GRandolph

I tried soldering the threaded coupler and pushrod (see photo) together but once again, the solder didn't stick. I sanded the end of the pushrod, cleaned the parts in acetone, dipped the end of the push rod in flux. I put the rod and the coupler together, held in a vise. Then, heated both parts using a propane torch until most of the flux had just bubbled away. Then, I touched the solder (in photo) to the parts at the joint and the solder just beaded up and fell off! Not one molecule of solder wicked into the joint. I am at my wits end. What am I doing wrong!

N1EDM

My Feedback: (2)

I've never used acid core solder. Maybe others have and can comment on how strong it is.

You seem to be doing everything right but there is one question... how hot are you getting the metal? I use a plain old soldering gun and I get very successful joints in a few seconds but this is not using a flame. Perhaps the propane flame is making things too hot (just a guess).

I would recommend that you get some Sta-Brite http://www3.towerhobbies.com/cgi-bin...&I=LXFS75&P=ML and a gun, and say away from the torch.

Just my $.02

Bob

N1EDM

My Feedback: (2)

Another question is to ask why you are using two threaded clevises? I would recommend using a single clevis, which you have, and a right-angle bend and keeper on the other end.

Just another $.02

Bob

GRandolph

I am heating the parts by engulfing them in flame. I did not use the hottest part of the flame (dark blue), i used the lighter part of the flame. I held the flame on the parts approximatelly 15 to 20 seconds. During this time, the flux began to bubble and boil. When the flux had almost completely bubbled away (after 15 seconds or so), I removed tahe flame and applied the solder. The metal was not red hot. The solder melted on contact, but did not wick. I then immediately put the flame on it full force until the metal glowed red hot. Then pulled the flame away and applied solder but it beaded up again.

Oh, I am not using z bends because when I have made them before they have had what i considered too much slop in them.

N1EDM

My Feedback: (2)

If you happen to have a good heat guy, give that a try. My joints don't get anywhere near cherry red.

Here is a trick, and please (everybody!) read it CAREFULLY before you start to flame me. Here goes:

If you use a gun or very heavy duty soldering iron, clean and flux the joint like you've been doing. On the soldering tip, put just a dab of solder on... this does two things. The first is that it tells you that the tip is hot enough. Secondly, if you put that little blob on the joint (the junction of the clevis and the pushrod), it will transfer the heat like crazy. Do NOT rely on this blob to do the soldering, only to transfer the heat. You still have to apply solder and it should wick all the way up. If you use that 'dab' of solder to do the actual soldering, you'll get an unreliable, cold solder joint.

Hint: If your gun/iron is not hot enough, don't even bother. The heat will wick away from the joint too fast and the joint will never come up to temperature.

I think that you are burning the flux all away, and then the metal is oxidizing, which is what is causing the solder to blob up. If you have to use a torch, I would recommend that you apply the solder before the flux boils away. Be careful not to anneal the clevis.

Just another $.02

Bob

foodstick

I doubt this is any of the problem, but I always clamp my soldering piece in a wooden clamp, like a clothespin. A metal vise will be pulling heat out of your part...

speedracerntrixie

My Feedback: (29)

Way too much heat. put the torch away and use a good 25 to 35 watt soldering iron. Place the heat onto the coupler and work the solder back and forth at the coupler/rod junction. When the coupler gets hot enough it will melt and draw the solder into the coupler. The solder will flow to the heat source so keep the iron on the coupler. Being brass it will heat pretty evenly with the iron. If you need some added heat conductivity you can get a small amount of solder on the tip and flow it onto the exterior of the coupler. After soldering I will usually sand off the excess and polish with an SOS pad and water.


What is happening now is you are overheating to the point of oxidizing the base metals. Clean everything with steel wool or fine sandpaper or even better, start over with new peices.

ARUP

The vise may be acting as a heat sink to 'steal' the heat from the parts before the solder has time to act. I use a propane torch exclusively. The key to soldering is to not get the parts too hot as you are doing. Apply the torch 'gently' and away from where you wish the solder to flow. Solder will flow towards the heat. I use liquid flux. It will bubble but should not boil away. That is a sign the parts are too hot. Hold the solder against the part but a few mm from the joint and pass the flame across parts opposite side from where solder is touching. The solder will travel toward the heat. You will see the solder melt so just keep feeding as much as you desire. It doesn't take much. Take the heat away then put a drop of liquid flux onto the joint. It'll really shine and freeze the joint to perfection. Don't get the parts red hot. They will lose their temper and won't solder together anyway. This is my method for soldering with Stay-Brite solder and is not the only way to do it. It works for me and I have soldered parts for my models to prove it. If you wish to see some of them then PM to me.

GRandolph

Thanks for everyone's help. I think I was boiling away the flux. When i first tried soldering (unsuccessfully) the parts they were arranged vertically as in the photo. I have since retried with the parts held horizontally as shown and the solder held! With the part almost horizontal, the flux melted and was able to run out. The vertical arrangement seems to trap the flux like a cup holds water. Also, I am not sure that much flux wicked into the parts. A better design for the GP threaded connector would be to have a weep hole in the bottom of the connector to allow flux to flow out and solder to flow in. I don't know if I can trust what I have soldered, any ideas on how to test the solder to be sure it will hold?

CanDo

Everyone here has some very good input. Good solder connections occur around 700F, an open flame is much hotter than that. Controlling the temperature with an open flame takes a lot of experience, a soldering iron or gun is much easier to control. Also, a vise will act like a heat sink and work against you. You can solder together a test article with similar pieces you plan to use and stress it (twist, bend, pull, etc), but understand solder is mostly lead, it's not like welding something together. Silver solder has a small amount of silver in it and is stronger than regular solder. Good luck!

qldviking

I personally use silver solder, I have 2 grades,, one is 40% silver the other 55%. I only use a pocket butane torch for soldering, with a small flame setting it does the job nicely. One thing I do is 'score' the steel rod, by running a coarse 'millsaw' file around the rod along the files teeth, just to give the solder extra grip. I'm not sure exactly what the flux is I have been using, the label fell of the bottle long ago. I do use vise grips as heat sinks tho, about 1 inch away from where I am soldering, I dont want to affect the tempering of the rods I am soldering too much.

Campgems

First, I didn't fully read all of the post, so I may be repeating something someone else has already said.

You show a paste flux and an Acid core solder. A paste flux is ok with a solid core solder, but two fluxes, IE the acid core and the paste can lead to problems.

Second, the first rule of soldering is to put the heat where you want the solder to go. In your case, the hot spot should be on the shank of the clevis you are soldering, and the solder applied to the wire just a bit away. When the heat is right, the solder will suck up into where the heat is, where you want it. If the heat is on the wire, the solder will flow to the hot spot on the wire, not to the joint.

Clean metal is a must for a successful solder. Any dirt, oil, or oxidization will prevent the solder from flowing. This is true for any type of solder. If you overheat a piece before the solder can flow, you will end up with oxidation and a bad solder joint The flux prevents oxidation, but will not remove any already present. The acid core lead/tin solder will to some extent remove the oxidation, but it isn't a sure bet.

Last, the metal your are soldering has to be bright. IE no finish. Some of the threaded Clevises have a black oxide finish. You need bright metal for a good joint. Your acid core solder may over come this to some extent, if it is fresh solder and you tin both pieces prior to the final joint.

A little solder is good, a lot is a problem. A tight mechanical joint is needed for a solder joint to be strong. You can't fill in a gap with solder and have a strong joint. This is so if you are soldering wires, copper plumbing, or steel to ? clevises.

A last point, the metal you are soldering has to be compatible with the solder you are using. A chrome/nickle plated part can't be soldered to a steel wire., or anything else. Make sure solder will flow on both pieces your are going to solder.

Don

ARUP

Yes, be sure to clean and score the parts. Get some small rifling files to score the inside of clevis or tubing and some flat metal files for scoring exterior of parts. When you are done wash the parts thoroughly with soap and water. I 'taste test' them. If there is still an acid residue on them then clean again. Unless you've lost your sense of taste this is a very sensitive method and won't kill you but your mileage may vary. As a disclaimer, I don't recommend you do this but it works for me! The acid (flux) will cause the joint to fail over time if not removed.

GRandolph

Thanks for the good advice. This morning I ordered a bunch of pushrods, threaded couplers and some stay bright solder and flux. Hopefully with a little more practice using the tips given here I can get four good soldered couplings.

AMA 74894

My Feedback: (1)

Here's an article that may help out also

http://www.rcuniverse.com/magazine/a...article_id=172

Twin_Flyer

My Feedback: (4)

Mixing two types of flux is also not a good idea. You have traditional soldering paste flux (non acid) in the tub but the solder clearly states acid flux.

Personally I use standard solder either with no flux core or with rosin flux (standard electronic type) and add a bit extra flux from a tub (again standard electronic type) and use a small, refillable torch, not the standard plumbing type.

keep the end your soldering a long way away from the jaws of the vise or it will absorb a bunch of the heat and make ti harder to solder.

Seconds after the flux starts to melt hit it with the solder and it should wick into the joint. Also be sure to heat the brass part at the same time as the wire.

As others have said be sure everything is clean and ready to go.

Good luck!
Bill S.

LesUyeda

I have been in this game for an awfully long time, and have never used anything other that standard radio grade 60/40 lead tin solder. Never had a problem.

Les

Rodney

I'm with Les on this, use 60/40 solder and rosin flux with never a problem. This is on large and small planes, some 4-40 some 2-56 size couplers. I usually use a 60/100 watt gun for this but also do well with both 40 and 60 watt irons.

Twin_Flyer

My Feedback: (4)

I tend to use the Stay Brite Silver solder and the included flux for anything structural. Its a lot stronger then standard 60/40 solder.

http://www3.towerhobbies.com/cgi-bin...&I=LXFS75&P=ML

Bill S.

Twin_Flyer

My Feedback: (4)

For some reason I am unable to edit my earlier posts.

I should have added I only use standard electronic solder on areas as throttle or nose/tail wheel control and never an elevator, aileron or the rudder systems.

All else gets the Stay Brite.

Bill S.

EscapeFlyer

My Feedback: (1)

+1

I would not use a torch on this. The soldering gun would do better.


Brian

bjbellino

My Feedback: (176)

Agree with the 60/40 solder, and I would dip the rod and solder into the flux and then bring the coupler, rod up to heat while touching the solder to the rod, the solder will tell you when it is ready to bond and solder the coupler and rod together. When the solder begins to get soft, back the heat away, and only bring the heat back in when the solder stops flowing. If needed stop the heat and dip the solder back in the flux and back to the job at hand, If the flux gets burned off it will not help the solder flow between metals. Do not apply heat directly to the solder. Hope this helps.

WhiteRook

My Feedback: (38)

too much heat was what i was doing wrong. i tried soldering music wire using silver solder, and once i cut the heat back it worked great.

epr3

Stay Brite is the best for the job

ssautter

The flux should not flame or boil rapidly. That indicates too much heat.
The fluxserves two purposes: 1) it cleans the joint and prevents oxidation of the filler material. 2) it aids in the capillary action or "wicking" of the joint.

I use a cheap Harbor Freight torch for thicker/structural joints, with the Stay-Brite Silver Solder: http://www.harborfreight.com/micro-torch-42099.html
Hobbico offers a similar torch: http://www.hobbico.com/tools/hcar0755.html

When soldering landing gear, or other T-joints, I first wrap the joint with a single-strand of small-gauge electrical wire....shown in the pic.

Keep in mind that non-ferrous metals require different solder, and particularly different flux, as opposed to ferrous metals.
As mentioned previously, the flux must also be compatible with the filler material.

To test the solder joint try freezing it and applying torque. As you become more proficient, a visual inspection will be all that is required.