can you point me in the direction of a post on nut-making

I have tried a site search, an advanced search and a google search; I am trying to find the post Geezer (I think) suggested using a threaded bolt insert to strengthen the construction of a roller-nut.  He suggested a threaded insert with a slot cut in but I can't remember if it was a bolt with head cut off, ground down or ground off - the angle my bolt is going through the nut at means the head of the bolt is protruding at an angle and also, I have used an allen bolt and am not keen on the dimple in the head, so was going to grind it all off flush but just wanted to check this was an OK approach

Geezer here, concerning nut making.  I make the sear-plug from threaded rod... allthread comes in two types, mild steel and stainless.  The stainless is harder to work and lasts longer, but given the inevitable wear between the distal end of the trigger and the sear, I'd rather rework the sear than the trigger, so I usually make the sear out of the mild steel.  I slot one end of a bit of allthread, then cut away a bit on one side.  That's where the trigger will engage.  Then I drill a slightly under-diameter passage thru the nut, from top to bottom.  Ideally this should come out between the lugs on the top of the nut, and slightly behind the bottom/center.  (a quarter inch or so) I tap/thread the passage to take the allthread, then screw it in from the bottom.  Trim it flush both at top and bottom, then cut a nice rectangular keyway at the bottom for the trigger to engage the forward (distal) end of the tickler/trigger. Make sure the bottom end of the sear doesn't protrude into the socket, or your lock will hang up. When the sear fits correctly, I usually put a bit of glue into the passage and then screw it into place.  When the glue dries, I drill the center-passage thru the middle of the nut (side to side) to fit the nussfaden cord, or center axle that keeps the roller from hopping out.  Does that make sense?   Questions?  Geezer.

Thanks Geezer, I'd missed the bit about screwing the rod in from the bottom, this is where I am at the moment, the hole being 5mm (3/16). Any thoughts?

Thanks Geezer, slot is 3/16 (4mm) deep, seer lines up with tickler. Just needs a gentle tidy up.  Is the slot deep enough?

It looks workable.  if you can get a screwdriver in the inner slot, that's deep enough, and the sear-step looks plenty deep.  That should work.  Geezer.

Thanks Geezer, I shall press on!

I was also looking for stuff on making a nut. Looking for links to jigs used to get everything lined up to cut the fingers. My drill press is worn out enough I don't trust it for anything approaching precision.

yeah, drill press, haven't got one, haven't got a lathe either, sometimes you've just got to go for it, you can always plug the hole and have another go if it all goes pear-shaped.  If you need to, drill a 1mm pilot hole to check the alignment and then ream it out

When I started making crossbows, I didn't have a drill press or a lathe either.  If you start with a pre-cut piece of material for a nut, that's already the right diameter and really cylindrical, you won't have to worry about that bit.  With my first crossbows, I used a 1.5 inch holesaw (the sort used for cutting holes for door knobs) and drilled not-quite all the way thru the stock.  Holesaws leave a big wooden plug that will need to be cut off with a chisel, but they are actually easier to steer if the hole appears to be a bit un-straight.  Forstner bits cut a flat-bottomed hole and are a bit more accurate, but they're also harder to steer.  Don't try to use a spade-bit.  They're guaranteed to run un-true, and you'll never get a satisfactory nut socket (How do I know??? Guess) I recommend you go to your local or online plastics supply and buy a piece of Delrin rod (Polyvinyl Chloride) I usually buy 1.375 inch diameter, but anywhere from 1.25 and 1.5 inch diameter will do. You'll want the nut-socket about 2/3 buried.... so 1/3 of the hole-saw will be outside, and 2/3 inside the stock.  Practice a bit on some scrap wood till you think you can drill a fairly straight hole with a hand drill. Go slowly, look at it from all angles, get a friend to stand off to one side and watch from a different angle.  When you think you've figured it out, Take your stock timber and drill the nut-socket before cutting anything else.  If it goes wrong, you can always turn the board over and go from the other side.  And remember, if you really screw it, you can just cut that bit of wood out of the stock, glue in a new, tight-fitting piece of hardwood in place, and do it again.  Yes, you can do this without a drillpress.  It's just easier with one.  Geezer.

Once you've got your nut-socket cut, take that piece of industrial plastic, fit it into the socket, and figure out where your lugs need to be... about halfway front to back, lugs about 1/3 width each side, slot is the center 1/3.  For a trigger-sear plug, I drill thru the roller from top to bottom @ 5/16 or 3/8 inch, starting near the center/ back of the lugs, and coming out just behind (quarter inch or so) bottom-center.  Then I thread the hole, and screw a piece of threaded rod (allthread) into the hole (cut a slot in one end of the allthread to take a flathead screwdriver) When it fits flush between the lugs, and flush at the bottom, take the allthread out, cut a bit of a flat on the bottom, and chisel a keyway from behind so the trigger can fit into the sear.  Yes, it's that easy.  Real medieval bows didn't have allthread, and they usually used a thicker wedge of iron for a sear, but I assure you the allthread will work great, and if it begins to show wear, you can always unscrew it and fit a new one easily.  Got it?  Okay, get to work.  Geezer.

When I first got on this website, there were some links to Crossbow makers in Scandinavia that had come up with some clever jigs for making nuts, including drilling for the rod for the sear, cutting the fingers and more. Having already shortened a couple of fingers I was hoping to do this smarte, not hurter. 
   I have a couple pieces of tropical hardwood, 1 1/4" thick that I was intending to use for the nut, maybe reinforce the socket with purple heart. I think that stuff is better worked like a metal. If it works, then on to moose antler and ebony.

Geezer speaks.  Most of my first crossbows used maple dowel for roller nuts.  As long as you orient the grain up and down that works out well.  I usually soaked the finished nut in hot paraffin for 20 minutes or so to help lubricate the wood.  I've never built a bow much over 100 lb. with a wooden roller, but you do see them occasionally in museums.  Just be a bit careful at the start.
Purpleheart is certainly very hard and would probably make a good socket for your roller.  It's a bit toxic and highly allergenic.  Don't eat it, and if you're going to work a lot of purpleheart, get a decent respirator and wash your hands before lunch.

I have worked with purple heart before and used paranoid level of dust control. My on hand supply of exotics include Cocobolo, which I am sensitive to, an think to heavy for a nut, Maca wood, Bubinga, Granadillo, Lace wood,Canary wood, Tiger wood, ebony, purple heart, and some domestic hardwoods. thickest pieces are maca wood, blood wood and ebony. Also some thick Osage Maple and Oak. Small piece of moose antler for a later, heavier bow. 
   Thought I would laminate some hickory, cherry and ash for the prod, with something exotic for a tip overlay, couple inches of reflex laminated in. Have Payne Gallway's book and thought I would proximate some of his dimensions, though aiming for longer limbs, lighter draw weight.

If you're comfortable with exotic woods, you might want to try Lignum Vitae for roller lock and socket reinforcement.  LV was a favorite in days of sail for the best rigging blocks... strong, long lasting, weather resistant and very low friction.  Only problem: the wood is so oily, it's difficult to glue to anything.  You would probably have to pin/peg reinforcing blocks in place.  Geezer

So I did some experiments on using a hole saw for making a nut. Lessons so far; De-bur the inside of the saw for a much smother cut, meaning you get something closer in diameter to what you are expecting without so much work. Back your work piece with something for a cleaner cut. Not satisfied yet but next attempt is going to be gluing a piece of softwood to my work piece with a piece of paper bag in between them. Looking for the weakest glue I have in my supplies.

Never had much trouble cutting Lignum Vitae, or anything else, with a hole saw in a drill press.  Work verrrry slowly with lots of pull ups to blow out dust.  Clamp the block you're drilling in a vice.  Back the block with masking tape.  If you feel you must glue a wood backer, use rubber cement or spray adhesive.