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    Adding a steel sear insert?

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    fester
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    Adding a steel sear insert?

    Post by fester on Sun Sep 10, 2017 3:00 am

    Whats the best method of adding a steel seer insert to a delrin nut. I've been through the wiki but cant find any info. Also whats the upper limits of prod draw weight for building a bow that is comfortable to draw by hand for an average guy.
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    Re: Adding a steel sear insert?

    Post by Geezer on Sun Sep 10, 2017 8:43 am

    Geezer here: re steel sears for Delrin nuts.  I make a lot of Delrin nuts.  My standard method is to drill a 1/4 inch hole from between the lugs, out the bottom (preferably slightly behind bottom center) I thread the passage with a 5/16 in. tap and then make a sear out of 5/16 in. allthread.  (threaded steel rod) I cut a notch and a step into the bottom of the allthread section, so I can get a flat-head screwdriver into the slot.  Then cut a square keyway at the bottom for the end of the trigger to fit.  It's easy, quick, looks professional. Given a choice between mild steel allthread and the harder stainless, I prefer the mild steel unless the bow is Very Strong.  Why? Because wear is inevitable at the point of contact. If you make your sear out of hard stainless, most of the wear will take place on the distil end of the trigger. If your sear is slightly softer, it will take most of the wear.  It's a 10 minute job to pull out a nut and install a new sear pin.  Reworking the trigger will take half an hour on the forge, plus filing.  If your bow is really strong... say over 200 lb. you might want to look at 3/8 in. allthread in stainless.  Good fortune.  Geezer.

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    Re: Adding a steel sear insert?

    Post by Andy. on Tue Sep 12, 2017 4:29 am

    Thanks Geezer, had wondered this myself, knowing how repellent Delrin is to adhesives and such.

    Like the idea too of a sacrificial/soft nut sear of sorts for the reasons you outlined.
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    Re: Adding a steel sear insert?

    Post by Geezer on Tue Sep 12, 2017 7:45 am

    I do ususally put a little glue into the passageway... gorilla glue or superglue, to help prevent the sear from turning in use.  The glue doesn't stick well to Delrin, I don't know a glue that does, but I think a bit of glue helps make the threaded sear a tight fit.  You can still unscrew it easily enough, and if by some miracle it actually sticks, just heat a piece of iron rod with a torch, then set the end of the rod against the end of the sear.  That will heat it enough to make the glue fail.  Geezer.

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    Re: Adding a steel sear insert?

    Post by Andy. on Fri Sep 15, 2017 3:39 am

    Geez... have you played with brass as a sear on low poundage bows?

    Granted it's softer than steel, but thought it's self lube properties may make it suitable for light crossbows, and improve trigger feel?
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    Re: Adding a steel sear insert?

    Post by Geezer on Fri Sep 15, 2017 7:13 am

    In the early days, I made a lot of paraffin/impregnated wooden rollers for lite bows (60 lb. or so) and fitted them with brass triggers and simple brass-plate sears (set in a slotted keyway in the bottom of the roller) If properly peened and glued in place, the brass sears lasted surprisingly long and had smooth release.  When I changed to steel triggers, I still made some wooden nuts with brass sears and they gave good service.  So yeah, if you don't go for excessive power, a brass sear can serve you well.  Just keep an eye on it for wear.  Geezer.

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