Another newbie question tools and parts

[WayWeGo]

Thank you for all the input it has been very helpful.

And a bit expensive for me. Scott got me thinking about how many times I have dragged a drill back and forth to the boat. Now I have a 12V Bosch drill with batteries that also fit the Bosch oscillating tool I already had. The drill will stay on the boat, not sure about the oscillating tool yet.

[P-Dogg]

Didn't see torque wrench listed yet. One of the few tools that I bring as needed is a 1/2" drive torque wrench, but I keep a 1/4" drive with assorted u-joint and extensions on the boat for torquing hose clamps. Each one. Every time.

[prowlersfish]

When I bring a torque wrench its not a good thing as It means I am doing major work . $$$

So I hope it stays at the shop

[P-Dogg]

And a bit expensive for me.

Black Friday is coming up! Knowing I was about to buy my first real boat, I dropped ten boat dollars on tools, taking advantage of Father's Day sales to stock up.....

[prowlersfish]

I just spent a few bucks my self pre black Friday sale $300 on gear wrench's .

[P-Dogg]

It seems that a discussion of U-joints and torque is in order. The question is: Is it acceptable to use u-joints in combination with a torque wrench? Like most things, it depends. While the ideal case is a socket directly connected to the output of the torque wrench, it is perfectly acceptable to use length extensions and universal joints (and blasphemy -- even lateral extensions!) when torqueing fasteners. Moderation is the key, along with an understanding of what you are doing. Reasonable use of a u-joint to gain proper purchase on a band clamp fastener is perfectly fine. To wit, I offer the following data:


We'll start by referencing manufacturer's installation data from the only type of band clamp that deserves to be on a boat: all-316 SS AWAB-brand embossed-thread band clamps, which happen to be made in the good ol' USA to boot. You can see that installation torques for most sizes of clamps likely to be found on our boats have a range of 15 in-lb.




I pulled the following chart from http://home.jtan.com/~joe/KIAT/kiat_3.htm:



It should be noted that the author only used straight-line interpolation between points, and did not use a polynomial or even a simple quadratic curve fit. A proper curve fit would show that the predicted data values would be closer to the zero degree angle value in the region between zero and 30 degrees, i.e., that they would have even less error.

There are two cases to consider, which are a function of the starting angular orientation of the components of the joint. Hence, the two lines on the graph.

I estimated the zero degree applied torque to be 320 in-lbs, because it appears to be about one-fifth of the way between 300 in-lbs and 400 in-lbs. Consider the data points at 30 degrees offset. I estimated the value of the upper plot to be 330 at 30 degrees offset, as it is about one-third of the way to 400. I estimated the value of the lower plot to be 280 in-lb at 30 degrees.

For the upper plot, this yields an estimated error of about 3%. For the lower plot, this yields an estimated error of about 12%.

Refer to the AWAB torque chart. For a 2" (max) hose clamp, the allowable installation torque is 45 in-lb to 60 in-lb, the average of which is 52.50 in-lb (call it 53). 12% of 53 in-lbs is about 6.5 in-lbs. Set your torque wrench to 53 in-lbs, use a u-joint at any angle up to 30 degrees, and you'll apply a torque that is within the manufacturer's specification irrespective of u-joint orientation (or presence).