Finney7 - 4200G Group Std Tender Build - Scale7

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  • Just the off piste deviations from the instructions

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adrian

Flying Squad
Hi Adrian,

Nice to see the build coming along, and you have made the springy beam system look easy.

I just wonder whether your new rear stretcher is going to interfere with the coupling? That hole may have a use!
Cheers - Good point I'm hoping the new rear stretcher won't interfere but I'll cross that bridge when I get to it.
 

adrian

Flying Squad
Hi Adrian

How do you add all the annotations to your photos ?

Thanks

Richard
Hi,

I'm using a Mac and the standard Photos tool and photo preview allows for "Markup"

Screenshot 2021-01-18 at 12.36.39.png

This gives you a little ribbon of buttons to add and edit the annotations - shapes, text, highlighting. Only simple stuff but fairly quick and easy. The hardest part seems to be finding a suitable colour to stand out from the photo!

Screenshot 2021-01-18 at 12.37.12.png
 

adrian

Flying Squad
Next little update - I forgot to mention in the last post the inner frame for the stretchers has a couple of half etched slots in the top - I suspect these mark where to trim it if you are modelling a narrow gauge version. Otherwise it all folded up nicely, with some half etched rebates to position the stretchers.

4200g-scoop-cylinder - 1 (1).jpeg

As per the instructions once it's folded up there is a length of brass rod to be soldered to this inner frame for the vacuum pipe - for this there is an alignment mark on the outside dummy frame. So I clamped the two together.

4200g-scoop-cylinder - 2.jpeg

Soldered the brass rod to the inner frame.

4200g-scoop-cylinder - 3.jpeg

Then checked from the outside that it all looked straight.

4200g-scoop-cylinder - 4.jpeg

Next was assembling the water scoop and linkage - no real problem with this just a bit of fettling on the white metal castings and the actuation linkage - the end of the cranks were drilled out and a short length of wire inserted to represent the pivot point. The linkage hasn't been soldered in yet - just dropped over the bars. I need to work out an arrangement to easily remove or pivot out of the way to help fitting or dropping out the wheels.

4200g-scoop-cylinder - 5.jpeg

It was then onto making replacement vacuum cylinders - nothing special but a little more 3D than the kit. Just a length of brass bar turned to size and then drilled and tapped 8BA. These could then be screwed to a strip of n/s soldered to be soldered into the chassis. Again all pivot points drilled and a short length of wire inserted.

4200g-scoop-cylinder - 6.jpeg

All fitted to the chassis.

4200g-scoop-cylinder - 7.jpeg

oops - the beauty of taking photos - just noticed one of the bracing wires in the water scoop has gone AWOL. Will have to sort that out!

4200g-scoop-cylinder - 8.jpeg

4200g-scoop-cylinder - 9.jpeg

So next instalment is probably the brake gear.
 

adrian

Flying Squad
On with the brake gear and another small deviation from the instructions. The brake rods and cross beams is one etching - all the joints were drilled and pinned for a little 3D relief. The ends of the beams had a little half etch tab to fit into the brake hanger so I cut these off and replaced them with 14BA screws - the slot neatly locating in the etch.

The other change is to replace the rather flat electrically conductive etching in the kit. Using a bit of the spare etch framing I soldered lengths together and using the etching as a guide marked out the hangers for 3 pairs. These were cut and filed to shape.

4200g-brakes - 1.jpeg

I then drew out and laser cut some plastic brake shoes. Three layers for a bit of depth and provides the slot for the hanger. Three lengths of nickel wire were cut to length and the end threaded again 14BA.
4200g-brakes - 2.jpeg

Starting to assemble the components, the brakeshoes are pinned to the hangers and so are free to rotate. A short length of copper tube was cut to space out the hangers away from the dummy inside frame.

4200g-brakes - 3.jpeg

The lower 14BA screws will have to be shortened at some point.

4200g-brakes - 4.jpeg

So the braking rigging can now be pivoted out of the way to get access to the wheels. Although I haven't soldered anything to the main brake rod at the front so this can be removed still to separate rigging from the rest of the chassis.

4200g-brakes - 5.jpeg
 

adrian

Flying Squad
That brake gear is really nice Adrian, shall steal that idea :thumbs::D
Feel free - that's why I post to share ideas in the hope that it helps. For the brakes if anyone is building the same kit I'm more than happy to supply the CAD files or lightburn files to allow you to cut your own plastic brake shoes - failing that I'm more than happy to cut a few more out and supply as required.
 

simond

Western Thunderer
Adrian
Which plastic did you use please? I’ve not been hugely successful with laser cut plastic...

thx
Simon
 

adrian

Flying Squad
Adrian
Which plastic did you use please? I’ve not been hugely successful with laser cut plastic...
I bit the bullet and got a sheet of Trotec. Given the size and output of my modelling it'll last a long time. I'm happy to send you a small sample if you want to try it. I suppose card could be an alternative if you want to make insulated brake blocks.
 

simond

Western Thunderer
Thanks Adrian, confirms what (I think) Giles said, and thanks also for your kind offer.

I'll bite that bullet too.

was it this stuff ? TroLase ADA LS401-104 Black 1mm? I'm waiting for them to authorise my account.

Card (or MDF if you want thicker) soaked in superglue is pretty tough, and would certainly do in that kind of application.


cheers
Simon
 

adrian

Flying Squad
Thanks Adrian, confirms what (I think) Giles said, and thanks also for your kind offer.

I'll bite that bullet too.

was it this stuff ? TroLase ADA LS401-104 Black 1mm? I'm waiting for them to authorise my account.

Card (or MDF if you want thicker) soaked in superglue is pretty tough, and would certainly do in that kind of application.
Same stuff I think but I bought LT404-102 Black 0,5mm - so slightly thinner. When I ordered I asked them to cut it into A3 sized sheets to help keeping it flat for postage as I wouldn't be able to use anything larger which they were quite happy to accomodate.

I would use card rather than MDF as the alternative because by using several sheets I can build up the 3D shape in layers and leave a slot down the middle for the hanger. You could do something similar with MDF but you'd still have to cut the slot in the brake shoes afterwards.
 

adrian

Flying Squad
So assembling it all together gives me quite a nice rolling chassis. I'm not too sure at the moment about the ride height - it's probably about right at the moment but I'll have to see what it's like when the full body is fitted. With my CSB design I'm going to wait until it's finished and check - changing the ride height will need a tweak to the 3D design and simply print off a new set of hornblocks.
4200g-dummy-frames - 2.jpeg

So in the instructions I'm onto the next page ( 7 - for those with the kit) which is the "frame assembly". There is the top plate with a small strip to solder on and the dummy side frames with a selection of half etched rivets to press out.

4200g-dummy-frames - 1.jpeg

The edge of the top frame is bent over - I then use a hide mallet and a length of square steel to knock it over and then draw along the length to get it smooth. Using a glass plate to keep it flat and the small strips are soldered to the outside.

4200g-dummy-frames - 3.jpeg

The next task in the instructions is the riveted strip to represent the angle between the top plate and the side frames. It's a thin strip with lots of half etched rivets - once these are pressed out it doesn't quite retain the flat square shape it started out as!!

4200g-dummy-frames - 4.jpeg

A little gentle tweaking through the fingers to get it flat again then the spring brackets are folded over. At this point I deviate subtly from the instructions by soldering in the little triangular reinforcing webs. The instructions suggest soldering these riveted strips to the frames first before the triangular webs. However for small details like this I like to be able to hold the little web in place and apply the soldering iron from behind to minimise flooding it with solder. Also the instructions suggest filing the top flush before soldering in the web - I did do this but wish I hadn't. I would suggest soldering in the triangular webs before filing the top flush. The reason is once it is filed flush you have removed the metal connecting the bracket to the strip so when you solder in the web there are 3 components and yes the brackets did start moving if I wasn't careful. So fold over and solder the triangular web (only 2 components) and then file the top flush.

4200g-dummy-frames - 5.jpeg

Once the ends have been folded to 90 degrees it is soldered to the dummy side frames.

4200g-dummy-frames - 6.jpeg

The frames are finished off with the steps, riveted, folded and soldered on. The front drag beam and rear buffer beam cutout and cleaned up. In the photo above I marked the location rivet for the brake pin retainers - I recommend punching them out but then filing them flush. The reason being the pin retainers are tiny[*] with a half etch hole on the rear to locate over this rivet. Unfortunately the half etch isn't that deep so they didn't sit very flush. By filing the rivet flush I had a marker where they needed to go and could get it to sit flush.

[*] Don't any 7mm modeller say 2mmFS is too small and fiddly - these brake hangar pin retainers are just as small as anything I have soldered in my 2mmFS kits!!

4200g-dummy-frames - 7.jpeg
 

adrian

Flying Squad
A small update as I have managed to get most of the chassis bit finished - end of the next page of instructions.

I have a small rectangular glass plate I use to solder up main details to ensure they are flat and square so all went together nicely the slots keeping everything square although the rear of the buffer castings did need quite a bit of filing to get to fit behind the outer frames.

4200g-chassis - 1.jpeg


4200g-chassis - 2.jpeg


Then a trial fit with the inner chassis went without any problems. So this is the stage where all the brass castings have been soldered on.

4200g-chassis - 3.jpeg

Just the white metal castings to fit. Not unexpectedly but everything just fitted, the castings just needed a little bit of cleaning up. There are 4 castings per axle box, the axle box, the spring and dropper and 2 hangar pockets. The hangar pockets were drilled out slightly for the spring hangers to fit into so the springs are not actually glued or soldered in. I low melt soldered the pockets to the frame, then fitting the axle box in place actually held in the spring so no cleaning up required. The only cleaning up required was the inner side of the middle axle box. This was filed flush with a coarse file so that the inner chassis would fit.

4200g-chassis - 4.jpeg

4200g-chassis - 5.jpeg

4200g-chassis - 6.jpeg

4200g-chassis - 7.jpeg

4200g-chassis - 8.jpeg

I think I need to make up a short length of twisted wire to hold up the steam heating (?) pipe otherwise that is basically complete and I can move on to the next page of instructions and the main upper body of the tender.

p.s. I forgot to mention when soldering in the vac pipe to the rear buffer beam make sure you dig out the main body floor from the etchings. It has a small cutout to fit around the vac pipe, so place this on the main chassis frame and it provides a reference point for soldering on the vac pipe. Otherwise you will probably found you haven't located it exactly right when you try to fit the main tender body as I found out!
 
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