Soldering Photo Etch

[bluenose2]

After a long and arduous trek I am finally on the back end of my build of the 1/72 Revell Corvette Snowberry. The thing I have left to the last is the build of the photo etch holders of the amunition for the 4" main gun. This comprises 3 miniscule pieces for the holders of the shells. 36 in total. I'm hoping someone has completed this part and could give me some advise. I can't figure out how to build a jig or some other way to make these units.

[bluenose2]

[bluenose2]

[bluenose2]

As you can see. These parts are very small. I don't think I can solder any of these. CA will be the way, but it is figuring out how to assemble them is what's got me.

[wefalck]

Perhaps trying to find a picture of the real thing may help to understand what the final product should look like. Otherwise, making a jig from a small piece of wood would probably help putting part 23 and 22 together. As 22 simply butts against 23, I would rather solder these joints than glue them. After cleaning up the part and perhaps some pickling, part 24 can go on with CA. Alternatively, one could solder 24 onto 22 first with a higher melting-point solder.

[bluenose2]

I have pictures in books but they are not close ups. I understand the assembly process and know what they look like, but I'm wondering if would be easier to leave 23 on the fret and solder 22 to it. Or reverse. Im concerned that any alligator clips etc. for holding parts may act as a heat sink and make it difficult to solder such fine parts. I use a Weller WES51 soldering unit for small work and a small hand held butane tourch for larger work. I guess what I'm saying is how would you guys hold the parts together so I can solder them?

[BANYAN]

I think experimentation is the only way to find out for sure.  Looking at the illustration, I think putting 24 onto 22, then that assembly onto 23 looks easier.  I would also use two different temp solders, and use the higher tem on 24/22 first.  it might also help to make two small wooden jigs/rests onto which to rest the parts while soldering - shape these so that the two parts are at their correct respective heights to each other, with a front and rear 'lip' ( or simply use a small piece of blue tack at front and extreme rear) to keep them in place; scrap wood will do the job.  I wouldn't worry about the blue tack being a heat sink as it will be far enough away from the joint.

 

I think your biggest concern will be 'blowing' holes in the brass with too much heat (depending on its thickness)so some heat sinks may even be beneficial.

 

cheers

Pat

[bluenose2]

Well here we go. No guts no glory. Thanks for your help. Fortunately two extras are included, so hopefully I can get this right before I start on the real ones.

[Jaager]

Does resistance soldering work for this sort of work?

[Dr PR]

I think you should form (bend) all three pieces before soldering/gluing them together.

 

You will want sharp bends at the acute angles in parts #22 and #23, and for that the pieces should be clamped between two things with sharp edges and then bent into shape.

 

I would make a rectangular wooden tool piece to shape part #24, and another for part #22. The thin "arms" or extensions would be bent around these.

 

The wooden shaping tool for part #22 could also serve to hold #22 and #23 while they are soldered together. You could clamp the two pieces to the wooden tool and then solder them together. The tool itself could be held in a vise. This would free both hands for the soldering.

 

Then solder #24 to #22. I don't think you have to worry about the #22-#23 solder joints becoming unsoldered while attaching #24 to #22 if you make the #24-#22 solder joint quickly. To be cautious you can just wrap a wet piece of paper towel or cotton around the soldered joints.

 

To get a really quick joint with good solder flow use a liquid flux and a hot iron. I like the citrus based flux for very small joints. I routinely hand solder 0.01x0.01 inch (0.025x0.025 mm) IC pins to circuit board pads using the liquid flux.

 

After soldering, if you have a bit too much solder around a joint, you can use a wire brush in a Dremel to remove excess solder and polish the joint.

Edited October 30, 2019 by Dr PR

[bluenose2]

Thanx guys. If I get this right I'll be able to solder fly hairs to a microbe.

[bluenose2]

As to resistance soldering I have looked at this and the equipment involved. I just don't know anything about it or if it requires different techniques to achieve the same results.

[Dr PR]

I have a resistance soldering unit, but I have never had really good results. This is mainly because I can do most things satisfactorily with a regular temperature regulated soldering iron, so I have never really learned how to use the resistance unit. The main problem with the resistance soldering unit that I have is that it uses carbon rods for the soldering tip, and they are brittle and break VERY easily. They are also pretty expensive and I go through a bag of them pretty quickly.

 

I have no idea why they use the brittle carbon rods.