Tender Structure

The Tender sole plate has already been made as described in the Tender Chassis section so the first job is to solder the base angle onto the sole plate . The angle used is 5/16″ and I will use this size for all the joints although the drawing does use 1/4″ angle in places.

I first marked the sole plate by scribing a line where the outside of the sides, front and back would finish and then cut the angle for the four lengths to a length that was short of the lines by the thickness of the sheet brass times two (18g brass in use so 2x 0.047″).

Initially I thought I would temporarily rivet the angle to the sole plate with 1/16″ copper rivets to secure the angle in place during soldering. However for the first piece of angle which was a length across the sole plate I clamped it in place having tinned the angle and the sole plate first. The tinning of the angle was done with a large iron of 175W with a 5/8″ bit and to tin the sole plate I used the same iron but used a low flame propane torch onto the bit to counteract the heat loss from iron to sole plate. The solder used was 170 degree lead free and I will come back to this shortly.

With the part clamped the iron and soft flame was used again to join the two but adding a length of solder to inside of the join which melted into the joint as I moved the iron along. Satisfied that the technique worked I next put a long side length on. More clamps were needed but the approach was the same and this time what I had feared came to pass, the sole plate ended up with a banana shape. Clearly the technique was no good for the long lengths.

The bowing was clearly due to too much heat combined with the extra length involved. Searching around for a solution I found that most people who had published their work on tenders on the internet used a much lower melting point solder and it was leaded to make for easy flowing. I have a lower melting point solder at 140 degrees so the next piece of angle to be put on will use this.

The lower melting point solder was a definite improvement. I also tried on the tender rear plate using solder paste and rather than clamping the angle to the sheet I attached it with 10 BA c/s screws every 1″ without a c/s hole as the heads would be eventually finished flush the angle being tapped rather than using nuts. This worked much better all round. The back plate grab handles wer soldered on at this time too as they have ot be watertight.

During all this experimental process I noticed that the tender was narrower than the loco cab according to the as drawn dimensions. This got me concerned as all the photos I had seen of the A1 seemed to have the tender at the same width as the cab. I checked my A4 and indeed its tender is narrower than the cab, I also asked club members and the general opinion was that it should be as wide as the cab. I then came across a photo of Sea Eagle in a book on Peppercorn A1’s and that appeared to have a tender narrower than the cab. Unfortunately most photo’s of loco’s always seem to be three quarter views and this was no exception so the appearance could just be a perspective issue. My conclusion was to build the tender as drawn.

With all this going on I then found that I had soldered the two long lengths of angle on the sole plate 1/8″ too narrow on each side! I must have mis read the rule. Nothing for it but to take them off and position them in the right place this time using solder paste.

Another problem troubling me was how to put the top bend in the side plates of the tender. I have no means to bend the length involved and 18g is quite stiff to put in a 1/2″ radius. After a couple of false starts I located a local sheet metal company who said they could do it for me. A few days later a call from them saying they were done and I collected them. They looked OK. Quite relieved at getting that problem solved I headed home a happy bunny only to find when I checked them against the drawing the bend had been put in too low from the top edge so the radius was in the wrong place! That was a blow. Could I perhaps straighten it out sufficiently to rectify the error, no chance, even trying to anneal the brass did not help but made the problem worse to solve as it just introduced distortion. So now two pieces of expensive brass plus the cost of having the bends put in are now scrap. Not happy.

Whilst sorting out what to do with the side plates I made a start on the rear plate. This was cut out to size on a guillotine and the top curve put on with a band saw except for the final curve that mates with the curve of the rolled side plate as I need to match the two and of course I had not got the side plates.

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The brass angle forming the frame was soldered in position using solder paste having first screwed the plate to the angle with 10 BA c/s screws. The picture above shows the plate screwed to the bottom angle that is already soldered to the sole plate. Once the angle is soldered in position the heads of the c/s scews are filed away leaving a flush finish.

As the two side hand rails will be fiixed with their staunchions penetrating into the water space I decided to mount those so the nuts could be softsoldered to make a permanent seal.

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The top hand rail is level ! its the photo perspective that makes it appear drooping.

The lamp irons I have made from steel and riveted them in position. I chose to machine them from solid as the top part is only 85 thou and silver soldering it in place was going to be fiddly. It did not take long to machine out the front and rear and then slice them up.

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slicing the lamp iron machined block.

The last items (but one) to go the rear plate are the steps. These were cut and bent and riveted in position with 1/16″ coper rivets.

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Also in the picture above can be seen the top support angle frame which is now fixed to the rear plate. At the moment the plate is leaning forward unsupported on the sole plate. The plan is to screw the angle in position with 10 BA c/s screws and the solder it to the side plate. When that is done the final matching 1/2″ radius curve on the rear plate can be matched to the side plate and the beading applied to the rear plate top.

The side plates …….. well I had another go at straightening the bend using my 12 ton press. That worked OK for the first one I did and encouraged by that I set about putting the bend in by using a large length of 1 1/2″ x 1 1/2″ steel angle and a 1″ dia  steel bar. The technique was to press the bar onto the sheet clamped across the angle so the bar and sheet went into the V. With the plate, angle and bar clamped up and in the bench vice the whole was gradually tightened by tightening the clamps and vice jaws gradually and evenly. This remarkably produced a nice bend and it just need to be trimmed to length which I did by clamping the side to the mill table and using a slitting saw to run along the whole lenth of the side, moving the clamps as the cut progressed. It just remained to trim the bottom edge of the side on the guillotine to get the right hieght.

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I felt quite pleased with the result so set about on the second side to straighten the bend out.

The result was a disaster. The sheet buckled and there was no way I could get the bend out to produce a flat sheet again. So back to the drawing  board.

The final solution (I hope) is to have the two sides laser cut and bent profesionally and my order is in with a delivery expected soon.

Whist kicking my hels waiting for the tender sides I decided to make a start on the hand pump.

Hand Pump

The hand pump is constructed from three castings plus other parts to be made. The castings are the main body, the pump head and the ram gland cover. The pump is quite larghe having a ram diameter of 5/8″.

The first job tackled was the cleaning up of the foot of the body to achieve a flat base and rectangular outline and to drill the fixing holes for mounting it to the tender sole plate. The casting was held in the mill vice to machine the flat base and outline and the drilling of the fixing holes could be done with the same set up.

The next task was machine the ram bore. I decided to do this on the mill as there was no way I could mount the casting on an angle plate in the lathe and counteract the heavy out of balance forces that would result. The set up on the mill was to clamp the pump to an angle plate and drill and then bore the hole. However what I found was that the in trying to set up the casting to be vertical the casting was in fact bowed slightly which ment that I had to find a compromise to the true vertical.

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A pilot hole was first drilled right through using a long series drill. Then A larger drill and finally a 1/2″ drill. The drilling of the larger hole showed how easily it was for the drill to grab and self feed. Fortunately no damage occured. To open the bore out to 5/8″ I used a boring head and long boring bar. Using only 20 thou cuts max the bore was succesfully done to 5 thou undersize and then a 5/8″ reamer put through to fininsh the bore.

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The two fixing holes for the ram gland plate were drilled at this time also.

The bore was counter bored for the gland at 3/4″ diameter and 1/4″ deep using a 3/4″ slot drill and the face squared off. I turned the pump over in the vice and squared off the face at the other end.

The next action was to drill the fin for the fixing pin that is used by the straps to conect to the pump lever.

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The straps were machined from 1/8″ brass sheet using my little CNC mill. They can be seen in the photo further down the page. Nothing special about them.

The pump head is a square section 5/8″ casting. However this is too small to make it to the as drawn dimensions as it requires  a 1/8″ deep 5/8 ” dia stub to fit into the pump body bore and the casting size does not allow for that. Fortuntely by making the internals of the pump head slightly smaller by 1/32″ in dia I could get the machining done OK.

The casting was put in the independant 4 – jaw chuck for facing and turning the 5/8″ di stub as the first job.

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This was followed by putting the casting in the chuck lengthways to drill the through hole 3/16″ dia. With the  casting blued and marked to make length to size one end was turned to length counetr bored 5/16″ and then drilled  and tapped 3/8″ x 40 tpi 1/4″ deep.

The casting was turned around and the other end machined likewise.

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The outlet from the pump head is to allow connection by 3/16″ copper pipe and a nipple is made to screw into the head just below the top.

The head can now be silver soldered onto the pump body.

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The connections to the outlet and the pump inlet are straight forward turning jobs as is the plug at the top which has a small peg to prevent the ball rising too far and blocking the outlet.

The pump ram is stainless steel and it is fitted with an O ring. The pump handle is machined from brass and not as drawn as there is a drawing error stipulating to make it from 1/8″ brass!. The finished handle is clearly seen above. An extension handle is used when driving.

The gland is machined from a casting, again nothingh special baout it other than I used O rings to make the gland seal. I say plural as two are fitted as I omly had small cross section O rings of the right size.

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The finished pump in place.

A test of the pump in a bowl of water confirmed its operation OK.