Last year I replaced my cellphone with an Apple iPhone, a smartphone that allows me to check my e-mail and go online. Tasks that once had to wait until I got home from work can now be handled on the fly. I don't have to leave the job site to exchange e-mail with clients, look up material specs, or order tools and supplies online.

Another great thing about this phone is that it can use apps. "App" is short for "application," a small program designed to perform a specific function on a smartphone. Most apps are inexpensive and many are free.

Apps that work on the iPhone's operating system can be downloaded from Apple's App Store. Similar apps are available for phones that use other systems — Android,

Windows Mobile, Blackberry, and the like. I'm going to talk here about the iPhone apps that have been most useful to me in my trim carpentry business.

One of the first apps I bought was BuildCalc (www.buildcalc.com), a construction calculator that can compute rafter cuts, stair layout, compound crown cuts, and just about anything else done with geometry or trigonometry.

Although made by a different company, BuildCalc is very much like a Construction Master calculator. It has a similar key layout and more or less the same functions. The biggest difference is the interface: Instead of punching actual keys, you hit virtual keys on the touch-screen display. Because BuildCalc is on my phone and my phone is always with me, I now have a calculator wherever I go. (If I forget to charge the phone, though, I'll be without a calculator — so I continue to carry my old construction calculator as a backup.)

BuildCalc has a terrific built-in help feature, a short on-screen manual that makes it easy to perform new functions. The help menu contains a series of slides that walk you through calculations.

Unlike a conventional calculator, BuildCalc — being software — is easily updated. During the months I've been using it, the app has been improved a number of times, and the maker has provided free online upgrades. BuildCalc is available only for the iPhone, but versions compatible with other brands of phones are supposedly in the works. BuildCalc sells for $20.

Calculated Industries (calculated.com) recently introduced Construction Master apps for the iPhone and phones that use Microsoft Mobile OS. I bought the iPhone version and have been trying it out. I haven't used it long enough to offer an opinion, but it too has an on-screen manual and the functionality appears to be identical to that of the Construction Master. It costs $15.

My Measures (sis.si) is a simple app that allows you to take photos with your phone and then label them with measurements you made. The resulting digital images contain more detail than sketches and can be saved or e-mailed from the phone.

I use this app to catalog the measurements for drawings I plan to make at home on the computer. If a question comes up on site, I can send an annotated photo to the customer, architect, or GC — and he or she will be able to see just what I'm looking at.

My Measures costs $4.

TimeCapture (www.norfello.com) helps you track your work hours. Its timer and customizable data fields allow you to assign time to specific customers, projects, and tasks. If you apply a billing rate, the entry will include both the time and the cost of the work. Different rates can be used for different activities. Time data can be exported as a spreadsheet and turned into an invoice or imported into QuickBooks.

I use TimeCapture as a time sheet on T&M jobs or when I want to compare my estimate with the actual hours worked. The app runs in the background and doesn't affect the phone's other functions. About the only thing you can do wrong with it is forget to clock out at the end of the day.

Although there are other time-keeping apps on the market, this is the only one I know of that lets you attach photos and notes to the records. I find that this information can come in handy on future estimates or when you want to show the customer exactly what you did. When I bought the app it sold for $10; it now sells for $2. At either price it's money well spent.

The iPhone contains a GPS device, and for $10 per month AT&T will provide audible turn-by-turn directions to your destination. It's like using one of those GPS units you find in a rental car. I chose not to pay for this service; instead, I rely on the free Google Maps app that comes with the phone. It works much like the Google Maps page on the Web, except it uses the phone's GPS to visually track your location on the map. This app saves me the trouble of printing out maps and makes my life a lot easier when I have somewhere new to go.

The RedLaser app (www.occipital.com) turns your iPhone into a bar-code scanner that searches the Web for pricing. To use it, you aim the phone's camera at a bar code and wait for vendors and prices (from Google Product Search) to appear on the screen. I recently used RedLaser at the lumberyard to get a better deal on a siding nailer. An online vendor was selling the tool for $100 less than the lumberyard. When I showed this to the salesperson, he matched the online price. Not a bad return on an app that costs $2.

Jesse Wright is a finish carpenter for Architectural Molding in Pleasant Hill, Calif.

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