7mm Pencarrow - Cornish BR(S)

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Pencarrow

Pencarrow

Western Thunderer
Up early this morning, so decided to do a bit more on the bridge.

The second layer of 20thou was laminated on to the underside of the arch. But first strategic holes added in the existing ring to enable the solvent to be added.
PXL_20250113_072105952.MP.jpg

I also finished off the bracing to the abutment faces. This will give something hard to press against when detailing the abutment stonework, plus it has really firmed up the rigidity of the structure.
PXL_20250113_081155528.jpg

Once the arch lamination was fixed and trimmed back, thoughts turned to the arch ring. The SEF brick sheets I'll be using for this are significantly thinner than the Wills stonework, so the arch ring needs building up a good 60thou first from two layers of 30thou (easier to cut).

Arch shapes are extremely wasteful in the sheet they are cut from, so instead I cut them out in smaller segments. The intention was just over 45deg but it appears they are just under 60deg...

The circle cutter came into its own again.
PXL_20250113_075828976.jpg

Starting to release the segments.
PXL_20250113_080118934.jpg

Very little waste.
PXL_20250113_080345169.jpg

Adding the first layer, with the second ready to go.
PXL_20250113_081056956.jpg

Bridge back in place with my current thoughts on curving the approaches shown on the wingwall.
PXL_20250113_081150876.jpg

(Bless car batteries and cold weather)
 
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Dan Randall

Dan Randall

Western Thunderer
Hi Chris

It’s great to see you making further progress on “Pencarrow”. :)

Much as I’ve enjoyed seeing the buildings you’ve made outside the railway fence come together, I’m really looking forward to seeing the bridge taking shape. I look forward to seeing the finished article on your demo stand at Guildex in September…;)


Regards

Dan
 
Pencarrow

Pencarrow

Western Thunderer
Dan Randall said:
Hi Chris

It’s great to see you making further progress on “Pencarrow”. :)

Much as I’ve enjoyed seeing the buildings you’ve made outside the railway fence come together, I’m really looking forward to seeing the bridge taking shape. I look forward to seeing the finished article on your demo stand at Guildex in September…;)


Regards

Dan
Click to expand...

Thanks Dan, I've been putting off the bridge of a while but have reached the point that I need to firm up on the bridge size and location as that affects other elements on the board.

I'm in a significant quandary about the girder bridge deck, particularly all the bolt heads and ribs etc. I'm wandering if brass or 3D print might be a more suitable solution than plastic.

Would welcome peoples thoughts...
 
Pencarrow

Pencarrow

Western Thunderer
Lyndhurstman said:
That's some lovely work, Chris. I seem to battle with my Oleo cutter. I'm probably doing it wrong! #whatdoyoumeanprobablyjan?

Cheers

Jan
Click to expand...

Thanks Jan, the compass curve cutter is great, but quite basic. It can be a bit imprecise and wander a bit if you try and do too deep a cut in one go, but multiple passes seems to do the trick.
 
daifly

daifly

Western Thunderer
This was posted on 10th Jan on the Guild forum by Jackie K.:
"Steve Robinson, Guildex Manager has asked me to post this message

"I would like to apologise to all layouts and demos expecting to hear about Guildex 2025.
Due to family commitments and holidays I am running behind with confirmations and bookings.
I will contact all those provisionally approached for this years Guildex by the end of January"."
 
simond

simond

Western Thunderer
"the girder bridge deck, particularly all the bolt heads and ribs."

There is a danger that, when the only tool you have is a hammer, that everything begins to look like a nail...

Resin 3DP would certainly work to provide details probably as overlays - the printing is relatively easy, but the time is in the 3D CAD
Brass with embossed rivets - I think @dibateg & @mickoo have proven that works - again time in the CAD, but time in the rivet press too. (and I built a Metalsmiths turntable which is a similar structure - lots of overlays, lots to assemble)
And @Jon Nazareth has also shown the way in drilling and inserting rivets.

A brass bridge would undoubtedly be strong enough - but I think I would take the easy way out and 3DP the overlays and stick them to something solid like PCB or ally angle.
 
Dan Randall

Dan Randall

Western Thunderer
Pencarrow said:
I'm in a significant quandary about the girder bridge deck, particularly all the bolt heads and ribs etc. I'm wandering if brass or 3D print might be a more suitable solution than plastic.

Would welcome peoples thoughts...
Click to expand...
Personally, I’d opt for etched brass or nickel silver (drawn with CAD), thus ensuring the rivets will be evenly spaced and in straight lines, where they need to be. :)

Obviously, this can be achieved with 3D printing too, but there’s always the prospect of the girders warping if they’re too thin (and you don’t want them so thick, they look like they’re made from concrete!) and/or displaying layer lines, which may be difficult to remove, without losing rivets too.

Plastic girders are also doable, festooned with 3D printed rivet transfers (which could work out expensive), or embossed by hand, which sounds like long, hard work especially keeping them evenly spaced and straight, but again, how thin can you go before warping becomes a distinct possibility?

Edit: Simon posted, while I was still typing.


Regards

Dan
 
mickoo

mickoo

Western Thunderer
Pencarrow said:
Thanks Dan, I've been putting off the bridge of a while but have reached the point that I need to firm up on the bridge size and location as that affects other elements on the board.

I'm in a significant quandary about the girder bridge deck, particularly all the bolt heads and ribs etc. I'm wandering if brass or 3D print might be a more suitable solution than plastic.

Would welcome peoples thoughts...
Click to expand...
Brass, do not consider anything else....please.....

Do not add 3D overlays to simplified brass structure, it'll look :shit: and the overlays will need to be thin and run the risk of warping during print, curing and at any time afterward.

3DP is not the right medium for this at all, it's far better suited to blocky objects or if you're doing panels etc, making them overly thick.

It's a simple single span bridge, you don't need to punch ut all the rivets, just add detailed overlays with half etched rivets. Even if you went for punched rivets I'd wager there's less on there than an engine tender or tank engine sides etc.

The CAD isn't hard, monkey see, monkey do work, couple of hours maybe.
 
Pencarrow

Pencarrow

Western Thunderer
mickoo said:
Brass, do not consider anything else....please.....

Do not add 3D overlays to simplified brass structure, it'll look :shit: and the overlays will need to be thin and run the risk of warping during print, curing and at any time afterward.

3DP is not the right medium for this at all, it's far better suited to blocky objects or if you're doing panels etc, making them overly thick.

It's a simple single span bridge, you don't need to punch ut all the rivets, just add detailed overlays with half etched rivets. Even if you went for punched rivets I'd wager there's less on there than an engine tender or tank engine sides etc.

The CAD isn't hard, monkey see, monkey do work, couple of hours maybe.
Click to expand...

Thanks Mick for your thoughts. In my mind I think that I'd already discounted 3D printing, more down to the potential for damage in such an exposed area. I can see the bottom and top flanges getting knocked during track cleaning etc. I'm a firm believer in Sod's Law - in this case, a more delicate item will attract damage causing incidents. Brass can be bent back.
 
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