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Rcpilot 12-01-2005 12:31 AM

Soldering Linkages
 
I have a question about soldering a clevis onto the pushrod.

Let's say you've got a 4-40 pushrod thats already threaded on one end. I'll twist a 4-40 ball link on there and then cut the rod to size. On the other end, I'll solder on a 4-40 steel clevis.

For years, I've been using brazing rod and a mapp gas torch for this operation. It works, but I always end up using my dremel and grinding off the little bit of excess brazing that invariably builds up.

Can I use silver solder for these pushrods? Is it strong enough for 4-40 pushrods?

2slow2matter 12-01-2005 09:38 AM

RE: Soldering Linkages
 
I've used resin core solder without any problems. At first I tried silver solder, but I couldnt' get the thing hot enough without ruining the clevise, so We switched to resing core--no problems. Plenty strong. Just remember to use lots of flux!

LSP972 12-01-2005 10:14 AM

RE: Soldering Linkages
 


ORIGINAL: 2slow2matter

I've used resin core solder without any problems. At first I tried silver solder, but I couldnt' get the thing hot enough without ruining the clevise, so We switched to resing core--no problems. Plenty strong. Just remember to use lots of flux!
Yup. With a 100-watt gun, its a quick and easy job. Mine died, and I got one of those hobby torches. It works just as well, and is actually better for doing wrap jobs like cabanes, etc.

Silver solder is nice, but I've yet to have a clevis come loose using the resin core solder. Like 2slow said use plenty of flux and get the joint HOT before applying the solder. Doan want no steenkin' cold joint...;)

jaka 12-01-2005 10:38 AM

RE: Soldering Linkages
 
1 Attachment(s)
Hi!
Of course you can..I sweet solder all my linkages and have done so for 30 years.
Best sweet solder on the market is Great Planes silver solder (stay-Brite) with the acid fluid that is included.
I use a 50W "Weller" soldering iron with exchangeable iron plated tips since 30 years back. It can handle everything from heavy duty 6mm piano wire to small electronic gadgets.

Regards!
Jan K
Sweden


Rcpilot 12-01-2005 01:56 PM

RE: Soldering Linkages
 
I don't have a giant soldering gun. I do have a pencil tip 40 watt gun, but I'm not sure that will do the job on material as thick as 4-40.

Can I just use my mapp gas torch for soldering?

JohnW 12-01-2005 02:29 PM

RE: Soldering Linkages
 
Pencil tip 40W is enough, but you can also use the mapp gas. The solder jaka mentioned is good, but the stay-brite flux is awesome. I've also used rosin core electrical solder with no issues, including 4-40 linkages on a 35% 3D ship, over 500 flights, not a single failure. In fact, I don't belive I've ever had a solder link fail and I've basically exclusively use rosin core solder, acid and paste flux and a 40W pencil iron. Obviously, you need to clean and flux first. Then on the iron, be sure the tip is very clean. Hold the tip to the 4-40 rod near the joint and wait. After about 10-15 seconds, apply solder to the joint. Be sure the solder is actually flowing becasue of the heat on the part, not the iron. Cheers.

Rodney 12-01-2005 02:36 PM

RE: Soldering Linkages
 
Plain old electrical solder and flux is adequate. The StayBrite silver solder works well but is unecessary as the other will do the job. The main thing is to make sure the rod is perfectly clean before starting to solder. I personally think a 40 watt iron is way to small for 4-40 rods but, if you can do it, fine. I'd suggest a 60 to 100 watt gun. If you do the silver solder, you definately need the 100 watt gun.

harvtom 12-01-2005 09:07 PM

RE: Soldering Linkages
 
Huh!
I've been using regular electrical solder for years- never had a failure- I suspect that's what the other 99% use.

harvee

Rcpilot 12-01-2005 09:32 PM

RE: Soldering Linkages
 
Well shoot:
I got electrical solder coming out my ears. I'll bet I got 20 pounds of that stuff. Dad picked it up at a swap meet years ago and gave it to me. Up untill now--I've just been using it to solder up extensions and battery connectors.

I might try some of that.

I still want to try the silver solder.

Thanks for the help.

fheppenheimer 12-01-2005 09:40 PM

RE: Soldering Linkages
 
Rather than soldering, could JB Weld be used to attach the clevis safely to the 4-40 rod?

sebo 12-01-2005 10:26 PM

RE: Soldering Linkages
 
I wanna hear the answer to this because I was considering using JB weld on my cabine struts (60 size bipe)

LSP972 12-01-2005 11:18 PM

RE: Soldering Linkages
 
1 Attachment(s)

ORIGINAL: fheppenheimer

Rather than soldering, could JB Weld be used to attach the clevis safely to the 4-40 rod?
It would work, but for how long would be the big question.

There's no big secret to a wrapped/soldered joint. It just takes patience... a LOT of patience.:D And there really aren't any shortcuts that I'd trust. You're talking a major structural component in cabanes.

Here's the cabanes on my GP Super Aeromaster. Just installed them today. Yes, they're somewhat of a PITA. Not as much as the N struts are going to be, though. But, hey... that's why I like to build these things... the challenge. I like ARFs too, but they are something you assemble to fly while you're working on a REAL project like this.;)

Edited to add: I DEFINITELY would not use JB Weld to secure a pushrod linkage. While the stuff is amzingly tough, i have seen it fail several times in model applications, particularly in high-vibration areas. Hey, it might work like a champ. But I'll let someone else try it out.:)

mirwin 12-02-2005 12:27 AM

RE: Soldering Linkages
 


ORIGINAL: Steve Campbell ". . . . There's no big secret to a wrapped/soldered joint. It just takes patience. . . ."
Steve nails it.

I hated to think of having to solder steel. But it was only because I didn't know what I was doing, so I asked a master builder in the club to teach me.

But you can't cut corners, or substitute materials. For example, if you're using silver solder, then use at least 45%, use the right flux and use MAPP gas (propane gas won't get the steel rod hot enough.)" For soldering a clevis to a 4-40 rod, I use MAPP gas; it's the only way I'm going to get that 4-40 steel hot enough to suit me. I won't risk my planes for anything less.

Take your time. Approach it as you would any other building challenge. Do it right. And the joint will look good (like Steve's job), and it will probably outlast the airframe.

And if you aren't sure what you're doing, ask. There's no shortage of experts in this hobby.


Mike

da Rock 12-02-2005 08:14 AM

RE: Soldering Linkages
 
JBWeld is magic stuff and will work great but it's like rosin core solder, acid core solder, no core solder, brazing or welding... you gotta apply it sensibly, by the book. I've got connections made with it 20 years ago that're still solid. But they were a good fit to begin with, the two parts were very clean, the joining surfaces were roughed up to give the epoxy something to grab and I look at them every so often (like when I plug in the charge cord).

Rosin core solder holds flex cable "push rod" in my motor connectors on all my a/c engines. I throw away the tightening screw, just stick the wire through the hole and solder it. Needless to say, I clean both first and use enough flux. After it cools, I clip off the wire sticking out the front and file the whole thing down to get rid of a lot of the connector body. When I first started doing it, I worried that it might not be strong enough so put it in a vice and tried to pull the wire out. Don't take my word, try that test yourself. But make sure you have a crow bar handy if you must test to failure to prove it to yourself. And watch out that you have room to fall without hurting yourself. :D I've also tested solder-on clevises soldered to piano wire. Regular 60/40 will hold excellently well. And especially if there is a bit of rod showing in the clevis and it takes solder as you're applying. That proves your heat is sufficient and you're flowing the solder where it needs to go. Test that for a chuckle or two.

Brazing and silver solder work too of course, but to me, that is way overkill. Truth is, I've got the soldering setup ready to go all the time, so that's what gets used for this job. Oh yeah, I also have work jigs setup, so I clean the parts, walk over, put the work into the "vices" and done.

pettit 12-02-2005 09:21 AM

RE: Soldering Linkages
 
Go the local building supply warehouse and get a roll of OATEY lead free solder. It's used for plumbing these days.

I use Stay-Brite flux with this solder. Clean the joint completely with alcohol after soldering and maybe put a drop of oil on the joint too.

It's a lot harder than electrical solder and a LOT cheaper than Stay Brite.

mirwin 12-02-2005 01:52 PM

RE: Soldering Linkages
 
Here's my last 2 cents worth (unless I think of another):

I believe that solder joints fail because the harder, more massive of the two components to be soldered didn't get hot enough to bond to the solder. Take soldering a 4-40 wire to a metal clevis for example:

The wire and the clevis might get hot enough for (1) the solder to properly bond to the thinner clevis and (2) for the solder to melt and run. But, being more massive, the wire doesn't get hot enough for the solder to bond to it. That joint will fail quickly.

When I solder such a joint, particularly when it's a critical joint such as a wire to a clevis to control an elevator, I do as darock does, I try very hard to pull the joint apart. If it's a good weld/solder joint, you won't be able to pull it apart.


Mike

2slow2matter 12-02-2005 02:13 PM

RE: Soldering Linkages
 
Yes, and then I put the linkage into the plane, and then I start to worry that I pulled hard enough to see that it wouldn't come apart, but maybe too hard--and that I might have weakened it, so I take it back out, and pull some more, then put it back in, then back out,,,,,oh, the compulsiveness of it all!!!:D:D:D

mirwin 12-02-2005 02:56 PM

RE: Soldering Linkages
 


ORIGINAL: 2slow2matter

Yes, and then I put the linkage into the plane, and then I start to worry that I pulled hard enough to see that it wouldn't come apart, but maybe too hard--and that I might have weakened it, so I take it back out, and pull some more, then put it back in, then back out,,,,,oh, the compulsiveness of it all!!!:D:D:D

LOL LOL

I bet you worry about whether you closed the garage door when you left the house too. LOL

2slow2matter 12-02-2005 03:25 PM

RE: Soldering Linkages
 
In the past, when I've had garages, I did--hehehe. Now, I just have a carport, so I don't worry about it so much. :D

flatspin1b 12-04-2005 07:41 PM

RE: Soldering Linkages
 
RE; Epoxy and metal joints: There are two types of joints when using glue or epoxy on metals,
The one that Failed........and the one thats Gonna!! (this was stated at a 3M seminar on epoxy)

desmobob 12-04-2005 09:37 PM

RE: Soldering Linkages
 

ORIGINAL: Rcpilet


For years, I've been using brazing rod and a mapp gas torch for this operation. It works, but I always end up using my dremel and grinding off the little bit of excess brazing that invariably builds up.

Can I use silver solder for these pushrods? Is it strong enough for 4-40 pushrods?

I use regular solid solder and paste flux like I'd use to sweat copper pipes. I keep a propane torch under the workbench and a small pair of vise-grips to hold my work out over the edge of the bench so I don't drip solder on anything important (or flammable!).

First, I brighten the end of the pushrod with sandpaper and clean it with alcohol. Then I dip the end of the pushrod in the paste flux and then use it to apply flux to the inside of the clevis. For regular solder, using the propane torch to heat the pushrod and clevis takes just a second or two.

I use the same regular propane torch and the Great Planes Stay-Brite silver solder and flux to wrap and solder landing gear legs, etc. Works perfectly. Quick and easy, too. I save the soldering guns/pens for electrical work.

Good flying,
desmobob

da Rock 12-05-2005 07:36 AM

RE: Soldering Linkages
 
flatspin1B,
That old saw also applies to epoxy and plastic (like hinges and control horns). It's why plastic hinges (the good ones) have lots of holes through the flats. When the epoxy fills the holes and continues on into the balsa on either side it doesn't have to continue to grip the plastic.

Nobody much goes to lengths to advise modelers to provide "holes" for every epoxy joint in metal and plastic, and we're the losers. But if you take a couple extra seconds to score the two surfaces or drill some holes and make sure both surfaces are nice and clean (acetone is cheap and a pint can has lasted me since the '60s) joints that rely on epoxy that's mechanically assisted will last a very long time. I was just checking the glued on horns and the glued on connecting rod ends, and the glued in nylon hinges on my 2m glider last night and noticed that I'd built it in 1984.

Every construction article ought to explain what you've mentioned. Any epoxy joint really should have more than just the epoxy's grip holding it. All that make the glued together surfaces have to pull apart through/over/around cured epoxy aren't going to fail. Just relying on surfaces touching with epoxy between will.


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