Styrene help or advice

I wanted a two track bridge for my layout. I decided to modify a pair of Marklin bridges and straight bridge sections by cutting off one side of one set with a razor saw. Please with the results so far but there is not a large surface area to glue the section together. I was thinking of bracing the underside with styrene but I have never worked with it before.

My question is how thick of a styrene piece do I need to provide support and what is the best adhesive to use?

Working with styrene is pretty easy if you abide by the rules. The joints can be as strong or stronger than the two parts being joined. Plastic model cement will join the parts together and it comes as a thin "liquid" type or thick gooey type. My preference is for liquid type, it comes with a brush mounted to the cap. Once the parts are positioned I put a dab of glue using the brush on the side of the piece which won't be visible once it's all dry. Capillary attraction will draw the glue between both parts for a good bond. Make sure all parts are positioned and clamped before glue application. Let the parts cure for an hour or so before taking any clamps off.

Plastic model cement joins the parts together by melting each part where the glue is applied, then when the solvent evaporates away all that is left is the plastic which has bonded together as one piece. Cement will NOT join parts together just because there is glue on one or both parts if the plastic parts are not in contact with each other, it is not a filler. So both parts MUST have good contact with each other for a solid glue job.

Cleanliness goes a long way here! As mentioned above, if the parts don't touch each other a solid joint will not happen. Dirt and oils can also prevent a proper joint. After cutting the parts to fit, wash them with dish washing soap in order to make sure it's free of oils (from your hands). After a proper rinse, just let them air dry.

I personally don't see any need to add any styrene to your project if it's glued properly. But that's up to you.

Another glue which will join more types of plastic together, not just styrene, but also ABS and plexiglass is a glue called Tenax7R. It's harder to find, but it will glue them very nicely. It comes with a needle applicator and it flows readily, so be careful once you start to apply it because it's easy to over apply. Tenax7R is a handy glue to keep in stock just because it glues more plastic types together, not just styrene.

After cutting of the edge, what is left is a thin deck plate that doesn't give a lot of surface area for adhesive. Also my cuts were not perfect so it does not line up flush all the way along the joint, further reducing the surface area. My idea was to add "cross braces" spanning perpendicular underneath both sections overlapping the major braces that already exist with a square bar of styrene. What I wasn't sure of was how thick that bar need to be in order to be stiff enough to actually help.

Would a 1mm x 1mm bar be stiff enough across the 47mm of the two sections?

Sure reinforcement won't hurt at several places. That should be fine. You can smooth and straighten the edge of the cutting by sanding it some. It will give more contact area for the glue, that would help a lot.

So what are the best places to purchase online? Found several but the shipping an handling in many cases is more that they styrene

The type of glue Guba talked about act the same as welding two pieces of steel. To get a good end match between the two parts, stand then on end, back to back, then sand the ends at the same time by passing them over 120 or smaller grit sandpaper. after a few swipes, the ends show match close enough to glue.

Testors plastic glue in the five sided black bottle with the needle style applicator works well with styrene.

mhommer wrote: So what are the best places to purchase online? Found several but the shipping an handling in many cases is more that they styrene

Ahhhhh, that's why I like to support my local hobby shop. I only do online purchases when it's the only place I can obtain it.

Easier said than done sometimes. There are none local to me (within 20 miles) so I did look while traveling for work yesterday. 0-3 so far but tomorrow is another day.

Bashed Bridge.

mhommer wrote: Bashed Bridge.

Looks nice, I take it you found the styrene you were looking for?

Took several hobby shops but finally yes. Most of the train shops around me focus just on the trains themselves and no so much scratch building and one hadn't replenished their styrene stock in years because "nobody buys that stuff anymore". Seems to be a dying art.