Duckets and Dynamos, slow progress on the Kirk Twins

Posted on July 16, 2018 by Rob Pulham

Although modelling time has been limited recently I have made a little more progress with the twins.

I was a bit remiss in not cutting out for the ducket while I had the sides in the flat but I managed.

We now have one of my silhouette cut duckets fitted. This in fact the second attempt because I was a bit heavy handed with polystyrene cement last weekend and the first effort just melted away – this one is stuck more patiently with limonene.

Silhouette Cut Ducket – On Kirk 7mm brake 3rd

I had also prepped some scrap etch for the mounting brackets for the dynamos last weekend and I got those fitted too although from the photo one of them need a minor tweak to it’s shape.

Dynamo Mounting brackets fitted to modified Kirk Dynamos

DJH Streamlined Coronation – Chassis running smoothly

Posted on July 5, 2018 by Rob Pulham

After Wednesday’s woe today is Sunshine and Joy. She runs at last. There are a couple of the fixings to sort out but the motion all works as intended after my repairs. I still need to add the reversing shaft and the speedo but then I think that I am onto the body.

https://youtu.be/ZiYigF7G_LI

https://youtu.be/U-jG77fY5ol

https://youtu.be/j2MgzGAFXXI

DJH Streamlined Coronation – From Woe to Recovery

Posted on July 4, 2018 by Rob Pulham

From “Woe to Recovery”, it sounds like the title of a book or film

Where do I start, when assembling the cylinders, one of the jobs was to drill out the valve guides. When I drilled the first one I managed to break a drill bit of in the middle of it. I attempted to get it out by cutting off the rear spigot and drilling small holes around the end of the drill bit but didn’t succeed in getting it out. I popped a bit of rod in the other end and it went a fair way in so I reasoned that I might get away with shortening the rod because the valve stems don’t appear to move that much.

This was what was peeking out of the end of the casting but it wasn’t quite enough to grip.

DJH Streamlined Coronation – Motion – Getting out of trouble with a broken drill bit in a whitemetal casting

When I broke the drill bit off in the first casting, I decided to make a collet to allow me to better grip the second casting without damage and I was able to drill the second one without issue.

This is the collet and another view of my attempts to remove the offending drill bit stub

DJH Streamlined Coronation – Motion – Getting out of trouble with a broken drill bit in a whitemetal casting

I advised the gent that I am building it for what had happened and that we may need a spare casting but I was going to attempt to work my way past it. During the assembly of the valve gear I carefully measured the amount of valve stem and progressively shortened it until it fit.

Fast forward to giving it a test run and it dropped out of the guide jamming up the valve gear.

DJH Streamlined Coronation – Motion – Getting out of trouble

When this happened on Tuesday evening I took the wise course and stopped to ponder.

First thing yesterday morning as I was getting up for work, Chris said I have the solution to getting the drill bit out and proceeded to explain the idea that she had dreamt while asleep. The idea was basically, to cut a cut down the side of the casting to relieve the grip from the whitemetal and then drift the stub out.

After dinner I went into the workshop to take the valve gear to bits and unsolder the valve guide casting. I then out the casting in the collet and after a bit of a fiddle managed to get the seam of the casting lined up with the slit in the collet and gripped in the vice.

DJH Streamlined Coronation – Motion – Getting out of trouble with a broken drill bit in a whitemetal casting

DJH Streamlined Coronation – Motion – Getting out of trouble, making the cut

That done and using an old Exacto Blade, I proceeded to cut through the side of the casting using some odour free white spirit as a lubricant (made more essential by the fact that this Exacto blade has a slight kink at one end). I kept steadily cutting until I felt the blade grating on the side of the drill bit stub (why I used an old blade) and then removed the casting from the vice.

DJH Streamlined Coronation – Motion – Getting out of trouble, making the cut

The next bit’s I forgot to take photos of but using another broken drill bit as a drift I placed the bottom end of the casting on a block of wood which I have on my bench with the protruding stub of the drill over a hole that I had drilled when going through something previously (it doesn’t quite look like swiss cheese but there are a good few holes in it).

The drift moved the drill bit out a few millimetres further, to the point where I was able to grip it in a pin vice. I was then able to grip the casting in my hand and a twist of the pin vice had it free.

DJH Streamlined Coronation – Motion – Getting out of trouble, success at last

I then filled the seam with 70 degree solder and using the collet as a heat sink I soldered the casting back on and cleaned it up. In the photo below the seam is uppermost and is to all intents and purposes invisible.

DJH Streamlined Coronation – Motion – Getting out of trouble, casting repaired

Lastly I dismantled and remade the valve stem. The original is two layers of etch. I made the replacement from a piece of 1.10mm brass rod. I am not too happy with the boss so I plan to have another go later this morning.

This is the shortened version.

DJH Streamlined Coronation – Motion – Getting out of trouble, shortened valve stem

This is with the bit that I had cut off

DJH Streamlined Coronation – Motion – Getting out of trouble, shortened valve stem

Lastly this is the replacement.

DJH Streamlined Coronation – Motion – Getting out of trouble, replacement valve stem

DJH Streamlined Coronation – Assembly of the motion

Posted on July 3, 2018 by Rob Pulham

Despite many distractions recently I have made slow progress on the Coronation.

One of the easier wins over the weekend was to epoxy the balance weights on – the instructions have you do this much earlier in the build but I seem to have a tendency to do them as late as possible and I am not sure why.

DJH Streamlined Coronation – Balance weights fitted

Then on to the fun bits, I wanted to make the valve gear removable for painting so some mods were needed

This is what the front of the frames looked like with slots where the cylinders fed through to attach to the top of the frame spacer.

DJH Streamlined Coronation Tender – Loco Chassis Brakes and minor details fitted

This was what they look like after a visit from my piercing saw.

DJH Streamlined Coronation – Cut outs to make motion removable

Then I needed to make some spacers to attach the two cylinders together

DJH Streamlined Coronation – Spacers to make cylinders removable

Doing this meant that the 2mm diameter screws provided were not long enough so I retapped the holes 8BA and added some longer 8 ba screws. to hold them on.

next I soldered the slide bars to the motion bracket frame and started to assemble the valve gear

DJH Streamlined Coronation – Assembled motion

DJH provide 14ba screws/nut to assemble the valve gear which I have used but I have also done a belt and braces approach by tapping all the holes 14ba too which allows the nut to be locked on. Most of them also needed to be filed back for clearance purposes.

DJH Streamlined Coronation – Assembled motion

Last night I fitted the motor into the basic chassis and ran it for a while with the connecting rods attached. It was a good sign that nothing decided to unscrew itself while it ran (which can be a sign of something amiss).

Hopefully tonight will see the valve gear fitted and tested before stripping it back down ready for Warren to paint.

DJH Streamlined Coronation – Motion parts laminated ready for assembly

Posted on July 2, 2018 by Rob Pulham

I fitted together all the motion parts in readiness for building it up.

DJH Streamlined Coronation – Motion parts

Crank Pin Bushes

Posted on July 2, 2018 by Rob Pulham

My method (it’s not my idea just one I have picked up from other builders) of fitting Crank pins to Slaters wheels.

For this build the front and rear drivers have the standard 12ba crank pin as provided by Slaters with their wheels. The centre axle has had the 12ba cheese head screw replaced with a 10ba countersunk screw. This is to allow the crank pin bush to be tapped 10ba and an additional bush to be added and again tapped 10ba so that they can be screwed in opposite each other to house both the couple and connecting rods (on this particular kit the extra bush was available because a pair of smaller bushes had been provided for the front axle to ensure clearance for the crossheads).

As well as tapping the crank pin bushes 10ba, I also tap the wheel itself allowing the screw to be tightened and retained.

I must admit for my own builds I tend to replace all my crank pins with 10ba and blacken the wheels but I was told not to for this build.

Use of 10ba crank pins for return cranks

You can see the difference in screw sizes from the back of the wheel.

Use of 10ba crank pins for return cranks

I also drilled and tapped the return crank itself but it will be soldered to the bush once I have cut it to the correct length and made sure that the crank is in the right orientation.