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Sweet Pea build

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Barneydog:
Hi All,
I have now moved on to my next loco build and have decided to post the build here for you. Several years ago I bought a part-built Sweet Pea consisting of fully built frames, horn castings, axlebox cast iron block, part machined wheels, a bag of assorted bits, the build book by Jack Buckler and a full set of plans.

It has sat on the back burner for all this time but it is now ready to build. I have collected a large amount of the metal required to more or less complete the build.


The frames were un painted but have been stored completely wrapped in kitchen clingfilm. Now they are out I have sprayed them with grey etching primer to avoid them rusting during the build. They are very well built from 5mm bright mild steel plate. They are perfectly square and not twisted atall. You will notice this is the 0-4-2 version. I have several changes I want to make to this model including either a change from Hackworth to walchaerts valve gear or a mod on the hackworth to improve it, change of regulator to a ballvalve system, a rosebud grate or possibly gas firing to name but a few. More of these as and when they are decided.
I have started on the horn machining but will post that later.

Cheers

Julian

Barneydog:
Hi Guys,
Yesterday I started the machining of the hornplates. They come as four bronze castings. Unusually they are generous enough on their size to not have to worry too much. As you can see from the photo they are an offset tee shape. The narrow side of the tee sits in the horn opening with the top of the tee facing the axle box and the leg of the tee bolted to the back of the frame. I intend following the build process of the book as much as possible as this is a proven build order. Th casting is clamped into the mill vice upside down on some packing to give a little clearance from the vice jaws.

On all the casting I am keeping the narrow side of the tee against the fixed jaw of the vice. This will ensure that they are all the same. The measurements given in the book and on the plans do not need to be deadly accurate but it is important that they are the same for every casting. If they are not it will put the wheels out of alignment. The leg of the tee needs to be 3/16". The sides of it change slightly as the frames are made from 5mm steel which is slightly thicker than the 3/16" alternative. Looking at it logically the only critical measurements are the narrow side of the leg and the top of the tee. The narrow side sets how far the wheels sit from the frames and the top of the tee holds the axle boxes. They are machined as one before being split into four so the faces need to be identical.

All top faces were machined but I left the narrow side slightly bigger than the required .244" for later squaring and adjustment.

Once all four were done they were each machined the other way up. The top of the tee needs to be 3/4" wide. The tee sat on a couple of spacers to hold it clear of the top of the jaws. The sides were machined on all four.

Next each tee sat flat on the top of the vice jaws and had the top fly cut so they were all the same thickness. Digital readouts helped with this. I machined the thinnest until it was correct then zeroed my readout. The other three were machined until each read zero on the readout.

All four were machined again on the narrow side of the leg to bring them all to a uniform size and to ensure the face of the leg is square with the top of the tee.

Here are all four completed just needing a quick clean on the edges with a file. Next job is to cut to length and fit them

Cheers

Julian

sco:
 :popcorn:

The old man has been building a Sweet Pea for 20 years or more - I reckon he is at about the same stage  ;D

Simon.

Barneydog:
Hi Simon,

Perhaps you need to give him a hand.
I want this built as quickly as I can. My last one was a Simplex which has taken me about three or four years. Too long but a steep learning curve.

Cheers

Julian

Barneydog:
Hi Guys,

Spent the afternoon outside today finishing the horns.

Marked and cut the four castings in half. There is a little spare length but nou much. Eaqch one needs to finish at 2 7/16" which only gives about 4mm spare. You will have to excuse my use of imperial and metric measurements. I work all the time in metric and only use imperial when it suits me. Mostly when reading plans. Often I will convert to metric.
Anyway moving on. I used the lathe to clean the cut ends of the castings and to finish to length.

I cleaned one end on each then marked them for length. Blue marker pen then a scratch with calipers set to 2 7/16". Shortened to the scratch mark in the lathe. I kept each pair from each casting together.

I marked them all 5/16" from the bottom for milling away to fit horn supports later. The top edge of the narrow side was filed away to a curve to match the curved corner of the openings in the frame.

In the mill and mill away the bottom edge.

They are now handed and will only fit on one side of the cutouts in the frames to I kept them tagged together when not working on them.

I made a rough axlebox from a bit of ali just to position the horns while fitting them.


Clamped onto frames, squared and drilled. The holes on the frame were 3.6mm for 4ba bolts but I used M4 stainless button heads with stainless nylok nuts behind. Drilled through 4mm whie clamps were on.

All four done and the bar of cast iron for the axle boxes sitting in front.

Next will be the horn support bars which will be made from Stainless. I plan to use alot of stainless to avoid problems with rust and excessive amounts of dripping oil.

Cheers

Julian

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