Hand tightening vs torquing

[Mach1]

So I have always wondered if there is a good rule of thumb on hand tightening fasteners in situations where you cant use a tq wrench, I can't find any good info on this, does anyone have any experience?

I plan on doing an experiment with different size fasteners and torquing them vs angle after finger tight.

So I would take a 1/4, 3/8, and 1/2 inch grade 8 bolt, tighten them until finger tight, mark the location, torque to spec, then see how much they rotated.

[Cooter]

thread count has a lot to do with angle vs. torque

[ceyko]

hmmm...never really thought about thread angle...makes sense.

I often wondered the same thing that the OP is wondering.

There are too many variables in my opinion though to have anything conclusive. Work space, physical condition, size of wrench/ratchet and so on.

[Mach1]

thread count has a lot to do with angle vs. torque

Thats a good point, i'll add it to the test.

[Chas_svo]

thread count has a lot to do with angle vs. torque

As does lubrication.

[jw33]

As does lubrication.

this x 100. Probably the largest variable when trying to get things just right.

If you could find a setup to measure the clamping force between two different pieces and then run some test with different types of lubrication in the threads that would be awesome.

[SOLOW55]

Turn it till it breaks and back off one .

[Mach1]

Turn it till it breaks and back off one .

lol thats exactly my problem, I always want to over tighten shit

[inline 6]

My dad always told me " a cross thread is a tight thread". All BS aside there is no rule of thumb on this. You can get it in the ballpark if you have done the particular torque a million times and can just feel it out. Otherwise its just pure wingin it. I use all sizes of torque wrenches probably 35-50 times a day on adverage with torque specs ranging from 15inlbs to 800ft lbs. I still would not be comfortable guessing on any of them.

[racrguy]

hmmm...never really thought about thread angle...makes sense.

I often wondered the same thing that the OP is wondering.

There are too many variables in my opinion though to have anything conclusive. Work space, physical condition, size of wrench/ratchet and so on.

I don't think the size of the rachet would have anything to do with it if he was making an angle measurement. However, the items being bolted together would. You can bolt two solid pieces of material together and two channeled pieces and get a different measurement for both simply because of the give in the material.

[JC316]

My dad always told me " a cross thread is a tight thread". All BS aside there is no rule of thumb on this. You can get it in the ballpark if you have done the particular torque a million times and can just feel it out. Otherwise its just pure wingin it. I use all sizes of torque wrenches probably 35-50 times a day on adverage with torque specs ranging from 15inlbs to 800ft lbs. I still would not be comfortable guessing on any of them.

Really the only things that I use torque wrenches on are the items that have to be torqued in sequence. Otherwise I will wing it, half of the time the torque specs feel way too loose to me anyway.

[Z06killinsbf]

Just make it "star tight"

(so tight you see stars)

[Stangs 4 Life]

The wrench arc method has always worked for me when a torque wrench cannot be used. Do not use this method to torque bolts requiring a specific method when a specific procedure is required by manufacturer or manual.

Taken from:

http://aviationmiscmanuals.tpub.com/TM-1-1500-204-23-9/css/TM-1-1500-204-23-9_146.htm

8-11. Torque Procedures Without a Torque Wrench. In certain instances, when a torque wrench is not available, the aircraft maintenance manual may prescribe an alternate method for determining that a fastener is properly torqued. The two methods which are commonly used are the wrench-arc method of tightening, and the use of preload-indicating washers.

a. Wrench-Arc Method of Tightening. The wrench-arc method of tightening will be used only when specified in applicable aircraft maintenance manuals. (1) Preliminary steps. The following paragraphs provide preliminary steps that must be accomplished before performing this operation:

(filler text deleted due to extremely dull content)

(c) Get the proper size open-end wrench with 15- degree offset heads to snug the nut.

NOTE The snug (no torque) condition is reached when, using an open-end wrench, a positive increase in resistance (on the nut) to turning is felt (greater than run-on torque), when parts appear to be properly seated, and when no looseness between mating parts is noted.

(2) Tightening to 15-degree wrench arc. Proceed as follows:

(a) Using an open-end wrench, snug the nut.

(b) With wrench still positioned on nut, establish a line of sight using wrench handle, as shown in figure 8- 24.

(c) Use angular difference between handle and wrench flats (15 degrees) to visually measure amount that nut will have to be turned.

(d) Turn wrench until flats on nut (engaged by wrench) are aligned with line of sight established by handle in figure 8-24

[Mach1]

The wrench arc method has always worked for me when a torque wrench cannot be used. Do not use this method to torque bolts requiring a specific method when a specific procedure is required by manufacturer or manual.

Taken from:

http://aviationmiscmanuals.tpub.com/TM-1-1500-204-23-9/css/TM-1-1500-204-23-9_146.htm

8-11. Torque Procedures Without a Torque Wrench. In certain instances, when a torque wrench is not available, the aircraft maintenance manual may prescribe an alternate method for determining that a fastener is properly torqued. The two methods which are commonly used are the wrench-arc method of tightening, and the use of preload-indicating washers.

a. Wrench-Arc Method of Tightening. The wrench-arc method of tightening will be used only when specified in applicable aircraft maintenance manuals. (1) Preliminary steps. The following paragraphs provide preliminary steps that must be accomplished before performing this operation:

(filler text deleted due to extremely dull content)

(c) Get the proper size open-end wrench with 15- degree offset heads to snug the nut.

NOTE The snug (no torque) condition is reached when, using an open-end wrench, a positive increase in resistance (on the nut) to turning is felt (greater than run-on torque), when parts appear to be properly seated, and when no looseness between mating parts is noted.

(2) Tightening to 15-degree wrench arc. Proceed as follows:

(a) Using an open-end wrench, snug the nut.

(b) With wrench still positioned on nut, establish a line of sight using wrench handle, as shown in figure 8- 24.

(c) Use angular difference between handle and wrench flats (15 degrees) to visually measure amount that nut will have to be turned.

(d) Turn wrench until flats on nut (engaged by wrench) are aligned with line of sight established by handle in figure 8-24

That is EXACTLY what I was looking for, I figured it would be aviation based.

[JimD]

Really the only things that I use torque wrenches on are the items that have to be torqued in sequence. Otherwise I will wing it, half of the time the torque specs feel way too loose to me anyway.

Yep, same here.