Plans and materials for my first build

First topic message reminder :

If this is in the wrong spot or in anyway not in line with forum policies, my apologies!

So I am an absolute beginner crossbow builder, but I have some wood working and bowyering experience as well as decently fitted out little wood shop in my basement. I think this is gorgeous and is what I'd like to try to build:



Am I out of my gourd? I think I'm at the reach of my abilities here... The parts where I have real concerns are the trigger mechanism (more on that in minute) and mounting the prod.

I am starting to gather materials and draw out plans. So far I have red oak for the stock and some steel banding to replicate the mounting plate as seen in the picture above. 

I am going to keep this fairly low draw weight at between 80 and 100 lbs and was wondering if delrin would be strong enough to make a nut from. Never having worked with it before, I'm not sure of its limitations.

The trigger/cam would be delrin, the lever steel, the nut delrin. All critiques are welcomed on this as I'm really not sure what I'm doing, lol.

The prod I'm considering would either be a manufactured one like on the crossbow pictured or using the tips of cross country skis to make my own. I'm not 100% how the prod is held in place in the photo, or in the series of photos this pic is taken from. Anyone have any guesses? Thanks in advance for any and all help!

I've done a few builds with similar foot stirrups- I liked the idea of folding it back to shorten the carry length, or even use it as a stand-in for a bipod. A round bolt or tube is more efficient to fabricate than a a flat plate for the foot step, as well. But I gave up on both those ideas after some field use- standing on the stirrup gave no support or stability to the weapon at all while drawing, I had to brace it with my leg while both hands were busy with the string. It really sucked one day when I got distracted and the crossbow flopped forward onto stony ground and damaged my new red dot sight!
Hope you have better luck than I did. If not, I'd recommend maybe stiffening up the swivel point so it stays where you want it and replacing the tube with something flat, or a rod with a generous bend out in the middle.
Looking forward to seeing how it all works out!
Gnome

Gnome wrote:I've done a few builds with similar foot stirrups- I liked the idea of folding it back to shorten the carry length, or even use it as a stand-in for a bipod. A round bolt or tube is more efficient to fabricate than a a flat plate for the foot step, as well. But I gave up on both those ideas after some field use- standing on the stirrup gave no support or stability to the weapon at all while drawing, I had to brace it with my leg while both hands were busy with the string. It really sucked one day when I got distracted and the crossbow flopped forward onto stony ground and damaged my new red dot sight!
Hope you have better luck than I did. If not, I'd recommend maybe stiffening up the swivel point so it stays where you want it and replacing the tube with something flat, or a rod with a generous bend out in the middle.
Looking forward to seeing how it all works out!
Gnome

Thanks Gnome! Yes, I've given that exact scenario some thought and I'm hoping sufficiently tight locknuts at the mounting point will allow me to position the stirrup to where I want and hold it there. But believe me, I'll be checking it regularly!

I have not read all the answers to your questions but I have used some of the materials/techniques you need.
Delrin is an Acrylic type material, brittle under pressure but strong in the right circumstances. I have used it for a nut but it needs a hard metal fillet where the sear catches the lower part of the nut.
The surfaces that come in contact with each other and slide together need to be almost glass hard because mild steel type materials will wear very quickly and cause premature releasing of the nut, dangerous. 
The stirrup bolt, foot bar and string catch on the nut need to be all in line otherwise you will have movement when drawing.
all surfaces that come in contact with the string should be mirror smooth or the string will wear.
Make sure the grain direction on the top surface of the stock where the string slides is pointing in the direction of string movement otherwise small slivers of wood could be caught in the string.
This is just the start. The main thing is that even a 80 to 100 lbs draw weight crossbow can be lethal to the shooter or anyone passing.

Been out of it for a few weeks as my kids' sports seasons are in high gear. Most of my free time these days is spent out at either a baseball or softball field. :-) Some pics of recent, but slow progress. The big "NO" on the side was to make sure I didn't do anything stupid like router out the wrong side of the stock, lol.

Looks like a Thompson Sub Machine Gun at this stage!!!   Good job so far.  I also mark projects Yes/No or Inside/Outside or Cut Me to prevent too many FUBARs

Some more progress - pics of the scope mount/guard... what do you actually call this thing, lol? Any way, it' shaped up and in position for the pics. Still have to drill mounting holes for it as well as attach the bolt holder to the underside, but hey - it's getting there. :-)

Some more progress. Here's a quick breakdown of what I've done since last time:

• Determined that I needed the side of the CB to be accessible for easier future removal of the trigger box
• Drilled, placed, and glued locating pins (1/4" dowels) in the stock, foregrip, and handle prior to full stock assembly to take measurements
   without clamps holding everything in place - permanent yet not permanent positioning. Worked great
• Drilled out the decorative "vents" along the foregrip to give it a bit of a machined/Star Wars blaster look
• Cut out the removable side of the CB - was a little nerve wracking honestly
• Permanently attached the stock and foregrip
• Drilled and mounted the scope mount to the stock
• Test fit the scope and have the scope mount ready to attach the scope mounting rail





Feels like I've gotten a lot done recently, still some big stuff left. 

• need to make a new nut, the hooks that hold the string are about 1/16" to an 1/8" too short on the one I have - just not comfortable with them like that
• finish the safety
• attach leather to the prod mount for cushioning
• mount the removable side trigger cover - either bolts into inserts or wood screws into wood
• adjust the rearward part of the table - don't need them as long as I have them right now
• make the trigger guard
• make the bolt keeper
• not happy with the shoulder plate/stock... working on ideas for fixing that
• string the prod
• sand, round over, smooth, stain, finish
• mount the scope
• test

I have three different ones  I've built using that same scope mount .I just get a  weaver bar and put on it. It's ready for a red dot or scope or for the matter you could use some of the clamp on iron sights. Have never had aproblem with the zero moving around, just remember , made of wood.It might not make it falling twenty feet down ,out of a hunting tree blind.