How to Attach a PVC Prod to a Stock?

I was wondering if there was a way to attach a PVC prod without using cord briddles? I am not a big fan of cord briddles as I think they don't suit all crossbows based on the design. I really only think they suit crossbows from the medieval period to the renaissance. I was considering building a PVC prod for one of my stonebows as they are more durable and resistant to things like dry fires than wooden prods are(not to say I am going to dry fire my prod lol. Even though PVC can take dry fires it is incredibly stupid to dry fire a bow/prod because even if the bow doesn't give the string will. I was only using dry fire as an example because I think shooting spherical projectiles from a bow has a similar effect to dry fires since the ammo is lightweight.) I was going to reinforce it with fiberglass rods to pump up the draw weight also. Taper the ends so it's not so much weight at the ends and it will increase speed. But the big problem I think with PVC prods is it's wider towards the ends and most narrow at the center. Now I am going to taper the ends so they are not as wide as if they weren't tapered. But that's only for the last 3 inches I believe. Pass three inches from the ends of the tips are still going to be wider than the center.

Steel prods sometimes use plates with a "prod-shaped" hole in them to anchor the prod.  The plates screw into the tiller.

That could work theoretically if the prod was widest at the middle/center. Unfortunately that doesn't apply to PVC bows. I thought of maybe making a slot for the prod at the top of the stock. You see this a lot with those Filipino crossbows they sell for tourists or those Wham-O crossbows. I had an idea of using a 1/8" aluminum plate as a top deck to keep the prod from coming out from the top of the stock. Also aluminum is slightly cheaper than mild steel is it looks better in my opinion also. It's probably also easier to work with since it's softer. I think it will also have less friction and wear on the string but, I am not sure if my assumption is true or not.

banuvatt wrote:I thought of maybe making a slot for the prod at the top of the stock. 

The slot at the top or end of the tiller is only to locate the prod properly.  It still has to be prevented from moving side to side as it is cocked and triggered, which is what the lashings or the prod irons do.

I found this picture of a stonebow by a man named Jeep. I thought since you can manipulate how PVC is shaped with heat I could just put a side to side bend in the prod. To make it shoot straighter as opposed to canting it heavily.

NO.  Crossbow prods are canted in most cases to prevent the string from dragging down the bolt-deck and losing much of their energy as well as fraying.  In this case of that stonebow the prod is canted to help make the stone fly over the tiller, not hit the tiller.

Remember when shooting a stonebow... If things are not arranged correctly, it is possible for a slightly over-long string to touch the fore-end of the stock, rotating the string.  In this case, the string cup retains the ball long enough to throw it Backwards, into your face!  How do I know??? Hint, I don't make stonebows any more.  If you are determined to do so, make one that shoots from a tube, or at least use a large peep sight that will protect your eyes.   Geezer.

PS: aluminum alloy makes a pretty good cheap crossbow prod.  I have made many of 7075-T6 aluminum.  It does fatigue and wear out (either bends or breaks, depending on how hard you are stressing it) after a few thousand shots, but it's easy to work, has low recoil and casts nicely.  My aluminum prods were 28 inches long, 1 and 3/4 inches wide at center (189 thousandths of an inch thick)  and about 3/4 wide at the ends.  Cut with a non-ferrous metal cutting blade on a standard 14 inch bandsaw, with plenty of lubricant, then filed/sanded smooth and nocks cut into the ends.  I built them with 1/2 inch of rise at the ends, to reduce string drag. If the prod was mounted square to the stock, 3/8 in. below top of stock, I got a nice easy run with little drag.  Geezer.
In recent years, I turned the making of aluminum prods over to Darkwood Armory (find them online)

Well Kehn, I just thought this because Tod from Tod's Workshop on a video where he showed a stonebow he made he said that there's a bend in the prod to make it shoot straight. He said that you can't make it heavily canted I made prototypes of stonebows I noticed if you make them just have a cant they like to shoot at a high arch.

Geezer I had an idea to prevent the ricocheting my idea was to use to set up a system similar to a lot of modern compound crossbows that have split limbs. So instead of having two pillars two keep the strings apart, there would be two pairs of limbs with two separate strings keeping it apart. What would keep the prods to act like one would be potentially two things I make end caps for each of the limbs that connect to both the top and the bottom limb. Another thing would be the pouch for the ball and the two string connectors that's similar to a d loop for a compound.

Hi Geezer.
Is 7075 t6 aluminum the same as "Dural" or "Duraluminum" as used on Wammos and Jayhawks ?
Do you buy as flat bar stock?

Not to interrupt or anything like that, but does anyone know where to get the fiberglass bars like the ones they use in children's bows? I was thinking of either modifying two used fiberglass kid's bows or if I have to start from scratch using a fiberglass flat bow.

Yes: the 7075 T6 aluminum is duralumin or dural, and is what is used in old WhamO bows and Jayhawk kits. Since I was in serious production mode, making about 100 bows a year (no longer, alas) I bought my aluminum in 4 X 8 foot sheets, 189 or 190 thousandths thick and had the sheets cut down to 24X28.8 inch sections for easier handling. I could get 12 prods out of each sections, so despite spending about $1000 a sheet, it was a pretty good deal in bulk.
By the way, 7075 is the aluminum alloy number while T6 refers to the temper or springiness. I have heard of T7 being used successfully as well.  
If you go to 1/4 inch thickness aluminum rather than 3/16 (190 thousandths) it will double your spring rate... so a prod that was 70lb becomes @140.  Generally spring rate varies by the cube of the thickness.  However, stresses on inside and outside surfaces of the prod are substantially higher with thicker stock, so you probably want to reduce draw length a bit and be aware that spring fatigue is related to how highly stressed the prod is.  I recommend covering aluminum prods with a very thin layer of goat rawhide, or at least use a 'sicher' strap down the back, in case of failure.  Geezer

Can anyone please tell me if my idea of an adaptation of the stonebow will prevent it from ricocheting? 
I hate repeating questions please forgive me for doing so but, does anyone know where I can get fiberglass bars the ones they use to make children's bows specifically?

The simple way to make a safe stonebow is to build a bullet bow, with the ball moving inside a tube.... you don't need a double string, just a tube with a slot for the string to run in.  Put span the string, drop the ball down the muzzle, point and shoot.  The ball will not come back on you unless it actually bounces off the target.  Payne Gallwey's "Book of the Crossbow" has drawings of these, as well as 'bullet bows' that still use a doubled string.  Geezer.

I thought about a bullet bow it's just the problem is I don't have the tools to make it. Although I could go to my campus once this virus is over they have a maker shop. I know you are definitely not a big fan of stonebows after one reversed and hit your eye.
I had a similar experience I helped built a stone bow for my friends' physics class. Although it was slightly different since we made it to shoot jello I used a PVC endcap since it wouldn't work with the pouch. I once made the terrible decision of putting a rock in it. It reversed and hit me in the eye luckily the rock was so large and non-aerodynamic that it traveled at since a slow speed that it didn't do any damage. Again I apologize for my persistence to build one I know they can be dangerous to the user and can be quite unpractical due to the number of parts they need to build one compared to bullet bows for instance. 
I just saw a compound version of one that could shoot both bolts and steel balls which gave me the urge to build one. Since this gave me the impression it's possible to build one while it still being safe to the user. 
Thank you for your patience for my excess stubbornness.

You don't need special tools to build a bullet bow, and you don't need a metal tube for the ball to run in. Get a piece of pvc pipe with the same internal diameter as the balls you want to shoot.  Then go borrow some time on a table saw to slot the pvc pipe wide enough for your bowstring to pass.  Smooth the slot nicely so it doesn't cut the string.  Of course the sloted pvc will be pretty floppy, but that's no matter.  Make yourself a little bracket of sheet metal or pastic and glue it to the upper level of the pipe to keep it in place.  Now build a stupid-simple notch and pushpin crossbow, fasten the tube to the top/center.  Attach the prod underneath.  Now you're ready to go.  You Can Do This.  I started out no more sophisticated, and eventually got quite good at crossbows.  Geezer.

Okay, thank you very much for your advice. If I wanted to build a bullet bow without using a push pin trigger mechanism what trigger mechanism would you recommend? I had built push pin crossbows in the past while I do like how simple they are. I don't like how it "slams the bolt" or in this case, the ball which makes it lose about 10% of its energy. Not to mention I have an excess amount of 3/16" mild steel plate that I am going to use for my other crossbow build lying around.

Thanks for the alli info Geeza! 

So my final decision is I am going to build a bullet bow, but would an aluminum or metal barrel be better? Also, I am going to put a magnet just in front of the trigger so I can shoot downwards. I think I found a way to make the trigger. It would be similar to a lot of the modern crossbows trigger mechanisms.

It really doesn't matter what you use for a 'barrel' to guide your ball, just so long as it keeps it in the track and the ball can't return on you. There are also 'slurbows', which have a simple plate mounted over a standard bolt-groove. The slurbow I made had 3/4 inch thick plate with a matching bolt-groove cut in the bottom.  It was held a quarter-inch (about) above the 'table' of the crossbow, with a simple sheet metal bracket at the very fore-end (so it wouldn't damage the string) and another bracket over the roller-lock. You can mount a sight on top of the slur-plate, and for shooting balls (I was shooting bolts) simply cut a little slot in the top of the slur-plate, just ahead of the lock and fit a simple spring to keep the ball from rolling forward.   It appears slur-bows were mostly used at sea for shooting things like fire-bolts, that the sailors didn't want to fall into their own rigging.  The slur-plate would hold the bolt securely, even if the heavy head hung substantially over the front of the stock.  Does this make sense?  Geezer.

Just do a websearch for slurbow-crossbow and you'll find lots of illustrations for slurbows.  Enjoy.

Thank you that does make some sense. How did you do a roller nut with a slurbow though? I thought that wouldn't work since a roller nut you would have to turn manually in order to reset it.

It was no sweat: My slurplate started just ahead of the roller-socket, and was supported by a half-inch wide bracket that screwed into the stock behind the nut. The nut was a bit over an inch wide, so there was plenty of material exposed to flip the nut back into the right position.  Of course if you were using a pushpin/notch lock, you would want the slurplate to cover the notch so the string couldn't overjump the projectile and maybe slam the slurplate.  Geezer.

I thought of making something similar to this but, without the trigger mechanism box. So when I load the crossbow I can just pull the string back far enough to engage with the back piece of the catch to set the trigger. I might make the back piece of the trigger I don't know what you would call it, a bit taller. This is so it be easier to engage the trigger.

Sure, that should work.  Geezer