Wardell Bridge and boat by Tecko - Small - 1:72

[michael mott]

Tecko, what a wonderful project. this is the sort of work that makes being a volunteer worth every penny that you don't get paid. I am really enjoying your approach to the solving of the various elements and of the mostly low tech solutions, These become much easier for the viewing audience to grasp in my view. And at the same time a greater challenge for the designer builder. opening up the control console is a brilliant idea which also helps the viewer to see that complex operations can be achieved with simple technology (if one can call any electronics simple that is) 

 

I look forward to the next installment.

 

Michael

[Tecko]

9 hours ago, druxey said:

It would be helpful to know how long you could make the vessel. Now it appears to be too symmetrical in side view and short.

Thanks druxey for your response.

The boat is 210 mm long. Any longer the boat will look too close to the bridge...

I am not sure what you mean by too symmetrical in side view. My goal is for not knowing any difference between bow and stern. So when boat moves forward or backward the leading portion of the boat will look like it is the bow. 

 

Yes I agree that the boat does look too short.

Perhaps if the upper deck was lower, such as... What do you think?

[Tecko]

Michael. Thank you for your comments. 

Yes you are right. It will add some insight what was involved, especially the wiring, to operate a bridge for maritime traffic.

[Tecko]

Finally finished painting the road. It was very restricted within the span.

Included road markings and reflectors.

Bottom photos shows the 1/72 scale cars I'll be installing at end of project.

 

[KeithAug]

I hope no one was injured in the accident. The red car looks in a particularly hazardous situation.

[Dilbert55]

Do you have an estimate of how many cycles (up/down) your model may experience per/day at the museum? My parents would have had to drag me away from something like this when I was a kid and now that I'm retired, my wife has that job.   

[Tecko]

Thank you Keith for funny incident report. I take it as a compliment considering the creative skills of realism you display in your models.

 

You too Dilbert55. Thanks for compliment.

I am not sure what the public response will be. The model (hopefully) will only respond if the control panel is used in the correct sequence.

I fear there will be many impatient youngsters abandoning the control panel before completing the cycle. Then a museum personnel will need to reset it all.

If that proves to be a problem, then the bridge may have to be operated under supervision by museum staff.

Ballina Naval and Maritime Museum only gets lots of traffic when a bus load arrives. Sometimes it's a school bus full of kids who have to touch everything. When they arrive there is always a staff member conducting the tour...hence the possible supervision over the controls.

[*Hans*]

Hey Tecko, what a nice (no - superb) building is this! I like it not only for the model work you are doing, but also all the electronics wiring and mechanical parts in it.  Chapo!

 

[Tecko]

Thank you Hans.

Talking about electronics!

 

I usually swap from one task to another for a change of scenery / focus.

I've been thinking it would be good to do more work on the electronics side. 

After a chat with the curator, a win-win situation occurred. I now got the console at home to work on, and the museum got more workshop space.

I wanted the console because I am more equipped for electronics than the museum is. It makes the task easier to do at home, though I am now more crowded in. 

 

 

[Tecko]

At last! The brass tubing from China finally arrived (after 2 months).

 

 

Now I can start making the swing gates that close across the bridge road.

The tubing will be used for housing the rotating shaft (90 deg rotation). I am using fencing wire for the shaft (it's an Aussie thing to use).

Radio control servo motors will be used for driving the shafts. However, these servos, despite their reduction gearing, rotate too fast for my liking.

 

At first I thought about using a speed control circuit for slowing the servo motor. However, this won't work because the servo motor already uses the same sort of circuitry for servo arm positioning. 

So the other two alternatives is to use further reduction gearing seems too complex and expensive. The other, is to use a lever system whereby a 180 deg rotation of the servo arm leads to a 90 deg rotation of the gate hinge - effectively reducing the speed by half.

 

If I have the electronic components, tomorrow I will experiment with a servo controlling circuit. Hopefully I'll get the servo arm to rotate exactly 180 deg.

 

 

 

[*Hans*]

Ohw - nice! I used to learn these kind of things at University, but have forgotten almost everything of it, it seems.

 

Maybe you could use some fixed stops at the servo to achieve the 180º

[Louie da fly]

I take my hat off to you and anybody who can do all this electronic and servo motor stuff (including RC). It's something I've never had any skill at, but I never cease to be impressed by the achievements of those who do.

 

When I first saw your project it looked terribly familiar. I've driven across the Clyde River bridge at Bateman's Bay, which could be the Wardell bridge's twin.

 

Steven

[Tecko]

Hi Steven. Thanks for the compliments.

 

Yes, many steel framed lift-span bridges of over 50 years ago had similar design structures.

 

The Clyde looks very similar to both the Harwood and Wardell bridges.

Both Clyde and Harwood have extended horizontal structures for strength. While the Wardell uses extra piers on submerged pylons for extra strength.

The Wardell, only 100 kms north of Harwood, is regarded as a smaller version of the Harwood. Though they are talking about the towers and span design.

I know that these are small discrepancies for us, but to a bridge engineer they see these things as major differences.

I only have learnt some of this stuff since I started the project. Heck, I didn't know what a lift-span bridge was until then.

 

 

 

[Tecko]

On 4/19/2017 at 1:27 AM, *Hans* said:

...Maybe you could use some fixed stops at the servo to achieve the 180º

Hello Hans. Thanks for your response.

 

I am currently waiting for electronic components for the servo controller circuit (SCC).

The common circuits used for SCC incorporates stops via a variable resistor (trim potentiometers). These set the number of degrees the servo moves. The servos I bought actually goes a bit beyond 180 deg. This type of servo is a position rotational servo and can be set anywhere up to 180 deg rotation.

 

However, I will be incorporating microswitches at each end of the 180 deg swing of the servo actuator arm. These are not for stopping the motor but for switching other circuitry; such as the red and green control panel lamps (indicating open/closed gates).

 

Well, this is my understanding of SCC. If I am wrong, I will post it here. In any case, I will let you know how the SCC works out.

[*Hans*]

I think the type of bridge is a very common one - used all over the world.

 

This one is in the Netherlands - close to Alphen a/d Rijn

 

[*Hans*]

And for the stops on the servo I would go for a mechanical stop at the gate arm, with some flexible connecting in between the arm and the servo - in case the servo would turn a bit more then 180º

 

But that's me - being a mechanical engineer (with some interest in electronics).

[Tecko]

Thank you Hans for the photo. It is a type of lift-span bridge I have not taken too much notice off. Where the operating hut is not being on the spam.

As for the stops on the servo, I will consider your suggestion when testing the circuitry.

The servos I am using already have internal stops just past 180 deg. I think about 190 deg.

If the servo arm wonders around the intended stops, I will first use the microswitches to cut power to the motor.

The servos use an internal gearbox, so soon as the power is cut there should not be any noticeable drift in the servo arm.

 

Thanks again for suggestion.

 

[mtaylor]

You already answered my thought... limit switches should do the trick to kill power and stop the swing arm.  I'll assume a multipole switch such that it can reverse the voltage for moving the other way?

[Tecko]

Thanks Mark for sharing. Good ideas.

 

I am having a limit switch where the gate is opened (against the railing). This switch simply controls the Control Panel Gate Indicators. Green for 'open' and red for 'closed' across the road.

The change of polarity for servo motors is controlled by the Control Panel Gate Switches.

I am currently relying on the servo controller circuits to be accurate and reliable. If they are not, then I will be considering the good ideas by you (Mark) and Hans.

I'll let you know how it goes.

 

TOP: Gate Limit switches:

CENTRE: Control Panel

BOTTOM:Control Panel Gate Switches and servo controller circuits:

I am still waiting for servo (electronics) components to arrive. Easter and ANZAC has delayed postage.

In the meantime I have created a wiring harness jig and have started to install the wires.

I never done one on a jig before. It's both challenging and revealing (I have made a few mix ups with wiring locations on my drawings).

 

[mtaylor]

Looks good from here.  Pity you can't combine the motion limit switches with the LED switches.  Might simplify the wiring even though it might create problems with voltage requirements for the various bits.  I'm an old fan of keeping the mechanicals simple because... well... kids and/or exuberant teens and adults.

[Tecko]

1 hour ago, mtaylor said:

Looks good from here.  Pity you can't combine the motion limit switches with the LED switches.  Might simplify the wiring even though it might create problems with voltage requirements for the various bits.  I'm an old fan of keeping the mechanicals simple because... well... kids and/or exuberant teens and adults.

Thanks Mark for pointing that out.

I forgot that the panel lamp switches are supposed to be the limit switches. 

I must have had a Senior moment . I've been working on the bridge for too long and forgot what I had previously designed for (electronically).

 

Thanks again.

[mtaylor]

Glad I could help.  I've done that myself where I got buried in one aspect of a project and spaced it on another part.  And yes... senior moments.. the bane of all of us.

[Tecko]

Sorry for my absence. Been ill lately, plus going through some grief and loss. So I have been somewhat preoccupied. Depending on certain test results I may be absent again soon. I hope not.

 

However, I have done some work on the bridge console since the last time I posted.

The wiring harness got completed. It looks like the nervous system of some weird deep sea creature.

The control panel got revamped. All instrumentation got cleaned, a few new labels, Added red points to a few switch handles, and a general touch-up with paint.

Since the console interior is to be a diorama as well, I decided to add a bit of drama by adding yellow stripes around one of the painted switch brackets.

Attached the wiring harness to the control panel instruments.

Then added the control panel to the console.

Got to go now. Will post some more tomorrow.

[druxey]

Good to see you back and more progress, Tecko. I'm sorry that you have had grief since last posting and hope your health issues are resolving. Quite the bundle of wires! Neatly done.

[KeithAug]

I'm pleased you building again. Hope all turns out well on the health front.

[Tecko]

Thanks fellows for your welcome and best wishes. In few hours I am go to get my test results (fingers crossed).

As mentioned, here are more pictures of what I've been doing to keep my mind away from worrying too much, or unnecessarily.

 

Another wiring harness was needed that went from the three terminal boards to the back of the console where two D-Connectors are mounted. These connectors will cable signals to and from the Control Box which will be located underneath the display table.

I decide to add a Passive Infrared (PIR) motion detector/sensor within the console. The aim is to have the console interior to light-up whenever a person approaches it. However, since there will be a metal kick-panel at the bottom of the perspex front panel, the PIR needs to be above it. A wooden bracket was made for mounting the PIR.

Decided to use strips of thin felt between the perspex and the console. Grey felt was not available, so I bought some light coloured felt and dyed it grey.

The PIR operates LED strips which are mounted on the inside edges of the console opening.

I soon found out that I forgot that Infrared is not so much a light source but a heat source. Infrared-waves won't pass through anything too thick like a glass window of a 1/4 inch thick perspex. So I had to drill a series of holes through the perspex for these waves to reach the sensor.

Notice the kick-panel in place. I re-attached the original manufacturers name-plate onto it (the company (1960's) does not exist anymore).

Here is what the console looks like in its dormant and activated states.

I had a hick-up when I first turned the power on. I blew the console fuse. I discover I had two white wires switched over to the wrong terminals. After minor repairs, all seemed to work okay. That is, without the console connected to anything else. That test will come later.

 

[KeithAug]

Tecko

 

Very smart. It's times like this when I remember why I chose mechanical engineering as a career.

[mtaylor]

Looking good.  I hope any additional testing goes just as well.  I also your tests come out good as well.

 

BTW, what's name plate?   Looks vaguely familiar but I just can't place it and not enough detail to see it clearly.  That's still a nice touch though.

[Tecko]

Hi, I got good news, my latest blood test results no longer showed abnormal levels. A change in diet, losing excess weight, and regular exercises has done the trick. But now I just need to keep doing that. Making it a new lifestyle or die sooner. Anyway, enough of that.

 

Mark. I am not sure if I am using the correct terminology, but to me a name-plate is metal tag with a name printed on it. In this case, it is the name of the manufacturer of the console. Here is a closer look at it.

[AndrewNaylor]

Tecko

Fantastic news on the test front Its funny what a little exercise and a new diet can do I lost 20lb and dropped certain levels just by walking nothing hard about that !!

the build is coming on famously I think one of these bridges in the UK has "Listed building status" so with any luck the scrap man will never get to wild his cutting torch on it  

All the best 

Andy