Brazing brass help

Martin: That's an interesting idea. I've seen Clickspring on YouTube do that kind of thing with great success.

Tim: I'd planned on making it 3mm, mainly because it looks like you can get polished brass sheet in that thickness. Now I'm wondering if I would be better off using 4mm milled brass to make the parts slightly less fiddly, and provide a bit more surface area.

Bazyle: I'm based in Exeter. It looks like there is a club in Taunton, so I'll reach out to them. At the risk of sounding stupid, could the jig be constructed out of something like plywood (easy to cut the curve into several pieces of ply laminated together), or would it hit ignition temperature too quickly?

I was thinking that you could probably form the curve just by tightening the screws when you fit it to the door. I am an ex member of the Taunton club ( I have been looking after my mum for the last four years, but now I have a bit of time on my hands)

A bit off the wall perhaps, but if you're going to have it plated how about making it from stainless, you'll easily find a fabricator who will stick it together then

Clamps are used to support joints and allow for thermal expansion. Clamping will cause more distortion.

Clamping to steel creates a massive heat sink making any joining technique involving heat more difficult than necessary. The link to the tutorial is great and will point you in the right direction for making good, strong joints.

Have you considered adhesives. Once the letter box is in place what stresses are being put on any joints? Superglue a nut to a piece of sheet and try to knock it off?

Other adhesives are available 😀.

Keith

If I were making it I'd put a couple of blind holes into the back at each side and have matching holes in the hinge lugs so some loose pins can be used to locate the lugs. Put a rod between the two to keep the pivot holes lined up and then hold in place while soldering with something like this which won't draw away much heat. If the hinge lugs were made a bit wider so the contact area goes up soft solder may do.

Not much point in getting pre polished brass as soldering will muck that up, leave it to the plates to polish and then polish the underlying copper plate before chroming.

Make 'L' shaped plates that incorporate both the the ear and the nut. That ought to make attaching them a lot easier too

There is a club in Exeter - EDMES - building a track at St Katherine's Priory next to Morrissons where it meets in normal times. If you are into Zoom we are having our weekly coffee morning Zoom meeting this morning at 10am and I have sent you details in a PM, look in inbox in the green bar at the top of the screen. If you miss that you can also turn up at the track building session on Tuesday from 10am, it's outside usual precautions, parking on site.

Don't forget a decent closing spring.

Tim: Yeah I think you're right that using the door as a former would work with the brass plate.

Duncan: Good idea! I rung a local engineering firm who gave a reasonable quote and where happy to assemble when I said stainless was okay. I think I figured that brass would be easiest, but obviously not!

CuP Alloys: Thanks for the tutorial, holding it together with fine wire is a really interesting method, and sounds very simple. I haven't considered adhesives, mainly because I'm paranoid that if the letter box fails, I may miss a copy of 'Model Engineer'.

Jason B: Seems like pins are the way to go to reliably locate things. I'll be interested to see how the engineering firm I found today do it.

Nicholas: That's a good idea, and gets the part count down too.

Bazyle: Sorry I missed the Zoom call. Thanks for the invite. St Katherine's Priory is very close to my home so I may pop down (hopefully clutching a letter box) to say hello.

Dave: Managed to source one today.

Just need to find someone who can nickel plate the stainless. A couple of firms I rung today said they don't touch stainless. They suggested doing it with mild steel, but were very vague about how durable the plating would be to stop it corroding.

Thanks everyone for all of your help on my random project! It's been a real delight.

If it's stainless you can just polish it, no need for nickel plate

Same here.

Some of the confusion possibly comes from the initial two letters of BRazing being the same as in BRass and BRonze. But the words come from different sources. Braze comes from the old German, then French then Old English word meaning to heat or to burn. Akin to brazier, the metal grid used to hold burning charcoal etc. Nothing to do with bronze, which comes from a Persian word via Italian meaning the metal we know as bronze. Pure coincidence they sound somewhat alike at the start. (The origins of the word brass are unknown but may have originally been to do with the "burning" of ore to make the metal. But today there is no relationship.)

Hi Theo,

As suggested, making your hinge plates with a bit more surface area would make the joint stronger.

A rought guide to types of solders:-

Electrical lead bases solder melts a 300-350 deg C,

Plumbing solder (aca soft solder) around 450 C. (Can be melted with a soldering iron or torch)

Silver solders contain 5% to 45% silver. The higher percentage of silver the greater the strength and also the price. They melt at 650 - 800 deg C.

Brass brazing rods melt at approx. 900 deg C but not recommended for joining brass parts as you could easily melt them.

Paul.

Unless it is to match other Nickle plated door furniture

Rough guide to types of solder.....

Check out the literature of any manufacturer. In 50 years never seen these figures before!

Joint strength has nothing to do with the silver content.

But yes, the more silver, the higher you pay for the material.

However that does not necessarily mean your joints cost more.

Keith

I wouldn't worry too much, our hobby inherits much loose terminology from three centuries of trade and industry!

Brazing was originally done with brass, which is huge range of alloys based on Copper and Zinc, but it was soon found that adding Silver or Cadmium produces a metal that's easier to use and makes stronger joints#.

Since toxic Cadmium was banned most brazing alloys are Brass with more-or-less Silver. Whether an alloy made of 30% Copper, 25% Zinc and 45% Silver is a 'Brass' or a 'Solder' is up for debate.

On the subject of 'Brass', the range of properties available are almost enough for some of them to be considered different metals entirely, especially when heat-treated. Cartridge Brass machines badly, while free-cutting Brass is useless for drawing cartridges. Fortunately the brasses available in most workshops are well-behaved, maybe only getting complicated when a design calls for a particular alloy, or we pick up some weird scrap.

Dave

Edit: #  makes stronger joints.   As soon as I hit send, I see Cup Alloys has posted denying adding Silver increases strength.   I read it somewhere:  he's more likely to be right than I am.  I withdraw in confusion!

Edited By SillyOldDuffer on 05/09/2020 10:27:07

JasonB and duncan: Yes it's to match the other door hardware, and hide any potential burn through from the welding of the stainless.