How to fix copper/brass strips and fittings to hull or other surfaces?

[Bobby]

I've had no luck glueing the fiddly little strips of copper required in a lot of places on model ships. I've figured out that CA doesn't work, wood glue is perfectly useless and for whatever reason I'm not even having much luck with 5 minute epoxy which is what I understand to be the best glue for the job.

 

A good example is the pintle and gudgeon on the 18th Century Longboat which a lot of builders have made here (pictured below). I can probably manoeuvre the gudgeon into place and have it lightly tacked on, but I can't achieve a secure fasten that I would trust in the long term to hold the rudder or even survive the installation of the rudder without coming loose.

What might I be doing wrong?

 

Things I speculate that could be the issue: epoxy not drying enough (it's 5 minute epoxy but I noted the surface is still gummy and loose even after an hour or so), surfaces not prepared properly beforehand (does epoxy not work on a painted hull?), the model ship gods have cursed my existence (is there a bloody sacrifice I can make to appease them?).

 

Also pictured below are the glues currently available to me.

 

Any and all feedback would be greatly appreciated.

[wefalck]

Copper ions (can) interfere with the polymerisation of cyanoacrylates, so its use is not such a good idea.

 

Copper forms in ambient an oxide layer (that feels slightly 'greasy'). This oxide layer becomes easily detached, as the glue/cement adheres better to it than the oxide layer to the metal. So the copper surface has to be made bright immediately before glueing, e.g. by burnishing it with steel wool, and then degreased, e.g. by rubbing it with acetone. Then epoxi cement and contact cements should work. It may depend on the formulation of the epoxi, as copper ions can also interfere with that polymerisation.

 

If your expoxi does not set, you may have used not enough hardener or there is the problem with copper ion inhibition.

 

It is never a good idea to glue parts on painted surfaces. The bond will only as strong as that between the paint and the surface that is painted. I would glue parts, such as the gudgeons before painting. At least one should scrape off the paint at the place where you want to glue something.

[Bobby]

Wefalk,

 

What a great answer! Very much appreciated. I'm going go follow your advice and keep you posted how it goes.

 

 

[Bobby]

I've figured out another issue is that my epoxy isn't setting. I've let it sit for a couple hours and when I come back it's sticky and the piece comes off when I remove the clamp. I'm working at the correct temperature so either I've got a bad batch of epoxy or my mix isn't right. I'm using Araldite 5 minute epoxy and it looks to me like my mix is fine so I'll have to practice a bit more.

 

Incredibly frustrating.

 

[wefalck]

Actually Araldite normally keeps for many years. So either the ratio between the components wasn't right or it wasn't mixed thoroughly enough.

[Bobby]

I think I must not be mixing it properly. It's too late to make another attempt tonight but I'll get back to it tomorrow.

[Moxis]

I have also found out that the 5 minutes Araldit does not always cure completely hard. That is why I have moved to use the 60 minutes Araldite which seems to work better.

[chris watton]

I always use cyano for stuff like that. However, if all else fails and I am unhappy with the result, I resort to using thin card or thick paper for the rudder straps, painted and cut to the appropriate colour/thickness, and applied using PVA wood glue. This method probably give a much better scale appearance, too (depending on scale, of course - large scale stuff should be fixed using pins anyway).

 

This is why I stopped using copper/brass strip for the blackened iron mast straps, black cartridge paper does a much better job in both ease of application and appearance. the same applies (sometimes) to rudder straps. In my own humble opinion, of course..

[Roger Pellett]

The directions for the epoxy that I often use say to mix the two parts for a full 60 seconds.

 

Roger

[Bobby]

So I’ve followed Wefalk’s advice and scraped the paint from the hull where the strip should be applied. I also roughed the strip so it would bite the epoxy better and this time shaped it carefully so it was very congruous with the hull where it was going on.

 

My two concerns about the epoxy were 1. my mix was wrong and 2. I wasn’t mixing long enough. Strangely I’ve read that epoxy is forgiving and that it’s unforgiving. In any case I made the cardboard jig so I would start the syringe pouring and then drag it over the little wall so I could avoid disproportionate mixing if one side or the other of the syringe faltered at the start. This gave me a perfectly equal mix which I blended thoroughly. I wrote the exact time of the blending next to the puddle so that I could observe how quickly it set. It’s far from the advertised 5 minutes but eventually did harden and the piece is now firmly set and painted.

 

Chris - Interesting advice. I’m now exhausted with copper bits at this point as I’ve been applying them for days to this project and my over one. I’m definitely going to look into your suggestion about the paper.

 

Moxis - I think I’ll switch to the 60 minute or try a new brand. I’m not at all impressed with this Aramite. 

 

 

 

 

[Griphos]

Not all resins are equal. A lesson I learned working on full sized boats. For models, this is the best stuff I’ve found. 

 

https://www.amazon.com/Bob-Smith-Industries-BSI-201-Quik-Cure/dp/B0166FFFD4/ref=sr_1_1?crid=2AKT6FAOKEKJE&keywords=bob+smith+epoxy&qid=1558359268&s=gateway&sprefix=Smith+epoxy%2Caps%2C194&sr=8-1

 

Portions don’t have to be exact, and it hardens quickly and cures fully and well. 

 

Btw, @chris watton  what is “black cartridge paper”?

[Jaager]

I may be incorrect about this, but to introduce another complication:

for proper function, should not the long axis of the pintle and the long axis of the gudgeon  be in the same plane and be perpendicular to the axis of rotation?

[deaz]

I don't think it's been said yet, regarding epoxies: working time and set time aren't the same. The times quoted on most off-the-shelf epoxies is the working time.  This is the time that the epoxy is easiest to work with and still fluid enough to move. This isn't an exact time 5 min might not be 5 minutes, 60 minute might be 45.  It depends on how much hardener was added, how well it was mixed, etc.   Set time for many epoxies is 24-48 hour. This is the time in which it will become fully cured, again not always exact. 

 

In the OP, after 5 minutes and through an hour it was still gummy.  This isn't surprising or unexpected, rather it's quite normal for that type of epoxy. I've used 5 minute epoxy that's taken a week to cure completely!

 

I won't go into the epoxies that only harden with UV light... or are flexible even after fully cured.... 

[tlevine]

Please follow Jaager's advice and look at the angle between the pintle and gudgeon.  This needs to be a straight line.  Take a look at other longboat builds to see how it should be done.