Questions on 4 mm Finney Dean Goods

[Robert Dawson]

So, having finally overcome the belief that the best way to make brilliant models is to leave them in their box and with thanks to the encouragement I got from my introductory post, I finally took the plunge and have started my 4mm Finney Dean Goods. To my eye it’s a beautiful prototype, one that I just about managed to put together from a K’s kit about a hundred years ago, and a fabulous kit. I intend to model it with polished brass dome and all; round topped S4 boiler and Indian Red frames.
Work has begun, and the frames assembled reasonably sweetly. But now I’ve hit a possible problem with the connection between the two halves of the coupling rod. i consider myself reasonably nifty with a soldering iron but found soldering the pin that joins the two haves, without seizing the lot up, challenging until I hit on the late John Haynes suggestion to use cigarette paper in the joint. But Mr Finney then says to file the back flush. With the pin fitting nicely into the 1mm hole there seems little opportunity for solder to attach itself to anywhere other than the back. I have filed the pin down to a knat’s whisker of the surface but- and here’s the question to those much wiser than I- will I get away with it or will the tiniest projection foul the wheels (ultrascale)? If so, what is the best way- is there a magic solution? (I wish there always to be a magic solution…)

 

[AJC]

Hello Robert,

Welcome! With regard to the question, I'd follow the instructions and file it flush - if it's secure, the soldered joint must be good and the solder will have penetrated the hole and thus filing flush should make no odds. The other thing you can do is to very gently countersink the outside of the rear rod which will increase the area of the joint.

Adam

PS - my preferred approach is to chemically blacken the bit you don't want soldered, though a permanent marker works well, too.

 

[Robert Dawson]

Hello Robert,

Welcome! With regard to the question, I'd follow the instructions and file it flush - if it's secure, the soldered joint must be good and the solder will have penetrated the hole and thus filing flush should make no odds. The other thing you can do is to very gently countersink the outside of the rear rod which will increase the area of the joint.

Adam

PS - my preferred approach is to chemically blacken the bit you don't want soldered, though a permanent marker works well, too.

Thanks Adam. I think you’re right so I’ll file it flush and see if the solder has penetrated into the join. Better it fails now rather than later. If it does I’ll try the countersink idea, though there’s precious little metal to sink into. Fingers crossed - there’s a spare set in the kit if push comes to shove..

 

[Robert Dawson]

Done- and holding nicely…Phew!
I think my initial problem was that I wasn’t using a hot enough iron and was holding the wire in a pin vice, which was soaking heat away from the wire. Thanks Adam for encouraging me to get it right!

 

[adrian]

The other thing you can do is to very gently countersink the outside of the rear rod which will increase the area of the joint.

That would have been my suggestion as well. Also I'm not clear what the arrangement is with the crankpins in the ultra scale wheels. If the crankpin is bushed then this will step the rods away from the wheel slightly and then the joint pin just needs to be thinner than the offset from the crankpin bush.

The other alternative is a true rivet pin, IIRC Alan Gibson used to make them. Rather than soldering, the back of the pin has a small counter sink so you can tap the pin with a centre punch and it swages the end over and forms a riveted joint.