Wednesday, October 13, 2021

Dirt stops solder - deliberatly

Time for a job I don't enjoy, soldering the washers on to the crank pins to hold the rods in place. It's one of those jobs where everything can go wrong, and you end up with a lump rather than a collection of moving parts. 

My solution is to put permanent marker everywhere I don't want the solder to go. Since the stuff will only stick to clean metal, in theory (and practise I'm pleased to say) it won't stick to the penned up bits. 

As an extra precaution, some light oil floods the crank pin hole in the rod. This is the old skool way of doing things, but I'm always concerned that the heat of the iron will boil off the liquid and let the solder do its worse. 

Anyway, in the photo, you can see the true horror of the over-large holes in the rods, but as the chassis works fine, I don't care how much it annoys proper engineers, I'm not bushing them. 

Another handy hind, ignore the washers provided with Romford crank pins, you only end up filing them much thinner, just use some 10BA brass washers and save some effort.


Woz said...

G'day Mate,

Have tried a piece of paper pressed over the crank pin ?

As you would be aware it's available in different thicknesses, it prevents the solder from intruding beyond & you simply rip it away when done.
Sure you may still stuff up the odd joint & have to redo it like no doubt you've done before all with no solder where you don't want it.

It works for me.

I find the oil a bit messy so what's your trick for an applicator ?

Cheers Woz

Phil Parker said...

Woz - aluminium kitchen roll is better than paper. It tears less and doesn't soak up the flux. I still prefer marker pen though as it stays where you put it and you can put it everywhere, including on the sides of crank pins.

Oil is just messy. Even using a tiny applicator, it still get around and needs cleaning off afterwards.