If you look at the UDT and Madd Maxx, you'll see that these are not "conventional" folders. Both have special components in their design that aren't found in most folding knives.
The UDT has a coil spring which helps minimize the rebound of the blade hitting the reinforced stop pin. It also has a button lock that is tapered and will take up minimal misalignment in the open and closed positions.
The Madd Maxx appears to utilize heavy thumb studs that rest against heavy frame scales to prevent wear.
Although the idea of using thumb studs to create the open and closed rest positions has been used before, not all makers and manufacturers have used heavy frame scales in the past. (Unfortunately, some of those knives wore out quickly from "flipping" or hard use.)
I have a Kershaw Whirlwind (zytel handled version) that wore out within a few weeks, with the liner moving over to the opposite side of the frame. One could speculate that this
particular knife would have suffered the same fate if the assist spring was removed and the knife was continually "flipped" open.
Perhaps the best thing to do when shopping for a folding knife that you wish to flip open often is to ask the maker or manufacturer if the particular model was designed to hold up to this type of continual cycling.
You should also be aware that all mechanisms (even those that are specially designed and reinforced to activate rapidly) do suffer from wear. Military personnel who depend on automatic knives and automatic firearms do need to have their equipment serviced or replaced on a regular basis. This is usually dependent upon how often they have the
need to deploy these weapons in the line of duty.
And, we should remember that terms like "occasional" are subject to personal interpretation. While some folks might try flipping open a folding knife just to see if it could be done in a "survival" situation, others seem to conduct this exercise hundreds of times a day! (They must live in a tough neighborhood.
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as a side note:
One might speculate that ANY conventional folder with a smooth action could be "flipped" open without a whole lot of effort. However, many experienced enthusiasts believe "flipping" is not a true test of a folder's smoothness and that many of today's knives with thumb studs, thumb holes, or other manual opening devices can be safely opened with your thumb in just about the same amount of time as "flipping!" Many of the experienced manufacturers, dealers, and makers I've met prefer the latter method. (One would think that the folks at CRKT might agree.)
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Tom Anderson
Hand Crafted Knives
www.andersoncustomknives.com
[This message has been edited by Tom Anderson (edited 04-04-2001).]