First and foremost, it seems
@Waiting has done some research and found out Snap-on are among the best when it comes to flare nut, also known as line wrenches. Good initial choice and many agree. But don't completely eliminate other high quality options.
So...lots can be said about these. I'll give it a go and try to provide a cliff notes version of key points I have learned over the years.
Snap-on has offered several different patterns of flare nut wrenches over the years,
with the most common being the double flare end six point.
Less common patterns include:
-Single flare end with a round handle
-12 point double flare end
-Combination flare with a thicker open end
-Above combination version with a "ratcheting" open end for speeding out fasteners
-Crowsfoot flare end
-Flare end interchangeable torque wrench heads
Focusing on
just the double flare six point wrenches, the older ones had V-shaped depressions in the beam.
-These were made for many years and are still quite popular to find second hand.
-These wrenches prior to 1967 (or 12 point pre-1965) did not have the off corner drive design Snap-on calls Flank Drive. This important feature is largely why they work so well. As such, I would not recommend the old ones without it. A patent number on the back of the wrench means it has flank drive,
but they don't all have it. Visually looking for the corner reliefs on the flare opening is the best method.
-Metric wrenches didn't appear until around 1970 so all of those should have the feature.
Pictured below:
-12 point single flare wrench
-Combination flank drive open/flare wrench
-Pre-flank drive RXV1314S with a "not guaranteed" limited warranty stamp
-Flank drive RXH1314S with the patent number. Notice the beefed up design.
Pictured below:
-Flank drive 15/17mm with the wrench flats parallel to the body
-Flank drive 19/21mm with the wrench flats clocked 15° to the body
-1967 early flank drive 12-point 7/8 & 1-1/8 without the patent number stamp, possibly pat. pending.
Around 1986, a major revision happened, and the beams were redesigned to the flat basic shape we know today. The suffix "A" was added to the end of the part numbers. These are not as common to find because they had a short production span due to a second major revision happening around 1990/91 when the "B" suffix design appeared. The changes were more subtle, but from my personal comparison, it seems like the offset head angle may have changed slightly, bigger legible markings, the flare opening design optimized for improved performance and a higher level of finishing. This version is still in current production today and also quite common to find used, but typically at a higher premium.
Pictured below:
-A suffix revision wrench - 5/8 & 11/16
-B suffix revision wrench - 16 & 18mm
-Williams USA flank drive 1/4 and 5/16 (Williams is a Snap-on industrial company and while they are not identical their flare wrenches do share features and are of good quality and value new. Unfortunately the USA made wrenches are only available in SAE sizes.)
https://www.williams-industrial.com...ut-wrench-set--5-piece-set--sae-pb_ws-14.html
In summary:
-Any of the Snap-on flank drive versions should perform well. The latest models are obviously slightly more refined and optimized, but not so much as to make the older versions not a consideration.
-Important: If buying used, inspect
closely for damage. Spread jaws can be hard to see. Damaged/cut/missing chrome can also be an issue as they often rub against surrounding objects. Hammer/cheater marks are a big warning sign.
P.S. Congratulations to the OP for his first post in 12 years!
