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tool to torque jam nuts?

alpinelakespilot2000

Well Known Member
Anyone know what kind of tool (and where I can get one) that will allow one to tighten a jam nut with a torque wrench? I assume it must exist. How else would one, for example, properly torque a jam nut or fuel fitting?

Thanks.
 
You can use a fish scale on a open end wrench, tape a stick on the wrench, drill a hole at the 12" mark, hook the scale here and pull. You get the idea---
Frank
Sanding wind screen fairring :eek:
 
GOO-TEN-TITE.....I couldn't resist. Honestly, I'm curious to hear an answer. The only things I recall torquing with a torque wrench (in the year 2000) were the fixed pitch prop, wing spar, motor mount-to-firewall and exhaust-to-cylinder nuts (that come to mind). Everything else was torqued GOO-TEN-TITE :) Rosie
 
If you have a regular torque wrench, you can use a crow's foot wrench on it to tighten nuts that don't accept a socket. That's how you torque the nuts on a constant speed prop. HOWEVER, make sure you make the proper calculation to take into account the extra moment you have added by extending the crow's foot wrench out from the end of the torque wrench. Someone has a slick little calculator on their web site for this, but I can't recall who...maybe it was Dan Checkoway???
 
if you stick the crows foot on 90 degrees to the ratchet handle, no torque conversion is nescessary.
 
Davepar said:
I use a crows foot as well, sometimes with a socket extension on it. Here's the calculator: http://rvproject.com/mechanic.html

By extension, do you mean (a) an extension that lengthens the handle of the torque wrench or (b) an extension that makes the socket longer? I'm assuming only the former would require any calculations to be made and that as long as the socket were still aligned with the head of the wrench you would set the same torque as always. Am I understanding this correctly?
 
alpinelakespilot2000 said:
By extension, do you mean (a) an extension that lengthens the handle of the torque wrench or (b) an extension that makes the socket longer? I'm assuming only the former would require any calculations to be made and that as long as the socket were still aligned with the head of the wrench you would set the same torque as always. Am I understanding this correctly?

If you only change the length of the handle, the torque value doesn't change...the correction term goes to 0. If you extend the other end, then you need to run the calculation. Since the calculation is based on the length, everything needs to be straight. At 90 degrees, the correction again goes to 0 (because the added length is 0). Any angle in between, you need to rerun the formula based on the new length....so no ratcheting :)
 
Thanks John. Makes sense about adding length to the handle not affecting the setting (I realized that right after I posted the message). I guess i'm still unclear about what one means by an "extension."

For example, in my normal socket set, I have 2 different 1/2" sockets. One is about 1" tall and the other is about 3" tall. Would using the 3" tall socket require a different torque setting than the 1" tall socket? (I can't imagine it would.) To extend this example further (no pun intended), my socket set also has a 6" extension: one end is attached to the wrench, the other to the socket giving my wrench extra reach. As with the previous example, the sockeet is still in the same line with the wrench head, so again no torque correction is needed. Am I correct?

This is all really hard to describe, so sorry if I'm not being clear. I'm still confused about what an "extension" (that requires a different torque setting) looks like.
 
There's just one caveat about making the handle longer. The pivot point where the wrench "breaks" is not directly over the socket. This means you can add a short extension if you just need a couple of extra inches of length in order to grip is and still be close to the desired torque. The longer the extension is, the further off you'll be. Depending on your wrench, it usually doesn't change much, but it's just something to be aware of. It's always best to add the extension to the socket side. You can't go wrong like that.
 
alpinelakespilot2000 said:
Thanks John. Makes sense about adding length to the handle not affecting the setting (I realized that right after I posted the message). I guess i'm still unclear about what one means by an "extension."

For example, in my normal socket set, I have 2 different 1/2" sockets. One is about 1" tall and the other is about 3" tall. Would using the 3" tall socket require a different torque setting than the 1" tall socket? (I can't imagine it would.) To extend this example further (no pun intended), my socket set also has a 6" extension: one end is attached to the wrench, the other to the socket giving my wrench extra reach. As with the previous example, the sockeet is still in the same line with the wrench head, so again no torque correction is needed. Am I correct?

This is all really hard to describe, so sorry if I'm not being clear. I'm still confused about what an "extension" (that requires a different torque setting) looks like.
Steve,
A socket extension in the typical sense of a tool set will not change the torque to a bolt regardless of the length chosen.
However, a change in the moment arm of the torque wrench will require calculations to get the actual twisting force applied to the bolt.
For example, if you needed a 6 inch long 3/8" combination wrench to access a difficult bolt and you connected the business end of your torque wrench to the box end of the 3/8 wrench and its open end to your difficult bolt then there will be calculations necessary to get actual torque applied from the torque observed.

If both the torque wrench and combination wrench are physically in a straight line, the torque applied will be greater than the indicated. If the pair are folded back on one another, the actual torque will be less and if you are able to create an isoceles triangle (not 90 degrees) using an imaginary line from your hand to the bolt that equals the length of your torque wrench, then indicated equals actual.

It sound more confusing than it actually is.

-mike
 
mlw450802 said:
if you are able to create an isoceles triangle (not 90 degrees) using an imaginary line from your hand to the bolt that equals the length of your torque wrench, then indicated equals actual.

It sound more confusing than it actually is.

-mike

Unfortunately, it is actually a little more confusing. An isoceles triangle will NOT allow actual torque to equal indicated torque. The correct formula for such a conversion appears to be:

Actual Torque = (Indicated Torque)*[(sinx)^2 - (cosx)|cosx - E/W|]

where E = length of extension, W = length of wrench, x = angle between wrench and extension.

Note that when x is 90 degrees we do get actual = indicated.

Steve Zicree
RV4 finishing
 
I'm looking at the book right now and it has one little diagram devoted to the subject of torque wrench extensions. It makes no mention whatsoever regarding angles. The problem with using an extension for our purposes is that the additional length usually causes such a reduction in the desired indicated torque that it exceeds the capabilities of our torque wrenches. Fiddling with the angle can overcome this. Specifically, using a 90 degree angle avoids having to do any conversion.

Steve Zicree
 
Wow. I might have to find a slide rule soon.

The extension I was talking about is like this one:
ext.jpg


As far as I know, this does not affect the torque whatsoever, because it's inline with the axis of turning.

When I use a crows foot, it lengthens the torque wrench roughly 10%. So I increase the torque approx 10%. (Edit: I meant to say I reduce the indicated torque on the wrench by 10%. That gives a number that's really close, but not exact.)

Dave
 
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Thanks Dave. That's what I was talking about too. I've never used, or seen a "crow's foot" so I still have some learning/math to do. Hurry and finish your plane so you can fly over the mountains and show me how to use it! :eek:
 
Davepar said:
When I use a crows foot, it lengthens the torque wrench roughly 10%. So I increase the torque approx 10%.

Dave

I'm sure you mean increase the actual torque by 10%, not the indicated torque. Geez I hate math!

As for what a crow's foot is, picture a really short wrench with one open end and the other end a square hole to fit on a ratchet. Something like this is needed when tightening prop bolts or rod end bearings. Sorry if the formula seems a bit "mathy" but I thought the correct formula could be useful to someone.

Steve Zicree
 
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Davepar said:
Wow. I might have to find a slide rule soon.

The extension I was talking about is like this one:
ext.jpg


As far as I know, this does not affect the torque whatsoever, because it's inline with the axis of turning.

When I use a crows foot, it lengthens the torque wrench roughly 10%. So I increase the torque approx 10%.

Dave

Actually, that doesn't work. It would imply that if you doubled the length (increased by 100%) you would decrease the torque by 100%...i.e. you require 0 torque. You absolutely have to use the formula because the "correction" term is really a ratio of handle length to extension length.
 
Hmmm....I was leafing through the Sears Craftsman torque wrench guide and it said in cases like this you don't have to adjust the torque setting. What to do? What to do?

43.15's section on torquing has all the formulas and when they apply. Their note says "when using a torque wrench adapter which changes the distance from the torque wrench drive to the adapter, apply the following formulas to obtain corrected torque reading.... It shows several adapters, none of which is a socket extender, which, as we all agree,doesn't change the wrench drive centerline.

So what formula would one use if one believes the socket extender would require a calculation. Because as near as I can tell,neither T, Y, L, nor E would apply.

Very confusing, indeed. EVeryone seems to know what they're tlakinga bout, but nobody seems to be saying the same thing.
Help.
 
1. Extending the handle of a torque wrench with a "cheater" doesn't require any adjustment to the torque setting.

2. Extending the drive of a wrench along its rotational axis with an ordinary socket extension doesn't affect torque settings either.

3. Extending the distance from the wrench drive to the fastener with crow's feet type extensions does require use of the appropriate formula. These formulas typically assume that the handle and extension are in a straight line; ie, meeting at a 180 degree angle. If this isn't the case, the formula I gave earlier should be used.


Steve Zicree
 
Bob Collins said:
Hmmm....I was leafing through the Sears Craftsman torque wrench guide and it said in cases like this you don't have to adjust the torque setting. What to do? What to do?

43.15's section on torquing has all the formulas and when they apply. Their note says "when using a torque wrench adapter which changes the distance from the torque wrench drive to the adapter, apply the following formulas to obtain corrected torque reading.... It shows several adapters, none of which is a socket extender, which, as we all agree,doesn't change the wrench drive centerline.

So what formula would one use if one believes the socket extender would require a calculation. Because as near as I can tell,neither T, Y, L, nor E would apply.

Very confusing, indeed. EVeryone seems to know what they're tlakinga bout, but nobody seems to be saying the same thing.
Help.

I was referring to the case he gave with the crows foot....i.e. 10% longer means 10% less torque. That's incorrect. It is also true that the "extender" he has pictured needs no adjustments at all. Now, depending on the type of wrench you have, it's also true that extending the handle will cause an innacurate reading, however we're talking fractions of in/lbs so we ignore it as meaningless.
 
OK, cool, so let me just be clear on this. Let's take the bottom, inboard prong of the landing gear weldment (which has to be torqued at the bolt head because there's no way to get a torque wrench on the nut side between the 704 halves without speniding big bucks).

I used a 9" socket set extender" on it...90 degrees perpendicular, of course, to the torque wrench. The guidance on those bolts is 50-70 inch pounds. I tightened it to about 65 while making no adjustments.

did I approach this correctly?
 
Bob Collins said:
OK, cool, so let me just be clear on this. Let's take the bottom, inboard prong of the landing gear weldment (which has to be torqued at the bolt head because there's no way to get a torque wrench on the nut side between the 704 halves without speniding big bucks).

I used a 9" socket set extender" on it...90 degrees perpendicular, of course, to the torque wrench. The guidance on those bolts is 50-70 inch pounds. I tightened it to about 65 while making no adjustments.

did I approach this correctly?

Yes....perfectly :)
 
How to "lock"

Somewhat related question, can anyone give instruction on "locking" nuts on fuel fittings? I'm assuming that fuel lube both seals and locks the nuts over the sleeve's, but what makes sure that the nuts holding the fitting to the bulkhead (like where the vent lines pass through the side skin, for example) don't vibrate off?

Just use fuel lube (even though it's not sealing anything)?

Loctite?

Drill for safety wire?
 
Proper torque. AC43.13 has torque tables for AN fluid fittings. Fuel lube doesn't lock anything. It lubes.

Those plain nuts on bulkhead fittings...i.e. on the fuselage side skin where you're talkin' about the vent line passing through...a thread locker wouldn't hurt there, but if tightened properly they shouldn't go anywhere.

FRICTION is a major contributor to keeping plain nuts like that tight.
 
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Fuel fittings

Java, I sincerly hope that on every fitting that passes thru the side of your tanks has a fuel proof o-ring on the fuel side. If not, then I hope the fittings were installed wet. Wet meaning the fitting was thoroughly coated with pro-seal before being installed and tightened. To directly answer your question, the o-ring or the proseal will provide enough of a lock. The loctite is a good alternative.
 
Proper torque. AC43.13 has torque tables for AN fluid fittings. Fuel lube doesn't lock anything. It lubes.

Those plain nuts on bulkhead fittings...i.e. on the fuselage side skin where you're talkin' about the vent line passing through...a thread locker wouldn't hurt there, but if tightened properly they shouldn't go anywhere.

FRICTION is a major contributor to keeping plain nuts like that tight.

Java, I sincerly hope that on every fitting that passes thru the side of your tanks has a fuel proof o-ring on the fuel side. If not, then I hope the fittings were installed wet. Wet meaning the fitting was thoroughly coated with pro-seal before being installed and tightened. To directly answer your question, the o-ring or the proseal will provide enough of a lock. The loctite is a good alternative.

My concern was more the locking nuts where the fitting passes through skins into the fuselage, or the floor where the vent fittings go. Anything going into the tanks will be installed "wet."

Sounds like proper torque (for the nuts over the sleeves), and perhaps add a dab of loctite on the jam nuts is the answer...

Thanks guys.
 
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