Sanding Blocks Introduction to Building by Phil Fearn (Continued)
Sanding Blocks In the previous Wet Weekend I mentioned the Permagrit sanding blocks . These are expensive and unless you are a committed (MAD) modeller The banker (wife) may have something to say about it if you come home with a set.
Sanding blocks can be made from the bits of rock hard balsa that are unsuitable for building .Blocks are necessary to keep the profile/flatness of the piece being sanded . If you use your hand to hold a piece of abrasive paper you will create a very poor and untrue finish. (You can hold the paper for final finishing as this is just a very light sanding and you are not removing much material). Cut the wood to the required shape or profile and face them with some scrap thin ply , this stops them denting and sanding funny shapes. Now glue some Aluminium oxide paper on to the front of your sanding blocks .(Don’t waste your time with glass paper or sand paper as it wont last five minutes) . Aluminium Oxide abrasive paper or Production paper is available from any car paint factors or Halfords (although a bit more expensive) Glue this to your blocks with some Evo Stick or Thick cyano (a bit quicker) Make some with40 or 60 grit for really coarse sanding or removal of large amounts of wood . Now go down to whatever grade you require depending on the finish you want to achieve. I make mine down to about 180 grit then finish with hand held 240 and 400 grit. Always use the various grades as it is much quicker and each finer grade removes the marks left by the previous grade easily.
A vital part of the modellers tool kit and for m that “extra pair of hand” so often needed when building a model. They can hold a joint together tightly while it sets ,this forces the glue into the grain making a stronger joint and squeezes out any excess glue so that it can be wiped off . All excess glue does, is add unwanted weight to the finished model which will affects its flight performance .
These small plastic clips are very useful for holding bits while the glue sets. Here they are holding a trailing edge of the sheeting on the flap until the glue sets so that it stays straight. They are inexpensive and come in a variety of sizes . Available from most tool shop /suppliers or from the cheapo tool dealers at markets and model shows . A good tip when using these clamps is to put some scrap balsa between the jaws and your model ,especially if you are using soft balsa) as the jaws can dent the balsa and ruin the finish of your build.
TOP TIP
If you do get a small dents in a sanded and finished part of your model you can quite often remove as follows. Wet the dented area an allow it soak in . Now use your hot air gun on the dent .As the water in the wood fibres heats up and expands , the dents wood resumes its shape.(most of the time). A light sand and all is back to normal.
Larger Clamps can be used for all sorts of jobs .
Here they are being used to hold a cross brace in place while glue sets . Again these clamps are quite cheap but are necessary and can be used for clamping bits to the bench while cutting or shaping .
I nearly forgot this one. A metal safety rule or straight edge is a MUST. When cutting strips of balsa or trim tape , the blade from your scalpel can , and will eventually ,ride up onto the ruler or straight edge and into your fingers. Don’t be tempted to use that old wooden or plastic school ruler I and many other modellers have done this so be warned A safety ruler has a steep edge that a blade cannot run up or a handle for griping it ,so keeping your fingers out of the way. The worst thing about cutting yourself like this is that the Wood or plan gets ruined ! only joking.
A very useful tool for the builder of smaller models as most model shop don’t keep balsa strip any more .If they do its extremely expensive and usually of the wrong grain and density.
Balsa strippers have a scalpel blade clamped into them and are very good for cutting strip up to about 3mm or 1/8th inch . Any strip thicker than that and the blade starts to follow the grain and you end up with a wonky strips.