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Lift-span Bridge

Beginners scratch-build 1/72 scale working model diorama.

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Peter Hausamann08/01/2018 09:35:01
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48 forum posts
84 photos

Added 3 mm Masonite sheets for road base, kerbing, and footpath to span plate.

img_0718 -sml.jpg

The underside has red and green navigational beacons, plus 8 contacts (shown later). To hide the wires, I decided to carve out trench to route the wires to far side of span where the framework will be. Then the wires can be attached to the framework and routed to the span hut without being too noticeable.

15_bridge model update _span part 1_sml.jpg

Then I drew up a template for the framework and started making the span frame. Used 2.5 mm bamboo skewer sticks for doweling wherever I could.

16_bridge model update _span part 2_sml.jpg

While building the frame a solution anchoring the span cables to the frame came to mind. I used half a fishing swivel attached to a bolt head.

17_bridge model update _span part 3_sml.jpg

Then I placed the span on the bridge to get an idea of how the rest of the bridge may present itself.

18_bridge model update _span part 4.jpg

XD 35108/01/2018 17:51:39
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805 forum posts
37 photos

WOW! that's some nice work there Peter !

I would never have thought a swivel could be used for model making !

Have you done any other model making work ? Possibly model planes ? You seem to be very good at it !

I'm looking forward to more of your project !

Must get back up to Ballina one day for a fish also to check out the museum and your model !

ian.

Jeff Dayman08/01/2018 18:29:37
1152 forum posts
23 photos

Hi Peter, you are doing a great job on the bridge model project and are moving right along. Thanks for sharing the pics too. JD

Peter Hausamann08/01/2018 20:00:58
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48 forum posts
84 photos
Posted by XD 351 on 08/01/2018 17:51:39:

WOW! that's some nice work there Peter !

I would never have thought a swivel could be used for model making !

Have you done any other model making work ? Possibly model planes ? You seem to be very good at it !

I'm looking forward to more of your project !

Must get back up to Ballina one day for a fish also to check out the museum and your model !

ian.

Hi Ian.

Another Aussie, Great!

Sorry mate, no other models. This is my first.

Though I have been in the RAAF, I cannot bring myself (yet) to model planes. It's not the same as the real thing.

Oh, by the way. The bridge won't be in the museum for quite a few months yet.

Edited By Peter Hausamann on 08/01/2018 20:02:33

Peter Hausamann08/01/2018 20:06:09
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48 forum posts
84 photos
Posted by Jeff Dayman on 08/01/2018 18:29:37:

Hi Peter, you are doing a great job on the bridge model project and are moving right along. Thanks for sharing the pics too. JD

Thanks Jeff Dayman.

At the moment, I am posting photos at piecemeal rate until the progress catches up to where I am at. Then things will slow down. I came to this forum late in the project.

Peter Hausamann09/01/2018 09:57:26
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48 forum posts
84 photos

I found some springy shim metal and cut out eight contact plates. Installed the contacts, LED navigational lights, and wiring.

The wires are routed to where the frame vertical beams are, so to guide the wires to the span hut.

19_bridge model update _span part 5-sml.jpg

I filled the trench work with wood putty (after I checked for electrical continuity). Then sanded and painted the span with white acrylic undercoat.

20_bridge model update _span part 6.jpg

Peter Hausamann10/01/2018 09:36:33
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48 forum posts
84 photos

Luckily I came across a few photographs of Wardell Bridge via a Company that uses drones for aerial photography. Form these photos I was able to draw a plan for the span hut.

drone photos of wb.jpg

The base plan:

22_bridge model update_span hut layout_1.jpg

Peter Hausamann10/01/2018 09:37:27
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48 forum posts
84 photos
Used 3 mm MDF board for hut and gangways, and matchsticks for rail posts.

The extra board you see is the hut floor. I am going to used its edge for gluing the hut walls to.

The rectangular hole is where the wiring will come up from under the span.

 

23_bridge model update_span hut layout_2.jpg

 

You can see the cable anchoring points have been inserted. I used microswitch actuator arms (the roller type) for bumper rollers. These ones are for longitudinal movements of the span. They are to stop the span from getting caught onto the towers when the span raises and lowers. On one corner is also an opto-couple used for triggering the vessel traffic lights from red to green once the span reaches its upper limit.

 

24_bridge model update_span lift attachments.jpg

 

Edited By Peter Hausamann on 10/01/2018 09:38:46

Peter Hausamann10/01/2018 09:39:52
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48 forum posts
84 photos
The wires got routed to the hut. Glued the wires against the framework for concealment.
 
25_bridge model update_span wiring to hut.jpg

Peter Hausamann11/01/2018 09:29:20
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48 forum posts
84 photos

Photograph of the bridge's bumper rollers.

26b_bridge bumper rollers.jpg

Built another set of four bumper rollers but for lateral movement this time.

Only used the rollers from the microswitch actuators this time.

26_bridge model update_span bumper rollers_sml.jpg

Added the vessel traffic lights to the centre of the span.

27_bridge model update_vessel traffic lights_sml.jpg

There are several containers on the balconies. These are made from block timber and painted.

Here they are drying on my window sill.

28_bridge model update_span boxed containers.jpg

Peter Hausamann12/01/2018 09:29:16
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48 forum posts
84 photos

Used 3 mm MDF board, 2 mm clear Perspex, and white card to build the hut walls. I was surprised how well the Perspex can give that glass window effect (slight reflection and parallax error). The four tabs at top of walls is for positioning the roof.

29_bridge model update_span hut-1_sml.jpg

Added split bamboo skewers for railings, and fly screen for mesh. Started to paint the span with a home mixed, Bridge Grey oil enamel.

30_bmu_span gangways.jpg

31_bmu_span_ gangways_boxes.jpg

Found some washers that fit over the LED nav; lights. Now they look more like beacons.
Added railings for the road and footpath. Gave that a paint. Will paint road later.

32_bmu_span_ undercarriage and railings.jpg

To be honest, at this point of model making I felt really good on how the span turned out.

XD 35112/01/2018 19:48:46
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805 forum posts
37 photos

Peter that looks fantastic ! It's amazing how a coat of paint can bring a model to life !

Ian.

Neil Wyatt12/01/2018 20:36:17
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Moderator
13075 forum posts
567 photos
67 articles

That last photo is knockout.

Peter Hausamann14/01/2018 00:06:51
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48 forum posts
84 photos

Thanks Ian and Neil for supporting comments.

Added blown fuse indicators for the DC voltages. Also replaced terminal numbers with new printed ones.

32_21&38_bmu_dc blown fuse indicators.jpg

Peter Hausamann15/01/2018 20:19:10
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48 forum posts
84 photos

33_bmu_bridge piers-1.jpg

Doweling the framework

34_bmu_bridge piers-2-dowling.jpg

Unbelievably, there is over 11 metres of framing put into the towers.

35_bmu_bridge piers-3.jpg

Edited By Peter Hausamann on 15/01/2018 20:20:29

Edited By Peter Hausamann on 15/01/2018 20:20:45

Peter Hausamann16/01/2018 19:47:30
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48 forum posts
84 photos

The pulley wheels I wanted were too expensive (to buy ten of them). So I came up with an alternative by solder-sweating different sized washers together.
My first attempt had too much solder, but got it right after that.

11_making the pulley wheels.jpg

SillyOldDuffer16/01/2018 20:35:34
2621 forum posts
542 photos

Most impressive Peter. Have you thought that your construction photos could be part of the museum display? The original bridge is interesting, your model bridge will be interesting and so is how you made it.

Dave

Peter Hausamann17/01/2018 19:19:48
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48 forum posts
84 photos
Posted by SillyOldDuffer on 16/01/2018 20:35:34:

Most impressive Peter. Have you thought that your construction photos could be part of the museum display? The original bridge is interesting, your model bridge will be interesting and so is how you made it.

Dave

Thanks Dave for response. I don't think there will be any call or room for that at the display. There will be a background painting to this display as well (no wall space for pictures). Besides, not many modellers, who are interested in such things, are amongst the visitors to the museum.

I am recording my design drawings, construction notes, troubleshooting and repair notes for a ring binder (Operating and Service Manual) as I go along. All photos are being stored on a memory stick. It will be stored in the museum library. However, any person can become a museum member ($2 annual fee) and have access to its extensive library, including the Bridge Manual (when completed).

Peter Hausamann17/01/2018 19:22:41
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48 forum posts
84 photos

Designing and constructing the pulley wheel brackets.

36_bmu_bridge pulley brackets-1.jpg

37_bmu_bridge pulley brackets-2.jpg

Peter Hausamann19/01/2018 02:28:28
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48 forum posts
84 photos
The towers are not actually in place in these photographs. They are just positioned to see how it will look, and how close the span bumpers would get to the towers.
The towers have to be installed at the same time as the road surface.
39_bmu_bridge pulley brackets-3.jpg
40_bmu_bridge piers-4.jpg

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