Today was one of those rare days when two separate discussions on two different forums intersect and are very relevant to each other. The discussion on Western Thunder started with a mention by a pro about getting his annual new Vallorbe files. The talk then went onto what does he do with the old ones (he uses them for whitemetal) and amongst the other suggestions I added that if you had a bench grinder you can make very useful scrapers from old needle files. One of the members who had scrapers made from old files by someone else, asked me how I would go about sharpening them.
This is the post that I made on the subject. On Mick's thread I made a comment about using old files to make scrapers and PaulC asked about sharpening them. Above are a few of the scrapers that I have made from old needle files they are very much the cheapo variety, bought before I even knew Vallorbe existed let alone bought some. The rather rusty looking example in the middle of the bottom photo is the one that I use the most for removing excess solder. Most of the others I tend to use when working on styrene. To answer Paul's question about sharpening them so far I haven't had the need but if I do I would just touch the face of the scraper to the grinding wheel to reform the edge. You will note that most of them are curved in the shape of my grinding wheels. Then I would rub the flat edge gently on a diamond stone just to remove any burrs and hone the cutting edge without removing much material.
Fast forward and I added a comment to York Paul's thread about the inherent lack of strength in solder. copied below for completeness. Paul took this comment in the positive spirit that it was intended and quipped in reply "Plumbers take note" Now this comment allows me to expand a little further for those new to soldering. When comparing what we do to what plumbers do, even though they are technically both soldering, is comparing apples with pears. We modellers solder two pieces of metal together to make a joint more often than not that joint is some form of butt joint. However for the most part* plumbers these days don't actually use solder to make the joint, that is done mechanically by the pipe fitting inside the copper collar. The solder is there to seal the joint. An important distinction. * I said for the most part because I assume that very occasionally a plumber may be called upon to solder up lead piping which would require a proper soldered joint but I rather suspect that soldering lead pipe is very much a dying art.
Before I finish this thread off for now, I will also add that when mentioning mechanical fixing the same applies to super glues. Super glues on their own are inherently weak unless the joint has some mechanical hep to fix it. try sticking two pieces of metal together flat face to flat face and then see how easy they are to pull apart or if you drop them on a hard surface they will break apart as the joint will shatter. However do the same with two piece of metal flat to flat with a hole drilled in them and a pin inserted with super glue. You will get a rock solid joint.
Finally stepping back to scrapers, while working on the Princess this morning soldering on the front smokebox saddle I noted that my trusty scraper wasn't touching the excess solder. So I took my own advice and gave it a rub on a diamond stone lubricated with washing up liquid (the washing up liquid habit stems back to my days a a butcher when we sharpened knives we used washing up liquid as we felt that using any kind of oil might contaminate some food preparation surfaces whereas washing up liquid would just wash away). What a difference a few minutes on the stone made it now removes solder residue very quickly.
In addition to the plumbers bit When solder is used as a joint and seal, there is considerable overlap of the copper parts, so the solder isn't getting any mechanical flex, the pipe takes the strain. And for lead pipe, were not technically soldering but welding, as for any weld, provided the surfaces are clean, the correct flux is used and there is enough penertration then the joint is as strong as the parent material. As for the scrappers great tip Rob, time to look out the old files. Joint reinforcement anyone thought of trying desoldering braid on the unseen side, not only does it wick up solder, but over a joint would would form a mesh a bit like plasterers taped joints, giving a joint over a bigger area and helping to prevent cracks forming and propergating. Paul
I have used solderwick (braid) instead of solid wire in the past, I used it when I made breakout boxes to join the terminals of banana plugs, the boxes allowed me to connect a number of battery chargers to one power supply (ATX computer PSU 12V rated at 19A). I found it easier to use that wire and when in position I soldered to make it rigid.
Hi Graeme, Yes, that's what I use most of mine for, admittedly in my case on plastic, I can't say that I have tried them on balsa but if they are sharp enough they should work like any wood chisel or scalpel blade.
