95 replies to this topic

[Pablo]

Robb, interesting how you don't agree that the jig is robbing (get it -"robbing? ) heat from your torch joints, yet your best joints are those up off the jig.

 

As for the comment from the gentleman from Norcross, "Sort of like the difference between an X-Acto knife and a machete...", I refer to my photo in post #9 and ask if that assembly looks like it was performed with a machete? Radio Shack minitorch, a couple alligator clips, 63/37 solder, and a wood block.

[Cheater]

Pablo and I have debating this topic for years...

 

Lemme see you solder them leadwires on with a torch, pal... LOL!

[John Streisguth]

Maybe with a billet guide flag.  

[Mike K]

63/37 solder

 

[robbovius]

It just keeps getting better. ;-)

[robbovius]

Robb, interesting how you don't agree that the jig is robbing (get it -"robbing? ) heat from your torch joints, yet your best joints are those up off the jig.

 
I see what you did there. ;-)  Yeah, are you referring to the solder joint on the axle uprights, along the frame tubes? I agree those have a cold-ish look to them, and that may have been more that I had a crap ton of metal laying around them holding things in place...
 
It's a bit blurry here, but this is the joint where the motor bracket and main tubes attach, and this was also done right down on the jig plate. On these these the silver solder flowed right in, nice smooth meniscus and capillaried through to the inside of the bracket and tube. 
 

 
The difference was, I didn't have any weights holding things in place, just the tension of the jig axle between the pins. So, no giant metal heatsink.
 
I may take the bare chassis and do a remelt of those joints along the frame tubes and see if I can get them to flow a bit better.

[Pablo]

Well, Robb, please don't re-do any joints just to make the "solder police" happy - especially me!

My suggestions are only aimed at your future builds. Please continue with the Vette.
 
Cheater, don't bet the farm I couldn't solder leads with a torch - using a "jig flag", and heat sinks on the wires, it could easily be done.

FYI, I'm now using an Ungar for day to day building. The Hakko 455 (machete) is for traveling, Hakko 454 for lead wires/ultra fine work, Weller Gun for tinning wires, and of course the RS Minitorch. Stay Clean acid, Aero paste, .032" RS silver solder, .063" RS Clear Flux 60/40, .032" Kester solid 63/37, and silver solder paste.

Just like golf clubs - you can't putt with a driver, and you can't drive with a putter.

[Bill from NH]

Yes, Robb, continue with the "Pink Vette" build. We want to see it completed.

 

NSP (Not the Soldering Police)                                 

[Cheater]

It just keeps getting better. ;-)

Robb,

The cool part of this thread is all the guys contributing their knowledge and experience.

Wasn't too many years ago that slot racers never shared such info and seeing the "corporate culture" change in this way is extremely pleasing to me.

Thanks to everyone who has chimed in!

[Cheater]

... of course the RS Minitorch. Stay Clean acid, Aero paste, .032" RS silver solder, .063" RS Clear Flux 60/40, .032" Kester solid 63/37, and silver solder paste.

Wonder where you guys are gonna get that RS stuff once the Shack goes belly-up... as is very likely to occur.

[Pablo]

All-Spec has all the Alpha and Kester solders, and Soder-Wicks, in all sizes and types one could ever want.

I just bought a one-pound spool of 63/37 and some .110" width Soder-Wick.

[Bill from NH]

This year I've seen four of my sic "local RS stores" close.

For awhile, Amazon carries some of the RS solder products. If I should run out of RS solder, I got a good supply of silver solder and several pounds of rosin solder. I'm still using 60/40 solder that came with Heathkit kits in the '70s.  

I worked in a local RS store for a few months in 2006. I could see some of their financial problems starting back then. I'm somewhat surprised it's taken this long for them to surface.

[John Streisguth]

Everything is available through other sources. 

I have a RS store local so it's quick and easy to stop in while I'm at other stores in the same shopping center. Or getting a treat at Rita's! 

[robbovius]

Well, thankfully since everything exists on the internet forever, I don't have to scribble notes on any of this.
 
When I wrote, "I may take the bare chassis and do a remelt..." that's since been modified to "I maybe not take the bare chassis and do a remelt..."
 
No worries about continuing the build, tho I will defintely include an experiemtn or two given all the above advice.
 
To wit:
 
Last night I fabbed up the beginnings of the drop arm using my usual method of "sand, flux, torch, silver solder..." with this result...
 

 
At the rear the solder joint looks nice...
 

 
At the front it looks a bit heavy... again I used too damn much solder.  
 

 
But can't say as how it isn't solid.
 
But given that that whole process took about 30 minutes from the first cut to the soldered item, I'm going to do another, only this time replacing the silver solder with some 60/40 rosin core.
 
I used the little pencil torch shown upthread, as the pistol grip torch valve seems to have failed, at any rate nothing comes out when I open it. Happened after I did a refill, holding it upside down. maybe it'll get better.
 
One thing I noticed, and this was a thing that went on with the Catalina frame, was that the tongue material (.5" x .063" brass) took much longer to heat and flow the silver solder than the tubes and rod did. The solder would adhere to the tube, but ball up on the bar below, until the bar got hot enough and then it adhered, and flowed through.
 
Going by what's been posted here, the 60/40 ought to flow much more easily. Don't know if I'll get to that much before Saturday, though we'll see. I have a window of opportunity tonight between work and the open mike I host every third week.

[Cheater]

Didn't pick up on the fact that you were using silver solder... yes, you'll have a far easier time with 60/40. I reserve the silver solder for places where its superior strength is needed.

[Bill from NH]

Robb,

Since you're going to build another drop arm, if you put a 1/2" length of piano wire or brass rod in the joint beside the hinge tube before soldering things up, this joint will be much stronger.

[robbovius]

Greg, yeah, so far I've used everything BUT 60/40. ;-)

 

Bill, you mean lay a piece of rod in the joint parallel to the tube, correct?

[Pablo]

Yep, that's what he means.

Robb, here is a soldering experiment I did about ten years ago:
 
"Torch vs. Iron experiment:

I performed a simple test to compare joint strengths of Minitorch vs Iron then trid and break each joint and rate its strength. I used a Radio Shack minitorch, a Hakko 455 iron, Stay Brite flux, and silver solder, and soldered 1.5" long pieces of .063" piano wire to .063" brass plate. Some with minitorch, and some with the iron. I didn't waste a lot of time trying to make anything perfect, I just fluxed them up, and fired away. 

 

Then I took pliers and tried to break the wire off of the plates.  Both joints on both plates held fast, the piano wire bending up to 45 degree angles with no breakage of the joints. This was no surprise to me, as I have tested my minitorch joints before with success. 

 

I did learn some new things. Here are my findings:

- Both minitorch and iron joints, when done properly, were very strong. Sometimes the iron joints would be stronger, and sometimes the minitorch joints would be stronger. My best iron techniques (clean tip, lots of flux, pre-tin the parts, heat the metals then apply solder) AND my best minitorch techniques (not going to divulge my secrets here, it's too lengthy) always resulted in the strongest joints. I did not notice a pattern either way, as far as one being stronger than the other.
- A poor joint caused by a dirty iron, dirty joint, insufficient heat, premature flux burning, poor solder positioning, and poor techniques will result in a weaker than normal joint, in BOTH minitorch AND iron.

- The iron method seems to benefit from lots of solder to make kind of a "nest" for the wire, and the minitorch method seems to do the same job with less solder.

I welcome your opinions and experiences. I'm not saying my methods are the right ones, I'm just searching for truth and happiness"

[Bill from NH]

Bill, you mean lay a piece of rod in the joint parallel to the tube, correct?

 

Yes, that's correct. You might never need the extra strength, unless that car ever hits a wall or another car just right. But that's one joint I might want to retain the extra strength of silver solde,r too.

[Cheater]

If you guys will forgive me for getting a little technical, perhaps it will be meaningful to discuss silver soldering in a bit more detail.
 
There is a lot of confusion between regular tin/lead soldering and silver soldering, which is more accurately called silver brazing.

The solders we use in building slot car chassis are more accurately called silver-bearing solders, not silver solders.
 
"Soft soldering

Soft soldering is characterized by the melting point of the filler metal, which is below 400°C (752°F). The filler metal used in the process is called solder.

Different combinations of tin, lead and other metals are used to create solder. The combinations used depend on the desired properties. The most popular combination is 60% tin, 39% lead, and 1% alloys. This combination is strong, has a low melting range, and melts and sets quickly. A higher tin composition gives the solder higher corrosion resistances, but raises the melting point. Another common composition is 11% tin, 37% lead, 42% bismuth, and 10% cadmium. This combination has a low melting point and is useful for soldering components that are sensitive to heat.

Tin/lead solders (soft solders) are commercially available with tin concentrations between 5% and 70% by weight. The greater the tin concentration, the greater the solder’s tensile and shear strengths. At the retail level, the two most common alloys are 60/40 Sn/Pb which melts at 370°F or 188°C and 63/37 Sn/Pb used principally in electrical work.
 
Hard Soldering

"Hard soldering" or "silver soldering", performed with high-temperature solder containing up to 40% silver, is also often a form of brazing, since it involves filler materials with melting points in the vicinity of, or in excess of, 450°C. Although the term "silver soldering" is used much more often than "silver brazing", it may be technically incorrect depending on the exact melting point of the filler in use.

 

In silver soldering ("hard soldering"), the goal is generally to give a nice, structurally sound joint, especially in the field of jewelry. Thus, the temperatures involved, and the usual use of a torch rather than an iron, would seem to indicate that the process should be referred to as "brazing" rather than "soldering", but the endurance of the term "soldering" serves to indicate the arbitrary nature of the distinction between the two processes."

 

Here's a chart showing the melting points of some common solder formulations.

 

 

I've greyed the boxes for the solders you should probably be using for chassis building: 60/40, 63/37, and what is commonly labled Sn62. This last contains 2% silver and was developed for soldering silver-plated metals, as the presence of silver in the solder prevents the plating from migrating into the solder. It flows beautifully because of its lower melting point and its tensile strength is almost 92% of the 60/40.

 

 

Slot car suppliers have at times offered silver-bearing solders with silver percentages as high as 8%; I know because I have some.

 

Yeah, I know, probably too much info...

[robbovius]

Greg, that's pretty kewl. Thanks for posting that.

 

We're all just geeking out on soldering right about now, and as OP, I personally welcome your fine escalation of the collective geek-out. Or in, as the case may be.

[Jay Guard]

Here are a few additional bits of info that may be of interest...

 

1)  You don't always want to use "stronger" solder, the most common of which are the low silver percentage (2.5-3.5%) alloys. Why, because our slot car chassis flex and take a lot of abuse. If the joints are too strong/stiff they will crack. Seems counterintuitive but here's an example. Back in the '50s when they first started making large metal airliners they made the wings very strong and stiff. After a bunch of them snapped off in flight they realized that overly stiff wings were the problem. If you've flown recently and looked out the window as you're taking off, hitting an air pocket, or landing you'll see what I mean, those wings flex a lot and that's a good thing.

 

2) Concerning alloys and flow. The 63/37 is used mainly for electrical work since it flows into very tight spaces better than the other alloys and has a low melting temperature. So if you got a tight fit and want it to flow well, go for the 63/37, if not, which is often the case, stick with 60/40.

 

3) Never, and mean NEVER, use the very low melting temperature solders for slot car work. The aren't very strong, they are brittle, and they don't flow very well, all bad things. Worse yet they really mess up the tinning of the tip of your iron. Once you've used a low-temp solder you practically have to throw your soldering iron tip away.

 

4) There's at least one place where the stronger, low-silver content high-temp solders are useful. One is for soldering pinions on some of the super high performance motors the Wing and Eurosport racers use. The motors can get so hot that it will unsolder the pinion if 60/40 is used. I know this for sure because it's happened to me!

 

Hopes this helps! 

[Pablo]

Greg and Jay, thanks for the good gouge, and thanks Robb, for allowing us to "geek out" on your thread. 

 

Question: if I soldered a lead wire using a minitorch, would it bother you if I posted a pic here? Just for fun. Or I can just PM it to Cheater. 

 

I'm tired of solder, I wanna see some pink paint!

[robbovius]

Pablo, go for it! that'll be a chall;enge ;-)

 

As an update, nothing build-wise got done last night.  But I did buy a new pencil torch - Bernzomatic by name, in this sweet little case.

 

 

Has MUCH finer flame control than any of the HF torches, and can hold both lower and higher intensity flames than the HF pencil torch.

 

it seems my HF pistol  grip torch has developed a hardened clog in the nozzle, going by the symptoms and what I was able to figure out after I took it apart last night.

 

 

its a really simple device, a tank and simple screw-valve. I might be able to fix it, though it isn't critical. mostly what bugs me is that the failure has wasted about 3/4 of a tank of butane. good thing butane is cheap.

 

I shoudl have more updates later on saturday...

 

 

[Pablo]

Rosin core solder. Flows easy, but leaves a nasty mess: