26 & 27/6/17 - Britannia

Ongoing work to the Britt was to rivet the engaging ring into the back of the smokebox and file/grind the rivets flush to clear the boiler and the cladding. Also a review of the drawings shows the boiler expansion pushes into the smokebox which we don't like as it will cause a misalignment with the regulator drive spindle and movement of the cladding. No thanks. The rear boiler support screw holes will be slotted to allow for expansion that way and M5 studs and nuts fitted instead of the socket head capscrews.

Also another job on the list was to decipher a way to operate the drain cocks. I ordered a bicycle bowden cable from China and have run it up a 1/8" copper tube. Also a union joint was required above the rear driving axle to be able to get it out after it was bent to shape. A few clips here and there and a clevis is required at either end.

The drawings I have, showed the lever and pull rod were to run along under the keeps, which at the front end causes an issue with clearing the leading bogie and also damage in the case of a derailment. Bowden cable seems a much better arrangement where a few twists and turns are required without needing bell cranks.

Happy steaming!

Nigel

21-23/6/17 - Britannia

A tool was made to check the alignment of blast pipe with chimney, squaring off the chimney bore. Made from a piece of steel bar and a 1/4" silver steel rod.  This revealed the blast pipe was 1/8" off centre and also the hole through the bottom of the smokebox wasn't central with the chimney either.

After some playing around the cylinders were removed to get access to the exhaust tee which measured 1/16" off centre. This was turned 180 degrees and improved the alignment. Also the saddle bolt holes were not central so the saddle was also turned 180 degrees. The combination of errors actually worked in our favour and a little bit of filing out the holes allowed sufficient clearance to set the smokebox up properly. Previous mention in last blog was the saddle radius is larger than the smokebox radius and no extra material available to fly cut it to match.

So the saddle was drilled 5/32" in four places for some dowel pins and all the bits set up square in the frames and bolts done up tight. Then smokebox was removed and drilled through the saddle into the smokebox for the dowels. Sits perfectly in the frame now in the exact position.

Happy steaming!

Nigel

20/6/17 - Britannia

Recommencing work today on the Britt the regulator access cover was turned 180 degrees and shortened up 8mm on the milling machine to make room for the whistle steam supply. This will become more apparent as the whistle steam supply gets fitted up to the smokebox.

The smokebox skates around on the saddle (I don't think the radii are the same) and needs to be more securely pinned so it doesn't move. There's plenty of clearance in the bolt holes and blast pipe hole and it's worth rechecking the alignment of the blast pipe. The rotation of the smokebox means the chimney may or may not be in alignment depending on where it's bolted down. It will need a plug and aligning rod machined to fit the chimney and see where the blast pipe is aligned off this axis.

Will check that out tomorrow.

Happy steaming

Nigel

19/6/17 - Princess Marina

Today's job involved finishing off machining the hornblock castings and drilling some crankpin holes in the driving wheels.

A simple jig was made from flatbar and 7/16" brass bar for drilling the crankpin holes at a consistent radius from centre.

Britt tomorrow!

Happy steaming!

Nigel

15/6/17 - Princess Marina

One of the things made up today was a little jig for setting up hornblocks in the mill.  This allows the hornblock to be set up on the flange for milling the face against the frame. The horns are a little distorted so one of the adjusting screws was tweaked for "soft foot". It's nice to see the top of the hornblock with a uniform thickness bolting flange!

Soft foot - A strange name from my real work days aligning turbines and motors at the power stations. First job was to put some feeler gauges under the feet of the machine to work out the first shims as usually one of the feet had a gap under it! Very common to have soft foot especially on large machinery. Trying to align a machine when soft foot was not shimmed first was a complete waste of time, as tightening down the bolts produced all sorts of readings on the dial indicators, not to mention the twist and distortion of the machinery!

Happy steaming!

Nigel

14/6/17 - Princess Marina

More happening on the Princess Marina. A big laser cutring order has been sent off for quote and work is progressing with some castings. Wheels cleaned up with the dremel and a sand blast, and the hornblocks are on the milling machine.

The hornblocks were linished on the inside face and the top of the was flange skimmed in the mill to give some reference faces.  A piece of ply was used on the rough side of the hornblock to push the reference face up against the fixed jaw in the vise. The rough side is not exactly parallel with the reference face, I used a piece of round bar to begin with,  but then found the ply to be much more forgiving without any chatter.

Happy steaming!

Nigel

8/6/17 - Princess Marina

After some more time on the layout designs of Princess Marina, I'm almost ready to send off the file for laser cutting.  Every hour on CAD is worth several hours in the workshop.  I thought the smokebox door parts I had been given were OK, but a little big on the diameter.  After silver solding a boss on the smokebox door and putting it in the lathe, the casting had buckled and was too warped to clean up fully at the new diameter.  I will have to machine a new one out of steel, which will have water cut door straps and a laser cut drilling template for all the holes.  Time saved right there.  I have a set of laser cut frames here which I won't be using as the horn blocks I was given are too big and will waste too much time milling out the frames rather than getting new ones with all the holes in.  More time saved.  The running boards and cab parts will also be laser cut with all holes in.  Brake hangers, brake shoe ring, etc.

Happy steaming!

Nigel

1/6/17 - Princess Marina

It's been a little while since the last update, but things have been busy.  A new loco in the shed (5" gauge Speedy) with a few problems in the chassis to sort out, a new axlebox was required amongst a string of other jobs.

Here we see a bit of progress on a 3-1/2" gauge Princess Marina (LBSC design) and I have been handed a bunch of parts to build the engine with.  The boiler has been constructed by me earlier, and I thought the rest of the loco was a rolling chassis!

Going through the drawings, I thought to assess the axle boxes and horn castings, what we have is bigger than the cutouts in the laser cut frames.  This revealed a few other questions, and I thought to lay out the frames in CAD to see what the running height of the loco was to be.  This is a critical dimenison for those who are not aware, as the loco cylinders are laid out off this.

The drawings and "words and music" are a great help to get going, but sometimes a few things get overlooked...something I can understand in the rush to spit out a design for a magazine going to press.  Not to be critical by any means.  But I found the running height using the dimensions as supplied meant the axlebox was almost at the top of the horns and some funny business with the dimensions of the motion bracket and placement of the cylinder.

Long story short I have been developing some views and dimensioned parts which differ slightly to the drawings but definitely lay out a working arrangement on CAD.  I have moved the axle 5/32" up in the axlebox, and it looks much better.  The lubricator drive was a mystery, and have since found buried in the writings to include another eccentric on the front axle...just in case the builders were up that far using the drawings and wondered how they were going to drive it!

I'm in the throws (see what I did there...) of driving the lubricator off a long rod on the axle pump gudgeon pin.  The running boards are not shown in plan view and a few long hard looks at photos reveals the cylinder protrudes a ways past the running boards, as also the swing of the expansion link fouls the running board valance and must be relived to clear this...an odd practice, looks like something the Victorian Railways did on the K classes!

Several cross sections have been done on the motion brackets and cylinders & crossheads to make sure it all lines up.  Have found some oddities & unhappy clearances with side rods and knuckle pins, can be a pest trying to find room in the bushes if there's not enough to prevent the knuckle pin dragging over the crank boss or hitting a 10 thou protruding axle.  By the end of this little exercise I hope to have a set of working dimensions to check this loco off against in it's construction, plus a good sized laser cutting order to speed it all up immensely.

The supplied driving wheels have been machined to size, but the spokes un-fettled.  I bluntened two files having a go, and resorted to a 1.5mm carbide cnc router bit in the dremel to get the hard bits off.  They look nice now.

Below are some screenshots of the CAD work on this engine, a couple of days going through drawings and reshashing things.  Almost ready to make a start....

Happy steaming!

Nigel