7mm David Andrews Princess - 6206 Princess Marie Louise
- Thread starter Rob Pulham
- Start date
Rob Pulham
Western Thunderer
This week has mainly been about working on the back head, one of my favourite parts of a build.
I started by making a driver's heatshield. The size and shape was worked out from an oblique photo and referencing it to other items located in the cab.
Once I had the basic shape I took a short length of nickel rod and filed it to half round to create the edging strip. I did have it fixed in place but then when I fitted the Drivers brake valve in place and started to consider the other pipework I realized that there would need to be some relief above the fire door rails to allow pipes to pass behind the shield.
The other castings that you can see in the photos are some of the few David Andrews parts that I have. The ready made holes in the back plate itself are causing a few issues as most are over sized and the ones on the fire hole door needed their placement adjusting to get the levers that open and close it to sit correctly with the two mounting brackets adjacent to the bottom rail.
The shelf on the other hand fitted perfectly .
I started by making a driver's heatshield. The size and shape was worked out from an oblique photo and referencing it to other items located in the cab.
Once I had the basic shape I took a short length of nickel rod and filed it to half round to create the edging strip. I did have it fixed in place but then when I fitted the Drivers brake valve in place and started to consider the other pipework I realized that there would need to be some relief above the fire door rails to allow pipes to pass behind the shield.
The other castings that you can see in the photos are some of the few David Andrews parts that I have. The ready made holes in the back plate itself are causing a few issues as most are over sized and the ones on the fire hole door needed their placement adjusting to get the levers that open and close it to sit correctly with the two mounting brackets adjacent to the bottom rail.
The shelf on the other hand fitted perfectly .
OzzyO
Western Thunderer
Hello all,
have you noticed that the part that you have lost always turns up in the last place that you would think of looking!
So I now start looking in the last place that I would think of looking, but to no avail as the part then turns up in the place that would have been the first place that I would normally start looking.
Figure that out!
OzzyO.
have you noticed that the part that you have lost always turns up in the last place that you would think of looking!
So I now start looking in the last place that I would think of looking, but to no avail as the part then turns up in the place that would have been the first place that I would normally start looking.
Figure that out!
OzzyO.
3 LINK
Western Thunderer
I think the last place I finally found the part takes some beating. I was soldering up some Slaters horn blocks and guides, when one of the small springs flew off into the wilderness. After looking just about everywhere on the floor and surrounding area , I gave up. Later that evening while having a shower I felt something pulling my chest hairs out, and you’ve guessed it, it was the bloody spring entwined in my chest hairs.
.
Dave Holt
Western Thunderer
Hi Rob.
I think you have mounted the driver's brake valve casting upside down. It also looks a bit low (compared with the tray over the fire hole and the washout plug) and too close to the loco centre-line. The centre of the main body (where the handle pivots) should be approximately 41" above the cab floor and 28" from the loco centre-line, although it might be the angle of the photo.
The heat shield is level with the end of the fire hole door runners, as you've got, and should be 201/2" from the loco CL.
When you come to them, the steam pipes from the manifold down to the injectors are not quite symmetrical, the LH pipe is 2'-07/8" from the CL and the RH pipe is 2'-21/2" from the CL.
Hope this helps.
Dave.
I think you have mounted the driver's brake valve casting upside down. It also looks a bit low (compared with the tray over the fire hole and the washout plug) and too close to the loco centre-line. The centre of the main body (where the handle pivots) should be approximately 41" above the cab floor and 28" from the loco centre-line, although it might be the angle of the photo.
The heat shield is level with the end of the fire hole door runners, as you've got, and should be 201/2" from the loco CL.
When you come to them, the steam pipes from the manifold down to the injectors are not quite symmetrical, the LH pipe is 2'-07/8" from the CL and the RH pipe is 2'-21/2" from the CL.
Hope this helps.
Dave.
Last edited:
Rob Pulham
Western Thunderer
Many thanks Dave,
I fitted the brake valve in the hole provided for it, which I had to bush. I didn't consider that it might be in the wrong place. As for getting it upside down too, what can I say...
Rob Pulham
Western Thunderer
Further to Dave's note in post #306 I have done a bit of measuring up of the back head casting this morning.
The brake valve as noted, is approx. 0.9mm (1.543in) too near to the centre line (of the back head casting). But it is actually higher rather than lower than the 41in (23.917mm) above the cab floor. It's 25.94.
It's also interesting that where I have the 'pipe' coming out of the 'bottom' which should indeed be the top, it was fitted into a cast hole. Looking at the WS GA (which I have imported into Fusion 360 and scaled) the top looks like some kind of cap so I don't think that it should have had a hole in it and unless someone advises different I will cut the bras rod off and file it flush.
The back head casting itself is/was, also over 1mm wider than prototype. I say is/was because it's still 1mm too wide and I had already taken some off to get it to fit, before relocating the right hand locker further outboard.
Unfortunately the sides of the casting are now only 0.7mm thick so If I were to take 0.5mm off each side to bring it to actual size, it would be very thin.
The brake valve as noted, is approx. 0.9mm (1.543in) too near to the centre line (of the back head casting). But it is actually higher rather than lower than the 41in (23.917mm) above the cab floor. It's 25.94.
It's also interesting that where I have the 'pipe' coming out of the 'bottom' which should indeed be the top, it was fitted into a cast hole. Looking at the WS GA (which I have imported into Fusion 360 and scaled) the top looks like some kind of cap so I don't think that it should have had a hole in it and unless someone advises different I will cut the bras rod off and file it flush.
The back head casting itself is/was, also over 1mm wider than prototype. I say is/was because it's still 1mm too wide and I had already taken some off to get it to fit, before relocating the right hand locker further outboard.
Unfortunately the sides of the casting are now only 0.7mm thick so If I were to take 0.5mm off each side to bring it to actual size, it would be very thin.
OzzyO
Western Thunderer
Hello Rob / all,
this drawing may help with the boiler front of L. M. S. locos, it's not to scale but it was drawn by the loco department Derby so it my be correct. It's in a book called questions for enginemen and such. They do turn up on the bay of e for some good prices.
It's a big file so you should be able to expand it to a good size.
ATB
OzzyO.
PS. if you want the full size file let me know.
this drawing may help with the boiler front of L. M. S. locos, it's not to scale but it was drawn by the loco department Derby so it my be correct. It's in a book called questions for enginemen and such. They do turn up on the bay of e for some good prices.
It's a big file so you should be able to expand it to a good size.
ATB
OzzyO.
PS. if you want the full size file let me know.
Dave Holt
Western Thunderer
Rob.
As you correctly say, the item on top of the driver's brake valve is a perforated cover (sometimes referred to as the pepper-pot), where air is admitted to destroy the vacuum and apply the brakes. On our scale of models, it would have a closed end. The connection to the large train vacuum pipe is at the bottom. The other smaller diameter pipes are steam supply and outlet to the steam brakes. The very small pipes connect to the vacuum gauge.
Dave.
As you correctly say, the item on top of the driver's brake valve is a perforated cover (sometimes referred to as the pepper-pot), where air is admitted to destroy the vacuum and apply the brakes. On our scale of models, it would have a closed end. The connection to the large train vacuum pipe is at the bottom. The other smaller diameter pipes are steam supply and outlet to the steam brakes. The very small pipes connect to the vacuum gauge.
Dave.
Dave Holt
Western Thunderer
Sorry. A correction to my earlier post. The device on top of an LMS vacuum brake valve is the vacuum relief valve - so probably does have a hole down the middle. I think the air to destroy the vacuum enters through the perforated front disc of the valve, where the handle attaches.
Dave.
Dave.
Rob Pulham
Western Thunderer
Thanks Paul,
The fun part is identifying which casting is meant to represent which item on the drawing.
Rob Pulham
Western Thunderer
Scale7JB
Western Thunderer
Hi Dave, yes the 'pepper pot' is used on a vacuum system to ensure that the ejector (and/or crosshead pump) doesn't exceed the desired amount of vacuum. It is adjustable by removing the perforated cover and screwing the valve down tighter for a higher vacuum system e.g. GWR 25" over everyone else's 21". And as you say the air is admitted in to the system to apply the brakes through the holes on the front of the brake handle.
JB.
Rob Pulham
Western Thunderer
Moving on from my last post, I had made a small brass bush to reduce the size of the hole but moving it as per the discussion above gave me the chance to re-drill at the right size for the brake valve stem.
Here we are nicely aligned.
I have also made a start on piping up the steam fountain.
The brake valve is piped up the right way up now too.
I had to remove a section from the inside edge of the heat shield to allow pipes to pass through it. The pipe at the side is one of the two main pipes coming down from the steam fountain and one thing that stands out on both drawing and photos is that there is a chunky union on the lower section.
These are the parts that will make up a representation of those unions.
Here we are nicely aligned.
I have also made a start on piping up the steam fountain.
The brake valve is piped up the right way up now too.
I had to remove a section from the inside edge of the heat shield to allow pipes to pass through it. The pipe at the side is one of the two main pipes coming down from the steam fountain and one thing that stands out on both drawing and photos is that there is a chunky union on the lower section.
These are the parts that will make up a representation of those unions.
Rob Pulham
Western Thunderer
I was working away on the back head this afternoon, filling the holes for the water gauges prior to redrilling the right size for the castings spigots when the door bell rang it was the postie with the final production version of the firebox print. I was then distracted so I will pick up the back head again tomorrow.
This was printed by Mike Hopkins @Mike Hopkins of Scale-Factor.
These show the firebox print as received with all the supports attached.
Then with the supports carefully removed. I still need to clean up the base and the cab end but I have tried the boiler on and it fits perfectly. A nice friction fit.
This was printed by Mike Hopkins @Mike Hopkins of Scale-Factor.
These show the firebox print as received with all the supports attached.
Then with the supports carefully removed. I still need to clean up the base and the cab end but I have tried the boiler on and it fits perfectly. A nice friction fit.
OzzyO
Western Thunderer
[/QUOTE]
Hello Rob,
that looks stonking.
But I do have a small criticism. The joint at the front of the fire box and the boiler in the front quarter looks to deep (big). This then makes the step in the horizontal joint look too deep and makes it have a step in the cladding band. The cladding band would have looked like it was just a single band with no step in it.
The cladding and bands would have only have been about 1/8" at most..
A very nice job and well done,
ATB
OzzyO.
Last edited:
Rob Pulham
Western Thunderer
Still working on the back head, because I am using a mixture of David Andrews and Just Like the Real Thing castings, I have had to move/reduce the size of all the holes except the one for the regulator mounting boss. The JLRT castings are really nice (as are the couple of David Andrews castings that I have) except for the cab dials which are a bit misshapen and the 'unions' for where the pipes are proving impossible to drill. The simplest and quickest way was to make some more swarf by turning some more.
Then I realised that I also needed a smaller version
It made sense while I had the set up to do some for the Rebuilt Scot at the same time.
Then I dug out the mountings and attached the dials to them.
Then I realised that I also needed a smaller version
It made sense while I had the set up to do some for the Rebuilt Scot at the same time.
Then I dug out the mountings and attached the dials to them.