SeeYou190 How do you deal with guard rails on a removable bridge?
How do you deal with guard rails on a removable bridge?
The guard rails should project somewhat onto the track abutting the bridge, but don't necessarily need to be secured there, as long as they're secured to the ties on the bridge.
All of my "steel" bridges are removeable as single units, simply by sliding the rail joiners at the bridges' ends out of the way....
...although the one in the last photo above is no longer easily accessible...
All three of the trestle-style bridges are "pinned" to their "concrete" footings by a piece of piano wire imbedded in each of the footings. The wire is mainly for proper alignment when re-installing the bridges.
Wayne
selectorThe secret to a removable bridge is the abutment
I have never made a removable bridge on a home layout, but the superstructure has been removable, and that seemed to be good enough.
-Kevin
Living the dream.
The secret to a removable bridge is the abutment...or rather, the sill or 'shoes' on which the end frame members of your bridge rest. Get them right, even shimming with thin packaging plastic below what will show when you remove the bridge, and the rest is easy.
You have to figure that the bridge, PLUS tracks, must have the bridge rails meeting the bearing surfaces of the rails resting on the abutment backs at grade. So, and it will take you as much as a full hour of fiddling, you keep placing the bridge, try to join the joiners easily, no tilting or forcing, and when you get the bridge at the correct height AND alignment, joiners in place, and a gentle rocking doesn't make anything shift, you have your permanent semi-permanent solution.
I have had several structure kits that required rails to be set into the simulated pavement. One was a hydrocal kit and the other two were plastic. I used epoxy and the rails have remained in place for over 10 years. Epoxy is usually my choice for bonding two different materials. If foamboard is involved, I use Loctite Power Grab. Strong bond and it grabs almost right away.
That is a great plan. I do not see why that is not possible as long as the ballast does not interfere. Will start paying attention to that.
Just ridiing shotgun fer ya, but is it possible, conceivable, that you'd ever wish you had made the bridge installation a little less permanent? Could it be that maybe one time, or six, you'd rather have it out of the way for an hour so that you can work on something nearby unfettered? I did, and am I ever glad I had the foresight to make the bridge removable. I just use half-size (ie, cut in half) joiners to keep the eight rail ends aligned, and to power the rails. When I need to remove the bridge, now for 'bout the 12th time, I just grab that dental pick, slide back the joiners, and lift the bridge out to set it aside, safely.
Used contact cement last evening with a toothpick. Let set for 10 minutes before bonding the surfaces. Laid flat and put weight over the whole surface area. Checked this morning before heading to work. It is a STRONG bond. I again appreciate all the advise given. Cannot imagine this contact cement will ever break loose once the bridge is installed and tied to the ballasted layout at both ends of the rails. Thank you!
I used to use all kinds of different adhesives for different jobs. My model building life is much simpler now.
Plastic to plastic: Testors liquid cement
Almost all others: Loctite "Gel Control" super glue
There are still some specialized joints, like clear windows, that require a special adhesive, but these are less than 0.1% of bonds.
The results are all just fine.
I would use the super glue on the joint you asked about.
I use gelled contact cement for holding the rails in place on my Central Valley bridge, and also use it where my track is rail on Central Valley tie strips and turnouts.It's advantage is that it's less stringy than regular contact cement, so a little neater to work with. The disadvantage is that, as far as I'm aware, it's available only in quart or gallon cans. I do encourage you, if using contact cement of any type, to read the instructions on the container - many don't, and complain when it doesn't perform as expected because they didn't know the proper procedure.
I first used it 32 years ago, when veneering kitchen cupoards for the house I had just built, and later used it for some furniture veneering, too. All of it is still held firmly in-place. I still use it for some modelling projects, too.
I was advised by a fellow mrr that Loctite 404 makes for an excellent bond between rail and plasic tie.
Cid (Memphis, Tennessee)
Thank you both for your advise. Think you have me steered in the right direction!
I favour contact cement or epoxy. You should use either one, but sparingly...you don't want it oozing out and forming big glossy globules where you (and others) notice them.
I would fit the rails as a dry fit, mark every fourth tie at the rail foot with a sharpie, both sides of the rail to be sure, both rails, and then lift the rails. Invert them, and use a diamond needle file to roughen up the nether surface of the rail foot at the marks. You do this for 'tooth' for the adhesive.
Apply, with a toothpick, a tiny drop of your adhesive, working quickly if it's contact cement, to the appropriate tie surfaces where the rails will lie, and then apply the rails, use a length of 1X2 or lath laid along the rails as weights with a few items sitting on the wood to keep the rails pressed into place.
Check track gauge before walking away for 24 hours, though, to ensure nothing has moved or been placed improperly.
My Central Valley HO truss bridge had little plastic nubs to be peened over the rail web. I used code 83 rail, if that makes a difference.
I found it difficult to do the peening well enough to secure the rails well, so (to your point) I supplemented that with some CA gel glue. I don't know if epoxy would be better but imagine it would also work. It has held up fine.
IMG_0606 (2) by Paul Ahrens, on Flickr
Paul
Modeling HO with a transition era UP bent
Completing a CVM truss bridge. Need to adhere code 55 rails to the plastic tie panel. What is the best adhesive for metal to plastic that will hold up long term?
Joe