PhilMortimer
Active Member
Clever!
7mm David Andrews Princess - 6206 Princess Marie Louise
- Thread starter Rob Pulham
- Start date
Rob Pulham
Western Thunderer
Back to the Princess this week after moving the J6 along.
In the end I decided to take a bit more of the edges of the cylinders and then I fitted the covers. Before I did that I soldered the slide bars in place as I didn't want the heat from soldering them in place to spring the cylinder covers loose. As it happens I had to adjust one of the slide bars as I hadn't got it quite square and the cylinder covers are such a good fit that although the solder softened, they never moved. Something to aim for on future builds.
After fitting the slide bars I mated them up with the motion bracket and realised that once I join the two together them crossheads become captive so I need to do work on the motion next to ensure that all is well before I solder the slide bars to the motion bracket.
The first hiccup is a result of using extras to the kit. I used the David Andrews Slide bars and crossheads for the simulated inside motion because they don't have as much details as the LG Miniatures versions. Now I come to fit the LG crossheads with the connecting rods which are replacements from Premier Components I find that the LG crossheads are different to those that I have used on other builds in so much as they have a slot in them rather than an open back. This means that I will have to mill the connecting rod ends to get them to fit in the slot.
A picture paints a thousand words or something like that...
In the end I decided to take a bit more of the edges of the cylinders and then I fitted the covers. Before I did that I soldered the slide bars in place as I didn't want the heat from soldering them in place to spring the cylinder covers loose. As it happens I had to adjust one of the slide bars as I hadn't got it quite square and the cylinder covers are such a good fit that although the solder softened, they never moved. Something to aim for on future builds.
After fitting the slide bars I mated them up with the motion bracket and realised that once I join the two together them crossheads become captive so I need to do work on the motion next to ensure that all is well before I solder the slide bars to the motion bracket.
The first hiccup is a result of using extras to the kit. I used the David Andrews Slide bars and crossheads for the simulated inside motion because they don't have as much details as the LG Miniatures versions. Now I come to fit the LG crossheads with the connecting rods which are replacements from Premier Components I find that the LG crossheads are different to those that I have used on other builds in so much as they have a slot in them rather than an open back. This means that I will have to mill the connecting rod ends to get them to fit in the slot.
A picture paints a thousand words or something like that...
Rob Pulham
Western Thunderer
Thankfully not, I thought so too when I first looked at the photo, but it's where I cleaned off some stray solder.
Rob Pulham
Western Thunderer
With the slide bars in place at the cylinder end it was time to start thinking about the outside motion. I decided to do it as two subassemblies and then join them together as I secure the rear end of the slide bars to the motion bracket.
Along with the Premier Components coupling rods, came a set of the rest of the motion parts many of them very nice but some just didn’t work (or at least in my view). These are the combination levers and the union links. Starting with the combination levers, those fitted to the Princess Royals were fluted and the Premier examples plain.
The union links in the Premier set are represented by a single dog bone shaped rod which is 0.9mm thick. The very visible, prototype union links have forked ends. After exploring options of combining the etches with the premier link I realised that they were each of different lengths so no chance of combining the two.
After consultation with the gent that I am building it for, I went with the DA etched combination levers and union links but used the Premier parts for the rest of the motion.
For me the most difficult bit of building motion, inside or out is “how do I fasten it all together”. For the front half I have tapped the valve rod 14ba and put a screw through from the inside. Visible in the photo below.
The union links I have riveted with 0.8mm brass rod. I have a small piece of steel that I use as an anvil so I drilled a shallow depression in one corner to use to form rivet heads. Once inserted I peined them over with a small ball pein hammer.
I also turned up some oil pots for the connecting rods. Not quite prototypical but they do look nice.
While I am using the Premier Rods, I still need to use the DA etched expansion link and that’s where I was second guessing myself
On all the other outside Walschaerts valve gear that I have built before, the radius rod is connected via a pivot below the main pivot of the expansion link.
I thought I had assembled it wrong but after searching through a number of photos and reviewing the outside motion GA for 6203-62012 on page 38 of the Wild Swann book. It seems that on the Princess Royal there is no lower pivot point. Phew!
Finally, I was pondering the brass bearing cap on the eccentric rod where it attaches to the return crank. There are some etched covers included but since the whole kit is etched nickel, they are nickel not brass. So, I had a quick go at mocking one up on the lathe.
Although it doesn’t have the small screw heads and the oil pot it does look more three dimensional than the etch and of course it’s brass. I will sleep on it and see where I decide to go next with that one.
Along with the Premier Components coupling rods, came a set of the rest of the motion parts many of them very nice but some just didn’t work (or at least in my view). These are the combination levers and the union links. Starting with the combination levers, those fitted to the Princess Royals were fluted and the Premier examples plain.
The union links in the Premier set are represented by a single dog bone shaped rod which is 0.9mm thick. The very visible, prototype union links have forked ends. After exploring options of combining the etches with the premier link I realised that they were each of different lengths so no chance of combining the two.
After consultation with the gent that I am building it for, I went with the DA etched combination levers and union links but used the Premier parts for the rest of the motion.
For me the most difficult bit of building motion, inside or out is “how do I fasten it all together”. For the front half I have tapped the valve rod 14ba and put a screw through from the inside. Visible in the photo below.
The union links I have riveted with 0.8mm brass rod. I have a small piece of steel that I use as an anvil so I drilled a shallow depression in one corner to use to form rivet heads. Once inserted I peined them over with a small ball pein hammer.
I also turned up some oil pots for the connecting rods. Not quite prototypical but they do look nice.
While I am using the Premier Rods, I still need to use the DA etched expansion link and that’s where I was second guessing myself
On all the other outside Walschaerts valve gear that I have built before, the radius rod is connected via a pivot below the main pivot of the expansion link.
I thought I had assembled it wrong but after searching through a number of photos and reviewing the outside motion GA for 6203-62012 on page 38 of the Wild Swann book. It seems that on the Princess Royal there is no lower pivot point. Phew!
Finally, I was pondering the brass bearing cap on the eccentric rod where it attaches to the return crank. There are some etched covers included but since the whole kit is etched nickel, they are nickel not brass. So, I had a quick go at mocking one up on the lathe.
Although it doesn’t have the small screw heads and the oil pot it does look more three dimensional than the etch and of course it’s brass. I will sleep on it and see where I decide to go next with that one.
Lancastrian
Western Thunderer
Rob,
Looking good.
I've drilled coupling and connecting rods in the past and inserted brass tube for the oiling point and then inserted brass wire to represent the "cork".
Ian
Looking good.
I've drilled coupling and connecting rods in the past and inserted brass tube for the oiling point and then inserted brass wire to represent the "cork".
Ian
Rob Pulham
Western Thunderer
Hi Ian,
Nice idea and one which I will store for future use.
Those on the Princess are cone shaped with a cork in the top. I had already made and fitted those before seeing this.
Richard Gawler
Western Thunderer
Rob, I am finding a huge amount of inspiration in this build. Simply seeing what is possible from a 7mm kit.
Len Cattley
Western Thunderer
Hi Rob, have you seen the build that Nick Dunhill did of 3 Princess Royals a number of years ago? It was inspirational as your build is to.
Len
Len
Rob Pulham
Western Thunderer
Thanks Len,
I sure have.
I refer to Nick's builds if I am struggling to see wood for trees.
I sure have.
I refer to Nick's builds if I am struggling to see wood for trees.
spikey faz
Western Thunderer
Rob, your loco build is very therapeutic. I'll almost be disappointed when it's finished! 
I see that you have access to various machine tools including a lathe. I've never had a lathe and not sure now whether I could afford one. However, out of interest, what do you reckon would be the minimum specification lathe for a beginner like me? I wouldn't have a clue what I'd need for O scale modelling.
Cheers
Mike
I see that you have access to various machine tools including a lathe. I've never had a lathe and not sure now whether I could afford one. However, out of interest, what do you reckon would be the minimum specification lathe for a beginner like me? I wouldn't have a clue what I'd need for O scale modelling.
Cheers
Mike
Rob Pulham
Western Thunderer
Thanks Mike,
Being a beginner, although I did have a Unimat SL lathe which I sold to a fellow WT Member, I didn't really start being confident in making things on the lathe until I bought a Unimat III. With an ER 25 collet chuck and a set of collets you can do many things on a Unimat for 7mm models.
I ultimately bought a bigger Sieg SC3 lathe because I wanted to do a little more adventurous things such as turn wheels (at some point and the Unimat III didn't really have a slow enough speed setting for wheel turning). And if I'm honest, because one became available via the GOG sales at the right price.
I did do a few upgrades to the SC3 which I documented in a thread on here. These were really inexpensive to carry out, but have resulted in a much more rigid machine.
In my case, the ultimate choice of lathe was governed not only by price but by the footprint of the machine itself. Had I been able to afford a Myford I wouldn't have been able to fit it in my workshop.
Being a beginner, although I did have a Unimat SL lathe which I sold to a fellow WT Member, I didn't really start being confident in making things on the lathe until I bought a Unimat III. With an ER 25 collet chuck and a set of collets you can do many things on a Unimat for 7mm models.
I ultimately bought a bigger Sieg SC3 lathe because I wanted to do a little more adventurous things such as turn wheels (at some point and the Unimat III didn't really have a slow enough speed setting for wheel turning). And if I'm honest, because one became available via the GOG sales at the right price.
I did do a few upgrades to the SC3 which I documented in a thread on here. These were really inexpensive to carry out, but have resulted in a much more rigid machine.
In my case, the ultimate choice of lathe was governed not only by price but by the footprint of the machine itself. Had I been able to afford a Myford I wouldn't have been able to fit it in my workshop.
Rob Pulham
Western Thunderer
Hi Ken,
I haven't any experience or knowledge of the Proxxon lathes. I did look at Proxxon milling machines when I was looking for one, as I am really happy with my Proxxon mini pillar drill. But all that I read online said that they were too fast for most work.
I had the Sieg recommended by a fellow WT member, and fortunately of the half a dozen or so models that I compared specs on at the time, they were actually the only one that was available to buy when I wanted it.
I haven't any experience or knowledge of the Proxxon lathes. I did look at Proxxon milling machines when I was looking for one, as I am really happy with my Proxxon mini pillar drill. But all that I read online said that they were too fast for most work.
I had the Sieg recommended by a fellow WT member, and fortunately of the half a dozen or so models that I compared specs on at the time, they were actually the only one that was available to buy when I wanted it.
chigley
Western Thunderer
Hello Rob ,yes they are quite fast, but i'm not doing any major work just little bits n pieces, but for the price i couldn't say no, i've got the mini drill as well and milling table. Ideal for those pesky brass castings, just recently purchased the bigger drill stand [used]with milling table
Ken
Ken
Rob Pulham
Western Thunderer
I have really struggled for motivation this week so haven’t achieved as much as I might have liked.
I decided that the etched return cranks were a little under nourished and 2D so I added a bit of detail.
First a turned a spigot on an offcut of rod and soldered the rear etch to it and drilled out the four bolt holes using 90 degrees spacing on my Proxxon mini pillar drill using the dividing head.
Next, I soldered them to a piece of scrap etch from the kit drilled through the holes to transfer them to the other layer and cut around them with a piercing saw. I forgot to take photos of that bit.
Then I made up eight (actually nine) studs from rod and microbore tube filed to a hex head and cut to length.
And finally I assembled all the parts.
Magnified as they are they look a little rough around the edges but it’s not visible at normal viewing distances.
I decided that the etched return cranks were a little under nourished and 2D so I added a bit of detail.
First a turned a spigot on an offcut of rod and soldered the rear etch to it and drilled out the four bolt holes using 90 degrees spacing on my Proxxon mini pillar drill using the dividing head.
Next, I soldered them to a piece of scrap etch from the kit drilled through the holes to transfer them to the other layer and cut around them with a piercing saw. I forgot to take photos of that bit.
Then I made up eight (actually nine) studs from rod and microbore tube filed to a hex head and cut to length.
And finally I assembled all the parts.
Magnified as they are they look a little rough around the edges but it’s not visible at normal viewing distances.
Dave Holt
Western Thunderer
Very nice Rob, but you will have to watch that the studs don't catch the back of the eccentric rods. On P&O (and on the Princess Royals, according to the motion drawing), the nuts are no deeper than the thread diameter and are recessed into the face of the return crank. The studs protrude only a thread pitch or so beyond the nuts. The re-built MN motion drawing shows the nuts standing 20 mm proud of the front face of the return crank and the studs 22 mm (7/8"). Say 0.5 mm in 7 mm scale?. Even so, there's not a huge amount of clearance.
The return crank has a raised boss on the back at the crankpin and on the front where the eccentric rod attaches. At both bosses, it is 34 mm thick and about 26 mm in the centre section, between the bosses.
Dave.
The return crank has a raised boss on the back at the crankpin and on the front where the eccentric rod attaches. At both bosses, it is 34 mm thick and about 26 mm in the centre section, between the bosses.
Dave.
Last edited:
mickoo
Western Thunderer
Rob Pulham
Western Thunderer
Thanks Dave,
I didn't have a photo as clear as the one that Mick has posted (thanks Mick) but I was expecting to have to file a bit more off them.
Rob Pulham
Western Thunderer
The first stage of fitting 3D printed brake blocks is the hangers. Sadly the nice cast brass hanger are far too thick for the replacement block so it was either make some new from nickel sheet or try to mill off the shoes from the etches supplied in the kit. with the make new ones as a back up plan I decided I had nothing to lose in trying to mill of the shoes and use the existing brake hanger etches.
So far so good. I now need to trim off the remains of the shoes, solder the fronts and backs together and then probably file a little more off to make the shoes fit.
So far so good. I now need to trim off the remains of the shoes, solder the fronts and backs together and then probably file a little more off to make the shoes fit.