G'day Chris here, and welcome back to Clickspring.
For some time now I've been using this temporary arrangement to blue screws,
but I've got quite a few parts to blue over the next few months,
so in this video, I make a more permanent version.
The idea behind a tray full of brass chips is that it helps to spread the heat evenly over the whole part,
so it's a great way to get a uniform color.
But I'd like to have something a bit more convenient than a visegrip holding it all together.
Before we get onto making it though, I'd like to show you the very first bluing pan I made
before I really understood what was required.
There's a few things that I did wrong when making it, that are worth pointing out.
For one thing, the brass is too thin, so the heat change on the plate is much too fast.
But the big mistake I made was to put too many large holes in it; I can't really recall
what I had in mind when I did that, but it was a bad idea.
All it did was remove even more mass from the plate,
and the holes permit the flame to lick around the sides of the part, and ruin the color.
It does have a few redeeming features though, the legs holding it off the bench were a good idea,
although they've oxidised quite a bit from the heat, so I might try brass this time and see if that makes any difference.
The handle is fine too, so I'll cut that off, and re-use it.
I'm also going to make 2 versions of the tray, that can screw onto the end of the handle as required.
One will be the more permanent version of the brass shavings tray I just spoke of,
and the other will be a plate version, with holes in it for for screws. This time with small holes!
I can also make more variations on the idea in the future, and reuse that handle.
I'm going to make the trays using this ring of brass left over from making the barrel,
and these 2 discs left over from other projects.
The feet will be turned from this brass rod.
So let's get started
The handle is just a hardwood dowel from the hardware store, mounted on a length of steel rod.
And as I recall when I made it, I formed a short tang on the end of the steel rod,
that was a good fit inside the dowel. I then formed a thread on the end of the handle.
I then formed a thread on the end of the rod.
The feet for the bluing pan are a reasonably straight forward part, with a taper on one end, and a thread on the other.
And I quite like holding small parts like this with an ER collet,
The opposing features will be closer to being concentric,
and it gives a much better grip on the part than the three jaw chuck.
I started out by forming the tapered profile, setting up the lathe to cut a 10 degree included angle.
Once I'd formed that tapered section, I extended the stock to mark out the other dimensions,
and then parted off.
The part was then remounted the other way around to form the threads.
Ok, now on to the trays.
The tray that will hold the shavings is fabricated from 2 parts that are silver soldered together,
so I spent a bit of time getting the surfaces clean and well fluxed, before making the join.
All of the outside surfaces now need a good trim, and to do that I need the part running
reasonably true before making the cut - another great job for the bump centering tool.
So with the shavings tray mostly omplete, I moved on to the flat tray. Which is really just a simpler version of the same thing.
All it needed was to have the surfaces cleaned up while it was being held on a super glue arbor.
Both parts were then marked out, and the positions of the holes lightly punched.
I'm extending those marking lines beyond the hole positions. I'm going to use them to help me align the part on the mill vise later
Each of the holes were then drilled and tapped on the mill.
Now I'm going to lightly rivet the ends of the feet once they've been screwed in place,
so I'm forming a decent countersink on the top side, to give the metal somewhere to flow as its displaced.
And thats all the bits and pieces complete, so lets give it a try.
In good quality clock and watchmaking, heat bluing is traditionally used as a final surface finish on some steel parts
As the part is heated an oxide forms on the surface.
The thickness of the oxide is directly related to the temperature of the part. The hotter it gets, the thicker the layer.
The color comes from a light effect called Thin Film Interference.
To get a uniform color, its essential that the thin film of oxide is uniform in thickness across the whole part,
which in turn means that the temperature must be uniform, hence all the effort in making this bluing tray.
The colors move through a range starting at a light straw,
and then passing through brown, purple and blue, to a light grey,
after which the thin film effect is no longer visible.
The composition of the steel, cleanliness and surface finish all play a role in the way the oxide forms,
and so can directly influence the quality of the final color.
Thanks for watching, I'll see you later.
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