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Poll

What is your preferred method for controlling the net activation?

Mechanically activated from track-side ($)
6 (54.5%)
IR activated on the coach, from specific reflective markers installed track-side ($$$)
3 (27.3%)
DCC controlled ($$)
1 (9.1%)
Combination of IR activation and/or DCC control ($$$)
1 (9.1%)

Total Members Voted: 11

Author Topic: Travelling Post Office - Nets  (Read 1728 times)

0 Members and 1 Guest are viewing this topic.

Offline Bealman

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Re: Travelling Post Office - Nets
« Reply #60 on: July 18, 2020, 01:28:57 AM »
We appear to have drifted off the nets!!  :worried:
Vision over visibility. Bono, U2.

Online Railwaygun

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Re: Travelling Post Office - Nets
« Reply #61 on: July 18, 2020, 10:58:11 AM »
We appear to have drifted off the nets!!  :worried:

Back to work people!
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Online RBTKraisee

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Re: Travelling Post Office - Nets
« Reply #62 on: July 18, 2020, 08:10:11 PM »
Ahem, yes, work...   I'll just leave Season 2 of BSG running in the background... :D


I went out and bought some tiny mesh net materials this morning and will cut a few samples out to see which look realistic or not.   I'll try to take some photo's of the samples later.


Another question I do have, is whether people would be interested in an electrically operated net, or mechanical?   Electric might be a bit more expensive, but I think it would work more reliably and more accurately.

I'm thinking a track-embedded IR system with a receiver in the coach (or perhaps DCC) would be a good trigger.   Then a small motor could be used to deploy and retract over a few seconds, which would be much more like the real thing and would avoid the 'sudden' slam-deployment, which is one of the main things that make the Hornby TPO's "toy-like".

Due to the extremely tight confines of the carriage, the doors, the delivery arms and the receiving net will probably need to all work off the same mechanism and at the same times, regardless - I don't think I could make them operate independently.   I suspect most people would be fine with this though, so I'm happy.

I'm also trying to think of any means whereby received bags caught by the net might be routed down the coach to the delivery arms without human interaction.   I do suspect that's asking a bit much, but it *just might be feasible* if the bags contained a small magnet to help orient them correctly when they come into contact with the delivery arms inside the coach body, before being deployed.   I'm making no promises on this idea though - if I were to try to quantify it, I suspect we're talking about maybe, at best, a 10% chance of making such a complex thing work!   But I'm going to give it a look-see, just in case!

Ross.
“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

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Offline crewearpley40

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Re: Travelling Post Office - Nets
« Reply #63 on: July 18, 2020, 08:16:15 PM »
Ross. The  videos I posted may have given a  clue as to operation sadly unsure if a working mechanism may work. Level crossing gates, points I've seen work, but good luck and looking forward to progress
 

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Re: Travelling Post Office - Nets
« Reply #64 on: July 19, 2020, 03:29:06 AM »
I met Phil from Railway Vehicle Preservations over on RMWeb (he models OO gauge so doesn't frequent this fine place). His team restored the TPO that runs on the GRC line and he is the guy hanging up the pouches inside the TPO on that GCR video.   He has been very generously finding detailed reference drawings and photo's for me :)

I could be wrong, but right now I don't see any showstoppers for developing a working mechanism.   I have a provisional concept that should allow two sets of doors to open, two of the delivery arms to be lowered carrying pouches that would previously be hidden behind the doors, and it would also deploy the net structure - all driven off one main pivot point.

I haven't worked out a method to activate the internal mechanism from a track-side physical structure.   I also haven't figured out the electronics for using a motor yet either.   But both methods ought to be feasible.

Ross.
“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

An Ex-Pat Brit:  Two decades living in Florida and still a shade of "British Tourist White"

Offline themadhippy

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Re: Travelling Post Office - Nets
« Reply #65 on: July 19, 2020, 03:40:54 AM »
Quote
I haven't worked out a method to activate the internal mechanism from a track-side physical structure
reed switch and magnet, infra red transmitter and  receiver,rfid chip?
Quote
.   I also haven't figured out the electronics for using a motor yet either. 
what about a servo instead of a motor,or if you only need a simple push pull a solinoid
Don't fart before your arse is ready

Offline crewearpley40

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Re: Travelling Post Office - Nets
« Reply #66 on: July 19, 2020, 05:29:02 AM »
Themadhippy could have provided a solution. Although  ross , this is for a larger scale could you not adapt?   https://www.16mm.org.uk/2018/04/01/april-2018-a-travelling-post-office/        and      http://www.bpodmore.co.uk/projects/ground%20gear.htm    the same mechanisms @RBTKraisee

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Re: Travelling Post Office - Nets
« Reply #67 on: July 19, 2020, 04:16:50 PM »
I'm going to experiment with a few different active drive systems.   I can definitely get a DC motor in there.   Servo's are an interesting idea, though I haven't personally come across small enough units, I'm sure they must exist so I'll go a huntin'.

The 16mm TPO is interesting and certainly shows what is possible at that scale.   I particularly like the use of the magnets for holding the mail pouches - that they've managed to make such a system work is very encouraging.   I've found some nice and tiny neodymium magnets and it might be a good idea to get some 1x1mm discs and some 1mm diameter x 4mm long cylinders, just to experiment with.

Although I'm really setup to do 3D printing, I'm contemplating etched parts for some elements - I just don't currently have any gear for that.   I've done PE brass extensively in the past (boy, have I!) so I'm sure I can, but it'll take a bit of time to get all the bits pulled together.   I need to make my own brass Hogwarts Castle (Hall) name plates anyway, so I just need to buy all the gear sooner.

Ross.
“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

An Ex-Pat Brit:  Two decades living in Florida and still a shade of "British Tourist White"

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Re: Travelling Post Office - Nets
« Reply #68 on: July 19, 2020, 04:22:42 PM »
Oh yeah, forgot to mention that I printed a quick'n'dirty piece of coach body for me to be able to hack up without risking any of my nice GF coaches :)   It's the same piece as the CAD that I showed earlier, just truncated to fit flat in my Photon printer.

Ross.

“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

An Ex-Pat Brit:  Two decades living in Florida and still a shade of "British Tourist White"

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Re: Travelling Post Office - Nets
« Reply #69 on: July 26, 2020, 07:55:10 PM »
I've just added a simple poll at the top of the page regarding your favourite method for controlling these deployable TPO nets.

I would really appreciate it if everyone reading this would take a moment and vote for your favourite option.

I'd also welcome additional options if the current ones don't fit your personal preference.

Ross.
« Last Edit: July 26, 2020, 07:57:20 PM by RBTKraisee »
“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

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Re: Travelling Post Office - Nets
« Reply #70 on: July 30, 2020, 10:55:39 PM »
6 votes, overwhelmingly in favour of mechanical track-side activation.

If you haven't already voted please do so at the top of the page!

Ross.
“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

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Re: Travelling Post Office - Nets
« Reply #71 on: July 30, 2020, 11:08:31 PM »
In other news, I have now received some 40 gauge light brass mesh/gauze (40 wires per inch) which looks to be just about perfect for the netting!

I have a long throw linear micro servo on order whenever Amazon gets around to shipping it, for testing electrically activated mechanisms with.   Also got some mini neodymium magnets coming too.

And I've designed an initial rough mechanism that looks like it will slide the various doors open first, then once they are open it will lower the delivery bars and also deploy the net, all driven from a single linear arm motion of about 8mm.

This two-step approach is deliberate.   The current plan (!) is that I can pre-stage some delivery bags inside the coach, just behind the closed doors.   The doors slide open first and the tiny magnets on the end of the delivery arms will 'collect' the bags from inside, and swing them out of the coach, ready for delivery.   I hope!!!  :uneasy:

I've got a couple of other prints for my Gresley RTS ahead of this, but I'm planning to try to first print of this mechanism some time this weekend.   I'll show progress! :)

Ross.
« Last Edit: July 30, 2020, 11:22:47 PM by RBTKraisee »
“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

An Ex-Pat Brit:  Two decades living in Florida and still a shade of "British Tourist White"

Offline crewearpley40

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Re: Travelling Post Office - Nets
« Reply #72 on: July 30, 2020, 11:16:12 PM »
Look forward to progress and more as this develops

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Re: Travelling Post Office - Nets
« Reply #73 on: August 01, 2020, 07:23:28 PM »
The tiny little micro linear servo motor came in today, along with some other bits, but I wanted to share the picture :)

Ross.

“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

An Ex-Pat Brit:  Two decades living in Florida and still a shade of "British Tourist White"

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Re: Travelling Post Office - Nets
« Reply #74 on: August 02, 2020, 08:43:41 PM »
I'm trying to find a good drawing of a Mk1 coach, end-on.   Using the ones I have found on the web (best one below) I can't quite replicate the roofline accurately - using those radius figures it just doesn't fit and when I fiddle with it it no longer look right to me, so I'd like to find some other sources.

Anyone got anything that might help?

Ross.

PS - Welcome home Dragon spacecraft with Bob & Doug!

« Last Edit: August 02, 2020, 08:47:02 PM by RBTKraisee »
“The meek shall inherit the Earth. The rest of us are going to the stars” -Robert Heinlein

An Ex-Pat Brit:  Two decades living in Florida and still a shade of "British Tourist White"

 

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