Silver soldering small components

[Murph1090]

The upside to alcohol is you can brush it on and have a layer of dry flux between the parts, where it can't burn off from the torch heat.

When I do parts, I use air-acetylene torch, that way you can't overheat your part, and I use a large tip, and lower pressure, so the flame doesn't blow small parts or the solder out of position. If I keep my distance with the torch, it all heats up evenly and joins near seamlessly.

Murph

[Toolmaker51]

Thanks!
That is a lesson I am just learning - take a few extra minutes to make a jig.
I have a couple chunks of metal with all sorts of holes in them - I don't recall what most of the are for now, but they were in just the right place when I needed them.

I probably look at every part as candidate for a jig or fixture. At the same time, quantity [and then repeated use] is what justifies how sophisticated a jig/ fixture is called for.
If the plan then calls for tooling, one additional feature is worthwhile; the means to remount and locate via a reference feature [a pin, a step, a hole...etc]

[thehomeengineer]

The clutch linkage is nearly complete and I thought I would share how I fabricated the shaft and made the the box housing with different soldering techniques I use.

The box is relatively straight forward as it is screwed together and a mounting flange at the bottom. However screwing matting faces together is not great for silver soldering as there is no gap for the solder to capillary into. To over come this I file notches and grooves where I want the solder to flow. This doesn’t give satisfactory joints for pressure fittings but is great for fabricated components. The notches and grooves allow the solder to penetrate the joint as can be seen in the photos below.
Components to be silver solder together.

Filed notches can be seen on the inner part of the flange.

Flat plates that are to be screwed to top bearing block.

All shot blasted ready for assembly and fluxing.

Top bearing housing fluxed ready to accept plates.

The seems are also fluxed on the inside.

Base flange is a tight push fit over plates.

The photo shows that the solder has penetrated the base flange joint.

The heads of the screws are filed off.

Completed box housing for clutch linkage.

The shaft is made from a commercially available stainless steel 8mm diameter 4 start thread and a brass flanged nut to suit.
As this requires a flanged section this is rough turned over size and silver soldered in place. The shaft and the flange section can then be placed in a collet and turned true to each other and to size. The shaft is 3/16”diameter and the flanged section drilled 0.004” (0.1mm) bigger to create the gap for the capillary action.

Shaft and flange

Again to stop the solder flowing we’re it is not needed the paint pen is used.

A silver soldering ring is bent up and placed on the joint and fluxed.

Heat is applied to the largest section and the heat draws the solder into the joint.

Completed shaft awaiting top bearing and locknuts.

Thank you again for viewing and hope this will help those starting out silver soldering.

The Home Engineer

[thehomeengineer]

Nearly on the final stretch of the clutch linkage. The last of the fabricated parts are the two dog bone links which again are a silver soldered fabrication. The most important thing is that the links have both the same hole centres (pitch). To achieve this a scrap piece of material is drilled and tapped at the correct pitch and the ends of the dog bone linkage are held in position with countersunk screws and the tie bar fitted into drilled through holes. The fabrication is completed by soldering the joints.

One dog bone link machined ready for soldering.

Soldering jig

Screws painted to prevent solder contact.

Soldering completed.

Removed from jig.

Cleaned up using shot blasting and the holes need to be reamed.

Completed assembly awaiting operating handle. (Not sure if you make single crank or wheel type).

Thank you for viewing
The Home Engineer

[Okapi]

It's very interesting to see how you make them by pair, soldering in an oven like those used by dentist can be a good alternative for a cleaner finish with less work after soldering, have you never tested the protection coating for a cleaner heated surface with less oxydising ?

[thehomeengineer]

Hi okapi
thank you for your comment. Correct me if I’m wrong but I think you are talking about a vacuum furnace which prevents oxidation and the need for flux. This is very specialised piece of equipment and has it drawbacks like brass can’t be used as the zinc is removed during the process. Also size of furnace and cost. The acid bath and the shot blasting cabinet I use are adequate and cost effective for the jobs I do. Please correct me if I have miss understood.

[Okapi]

No, I'm simply speaking of the very cheap furnace used in the past for the dentistry mechanical use which are no more usable with new norms about sterilization etc.
They can go to 1'200° C and are generally less than 200 €, they can be use with inert gas generally by a very simple hole in the back but for me using borax is less expensive, I have two of them, one used for oil or water hardening and the other for carbon hardening with powder which make a lot of smoke and leave some residues in the furnace.
Using the hole for the gas introduction they are regulated by a captor and an electronic command unit.

[thehomeengineer]

I have never considered this but am always interested in other ways of achieving results. At 200€ a bottle of inert gas and another piece of kit to store in an already crammed workshop I don’t think I can justify the outlay. Have you had success using this method?

[Okapi]

I'm using this technique since I was an apprentice, we use that for small pieces or for pieces which doesn't be cleaned, but near never with inert gas, just with borax or in special ignifugated bags for medical components, What is expensive with inert gas is the bottle but you can find small bottles very cheap made for small soldering units in the discount stores normally, here it's a current thing, for me I use a bottle I've bought at one time and it cost me about 40$ for a full new one and it's for two years approximately.

[willyb]

If you don't happen to have a paint marker available, another material you can use to prevent silver solder from sticking is correction fluid also known as "White out".
It's a opaque liquid that dries after it has been applied and was used to mask text errors on paper.

Cheers
Willy