Some hex tools have ball hex ends, others are straight.
There are pros and cons to both styles. Sometimes they can be used interchangeably, but that’s not always true.
Here’s a quick example I just uploaded to our Instagram channel, shown an application where you NEED a ball end hex tool, either in the shape of an L wrench, T-handle driver, socket, or other type of driver.
It can be possible to get a straight hex tool in there – the short arm of an Allen key – but it’s not going to work easily, quickly, or effectively, due to a highly restricted arc swing. In other words, let’s say you do get a straight hex tool in there. But will you be able to turn it?
The second image in that Instagram post shows the advantage of ball end hex keys, which is the fastener access angle. You don’t need to approach the fastener directly, from 90°.
This image, from when Wera released new ball hex keys, shows that you can fit a ball end fastener into a socket cap screw, or other hex fastener, from an angle.
The downside is that you do lose some fastener engagement. For that reason, ball end hex keys are not ideal for higher torque applications.
You will often see ball ends on the long arm of hex keys, and straight hex ends on the short arms. That way you can have an easier time turning a loose fastener, and rely on better engagement and higher torque delivery on tight ones.
There are ball end sockets and T-handle tools, but greater care needs to be heeded when using them. Ball hex ends CAN break off, and when they do, you’re in for a world of trouble.
Bondhus, a good USA brand of hex tools, doesn’t sell T-handle ball hex drivers in certain smaller sizes, due to the higher likelihood of breakage and a bad day. In my set, the smallest sizes have straight hex tips, then there are 2 ball end hex drivers with smaller handles (to limit torque levels), and the larger sizes have ball ends and regularly sized handles.
There are some tasks that you should use straight hex tools for, others where you almost need to use ball end tools, and many where you could use either one.
Personally, if I can use a ball hex tool over a straight hex tool, that’s what I do. I don’t always need to approach fasteners from an angle, but the freedom to stray from perfectly straight-on allows for a little flexibility in hand motions.
But that’s also not a strict tendency. Sometimes I prefer straight hex tips, even in lower torque applications, due to better fitment with certain fasteners. I’ve still been meaning to take measurements, but I think that the finish of those Bondhus hex keys are out of spec.
Some hex fasteners are a little shallow, and I’ve found that they work better with straight hex tips. Driving them in just feels a little more confident.
It’s not really a discussion about which is better. In the same way that you might sometimes use the box end of a combination wrench, and other times you’ll need the open end wrench, sometimes it’s good to have ball end and straight end hex tools available.
And as you can buy wrenches with two open ends, and those with two box ends, you can buy combination hex tools (mainly L wrenches and “P handle” drivers) with straight end tips, although they can be less visible at retailers, as talked about in today’s earlier post.
You won’t find L wrenches with two ball hex ends, or at least you really shouldn’t, since ball hex ends are not usually recommended for higher torque applications.
That all said, which style of hex tips do you find yourself using most? Ball or straight?