Author Topic: Sweet Pea build  (Read 21180 times)

Offline Barneydog

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Re: Sweet Pea build
« Reply #60 on: February 19, 2021, 09:42:33 AM »
Hi Guys,
You can see a raised edge around the centre hole on these brasses. This edge is the correct size to fit the 1/2"bearing surface on the drive pins. I have cut back the rest of the surface a millimetre or so to avoid too much friction against the return cranks. The cranks help to retain the con rods.

The gudgeon pin end of the conrods is made from some 3/8" by 5/8" mild steel bar just over an inch long. They are drilled at one end. I put them in the mill and finished the hole with a mill bit 11.8mm. The plans say 7/16" but I don't have a bit that size. There will be a bronze bush pressed in so I will just turn that to fit this hole.

The bush needs to be 3/8" finished size so while in the mill I removed half a millimetre from one face to allow clearance.

Using the mill cutter to hold them aligned I filed the end of them to a rounded shape to match the hole. In the drill press I drilled a 1/4" hole centrally in the opposite end.

Using the same process of measuring used for the coupling rods I marked the round rod that will be used here. They need to be 8 5/8" centre to centre. In the lathe the ends are turned down to fit the centre holes in the brasses and the gudgeon ends.

I silver soldered the gudgeon ends onto the rods. Once cooled they will be machined and the brasses soldered on.

Cheers

Julian

Offline Barneydog

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Re: Sweet Pea build
« Reply #61 on: February 19, 2021, 11:12:16 AM »
Hi Guys,
As promised video of coupling rods moving uploaded to youtube.
<a href="https://www.youtube.com/watch?v=19YBe9diK-0" target="_blank">http://www.youtube.com/watch?v=19YBe9diK-0</a>

Cheers

Julian

Offline cnr6400

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Re: Sweet Pea build
« Reply #62 on: February 19, 2021, 03:42:49 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline Barneydog

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Re: Sweet Pea build
« Reply #63 on: February 19, 2021, 06:43:28 PM »
Thanks cnr

Hi Guys,
Bit of work done today. Shaped the gudgeon pin ends of the con rods. The shaping has left some marks but these will be cleaned up later.
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Set up square and silver soldered the base plate for the brasses.


Cleaned up and rounded they look ok.

The gudgeon pins in the crossheads will be 8mm stainless so the ends of the con rods need phosphor bronze bushes. Turned and reamed in the lathe to be a press fit. They are a touch over 3/8" and will be trimmed later.

Pressed in and reamed again to 8mm to allow for any distortion after being pressed in.

Both are now ready for fitting.

They sit well on the drive pins and now need the return cranks fitting to hold them in place.

Remember these I made last week? It is now time to press them into the return cranks.

I pressed them in and drilled to pin them in. Unfortunately I blunted several drill bits trying to drill through the stainless. Got the first one done and realised it was back to front so the crank would not fit in its previously set position. Once the pin was pushed out I turned the stub through the opposite way but was unable to pin so silver soldered them from the back. No pic as I forgot to take one. The return cranks fit back on in their original positions and have the pins tapped in.

They are sitting in position lined up with the marks I used earlier and hold the con rods onto the drive pins. I have tied the conrods to the coupling rods to keep them out the way. Everything turns nice and smooth. The bolts will be changed later when they arrive in the post.



Tomorrows job is the vibrating levers and hopefully start on the slide blocks.

Cheers

Julian.


Offline Barneydog

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Re: Sweet Pea build
« Reply #64 on: February 20, 2021, 09:19:55 PM »
Hi Guys,
Some of todays work. The next job is the vibrating levers. These go from the return crank to the slide blocks. There is then a connection for the valve control rod.

Two bits of roughly cut 3/16" bar. Two 4.9mm holes 1" apart and then an 8mm hole a further 2 3/4" further along. I drilled to 4.9mm because they will be reamed later to 5mm.
There are three bolts holding the two pieces together. The holes on each end have button head bolts in them to give the curved ends. Clamped in the vice in the mill the fly cutter is set to mill the edge to line up with the sides of the button heads. When both sides are done this will give a tapered lever.

With both sides done I used my sander to round the ends to match the button heads.

On the middle hole the outer face has to have a step 1/32" milled into it 9/16" long. I went slightly over 9/16" but it should not matter.

Once done they were split and cleaned up with a file and the belt sander.

The bottom hole is the wider end with the 8mm hole. A small bronze bush was turned to a tight press fit with a 1/4" hole in the middle and pressed into the hole. The levers fit on with the slot to the outside. With a little fettling the levers fit onto the return cranks and are held in position with a washer and an M5 nylok nut. The design uses a split pin but I prefer the stainless nut. The lever must be able to easily rotate on the return crank.


Next job is the weighshaft to hold the slide blocks.
The rear horn blocks had some M4 holes drilled and tapped into the inside face and some plates were made. I bolted these plates on and made sure they are square to the frames and aligned with each other.



Next will be the tube between them for the shaft to go through. Once it is made and fixer to these brackets the whole assembly will be removed for painting. This should be tomorrows job.

Cheers

Julian.

Offline Barneydog

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Re: Sweet Pea build
« Reply #65 on: February 21, 2021, 07:25:21 PM »
Hi Guys,

Managed to get the morning outside today so got going on the weighshaft and its guide. A piece of 1/2" steel tube plugged each end with brass plugs pressed in.

Back in the lathe and turned the brass to match the tube.


Both ends were machined down to the design length of just under 7" and were then drilled and reamed to 8mm.

To suit the 8mm stainless that will become the shaft


Slide bars next time to fit the shaft.

Cheers

Julian

Offline Barneydog

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Re: Sweet Pea build
« Reply #66 on: February 23, 2021, 06:15:01 PM »
Hi Guys,

Managed to get half a hour today so rather than starting the next job I decided on a quick strip and paint job. I have decided to  paint the steel ends of the coupling brasses and the vibrating lever with red enamel. In the absence of any decent enamel available I have used Smooth red Hammerite. It hardens well and is waterproof and hard to damage once hardened. Also the new stainless bolts have arrived for the brasses so it seemed a convenient time to strip and paint while there is not too much to paint. Further bits will be painted as they are made and fitted.

I took all the rods apart and suspended them by their top holes on a couple of tig rods zip-tied to the frames. Though they will not be painted the brasses are also hung there so everything stays together in the correct orientation including the left and right parts staying on their correct sides.

The rods themselves are chromed stainless so were masked off to remain unpainted. The bronze parts are taped in pairs to keep them together. I also decided to paint the bosses of the wheels and the return cranks aswell. The buffer beams will eventually be red but the rest of the frames will be black.

Later this evening I will nip outside for a few minutes and give them a second coat so they can be reassembled tomorrow morning.

Cheers

Julian

Online Kim

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Re: Sweet Pea build
« Reply #67 on: February 23, 2021, 08:36:44 PM »
I think the red highlights will make for a very sharp looking engine!  A very nice bright color to contrast with the black.  :popcorn:
Kim

Offline Barneydog

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Re: Sweet Pea build
« Reply #68 on: February 23, 2021, 09:15:33 PM »
Hi Kim,
Many thanks for your comments. The Pea on the front cover of the build book by Jack Buckler has bits of red on it with a black frame. Looks good. I like red. This is the full colour of my Simplex but my five year old grand daughter has decided this loco needs to be yellow. During lockdown and home schooling they have used colours for little kids to use to describe how they are feeling and yellow is happy and my favourite is red i.e. angry!! Red and yellow could be a bit of both! We will see. Yellow tends to attract flies and wasps. I may go with purple as that is the colour Paris Disney used as apparently it stops the birds crapping on them. Saves me being a target I suppose!!!!!!!!

Cheers

Julian.



Offline Barneydog

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Re: Sweet Pea build
« Reply #69 on: February 24, 2021, 09:01:43 PM »
Hi Guys,

Last night all the red bits had another coat.
This morning everything was dry so went back together with new bolts.



Todays job is to make the slides and slide blocks. The slide blocks are moved up and down the slider. They are moved by the top of the vibrating lever. Because of the movement of the slide and the turning of the return crank the vibrating lever moves the slide valve on the main cylinders to move the pistons.
The design on the plans uses mild steel for the slide and the pin on the slide block. The slide block is phosphor bronze. It is my understanding that this is the worst point on the loco for wear so I have opted for cast iron slides with stainless pins in phosphor bronze blocks.
The first job is to cut a slice of cast iron 2" by 2" by 1" thick. This was then cut in half to give two bits 2" by 1" by 1". The block is actually 2 1/8" so gives spare for cleaning and sizing.

The blocks went into the four jaw chuck on the lathe to be squared and cleaned up. I still left them oversized for later sizing.

Next they are moved to the mill to have a slot milled centrally on one of the long faces. It needs to be 1/2" wide and 3/8" deep

One went a touch too deep but it is not a problem. It will be corrected next.

They went back into the four jaw and were turned to their final sizes. First was the front face with the slot in it. Skimming the front allowed the deeper slot to be corrected. They were then turned and the sides were turned to make the sides 5.5mm from the edge of the slots.

The back and ends of both were then turned to make them match each other. 2" long and 7/8" thick.

A bar of phosphor bronze 5/8" thick had a piece 7/16"" thick sliced off in the band saw.

This slice had two pieces cut off just over 1/2" long. Both were then machined on the mill to a final size of 5/8" by 1/2" by 3/8" to fit the slots on the slides. They were machined very carefully to be a good fit that can slide easily but with no play.

The top face had a millimetre remover in the mill leaving a ridge at the front edge. This will act as a small reservoir for oiling the slides.

The four jaw was used to drill the slide blocks centrally with a 1/4" (6.3mm) drill and slightly counter sunk on the back with an 8mm milling bit. The nut in the picture is to save the ridge on the top being damaged by the jaw.

Next I need two pins to fit these blocks. The end of some stainless rod is turned to be a tight fit in the countersink. It is then turned down to 6.4mm leaving enough distance for the countersink. I left enough of this portion to fit through the block and have a further 5mm to clear the covers. The next bit was further turned down to 5mm diameter. Allowing enough shoulder for the 5mm vibrating lever I tapped the end to M5.

The pin was cut off and the sawcut cleaned and sized to fit into the countersink in the slide. Below should explain it all.

The pins are then ready to be pressed into the slide blocks from the rear countersunk face.

Next I cut some 2mm mild steel plate slightly over size to cover the slotted faces. They went into the mill and had a slot milled 8mm wide and 1 3/4" long. It was cut with a smaller milling cutter and then opened out to final size in several passes as an 8mm cutter will not give an 8mm slot.
.
That was all I had time for today so tomorrow I will drill the lids and fit them on with the slide blocks in place. The completed slides can then be fitted to the weigh shaft and the forward reverse lever made to hold them in position.

Cheers

Julian


Offline cnr6400

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Re: Sweet Pea build
« Reply #70 on: February 25, 2021, 12:08:09 AM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline Barneydog

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Re: Sweet Pea build
« Reply #71 on: February 28, 2021, 05:06:47 PM »
Thanks cnr6400

Hi Guys,
Done a bit more work the last couple of days. I had machined the two covers for the slides but realised they were too thick so made some new thinner ones. They were drilled 2.5mm with four holes down each side of the slot. They were held in the vice to be drilled 2mm and tapped M2.5 very carefully to avoid snapping a tap.
 
They were bolted up and turned over to do the opposite edge. The lids were oversized so were trimmed down to match the slides.


Spent quite a time on both with a file until they slid up and down easily. The left slide has a bracket on it to take the forward reverse reach rod. This was a simple drill and file job from some 1/2" by 1/2" by 1/8" steel angle about 1 1/4" long.

It bolts near the bottom of the rear face of the left hand slider. I also changed the front plate bolts from cap head to hex as they are shallower so give better clearance for the vibrating lever and look better.
.
The sliders need to be pinned to the weigh shaft and need to be exactly level with each other. The mill table is ideal for this.
I clamped them down and drilled them 2.6mm diameter. I pinned one end and marked the other ready for correct reassembly.


The shaft was pushed through the holes in the support brackets on the rear axle boxes and the other slide pinned on through the previously drilled hole. Two screwdrivers were used to hold the assembly aligned with the top of the holes and the vibrating levers.

Rather than sliver soldering them together I used my welded and put a couple of spot welds each side.
. The whole thing was removed and cleaned up and painted with black hammerite paint  then refitted when dry.

While the paint was drying I used my cnc mill to make two support brackets. In the design these are the brackets that should hold the weigh shaft but I have chosen to mount them to the axle boxes so the shaft and sliders move with the axle. The design update for this calls for the original brackets to changed. Instead of a hole they have a slot for the weigh shaft tube. They take the stress of the pistons and rods and guide the shaft rather than the axle boxes taking it. I drew them on the computer using Cut2D and here is the simulation it does on the screen to show the tool paths.

A piece of 3/16" mild steel plate is clamped to the mill with some ply under it to avoid damage to the table.

G code produced by Cut2D is loaded into mach3.

Press cycle start and away it goes.
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After just over eight minutes its done.


After a quick file they are ready for use. They were painted with the weigh shaft for fitting next time I am in the workshop.


As it was a nice day yesterday I decided to warm up my last build...a Simplex. I though you may be interested in a couple of pictures.


It is fired on gas. You can see the canister hanging from the track. This firing was to test the burners I plan to use for this and Sweet Pea. This firing was a success with just one burner. It managed to reach 90psi and topped out there. Not enough to blow off the safeties but I just wanted to heat the boiler and test the burner. Raised steam with no blower used. I will be using two burners eventually. Sweet Pea will probably have three.

Cheers

Julian


Offline Firebird

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Re: Sweet Pea build
« Reply #72 on: February 28, 2021, 05:32:57 PM »
Hi Julian

Nice looking loco there  :ThumbsUp:

Cheers

Rich

Offline cnr6400

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Re: Sweet Pea build
« Reply #73 on: February 28, 2021, 06:39:58 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:  for the Sweet Pea progress and the Speedy!
"I've cut that stock three times, and it's still too short!"

Online Kim

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Re: Sweet Pea build
« Reply #74 on: February 28, 2021, 07:02:08 PM »
Wow!  That's really nice, Julian!   :popcorn: :popcorn:

I don't remember having seen the boiler before.  You're a lot farther along on your sweat pea than I'd realized.  It's looking great!

Kim


 

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