Plugging holes under coupler boxes

[locochris]

I'd like to hear your recommendations on what to use to plug holes under coupler boxes so that a hole can be drilled and a different coupler box can be attached.  In my most recent case, I removed a junk Intermountain coupler box, but then I messed up drilling the hole, so I have to plug the hole with something and try to drill again.  Styrene rods are one option, but getting the right size can be a pain.  I've heard of people using various things like carpenter's glue, and some kind of epoxy glue.  I need something that will be secure enough to be tapped and hold the coupler box.

[edwardsutorik]

My recommendation is to feel your pain and get the proper styrene rod.

These days, with the Internet and all, getting styrene rod seems pretty doable.

I've even done it myself.



Ed

[bn7023]

When I make a mistake in drilling a hole in styrene, I use the leftover runner from plastic kits to fill in the hole. Sharpen the tip (into a cone shape), moisten the hole thoroughly with solvent, and then insert it. Wait approximately 48 hours (depending on temperature) for it to harden. After that, cut off the protruding part with nippers and finish it flat with a chisel edge.

The solvent used as adhesive is MEK = methyl-ethyl-ketone.
I have no experience with ABS resin, but I think the same method will work. If you are worried, use a special adhesive for ABS resin. The way to distinguish between styrene and ABS resin is that d-limonene does not dissolve in the latter. You can also ask the manufacturer which material it is made of.

[tom]

Similar to the above but I use the stretched sprue approach where you soften a round sprue and then carefully stretch it until it narrows down. Cut it then you have a nice cone shape. Using liquid cement (I use Testors or MEK) force it into the hole then let it cure. Most of the time I use Evergreen styrene rod for smaller holes and round sprues for bigger ones. Once you get the hang of it works great plus you do not have to worry about getting the correct diameter...just has to be a little bigger than the hole.

[drolsen]

Feb 9, 2024 20:03:46 GMT -8 locochris said:

Styrene rods are one option, but getting the right size can be a pain.

Keep a few sizes of styrene rod on hand and then drill the hole out to fit the closest larger size rod. That way you get a good fit and a clean hole to start from, but make the hole slightly undersized if possible, and soften both the hole and rod with liquid cement. That will make for a stronger bond.

I've filled a lot of holes like this, and it's best to use the same type of plastic whenever possible. This was easier back when kits were more common, because you'd have leftover sprue that you could use as others already mentioned. One of the drawbacks that I've found with styrene rod is that the plastic tends to be softer than what the model car body is made from, so if you have to drill a new hole that overlaps the joint between the styrene rod and the body, the drill wants to wander into the softer styrene rod plug. When you can use sprue made from the same plastic as the model, it creates an even surface that's easier to drill cleanly. I'm also not a fan tapping Evergreen styrene because it's soft, and it's easy to strip the threads. When possible, I'll add an extra layer of styrene inside the car (like a piece of wide .040" strip) to make the screw hole deeper with more threads. That's easy to do with a boxcar model, but only if you can remove the roof or floor. With today's ready-to-run assembled models, that's not always possible.

Dave

[locochris]

Thanks, I did not know about needing to soften anything. I have some Timya liquid cement I will try.

[locomotivebreath]

Feb 10, 2024 4:22:23 GMT -8 tom said:

Similar to the above but I use the stretched sprue approach where you soften a round sprue and then carefully stretch it until it narrows down. Cut it then you have a nice cone shape. Using liquid cement (I use Testors or MEK) force it into the hole then let it cure. Most of the time I use Evergreen styrene rod for smaller holes and round sprues for bigger ones. Once you get the hang of it works great plus you do not have to worry about getting the correct diameter...just has to be a little bigger than the hole.

I do this often to fill those dang sunshade holes Atlas puts on everything. Conrail rarely had sunshades on GP40s and never on C40-8Ws. And Kato SD40-2s.