Torre Station - Western Region in the 1950's in P4

[Siberian Snooper]

6 hours ago, MAP66 said:

Yes, there beautifully engineered and designed those horn block assemblies. I'm completely new to chassis building (this is my first build) and if I can put them together without any difficulty, then they must be good. Well done for identifying that the front ones will need the collars filed down a tad to clear the inside motion. I missed that point and had to take evasive action later. I'll mention it any way, but the driven axle bushes need the collar completely filed off to clear the gearbox. I found that the flange of the horn block etch was an ideal place for clamping tight to the side frame when soldering them in place. The wooden peg in the back ground has nothing to do with this engineering feat, it's simply there to prop up the chassis for the photo 😀

 

 

 

Are you using the space saver horn blocks and guides?

 

 

[MAP66]

1 hour ago, Siberian Snooper said:

 

 

Are you using the space saver horn blocks and guides?

 

 

No, I don't think so, these are the ones supplied with the kit. I'm not that familiar with the space saving ones - I'm guessing their profile is thinner?

[MPR]

13 minutes ago, MAP66 said:

No, I don't think so, these are the ones supplied with the kit. I'm not that familiar with the space saving ones - I'm guessing their profile is thinner?

https://www.highlevelkits.co.uk/suspension
Standard width are supplied with the kits, my kit is being built to P4, but the driven axle bearings will still need to be thinned down.

[MPR]

On 29/11/2023 at 09:48, MPR said:

 

The horn-guides were even easier than I thought - four folds and you are done on each. As the front ones will need to be filed a little to clear the inside motion etch, I'll add a little solder to them, but it is certainly not required for most applications. Even with final tweaks and polishing yet to be completed, the axle boxes are sliding freely.

The hornguides have now been soldered to make them more robust - the front (left of image) parts are going to be filed to fit around the inside motion. I also added a little solder to the fold of the bearing surfaces, just to be sure. The rear axle boxes have had the circular bosses removed to give clearance for the gearbox.

I then fitted each axle box, gently rubbing down the bearing surfaces with 600 grade until I obtained an easy sliding fit with no slop. Lastly I marked up each axlebox with one or two dots on the upper surface (left and right, respectively) and similarly with the hornguides. As the front hornguides and rear boxes are modified, that will be sufficient to ensure identification when assembling everything.

[MPR]

The coupling rods were now assembled, they are double layer, with the fronts being half-etched and rather delicate - I distorted one of them slightly when cutting out.

Fortunately, it  was easy to bend roughly back to shape and as it is etched slightly over width, it could be filed back later on.

I drilled out the holes somewhat undersized at 1.4mm and used the drill bit to align one end, aligning the other end by eye, before soldering.
Each side was cleaned, lightly tinned and fluxed, then tacked together by applying a freshly tinned bit to the sides, applying pressure from the top with tweezers. I worked my way round until I was sure that the joint was solid over the whole area.

I now opened the hole up to 1.5mm, still slightly undersized.

Finally, a tapered broach (thanks CK!) was used to ease each hole until it just fitted over the axle jig ends. 

This allowed me to check that the centres were spot on and held them neatly so the sides could be filed to shape.

 

The front hornguides were modified to clear the inside cylinder etch by removing a slice 1mm wide at top, tapering to 0mm at the bottom. I used an indelible marker on the surface, then scribed it with a compass point, just more than 1mm wide. Needle files were then employed to cut back to just before the line, checking the fit in the frames regularly.

Marked…

…and cut. 
The next step will be to clean the parts up ready to align and assemble to the mainframes.

 

 

Edited December 15, 2023 by MPR

[Captain Kernow]

10 hours ago, MPR said:

The front hornguides were modified to clear the inside cylinder etch by removing a slice 1mm wide at top, tapering to 0mm at the bottom

Marked…

…and cut

I have a feeling that I had to do something similar on my 74XX chassis - is this mentioned in the instructions, Martin?

 

[MPR]

4 minutes ago, Captain Kernow said:

I have a feeling that I had to do something similar on my 74XX chassis - is this mentioned in the instructions, Martin?

 

Hi Tim,

Yes, the requirement for this modification and the amount to be removed are explicitly stated in the instructions, which I have found  comprehensive and helpful (and can now be downloaded from the website free of charge). Soldering the two layers together was definitely helpful in keeping everything straight when filing down the edges.

 

[MPR]

The axle boxes are finally in place!

I followed the instructions for this, starting with one of the centre horn-blocks. The surfaces to be soldered were cleaned up and tinned, then the axle boxes were carefully oiled.

There is a 0.5mm hole etched into the centre of the top of the hornguide, with a corresponding hole in the mainframes. A piece of wire was pushed through to ensure alignment, then a lump of blutak was used to hold the block temporarily in position. The opposite side axlebox was similarly located and finally the spring was compressed and fitted, pressing both axle boxes against the hornguides/frames.

A long piece of 1/8” bar was then used to check that all was aligned and each side of the hornguides was checked for parallelism, then reflowed with a lot of flux and a little extra solder.

The extended axle was then fitted in place of the long bar and the exercise repeated with the front pair, slipping the coupling rods over the pair of extended axles to ensure the correct spacing before soldering. The coupling rod holes were deliberately left very tight to minimise error - they will be opened up to “not-quite-sloppy” later on.

 

Edited December 16, 2023 by MPR

[lezz01]

It's looking good mate, coming along very nicely.

I have one of HL chassis kits for the Jinty to build so this is very useful information for me although I'm working in EM not P4. I have modelled in P4 in the past.

Regards Lez.

[MPR]

Moving on to the cosmetic parts between the frames, the first step was to add the slide bars. These fitted well, but needed to be filed to remove the etch cusp to fit into place - a 0.5mm drill bit was used to poke at the edges of the slots they fitted into as well.

These parts are handed, but have been thoughtfully marked “L” and R,” so there is no excuse for getting the wrong way round. They are inserted into the rear slot, pushed as far as they will go, then slid forward until engaged in the front slot too and soldered into place.

The top piece is then added in the same way, followed by the middle packing piece.

The process is then repeated for the other upper slide bar.

 

Next step is the valve linkages, which will require some thought and even more fiddling to assemble.

Edited December 18, 2023 by MPR