`The optician's trick: The serviceman looks over your door with lots of scowling, chin-scratching, and tsk-tsking. You ask, "how much?" He replies with the fair price. If you don't flinch at that price, he says, "for the parts", while quoting a large additional cost for the labor. If you still don't flinch, he adds, "each," while pointing back and forth to your pair of springs. (I hope none of you service people are reading this!) I call this the "optician's trick" after the old vaudeville joke about lenses, frames, and left/right.`

In the photo, you can see an extra lag screw on the bottom of the plate, reinforcing weak anchoring from the original two screws (hidden behind the springs). This extra screw was applied by a professional garage door technician on a previous repair visit. I have since replaced the backing with a sound plywood panel anchored into the concrete door header. Since these bolts clamp all the opposing torsion to the wall, the attachment must be sturdy.

**We are a family owned and operated, local garage door company in the Carlisle area that believes in attention to detail and an emphasis on customer service and satisfaction. We even offer same-day service because we know that when your garage door isn’t working the way it should, you need it fixed fast. We offer affordable rates that will fit your budget, and we’re confident you won’t find another garage door installation company in Carlisle or the surrounding areas with the same dedication to our customers and the quality of our work at the affordable rates we offer our clients.**

### Garage Door Opener Company

**Trading wire size for length, diameter, or cycle life: Now we are really going to save you some money, if you just recall your high school algebra class (and I don't mean that cute cheerleader who sat next to you). If you further understand the role of the 4th power of the spring wire size (letter d in the formulas above) in the numerator of the spring rate formula, and how to increase or decrease d to compensate for changes in length, diameter, and cycle life, then you're qualified for elite spring calculations. Matching springs is a matter of equating the 4th power of the proportion in wire size change to the proportion of change in the diameter or length or the product of both diameter and length. However, it is usually best to only increase wire size when substituting a spring, since this does not derate the cycle life. If you observe that the formula for bending stress is proportionate to the inverse 3rd power of the diameter, then physically a proportionate increase in wire size will result in a dramatic increase in cycle life of the 3rd power of that proportion. Trade-off example: Yawn with me while we ponder my original spring once more. Let's say I was in a fit of engineering mania, and wanted to replace my spring having a 0.2253 inch diameter wire (d = 0.2253) with a 0.262 wire version (d = 0.262). How much longer is the spring with equal torque rate, assuming we use the same coil diameter? The proportion of this change is 0.262/0.2253 = 1.163, and the 4th power of that is 1.83. This means the length must increase by a factor of 1.83 (again, not counting dead coils). Recalling that the length in Example 1 was 102 non-dead coils, the heavier wire spring must be about 1.83*102 = 187 coils, which when adding 5 dead coils and multiplying by the wire size to get the overall length, is (187+5)*0.262 = 50 inches, versus 24 inches in the original. So using this heavier wire more than doubles the length (and thus the mass and thus the cost). While the cost about doubles, the stress goes down by the inverse 3rd power of the wire size proportion, or 1/(1.163**3) = 0.64. Sress is favorably, non-linearly related to cycle lifetime (halving the stress more than doubles the lifetime), so this decreased stress should more than double the expected lifetime of the spring. While the up-front cost is more, the true cost of an amortized lifetime is much less. In short, per cycle it is cheaper. Ah, the wonders of engineering calculations! Conclusion: Observe that the stress formula (and thus the cycle lifetime) depends only on wire diameter (d) for equal torques. Thus the only way to improve cycle lifetime is to use heavier wire. For equal torques, heavier wire size, due to the exponents in the formulas, increases cycle lifetime much faster than it increases mass (and thus cost), physically speaking.**

Install the stiffening strut on top of the top section of steel doors with the section lying flat. Then install the opener bracket that replaces the center bracket between the top two sections. While you’re working on the sections, protect them from scratches by putting carpet scraps on top of your sawhorses. Now, slide the rollers into the roller brackets.