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Working Lift Bridge Diorama


Getunderit

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On 10/8/2018 at 9:33 PM, Derek A said:

...Pete, keep up the excellent work!

Thanks Derek. I will do my best. Though at times the end result appears as if I did my best to stuff it up. But of course, you guys don't see those bits. 😉

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40 minutes ago, Getunderit said:

Though at times the end result appears as if I did my best to stuff it up. But of course, you guys don't see those bits

I often describe myself as a jack of all trades, knowing full well that I'm master of none, but from what I've seen, you are a jack of all trades and master of most.

 

In fact, your even good at modesty – damn you. :dull:

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19 minutes ago, Gorby said:

I often describe myself as a jack of all trades, knowing full well that I'm master of none, but from what I've seen, you are a jack of all trades and master of most.

 

In fact, your even good at modesty – damn you. :dull:

Thank you Gorby for such a fine complement.

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Unpacked the rollers and found them well greased. However the viscosity was too high for free flow, so I added a drop of road bike chain lube to free it up.

 

Note: Never use a degreaser, like WD40, on bearing surfaces such as chain links, etc. It washes the grease out and before you know it, the bearing has worn out. Bearings need grease/oil, not degreaser.

 

paOWhQp.jpg

 

This rolls down the track so easily.

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7 hours ago, Getunderit said:

Created bracket for containing tension springs for pulley cable.

First, impressive craftmanship here!

Secondly, I'm trying to understand what you really are doing here  🙂 The tension spring, what is it for? To smooth things out and avoid jump starts when the pulling begins? Or is that a total misunderstanding?

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3 hours ago, Svedberg said:

First, impressive craftmanship here!

Secondly, I'm trying to understand what you really are doing here  🙂 The tension spring, what is it for? To smooth things out and avoid jump starts when the pulling begins? Or is that a total misunderstanding?

The pulley cables to the boat vane are slightly under tension by the pull-springs. This is to keep positive attraction on the pulleys and motor shaft.

I have not yet tested this, but it may also do as you suggested _ smooth out the initial start.

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To stop the boat at either end of traveled distance, an optical-switch is being incorporated. The switch is triggered when the boat vane cuts the light beam between its 'U' structure. Two sets of brackets are needed for both ends. The switch needs to be positional to compensate for any vane drift after switch-off. In other words, I can position it to have the vane stop before crash into end of travel (slot in display table).

 

Changed design of track supports. It already is supported at both ends, so it does not need to be also screwed to slot braces (as in original drawings). Instead, another track support will be placed half way along the track. This will stiffen the track and eliminate any sagging.

 

3T6vVKB.jpg

 

E8LvgcN.jpg

 

You will notice two slots per side bracket. Originally it was to be one long slot. I realized that the centre portion was not really required, so I left it in.

 

fFCUlxl.jpg

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Its just amazing the amount of work involved just to move the boat from one side of the scene to the other.

 

At least you have the workshop and materials to, seemingly, build what is required, bracket supports & endless supply of the correct nuts & bolts . . .  LOL

Your innovative approach to the construction makes me realise that we take such diorama  for granted and what with the electronic circuits, its just a feat of marvellous !!

 

I too look forward to seeing this operational

Ian

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@Mancunian airman, Ian, the boat operates automatically after the bridge span is raised to top of bridge. It's the automatic portion, plus switching over the navigation lights on return trip, which makes it a complex arrangement.

 

Anyway, today I trimmed quite a few bolts to minimize future hassles of restricted space problems.
Drilled two holes which used would have the bracket upside down. Added centre support bracket.

 

dSsUtZK.jpg

 

After assembling brackets, it was time to test to see if the vane will align in between the optical switch.
Though it looks all well and aligned, I may still incorporate a simple tin plate funnel, and file edges of vane to a bow point.

 

3Jl55F0.jpg

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My brain seems to be rebelling because this bit is too complicated for it this time of the morning. I'm going to have to take the dog for a walk to give it a rest (my brain not the dog).

 

All I can think is, “why are those little fat people running away?”

 

6f35d3c0-dd0c-43d4-bc3b-37552fff7ec9.png

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38 minutes ago, Gorby said:

...All I can think is, “why are those little fat people running away?”

If you can rest your brain while walking your dog, then either the dog is so well trained or it is taking you for a walk.

 

Gorby, this build has not yet been fully worked out. I am still facing hurdles as I proceed. At times I get the dreaded jitters thinking that I missed a key part, or concept, for it to work. If so, I fear having to go back, way way back, and start again. I like to keep things simple yet lasting. It's complicated due to two things, 1) the boat operates automatically, no-one operates it. 2) The nav lights need to exchange position on returned trip.

 

If you returned from your walk and find yourself eating the dog biscuits, then the dog took you for a walk. :D

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 Wait!  Now I'm confused. You are going to make a pie, tin (as apposed to apple I guess) so the optical switches can.....optical? Then you need to wait for Gorby to come back with his dog, ( his eating dog food seems optional), so then you will have time to jump over some hurdles. All this before you automatically operate the boat under the bridge with the green and red lights switching on and off, fore and aft?-- Have I got that right?-------Well never mind, I'll just keep watching.

[To Self]

hummm.gif????Why would Gorby eat his dogs food???? Why would Peter wait for him to do it???      idontknow.gif  I don' know, sometimes I get confused by the  OZ-I-eans.   Though, they seem like a fun loving folk.

 

p.s. In all seriousness, I am enjoying seeing you work your way out of situations with consummate skill and craftsmanship. yes3.gif

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I was wondering about the optical switch. Once it triggers (light beam blocked) will the pulley motor stop flat, or is there a delay before it actually stops? If it stops flat is there any chance the pull-springs will make the boat and the vane pull backwards thus letting light through again, turning the motor on once more and... I guess you see what kind of situation I visualize.

Can this ever happen? And if it does, would it be a problem or not? I have never built any automated system so I have no clue.

 

Afterthought: When I wrote the above I for some reason assumed that the boat would stop for a while once it reached one end of the dioarama, before it headed out again in the other direction. But perhaps the intention is to let it turn immediatelly, in which case the situation above never happens.

Edited by Svedberg
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@Svedberg, all good questions which the answers have not been tested.

 

There is a drift of motor axle after switch-off. The motor is attached to a 1:148 gearbox, which has a high torque, so it is unlikely to 'just stop' with an equally negative load of the pulley system. The tension on the springs is minimal. The spring resting tension is greater than the load. The boat, and vane on wheels, pose hardly any resistance. I do not foresee any spring isolation. The springs are mainly to keep a positive tension on the cable.

 

Anyway, I will let you know what happens when I get to that point of construction. Thanks for asking.

 

About boat travel, your assumption is correct. The boat will (I hope) dock (disabled) at one end. Then the bridge needs to be lowered and raised again before the boat once more becomes enabled. When it does, the nav lights need to change over and the boat motor polarity reversed.

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Nothing much to show. Today was mainly spending time on other volunteer work. However, was as able to figure out where and how to attach two microswitches to both ends of the transport frame. These are emergency limit switches, in case an optic switch fails. If this happens, the microswitch will switch motor power off, but the boat vane will hit the end of travel. The Perspex bracket will take up the brunt of the impact, and save the switch from being smashed. Besides, the springs will take up the 1/2 inch drift of the pulley cable.

 

EScTte6.jpg

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The boat has its own power source, a 9V rechargeable battery. However, it needs to be recharged. A docking connector has been made.

 

7EaSQ0n.jpg

 

cT83xls.jpg

 

Upon assembly, I discovered that the connectors are misaligned. Will have to make a new wooden terminal block for the battery side of the connector. Will do this tomorrow.

 

lT5joR3.jpg

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BOAT NAV LIGHTS CHANGEOVER TRIGGER
Had difficulty figuring how to switch the boats navigational lights from downstream to upstream travel. Mechanical switching proved troublesome to arranged when boat reverses direction. Decided to use an "old party trick" using a light beam to trigger a change in nav lights.

 

The idea is that the LED light beam is ON whenever the pulley motor is in clockwise (CW) rotation (boat to travel upstream). This light is fixed at on one end of the tracks. On the boat vane is the light beam sensor, known as a Light Dependent Resistor (LDR). While the vane moves back and forth, the LDR is always facing the LED light source.

 

When the light is OFF, the LDR resistance becomes high (135,000 ohms). This keeps a transistor in OFF mode. When the pulley motor is switched to CW operation, the LED light turns ON, and shines on the LDR. Its resistance instantly drops to 62,000 ohms. This low resistance allows a transistor to be in ON mode, tripping a relay. The relay switches the boats nav lights over from downstream to upstream configuration.

 

Here, I am experimenting with the LDR.


uxRRMlB.jpg

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17 hours ago, Getunderit said:

BOAT NAV LIGHTS CHANGEOVER TRIGGER
Had difficulty figuring how to switch the boats navigational lights from downstream to upstream travel. Mechanical switching proved troublesome to arranged when boat reverses direction. Decided to use an "old party trick" using a light beam to trigger a change in nav lights.

 

The idea is that the LED light beam is ON whenever the pulley motor is in clockwise (CW) rotation (boat to travel upstream). This light is fixed at on one end of the tracks. On the boat vane is the light beam sensor, known as a Light Dependent Resistor (LDR). While the vane moves back and forth, the LDR is always facing the LED light source.

 

When the light is OFF, the LDR resistance becomes high (135,000 ohms). This keeps a transistor in OFF mode. When the pulley motor is switched to CW operation, the LED light turns ON, and shines on the LDR. Its resistance instantly drops to 62,000 ohms. This low resistance allows a transistor to be in ON mode, tripping a relay. The relay switches the boats nav lights over from downstream to upstream configuration.

 

Coo, clever!

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