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Lift out bridge

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Lift out bridge
Posted by Afdahl Flats on Thursday, May 28, 2020 9:21 AM

Hello, I am looking to redo my current drop down bridge on my ho scale layout. I built it in the winter and now that it is summer, the whole layout has shifted ever so slightly that it throws off the drop down bridge completely. Does anyone have any suggestions on how I can get around having to duck under and still deal with the seasonal shifting of the table? It needs to cross a 38" gap. Thank you

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Posted by RR_Mel on Thursday, May 28, 2020 9:30 AM

How much difference between summer and winter?


Mel



 
My Model Railroad  
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Posted by Afdahl Flats on Thursday, May 28, 2020 9:34 AM
If you're talking about temperature, it's -30 to 80 degrees... If you're talking about the amount the table shifts, it's about 1/8th inch
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Posted by SeeYou190 on Thursday, May 28, 2020 9:40 AM

I fought the drop bridge/lift out problem on my spare bedroom layout for years. Eventually I decided to install a duck-under.

I was not happy with the track plan, so I decided to modify it to a switching layout and get rid of the duck-under.

The modified track plan was not good either. in 2017 the layout came down.

Sorry I don't have a good solution for you, but I can talk about my failures.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by RR_Mel on Thursday, May 28, 2020 9:42 AM

1) A 1/16” gap on each side should be doable.  2) Two bridges.  3)A jack under the bridge to widen the gap in winter.


Mel



 
My Model Railroad  
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 

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Posted by Afdahl Flats on Thursday, May 28, 2020 9:53 AM
Ok thank you, I will give some of them a try
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Posted by selector on Thursday, May 28, 2020 12:18 PM

Let's slow down a bit.

What changes are we talking about that happen seasonally?  In my experience, temperatures affect lubes and maybe plastic dimensions some, and could melt shells if high enough, and could also affect electronics.  Wood, not so much.  Wood is affected more, much more, by humidity.  If humidity shifts are substantial, I would simply control that in the train environment using a $200 dehumidifier.  I have two, with one at least six years old and currently providing security in my train room. 

A drop-in bridge works well.  You create the gap, take note of its length, and then place four blocks of 1X2, two at each end, spaced.  They will serve as the true abutments.  Atop each block, you will screw an inverted steel L-bracket of the kind you'd find in cabinetry. The long shank goes down inside, facing the opposite block.  The top flange, curved over the top of the block, is actually the rest AND the electrical connector for the bridge's one rail.

You construct the bridge with a T-shape.  The top surface is the track surface, the bottom shank is the bridge's structure that slides between the metal L-brackets.

Under the T-shape, you insert four 1/2" wood screws, the steel ones with zinc, and each one of them will sit on one of the four L-brackets.  This way, your bridge is fully adjustable for height, and you can shim to get lateral alignment.

For electrical, you wind a feeder wire from the bus around any one of the two screws mounting each wooden block.  You do the same for the smaller wooden screw 'bridge shoes', four of them.  

You feed up to the bridge rails and solder where appropriate.

Now you have a lightweight (hopefully) lift-out bridge that is supported by four metal screws resting on four metal brackets draped over four 1X2 wooden blocks at each frame end of the bridge's gap.  The brackets and screws are energized by feeders first and then mechanical contact.  In turn, each rail gets power.

I have powered both a lift-out and a swing-up bridge by winding feeder wire ends around screws holding one side of a hinge or of a bracket.  Then, the other half of the hinge or the screw 'feet' provide power to the rails via short feeders.  100% reliable, every time, for years now. Don't even need to solder anything.

If you'd like a picture showing how it works, please let me know.

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Posted by SeeYou190 on Thursday, May 28, 2020 12:29 PM

selector
Let's slow down a bit.

I don't think we were moving that fast.

I know humidity effects wood more than temperature, but I have had different experiences with it.

Since my train rooms have always been air conditioned, there is little humidity in the air.

The lumber I buy from the yard has moisture in it. Over the period of several days in the A/C it will lose its humidity, and sometimes change, twist, or warp slightly.

Moving it back to a humid environment does not make it return to its orignal shape.

My experiences have been that changes to wood due to humidity changes are a one-way street.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by MisterBeasley on Thursday, May 28, 2020 1:22 PM

How does power get from one side of the bridge to the other?  It's best to not route the power over the bridge.  Think about how many types of wiring you might need.  I have a DCC track bus, a DCC control bus, power for lighting, power for twin-coil turnouts an power for stall motor turnouts.  I simplified it by providing separate lighting power, using DCC control of turnouts with stationary decoders, and adding radio control instead of a control bus with jacks.  Still, I needed a pair of wires for DCC track power to get to the far side of the gap.  I would design that differently if I were doing it again.

It takes an iron man to play with a toy iron horse. 

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Posted by Track fiddler on Thursday, May 28, 2020 2:31 PM

Unfortunately any building product composed of cellulose is going to have expansion and contraction due to temperature or humidity swings.

Cellulose is basically anything in a house from natural wood to man-made fiber materials, even sheetrock expands and contracts and cracks but the tape keeps you from seeing it.

From what I know about building products after being in the business all these years is if I was going to build a lift up.  I would use Russian or Baltic birch plywood fastened to my framing.  Half-inch has 9 layers and 3/4 inch has 13 layers.  This stuff comes straight as an arrow and is known not to expand, contract or warp the lesser of all plywood's.

I would then put 2" of extruded foam on top but not glue it.  I would drill holes in the plywood and use nylon screws to accommodate movement of the cellulose wood below.  An 8-foot length of Owens Corning extruded foam insulation only expands and contracts up to a 1/16 of an inch in an uncontrolled enviorment.  My 4 by 8 sheet under my layout has not changed a bit in 3 yearsYes

Unfortunately the other side of the coin is the layout benchwork on either side of the lift up could be moving and probably is.  If that being the case one has a whole new can of worms.  Your only solution now is your hinge fastening system and the latch system where it closes would have to become more heavy duty to prevent movement.  You may have to attach your layout benchwork on the opposing walls on either side with exspandable fasteners such as hinges or slide rod fasteners to allow movement to accommodate the lift up.

 

Hope this can helpWink

 

 

TF

 

 

 

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Posted by selector on Thursday, May 28, 2020 3:54 PM

The four short screws I mentioned, that ride on the inverted brackets, can be adjusted inward or outward as the need demands.  This makes the roll, pitch, and yaw of the upper deck infinitely variable, and makes sliding joiners over a cinch, and effectively neutralizes changes at either end of the gap from moving benchwork.

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Posted by selector on Thursday, May 28, 2020 3:56 PM

Kevin, I intended for our OP to slow down. I replied to his post just above mine where it sounded like he might leave the thread and attempt to construct something. I realize I used 'let's', but.... 

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Posted by doctorwayne on Thursday, May 28, 2020 4:31 PM

My layout is partially double-decked, so there are two lift-outs at the entry to the layout room, both on 3/4" plywood, with corded-plugs to provide power to the lift-outs, when in-place.  Layout power is provided across the gap by wiring above the suspended ceiling.

While the upper level lift-out is only a few years old, the lower one has been in use, without issues, for about 30 years.
The layout is in an unheated and non-air conditioned basement room, with little temperature variations, despite Canadian winters and warmish summers, with high humidity.  There is a dehumidifier in the basement. 

Never a problem with expansion or contraction of the wood or the track, and never a variation in track alignement either.

I'd offer a couple of photos, but photobucket continues to have difficulties.

Wayne

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Posted by tbdanny on Thursday, May 28, 2020 6:51 PM

I have a lift-out bridge on my layout, which sits in my garage.  It's in QLD, Australia, so humidity does affect it.  I've done two things that guarantee track alignment, and prevent too much shifting.

Firstly, the lift-out has plywood holding it in alignment at each end, as well as a bolt securing it in place:

(The AV connectors are for power, accessories, etc.)

Secondly, the track is held in alignment by a connector I made myself:

I took two rail joiners, put them in place on a piece of circuit board, then soldered them to the PCB.  I then cut the copper of the PCB down the middle to prevent a short circuit, and removed enough ties to allow this to slide on and off the lift bridge as needed.

Both of the above arrangements are in place at both ends of the lift bridge, and I've yet to have a problem with it.  Maybe something like this could work for your situation?

The Location: Forests of the Pacific Northwest, Oregon
The Year: 1948
The Scale: On30
The Blog: http://bvlcorr.tumblr.com

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Posted by doctorwayne on Thursday, May 28, 2020 8:23 PM

With annual temperature swings in excess of 100º, I'm fairly certain that rail length will be affected, and that humidity values are likely all over the place, too.

My situation was easy to accomplish because seasonal temperature variations were perhaps only 10ºF, and humidity was controlled.

Rather than the suggestions regarding a lift-out or other engineered options, I'd think the most logical solution would be to better-control the environment in which the layout is situated.

Wayne

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Posted by SeeYou190 on Friday, May 29, 2020 12:43 AM

Wow, I guess i am a bit lucky here.

My layouts have been 70-75 degrees year round with low humidity.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

jjo
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Posted by jjo on Friday, May 29, 2020 9:32 PM

I uderestand your frustration...   But 1/8" should be "correctible".. In my case, Humidity is usually the culprit...I keep a dehumidifier going in summer as well A/C from upstairs.....Perhaps, a simple adjustment twice a year as the temp/humidity changes...G'Luck

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Posted by gregc on Saturday, May 30, 2020 6:43 AM

large gaps shouldn't be much of a problem as long as rails are aligned.

fix ends laterally but allow ends to slide longitudinally (parallel to track)

 

greg - Philadelphia & Reading / Reading

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Posted by Afdahl Flats on Saturday, May 30, 2020 6:16 PM

My layout is screwed to the wall on one side and has legs on the other. Because of the wonderful Wisconsin weather, and the fact that it's constructed in a retired Millhouse, I figured that the expansion and contraction of the gap where the bridge used to be was inevitable, so I just gave in and made a permanent bridge across the two ends of the table. I made it as shallow as I possibly could to ease the process of entering the layout.

 

I've got plenty of life left in my knees, I'm only 15...

Thanks for all your suggestions, I'll probably use them when I make another layout after I pass the point when I'm not obsessed with cars and girls like all teenagers seem to have at 17

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Posted by doctorwayne on Saturday, May 30, 2020 7:09 PM

Afdahl Flats
....Thanks for all your suggestions, I'll probably use them when I make another layout after I pass the point when I'm not obsessed with cars and girls like all teenagers seem to have at 17

Are you saying that those obsessions will actually fade?   I'm decades past that age, and expect to be long-gone before those interests fade.

Wayne

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Posted by doctorwayne on Saturday, May 30, 2020 7:31 PM

doctorwayne
...I'd offer a couple of photos, but photobucket continues to have difficulties.

I suppose that this could be my version of "Photos at eleven"

 

Wayne

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Posted by BATMAN on Saturday, May 30, 2020 7:40 PM

Well I made a section out of 1" angle iron and cement board. I welded the angle iron into a retangular shape and dropped two 1/2" pieces of cement board into it. Cement board is easily cut with a circular saw.

It was over the fireplace and subject to heat when the fire is on and living on the wet coast, humidity can be an issue if not controlled. It worked so well that I know two people that have built bridges using cement board and angle iron.

Brent

It's not the age honey, it's the mileage.

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Posted by Track fiddler on Saturday, May 30, 2020 7:50 PM

You know Brent,  I've said it before but I'll say it again.  Sometimes you never cease to amaze me.  What's better than enjoying a nice fire in the fireplace in the spring, fall or winter.... Well, ... Ummm,  Maybe a train or two running over it Eh! Laugh  Right onYes

 

 

WinkTF

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Posted by mbinsewi on Saturday, May 30, 2020 9:45 PM

doctorwayne
Are you saying that those obsessions will actually fade?   I'm decades past that age, and expect to be long-gone before those interests fade.

Yes Mischief Surprise Smile, Wink & Grin

Mike.

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Posted by Track fiddler on Saturday, May 30, 2020 9:55 PM

Wayne

I have never seen any example of your modeling that I did not like through the years I have been here.

I consider myself a good modeler but I have always payed attention to your modeling and have learned so much from you through the years.

I just wanted to let you know that.

 

 

TF

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Posted by Afdahl Flats on Sunday, May 31, 2020 8:25 AM

I'm not saying that interests fade, it just sounds like (from all the articles I've read) most people start to prioritize other things over model railroads at the age of 17, only to get back into it ten to twenty years later

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Posted by ATLANTIC CENTRAL on Sunday, May 31, 2020 8:38 AM

Afdahl Flats

I'm not saying that interests fade, it just sounds like (from all the articles I've read) most people start to prioritize other things over model railroads at the age of 17, only to get back into it ten to twenty years later

 

Guess I'm not "most people". While I had (and still have) a healthy interest in girls and cars at that age, I was also working in the hobby shop, building a layout, a member of a nationaly recognized model railroad club, and was building hot rods from the ground up, all while getting married and starting a family at age 19.

Sheldon 

    

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Posted by RR_Mel on Sunday, May 31, 2020 9:14 AM

Afdahl Flats

 

I've got plenty of life left in my knees, I'm only 15...

Thanks for all your suggestions, I'll probably use them when I make another layout after I pass the point when I'm not obsessed with cars and girls like all teenagers seem to have at 17

 

OH to be fifteen again! Wow Or at least have the ability to get down on my knees again. Laugh

Other things occur that will ding your hobby like your career.  I married at 21 and at 23 my job got in the way of my hobby then the rug rats started popping out.

I piddled a bit with my trains at 31 and built a layout for my kids at 34 (4' x 8' John Allen's G&D).  The rug rats started leaving the nest at 41.  We moved when I changed jobs at 46 and all but 1 rug rat (7 total) had moved out.

I built My first layout, 4’ x 8’ at 47 (actually my first model railroad was on a shelf around a room behind my father’s garage in 1951 at 14).  Moved again when I was 50 and began my final layout (14’ x 10’) at 52.  Built a N gauge layout for a grandson when I was 64, didn’t last very long.  Tried again for a great grandson at 72, another failure.

I’m still going at it at 83 and I have to say that Model Railroading is GREAT!!!!  The best hobby in the World!!!!


Mel



 
My Model Railroad  
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 

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Posted by doctorwayne on Tuesday, June 2, 2020 11:39 PM

Track fiddler
...I have never seen any example of your modeling that I did not like through the years I have been here....

TF, I sent you a PM a couple of days ago, but am assuming that you've not enabled notifications...or, like mine, notifications no longer work.  Anyway, I just wanted to let you know that your kind words are very much appreciated.

Wayne

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