Blueprints help you to know what materials and equipment you will need, help you to avoid making mistakes, and can be used to estimate the cost of your project.
Where does one find such a thing? Ideas and plans can come from many places. There are countless woodworking books and magazines with many of them having scale drawings. Furniture brochures and catalogues can also be a source for plans. You can even go down to a furniture store and have a look for something that is close to what you want to build.
The blueprints you find in magazines and books are good for a start. They give you an idea of how the unit is constructed. However, you should still make an effort to draw or sketch it again. This gives you the advantage of having built it once in your mind. As you are drawing, you have to visualize how it is assembled. If you can draw it, you can build it. Also, some of the plans in magazines are made with the assumption that specific equipment will be used to construct the unit. You may or may not have this equipment. Or, perhaps you have better equipment than the blueprint assumes. The point is, don’t be afraid to modify the plans to suit your needs, tastes or equipment.
Furniture brochures and catalogues give you only one view of a unit and basic dimensions. You can still use this as a reference. If the description gives you the width, height, and depth, a scale can be established from which other measurements can be closely approximated. For example, if the width of the unit is 1200mm and you measure the actual width in the picture at 40mm, you know the scale is about 1/30th. Armed with this scale, you can now measure the drawer in the picture and multiply it by 30 to give you the real measurement. Be careful though when you measure lines that are at steep angles to the line you chose when establishing the scale. They may give a false reading. This is called “foreshortening”. The measurement will, in reality, be longer than you have calculated.
For those of us who have trouble visualizing how a piece of furniture goes together, a trip to the local furniture store is in order. Actually seeing how the individual pieces are put together will help you to plan your own unit. Be aware, however, that some construction techniques used in mass-produced furniture are not reproducible in the home workshop. Indeed some of the practices used by manufactures are done so for ease and speed of construction and are not necessarily the best way to construct furniture.
Once you know how the unit goes together and you have a blueprint, it is advisable to make a layout diagram and a material list. The layout diagram is a scale drawing of exactly how you will cut the pieces out of your sheet material. This is a crucial step in determining the quantity of material required. You can try different ways of laying out the individual pieces you require to give you the least waste and easiest cutting pattern. Perhaps you can alter one dimension and save buying an extra sheet for that one small piece that just won’t fit on one sheet.
Once you know how much sheet material you need, a material list can be made. This will include all items required to build the unit including glue, nails, sandpaper, sheet materials, solid woods, stain, finish etc. From this list you can arrive at a cost for your unit.