7mm DJH Streamlined Coronation.

[simond]

Thanks Rob,

You’re probably aware of my Premier-framed build on RMW, I doubt that the double row will be visible behind the cylinders, so I’ll not lose sleep over them, similarly the ones around the weighshaft pivots are pretty well hidden by footplate and the lifting levers.

The ones where the rear frames come off the main frames are perhaps another story. In any case, visible slotted csk screws in this area are perhaps not quite de rigeur.

Thanks again
Simon

 

[Rob Pulham]

No problem, and yes I have been looking in at the goings on It's a real challenge trying not to disturb the paint job...

 

[Rob Pulham]

I was cracking on quite nicely with the chassis but when I got to the next phase of the instructions I found one of the castings missing.

This is the offending article, there should be one at each side.

After umming and ahhing as to what to do I decided it would be simpler to scratch another than to wait for the owner to source one from Tower/DJH.

Poor photo but this is it made from scrap etch and some wire filed half round.

Next saw me make up the coupling rods which all went swimmingly until I got to pinning them together at the joint. The instructions have you tapping one side 12ba to screw a cast threaded pin into. Having done the first side I quickly realised that the thread on the pin is way smaller than 12 ba Bah!! :headbanger:

The other side I tapped 14ba and I ran a 14ba die down the cast thread, I screwed it into the tapped hole and the threaded section promptly broke off in the hole The next task was to solder the pins into the back of the hole as I would have done with a rivet of Premier Rods. Onwards and Upwards.....

 

[Rob Pulham]

Apologies for the slight step back in time on this one but my trip to the NRM last Friday afforded me this comparison shot:

This was one of the better shots most were quite poor due to the abysmal lighting....

 

[P A D]

Hi Rob,
City of Birmingham also has the lower ram missing. I think towards the end of steam they were just removed if they needed repairs.
Cheers,
Peter

 

[Scale7JB]

Tender looks great Rob!

Lovely work..

JB.

 

[Rob Pulham]

Following on my my note on the coupling rods I managed to get a couple of photos of them now that they are soldered up.

And then a couple that will hopefully show how much I had to file out of the cylinder castings....

Essentially the slots bottom left and top right were almost full of whitemetal so I used an older square file to remove the material. Now that I have the lathe with the milling attachment I suspect that I might have used a burr to mill out the material much more efficiently. Something to remember should I encounter anything similar in the future.

 

[Rob Pulham]

After doing battle with the cylinders and struggling with a drill bit broken off in one of the valve guides which I have yet to resolve (but I do have a fall back position should I need it) I decided that for a bit of light relief I would make up the bogie and trailing truck.

I started with the trailing truck for now other reason than I had some of the bit's already removed from the fret during the course of removing other bits.

Sadly I had got to this bit when I realised that I had made an error in my interpretation of the instructions. You get two options of spring/axle box for the trailing truck. You get an axle box and full thickness spring combined and an etched spring separate axle box and some hanger castings. There are also a pair of thinner springs which I had attached as in the photos above.

The idea being that you use the full thickness castings for loco where they are to be used on track radius of greater than 7 feet or use the etched ones for less than 7 feet radius. It was only when looking at the bogie that I realised the the thinner cast springs were in fact for the bogie rather than the trailing truck and it all made sense. thankfully it was the work of a few minutes to swap them over and put the etched ones where they belong. There were some castings provided for the spring hangers as I mentioned but 2 of them were missing so I cut some off the thicker castings to make up the set.

 

[Rob Pulham]

With the trailing truck behind me (see what I did there), I started on the bogie.

Sadly having rescued the and fitted the springs where they should go, you don't see much of them once it's assembled.

Now you see them....

Now you don't....

I also made a start on the valve gear but more on that later.

 

[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.

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.

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

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

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 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.

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.

 

[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.

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

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.

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.

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.

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.

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.

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.

This is with the bit that I had cut off

Lastly this is the replacement.

 

[simond]

nice recovery...

best
Simon

 

[adrian]

Chris said I have the solution

you really need to get that lathe up and running - 11 out of 10 for perseverance though.

 

[P A D]

Hi Rob,
I see you've been walking on water.

By the way, the expansion link is back to front in the photo showing the valve gear. Probably made no difference when you tested it, and I'm sure its is only fitted temporarily.

Cheers,
Peter

 

[lankytank]

Nice one Chris....

See Rob, she was paying attention......

 

[Rob Pulham]

you really need to get that lathe up and running - 11 out of 10 for perseverance though.

I couldn't agree more, I would have turned a replacement as a first choice.

The toolpost has been despatched from the US so it's a waiting game now and I am not sure how long things take to get here.

 

[Rob Pulham]

Hi Rob,
I see you've been walking on water.

By the way, the expansion link is back to front in the photo showing the valve gear. Probably made no difference when you tested it, and I'm sure its is only fitted temporarily.

Cheers,
Peter

Hi Peter,

It is, but thanks for pointing it out - the other side is the right way around

 

[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.

 

[michael080]

Rob,

just wondering, has the broken drill been a HSS-steel type or a carbide type?
I like to use the "soft" HSS drill bits for white metal, but I use them only with a pin vice.

Michael

 

[Rob Pulham]

Rob,

just wondering, has the broken drill been a HSS-steel type or a carbide type?
I like to use the "soft" HSS drill bits for white metal, but I use them only with a pin vice.

Michael

Hi Michael,

It was from one of those multi-boxes of drill bits (0.4-1.6mm) so the odds are that its the soft HSS type - I do have better quality drills in some of the sizes but not in the 1.2mm that it needed.