Installing posts is one of many home fix-up projects that have been simplified by new technology, although it is sometimes best to stick with more time-honored methods.
For example, it is possible to install a sturdy wood mailbox post or fence post in a few minutes, without digging, by using a pound-in post support such as Post Ups, made by Gordon Corp. of Southington, Conn.
Post supports are formed of heavy sheet steel and feature a bayonet-like shaft up to 30 inches long. A bracket on top of the shaft grips a standard 4-by-4 wood post.
To install a post support, a wood pounding block, furnished with the support, is inserted into the bracket. The shaft is then pounded into the ground, using a sledge hammer.
While pounding, check the support occasionally to make sure it is plumb.
When a post-support shaft is buried, the pounding block is removed and a post of the correct height is inserted into the bracket and held with clamps included in the kit.
Pound-in post supports are fairly expensive (about $15 each at some home centers and hardware stores) and are not a good choice for rocky soil, where it can be difficult or impossible to pound them in properly. However, they are fine for some uses, including supporting mailboxes, privacy screens and low fences. It is also possible to remove a pound-in support, by prying with a long bar.
For heavy-duty projects, however, I recommend traditional post-setting methods. A clamshell-type post-hole digger, for digging narrow holes needed to install strong posts, costs about $20 or can be rented at some tool-rental agencies. The sharp blades of this digger are simply jammed into the soil again and again until a hole of the correct depth is formed. The blades come together to lift out loose soil.
If many holes are needed, an auger-type hole digger powered by a gasoline engine can be rented.
A tamper-digger bar made of heavy steel is helpful as an auxiliary tool for digging holes in rocky soil or loosening very hard soil.
In general, a hole should be at least 24 inches deep for any post up to 6 feet high. Taller posts require even deeper holes. Use a yardstick or steel tape to check depth of holes.
When a hole is deep enough, shovel 4 to 6 inches of gravel into it and tamp down firmly, using the post or a tamping bar. The gravel promotes drainage under the post. Set the post in position and shovel some additional gravel around the sides.
For the strongest posts, fill the rest of the hole with dry concrete mix. Use enough mix to form an above-ground collar around the post shaped so rain water will run away from the post. Rain and soil moisture will harden the rest of the concrete mix.
Choose long-lasting woods when buying posts. Wood that is pressure-treated with preservatives has a long life, but some pressure-treated posts will split and twist in time. Cedar, redwood and cypress are naturally resistant to rot and make attractive posts that will last for many years.
Readers' questions should be sent to Gene Austin, c/o The Baltimore Sun, Box 8263, Philadelphia, Pa. 19101.