Looking for universal joint with 1/4 hex M/F interface

[cleaner]

Does anyone know of a 1/4 hex male/female universal joint adapter? I need something to enable the use of a torque wrench in some tight quarters.

The preferred torque wrench accepts 1/4 hex male and I need to load it with 1/4 hex bits (torx or hex). It may also work with a square drive to 1/4 hex universal adapter but I thought I would search for the preferred set up before buying an adapter.

 

[TuxThePenguin]

Wouldn't that throw off the measurement?

 

[mille755]

Have you ever seen the DeWalt right angle adapters? With a short bit, they are about as compact as you can get

 

[2oolhound]

Wouldn't that throw off the measurement?

I think you are right. As soon as you change the angle of force from the torque wrench the measurement is off. That's why torque extensions need to be at 90' only. The distance from the pivot in handle to the axis of the drive can't change.

 

[Samuel D]

Universal joints have variable mechanical advantage. As the input side is turned smoothly, the output speed varies depending on the point of rotation and the angle through which the axis of rotation is bent.

As surely as the speed varies, so does the torque. Since the average speed must be the same over a full rotation, the speed at any moment can be higher or lower than the input speed. Therefore the torque may also be lower or higher than the input torque.

All that said, these effects are probably negligible with the joint less than, say, 10º off straight. Much more than that would cause problems.

 

[Wrench97]

How about a flex shaft extension?

You'll probably have to verify the torque remains constant though out the different angles.

https://www.amazon.com/dp/B07MSBQLYD/?tag=atomicindus08-20

 

[2ndGearRubber]

I think you are right. As soon as you change the angle of force from the torque wrench the measurement is off. That's why torque extensions need to be at 90' only. The distance from the pivot in handle to the axis of the drive can't change.

Some of the manufacturers, Ford IIRC, has a tsb discussing this. Wobble extensions with maybe 10 degrees or so of rotation are fine. It's all about not increasing or decreasing the length of the lever arm. Their testing said the wobble extensions didn't make a huge difference and were considered okay.

You could use a universal bent at 75*, so long as the torque wrench is offset 90 from that bending plane of the universal. Same concept as using a torque adapter 90 degrees offset from the torque wrench as not to change the length of the lever.

 

[Samuel D]

You could use a universal bent at 75*, so long as the torque wrench is offset 90 from that bending plane of the universal.

Not for work that needs a torque wrench in the first place. The universal joint itself alters the torque; the more it’s bent, the jerkier the output speed and torque for a smooth input.

That means the torque wrench may go click at a point in the rotation with substantially higher or lower torque at the bolt.

 

[2ndGearRubber]

Not for work that needs a torque wrench in the first place. The universal joint itself alters the torque; the more it’s bent, the jerkier the output speed and torque for a smooth input.

That means the torque wrench may go click at a point in the rotation with substantially higher or lower torque at the bolt.

Obviously any use of a torque wrench means best practices apply. Smooth sweeps, etc. There will be no significant change and torque output using a universal joint in an extremely mild angle. As angle increases and binding becomes a legitimate concern, this takes you out of the accepted limits of best practices for using a torque wrench. The fact that the universal is binding is the problem, not the fact that you've changed the angle, unless of course that has increased or decreased the length of your lever, with will change the torque output to a degree.

I wouldn't sweat torquing with a universal for the vast majority of applications. Not ideal obviously, but if that's the only way to get a torque wrench in there....

 

[JR 42]

I'm not an engineer or a mechanic, but my understanding is that torque wrenches are a sorta crude but accessible method of achieving adequate bolt stretch/ clamping force... so being a little off axis probably won't ruin your day. Being way off could be a problem.

OP, I can't recall ever seeing a 1/4" hex male drive universal bit holder, but I bet some company like Vim or Koken made one at some point.

 

[Samuel D]

There will be no significant change and torque output using a universal joint in an extremely mild angle. As angle increases and binding becomes a legitimate concern, this takes you out of the accepted limits of best practices for using a torque wrench. The fact that the universal is binding is the problem, not the fact that you've changed the angle, unless of course that has increased or decreased the length of your lever, with will change the torque output to a degree.

You mentioned 75° but I may have misunderstood something about that.

Wikipedia has a graph of output speed for a constant input speed here:

https://en.m.wikipedia.org/wiki/Universal_joint#/media/File:UJoint1.png

As speed varies, torque goes the other way. So a doubling of speed (as the red line for a 60° bend shows) halves the torque.

You can see that a 30° bend produces speed and torque variations outside those that would be useful with a torque wrench.

15° starts to get into the useable range, albeit with more error than people would accept in their torque wrench calibration.

This peaky irregularity is felt as binding long before the joint locks up. The binding is the sudden collapse of torque at the output shaft for a constant input torque.

 

[2ndGearRubber]

Right, so if it's binding, you're outside best practices. A clever user would just run the fastener down almost all the way, then clock the universal joint to a position of minimal binding prior to each sweep. Remove from fastener, twist the extension however many degrees you spun, place it back on the fastener. The graph shows that very fact, binding through the range of motion is the issue.

Automotive torque applications are surprisingly unpicky, outside perhaps bearing and head gasket surfaces.

 

[glenng]

I think this might be what you are looking for:

https://www.amazon.com/dp/B000UO9RJG/?tag=atomicindus08-20