Use these links to jump to the section you are interested in on this page :-
Making a former for the Throatplate Flanging the Throatplate Drilling holes in Throatplate for Stays Fitting Barrel to the ThroatplateOr try one of the other pages on building Spencer :-
Machining the Driving and Coupled Wheels
Spencer Start page, frames, Axle boxes, painting wheels
After the debacle of flanging the plates I was dreading adding a second flange to the throatplate. It quite a while but the experience gained on the previous plates helped a lot. First job was to make a former. I needed a hole 2.881" in diameter as the flange was to go inside the barrel. As this is a one-off I'm just using chipboard. I selected a 2.5" hole saw to start the job off.
It makes short work of the chipboard. Note there is a thin sheet of hardboard protecting the faceplate.
The final 0.331" was bored out using a carbide tipped lathe tool, I didn't even bother getting it to the correct height.
I'm not keen on wood working in my Myford as it makes a hell of mess which has to be cleaned straight away.
Next job was to centre the former over the throatplate, I did this using a the Smokebox plate and a ruler - bad move the parallax meant it was well out. I should have used the scribing block with successive approximations.
This picture exaggerates the error! I have scribed a centre circle 9mm inside the former.
I had a hole saw which was a very close fit so decided to try it out in the drill press.
It took quite a while and needed lots of lubricant, I think it would have been more successful trying this in the lathe as it needs a fair bit of power.
Getting the flange started was tricky. If just the chipboard former was used the plate distorted so the paxolin former couldn't be re-fitted. I ended up levering the flange up with a screwdriver to get it started. It's not pretty.
Once the flange is lifted a bit I could get my conical hammer in. This pic shows the setup. the Paxolin former is on the bottom, then the Throatplate, with the chipboard former on top. A couple of G-clamps keep things under control.
This hammer (part of a set for bodywork repair) is pretty good for getting the edge lifted up.
I could work round the periphery a couple of times before the plate needed annealing After about four annealings this is what it looks like,
Next stage is to get the flange vertical. I used a 1" bar and a ball pein hammer.
This got the flange stretched out more evenly, however rather than being vertical it started to curve back on itself producing a concave edge. See Right Hand Side.
The answer to this was planishing the flange against a 2.5" diameter steel bar.
Had to be careful not to mark the curved part of the flange.
With the barrel flange formed. I noticed the Paxolin former was no longer a tight fit to the plate. The top and bottom corners were loose.
The plate/former sandwich was held vertically in a vice and the corners planished with a piece of bar.
All in all it took about fourteen annealings to get to this stage!
Drilling the Throatplate stays holes can be awkward once the barrel is in place so I decided to drill them first.
The throat plate was laid on the firebox and a centre punch was used to transfer the position to firebox. Which was drilled.
The holes were drilled 2.5mm to give a loose fit on the 3/32" rivets. This leaves a bit of adjustment room. Once I was happy with the alignment I clamped the two together.
The holes were then enlarged to take the rivets I am using as stays. I have had to calculate the size as the original design specified 5BA Phosphor-Bronze stays.
These are pretty chunky I'm hoping they will save some time - I didn't fancy machining 37 stays.
A small piece of 1/4" square copper bar was cut for the front part of the foundation ring and trial fitted so I could get some idea what it would look like.
The flange was a tight fit on the barrel and a set square was used to get the barrel at 90 degrees to the throat plate.
With three rivet holes drilled (2.5mm again) I cleaned the high spots on the flange with a file. Blue marker pen was used to identify the high spots. I went a bit mad here and the gaps were a bit big as I discovered later on.
Here's a nice shot of the cleaned up throatplate (after pickling) I have filed the top edge to make it level.
The Barrel joint face was given a good going over with Emery paper and also pickled.
The two parts were given a good fluxing.
And then riveted together.
This was silver soldered with SilverFlo-24 and the two Sievert Burners 2944 and 2943 Unfortunately the gap was too big. I didn't realise this for two attempts! Luckily I've found an efficient way of removing the horrible Tenacity 5 flux - A Dremel clone with a brass brush. You can see the gap here on the bottom left hand corner.
For the third attempt I closed up the gaps using the planishing hammer and the 2.5" dia steel bar.
This went from a 0.20mm gap to less than 0.10mm. Obviously I couldn't close the gap where the barrel was already soldered so this made the most sense.
The Dremel tool doing it's thing, alternating pickling and this soon shifts the burnt on Flux.
To make sure there was enough Solder I wrapped two rings around the inside above the joint. This may have been slight overkill as one of the rings wasn't melted in one place.
I let the flux dry for an hour or so before getting the burners out.
The main difference was that it was heated with the barrel pointing vertically up (it was lying down on the first two heatings) this makes it more difficult to see what is going on but gave better results, helpfully I could see the Solder flow through onto the lower throat plate so knew it had melted.
Note the piece of unmelted wire on the left of this shot, it hasn't affect joint integrity.
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