Bending 1/8" Steel Plate

This was my effort, the crank was cold bent from 6mm mild steel in a 5” vice, a bit of work with a file cleaned it up and a good friend welded the boss for the handle and the other end to the main shaft. It was a completely ad hoc build and turned out to be functional. Being a thicker piece of material and the dimensions not critical means any marks from the hammer can be dressed away with a file to tidy it up, the edges were given a radius to improve the feel when handling.

Mike

Very nicely done, Mike

Looks like it was ‘meant to be’

MichaelG.

I have another question regarding silver soldering or brazing the crank onto the handle. This is a larger item that I've silver-soldered in the past. Can anyone tell me whether they think my yellow bottle Bernzomatic/Rothenberger torch would get the item hot enough to silver solder? From my limited research I understand that silver soldering is done at a temperature where steel becomes (at least) a dark red heat. Am I right?

A summary of my equipment and materials follows:

• The joint to be soldered is 3/4" mild steel rod to 1/8" x 1" mild steel crank
• The torch is a bernzomatic on a yellow MAPP gas cylinder
• The solder is Cooksons silver solder wire
• The flux is Johnsons EF flux

Hi Mike, if you have a suitable brazing hearth as in this Brazing Hearth then you will be in with a good chance I think.

Otherwise, you may have to get a larger torch Torch Kits. You could also consider Heating Equipment

Regards Nick.

P.S. reading Mike's post below, you could always try it on a bit of scrap the same size, that way you wouldn't have to clean your real job up if it doesn't work out.

Edited By Nicholas Farr on 15/05/2020 10:33:52

If you have silver soldered with it before then it can produce the required temperature but can it produce a large enough amount of heat to get the larger mass to temperature. Conserving the available heat is important if you think the amount of heat may be marginal A surround of insulating blocks like skamolex or vermiculite will keep the heat on the job and not absorb it. What is plan B if you try it and it won’t do the job? Other than having to do another clean up it shouldn’t do any harm to try it, just make sure you can make the best use of the available heat.

Mike

Edited By Mike Poole on 15/05/2020 10:22:59

I'm trying to keep costs as low as possible, as this may be a one-off job. Do you think these vermiculite bricks from eBay would be okay for a small hearth (£10 for 5 bricks, delivered):

**LINK**

That’s the sort of thing I use and they are fine for my occasional use, they are not the most durable things but with care they should give useful service.

Mike

On silver-soldering again, if I am able to get the workpiece(s) up to a dull red heat, is that a good indication that I should be able to silver solder it?

Even house bricks can do the job - but they will initially absorb a lot of heat, so use a lot more energy for the job, especially with a small burner. Just so much easier and faster with the right kit because they maximise the reflected heat.🙂. Gas is not cheap.

Hi Mike, it depends on the melting point of your silver solder, of which there is quite a range from low to high. Dull red is about 700 C, cherry red about 800 C and bright red about 900 C, but of course it will depend on one's interpretation of what is dull to what is bright, as we all see colours differently. Best to slowly heat a small piece up and determine exactly what colour your solder melts at, but the whole area of your joint needs to get to that colour at the same time and stay at the colour for the time it take to apply the solder.

Regards Nick.

A lot depends on what your silver solder wire actually is. Silver solders come in lots of grades from "extra easy" (mp 670) up to "hard" (mp 760). The normal braze alloy for model engineering is AG455 which melts at 650. If you use that with EF flux it's pretty much self-indicating - the flux will dehydrate to a white, fluffy powder on heating and turn to a clear liquid when the work is hot enough to melt the braze alloy. So apply flux as paste, heat gently till it dehydrates then as strongly as possible until the flux turns clear, then apply the alloy - use the work not the flame to melt the alloy.

I'd be very cautious about using house bricks for a hearth - they can contain a fair bit of absorbed water which boils and cause bits of brick to come flying off. The compressed vermiculite blocks are good or you can get proper firebricks very cheaply. With half decent insulation, a MAPP torch should have no problem brazing a job like that.

I'd be very cautious about using house bricks for a hearth - they can contain a fair bit of absorbed water which boils and cause bits of brick to come flying off

Anything porous containing moisture will spall if heated too strongly until the water has had time to boil and dissipate safely. Gunnnited flues need to be heated carefully to avoid this issue. I think it used to be around 50 degrees Celsius per hour surface temperature, IIRC. But the main problem there was of the whole lot parting company from the supporting steelwork.

Thanks for that Duncan, I've just got to the stage of bending a piece of 2mm plate into a W shape and was wondering how I was going to do it, sounds perfect.