Steve Cook
Flying Squad
One of the most difficult things I have found when modelling things is cutting a straight edge in sheet material, particularly for wagon roofs or loco side frames. I've now got a method that gets me pretty close, although I've not used it on anything below 20 thou - mainly because at that point, unless its steel, you can cut through with a sharp implement and thus this technique is largely irrelevant.
Anyway, to demonstrate I'm making one of the corner plates for a 7.25" narrow gauge wagon body. The material is 1.4mm thick steel and I'm having to cut smaller pieces from a larger sheet. At this point, I've already cut and flattened two edges, I'm now working on the bottom edge to bring the sheet to the desired width. The sheet is covered with black marker pen and the desired width scribed in.
The excess is then removed, as close to the line as possible, with a jigsaw. It is possible to do the same with a hacksaw, just cut at a shallow angle which also has the advantage of helping to cut a straighter line. Go slowly at this point, what ever method you use, as time spent getting close now means less filing later on.
With the excess removed, its time to file down to the line. I did the first two plates with a hacksaw and file, then got new blades for the jigsaw and got my disc sander out - the power tools make it quicker, but there is no difference in the end result. When using a disc sander, present the material at a very shallow angle and move the piece from right to left. Go slowly and regularly eyeball the edge by looking along the marked line.
When you have got it close, use a marker pen and completely cover the cut edge.
Put a piece of sandpaper on a flat surface and run the edge over the top of it, keeping an even pressure on it.
It isn't a large movement, even half an inch will be enough to remove the marker pen from the high spots.
Draw file the high spots, staying away from the areas that still have the marker pen on.
After a bit of practise, you'll be surprised at just how flat you can get a cut edge - it still amazes me that when held against a square and up against the light its practically bob on.
The truth is always in the measurements though, so the final width at one end was
and at the other
Pretty good really considering its all hand finished
Of course, at this point I have to confess the target width was 90mm
Thats the joy of marking out with a plastic ruler, then measuring with a micrometer. As you can guess, I left it alone, and trimmed the length down using the same method, some things you can just let go.
The technique also works on wood and plasticard (using pencil as the colouring in tool), if you have a really long length to do then it works best using a surface plate to rub the marker pen off, but I don't have one of those so I can't demonstrate. Red marker actually works best as I find it easier to see, but I only had black in the workshop so thats another thing to add to the shopping list.
Steve
Anyway, to demonstrate I'm making one of the corner plates for a 7.25" narrow gauge wagon body. The material is 1.4mm thick steel and I'm having to cut smaller pieces from a larger sheet. At this point, I've already cut and flattened two edges, I'm now working on the bottom edge to bring the sheet to the desired width. The sheet is covered with black marker pen and the desired width scribed in.
The excess is then removed, as close to the line as possible, with a jigsaw. It is possible to do the same with a hacksaw, just cut at a shallow angle which also has the advantage of helping to cut a straighter line. Go slowly at this point, what ever method you use, as time spent getting close now means less filing later on.
With the excess removed, its time to file down to the line. I did the first two plates with a hacksaw and file, then got new blades for the jigsaw and got my disc sander out - the power tools make it quicker, but there is no difference in the end result. When using a disc sander, present the material at a very shallow angle and move the piece from right to left. Go slowly and regularly eyeball the edge by looking along the marked line.
When you have got it close, use a marker pen and completely cover the cut edge.
Put a piece of sandpaper on a flat surface and run the edge over the top of it, keeping an even pressure on it.
It isn't a large movement, even half an inch will be enough to remove the marker pen from the high spots.
Draw file the high spots, staying away from the areas that still have the marker pen on.
After a bit of practise, you'll be surprised at just how flat you can get a cut edge - it still amazes me that when held against a square and up against the light its practically bob on.
The truth is always in the measurements though, so the final width at one end was
and at the other
Pretty good really considering its all hand finished
Of course, at this point I have to confess the target width was 90mm
Thats the joy of marking out with a plastic ruler, then measuring with a micrometer. As you can guess, I left it alone, and trimmed the length down using the same method, some things you can just let go.The technique also works on wood and plasticard (using pencil as the colouring in tool), if you have a really long length to do then it works best using a surface plate to rub the marker pen off, but I don't have one of those so I can't demonstrate. Red marker actually works best as I find it easier to see, but I only had black in the workshop so thats another thing to add to the shopping list.
Steve