The not-so-competitive advertising trick: How about this racket: We have all heard how you should get at least three bids for any home improvement jobs, right? In some areas the largest ads in the yellow pages are from a single business using various names and phone numbers, masquerading as independent competitors. When you call asking for prices, "they" all quote you very high numbers. You are tricked into thinking you have shopped around for the prevailing price. (The more modern version of this is multiple Web sites that all direct you to call the same person.) If you've ever had to call a plumber you may have unknowingly been a victim of a similar trick.
Cycle lifetime unchanged by diameter-versus-length tradeoffs: Since the material stress (and thus cycle lifetime) for equal torques varies only with d, and not D or N, trading coil diameter (D) for spring length (N) in this fashion has no effect on cycle lifetime. Long and skinny, versus shorter and fatter, they'll wear the same if they have the same wire size and diameter-length product. The game of life is all about wire size when it comes to springs (see below).
Stress and lifetime: Calculating the maximal stress in the wire is useful for estimating the lifetime. Using the formula above, the bending stress S in the spring wire is 32*238/(π*0.2253^3) = 212 Kpsi. The spring index C is D/d = 2.23 / 0.225 = 9.88. The Wahl correction factor is Kw = (4C-1)/(4C-4) + 0.615/C = 1.15. The Wahl-corrected stress is Kw * S = 1.15 * 212 Kpsi = 244 Kpsi. This predicts about a 10,000-cycle lifetime, which is the standard "cheap spring" configuration originally installed. Note that while this stress is proportional to the torque being applied, it is also in proportion to the inverse third-power of the wire size. Thus slightly heavier wire sizes (and suitably adjusted D and/or L) radically improve the expected cycle lifetime of the spring.
Wood garage door: There’s no substitute for the distinctive look of wood. It’s typically made of moisture-resistant cedar, redwood or cypress and offers the most flexibility for custom designs. Depending on climate and exposure, wood doors require more maintenance. The average cost for a 16-by-7 double door made of quality wood: $1,200 to more than $4,000.
When your garage door starts acting up, more often than not it is telling you it's time to do a bit of maintenance. So, before hitting the panic button, try these simple repairs. First, examine the rollers and tracks. If you can't remember the last time you cleaned them (and they look the part!), give them a good brushing and then add some lubricant. Next, perform these simple garage door maintenance tasks.
You might genuinely need some extra parts when you thought you simply needed a broken spring replaced, and a good serviceman will perform a simple inspection to identify such parts. Nor is it unreasonable for a business to charge separately for a service call versus repair work actually performed. But the best protection for you as a buyer, being somewhat at the mercy of whomever you decide to bring on site, is to understand what is being done, and ask intelligently for a clear explanation or demonstration of why extra parts are required.