Kitto M-7 trigger mechanism

    After reading that JBL is using the Kitto M-7 mech in their new spearguns I did a little searching. Here's the mech.







    The internals are not a huge concern for me because the Neptonics Reef mech has proven to be a good reliable mech for my purposes. The Reef mech BTW has only two pieces; the sear and the trigger. What's curious to me is the top of the housing of the Kitto M-7. I see a couple of advantages. First it seems to me that a shaft to fit the Kitto mech does not require a flat spot over the notch, this means less work to make the shaft, and maybe less play for the shaft inside the housing which makes the mech more secure in some situations. Second this mech can be installed in a thinner gun as the width of the housing is not dictated by the diameter of the shaft. This thinner lower housing also eliminates sideways play of the internals.


    The disadvantages that I foresee is that this mech is better suited for an open track gun. To flush mount the housing for an enclosed track gun you'd have to get a little more creative in making the slot. Really just flaring out the hole towards the top. Another concern is about how easy it is to engage the shaft in the mech. With flat top mechs the shaft can only go in the correct way so it always engages properly. If the shaft for the Kitto mech can indeed remain round, then it can be inserted the wrong way, the notch turned to the side for example, and loading will take longer.


    There have been other mechs of this design before, but I've never used a gun that had such a housing. The Riffe mech follows along with this concept a little although it still requires a flat spot over the notch. Are there any serious disadvantages to the Kitto M-7 style housing?

    Quote from Dan

    Second this mech can be installed in a thinner gun as the width of the housing is not dictated by the diameter of the shaft.


    It may be true that this housing design could potentially be thinner. But my M7 is very close to 1/2" thick across the straight sides, and a little wider across the max OD of the rounded top.


    Quote from Dan

    If the shaft for the Kitto mech can indeed remain round, then it can be inserted the wrong way, the notch turned to the side for example, and loading will take longer.


    Perhaps in an open track, but not an issue in an enclosed track gun, as the shaft fins captured in the top of the track keep the shaft orientation correct.



    Quote from Dan

    Are there any serious disadvantages to the Kitto M-7 style housing?


    I originally installed an M6 in my Bay gun, and I had a lot of problems with misfires. I think that there were a number if reasons for that, but in part, because the trigger pull is so light with the three part mech that any little jarring could set it off. Kitto upgraded me to an M7, but I haven't had it in the water with the new mech. I'll have to pull it out of the gun to be sure, but I believe that my M7 is different from the pics you show. I believe that it has at least one additional spring.

    These are some pics of my M7. I have no idea if this is the current version that JBL is using, except to say that I just got this one last fall.


    You can see that there are three additional small pins, and each supports one of the three springs. I'm not about to completely disassembly it.





    Thanks. I'd be interested to know more when you'd have used it.


    Is your shaft completely round in the back? If not can it be?


    At this point the Kitto M-7 seems unnecessarily complicated to me. This offsets any advantages. Grinding the back of the shaft down is not difficult.

    The revamped JBl´s look indeed improved, but still look a bit odd and heavy compared with other spearguns. Kittos Mechs are strong and well made. I had one rigged in a BW gun that belonged to R. Mullins. (The pics are in a past thread I believe) The mech was overkill IMO. Just too heavy.

    I'm a Speardiver, not a freediver

    Quote from Dan

    Is your shaft completely round in the back? If not can it be?


    I'm shooting standard Riffe and Ray Odor shafts, so yes, they are all ground flat at the back. But for the M7, they would not need to be.


    Quote from Dan

    At this point the Kitto M-7 seems unnecessarily complicated to me.


    For a 1-4 band gun, I would agree. If you were building a canon, the mechanical advantage of the 3-part mech might be desirable.

    I got this trigger last year(M6) I was building the gun and i notice that it was too smooth, Kitto send me an email that there was some problems with it(Tin Man and Griswold write some comments on spearboard and Kitto answer them) I send the trigger and he fix it, like in the pics of tin man I notice that he move the pins and the springs, I made a 62" gun enclose track, 3/8 Riffe shaft and 4 5/8 bands, trigger is smooth as butter it can easily hold few more bands. This trigger is too much for 2 band gun, this is a trigger for BIIIG multi band guns.

    Pucho
    Aguadilla, Puerto Rico

    Here is a pic of the enclose track and trigger, I only open a little bit the wood with some sand paper so it get a bit deeper to align with the track, I havent use this gun for spearing yet, but have use it on target shooting while ballasting, this trigger is smooooth and no misfires up to date.

    Yes Dan, he made new holes and put pins to move the springs, on the first pic you posted you can see that there is only 3 pins that hold the trigger, sear and other part, also the springs are holding the 3 parts, on the pic of tin man you can see 3 more smaller pins on the body of the mech were the springs are conected.


    Well monster it was diffucult because it was my first enclose track, I was nervous when put the blank on the router table, I learn a lot with eacho gun that I made so next time will be easier.

    Pucho
    Aguadilla, Puerto Rico

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