tip? Larger tips can solder better. Tiny, pointy ones like the ones used for circuit boards can be too small to transmit enough heat to the relatively larger brass effectively.

CrateCruncher
09-13-2011, 06:56 PM
Good discussion. I have a 25w/40w unit I bought from Radio Shack for about $25. It works great. I heat it up set on 40w and usually leave it there unless I'm doing a complicated part with multiple joints in close proximity. Even when I use the 25w setting I warm the unit up on 40w to save time. The tip is an odd shape. Instead of a point the end has a cylindrical section like someone drilled a hole through the side of the tip leaving a channel in it. I didn't think it would work very well but it turned out to work beautifully for the tubular spaceframe stuff I normally solder. Go figure.

To the original poster: Try applying a flux paste on the solder surfaces like everyone else has said. Soft solder simply won't work without it. That's usually the step beginners omit for some reason.

935k3
09-13-2011, 09:46 PM
I have soldered for my jobs most of my life(mostly electronic stuff) and one thing I have learned is a greater heat that heats up the parts quickly and removed as soon as possible is better than not enough heat that takes the parts longer to heat up, it's bad because the part holds the heat longer and the joint isn't as good. It also makes the job easier and quicker to use plenty of heat. Using the right size and shape of tip for the job at hand is also important.

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