Crossbow strings

Hi everyone, been a while.
Ok I got my hands on a roll of B50 would have preferred fast flight but this stuff was cheapest, ok made a continues loop with 60 strands total , came out lekka, but after about 5 shots the one loop at the knock snapped, my question is how do you guys make your strings and do you put padding on the knock, the are no sharp edges on them so I can only put it down to the string not being strong enough. One more thing, iv seen some very nice knotted serving, how is it done.
Thanks kindly.

Reading your other post where you said it draws 400 pounds. based on that I would say the string does not have enough strands. I think you need around 100 strands. My 205 pound steel prod from Alchem uses 50 and even so I needed to make my nocks well rounded, smooth is not good enough if the string makes too hard of a bend around the nocks. Some others may pad the the tips with leather but I myself do not have any experience with that.



Todd

don't forget like i did that when making a continuous loop string you only have half the strength on the ends and either need to add a short section of equal amount of strands to the ends or use twice as many loops. twice as many will end up in a thicker string center and slow it down a bit. you could also make a flemish twist string. they take a little longer to make but i find they take a bit more abuse.

Good Morning.

You should consider every string material has some important factors.
The breaking strength of B50 is usually around 50lbs.
This means a single strand without bendings or knots will break when a force of 50 pounds is applied.
But have a look to a string and you will recognise there are several spots that are not straight, you have bendings, perhaps knots, and perhaps "sharp" edges that apply force.
So you have a modifier for your string to break earlier. Even with a moving string you have much more dynamic force output than just your 400lbs.

In conclusion you should make your string much heavier and protect it from edges (hope you have a serving??).
Since we don´t know yet if you doubled the string in the nocks (full 60 strands??) were just guessing you didn´t and have only 30 strings there.
30strings with an estimated dynamic breaking strenght of around 30lbs (because of edges and bendings) would stand ~900lbs.
Force output to sthe string during a shot should easily outnumber this by some hundret pounds.
For security aspects you should calculate your draw strength and factorise the string strength value at least by 4.
This means it is a thicker and slower string center, but in comparison to the dangers of a breaking string its worth it.

You should stay with endless looping and perhaps extra reinforcing, there are some medieval ways of making a knotted string, but for your modern style and narrow nocks they would not be useful.

btw: I have no ideay how to build a flemish string for a crossbow with more than hand bow draw weight?

I just built a 140/70 string for my new prods, it is around 7,5mm wide in the center, for me it will be fine, even if used with the lighter prods at 200# beside it is strong enought for the heavy ones.

My 600 lb. bow uses 60 strands of Dynema/70 lb . I used flemish twist with two loops.
B 50 stretches too much. Fast flite or Dynema are much better. I also doubled the ends
of the string before I made the loops. My first string for this bow was an endless made of craft store hemp. I don't remember how many strands but it was at least half inch in dia. I didn't double up the loops but did serve them. That string was heavy and slow.
Finally broke when accidentally dry fired. I'm pretty sure endless string loops are just as strong as the main body. A double loop flemish string is pretty easy to make.
cheers fiddler49

Ok well iv built a flemish with 60 strands made of two bundles, this thing is ugly but works, i think what could have helped cause the endless string to break was the bolt it was quite a bit lighter than the others and think it loaded the string to much. I will be building another one with stronger loops, but i do thing the b50 streches way to much , when the bucks allow il grab some fast flight and have a go with that, thanks guys for the help, il post some full draw shots as soon as i am happy with the string.

For my personal interest because I just don´t get it.
Can somebody please show me a pic of good made a flemish string (40+ strands)?
I really want to know what it looks like.

there are quite a few videos on youtube on how to make a flemish twist string. it's basically a Z twisted cord with the loops made by twisting the loose ends into the main body. they are tedious but easy to make. the hardest part is remembering to untwist the cord to twist in the second loop without untwisting the first loop. learning to z twist your own cordage is a very valuable skill to know that has plenty more uses than just bow strings.

a wire tie or piece of twine tied around the first loop works great for that part. a flemish twist can also be twisted up a bit more than a continuous loop if you make it a bit too long and is stronger since the fibers are twisted against each other in two directions. with 40 strands of b50 adding an extra 20-40 strands on the ends of a continuous loop like i did for my light weight jayhawk would probably end up too thick for your nocks, unless they are pin type.

if i remember correctly i used 30 loops and added 30 strands to each end by serving around them. the polyethelene i used is very similar to b50, but has only a 10 pound breaking strength. i haven't noticed it stretching much if any. a string that has a bit of stretch will be more forgiving than strings made of no stretch materials. from what i read fastflight doesn't last very long. personally i'd have to go with more forgiving, more shooting, less money and less time making strings, than the little bit of FPS gain the fastflight will yield.

Oh, sorry you misunderstood me, I made 20-30 flemisch twisted strings for a couple of selfbows.
But I doubt flemisch style to be a good string suitable for a short 400lbs crossbow prod, especially with 2 loops correctly twisted.

a- because it seems to me impossible to let this amount of strands run out tidy in that short amount of space

b- flemish twisting is really good in lets say up to 30 strands,but when its getting thicker i just dont believe it to be practicable

c- compared to a endless string there are several more weakpoints, especially when there is not enought twisted material to hold strands together

That is why I want to see a picture, I just do not believe in its proper use...

By the way, there is a reason why flemisch strings were not used in historical made, or I would assume strong crossbows.
Simple: it just wont work well.

There are several more Ways to compensate the reinforcing of the edges (knotted strings for example).
Endless looping is just state of art, easiest and most durable.
For bows and crossbows.

i can see where you are coming from with trying to get the ends to taper in neatly in such a short space with 40 strands. i'd be tempted to try some type of rope, particularly braided no stretch drum making rope used on djembes and ashikos.

I think if you where to run the tapers almost to the center of the string, it might not look to bad, but aside from that i don't think its worth it, iv made flemish strings for long bows and they hundreds but when you start twisting thick bundles it gets out of hand and ugly, also my opinion after thinking a bit about it is, that a highly twisted string will act like a shock absorber, might be good for protecting a prod but not good for fps and speed is important if you want to hunt, so all in all , like rizzar said an endless string is the way to go, can anyone explain how you tie in the extra strings to the loops, I'm building a string jig from aluminum box tube and keen to make a good string first off on it.

when i rotated the ends to the center of my jig to serve them i wrapped around a roll of masking tape with the string material 15 times then slid it off the roll and pulled each end to make a short 30 strand bundle. i tied it onto the area and served over the whole thing making it twice as thick. i then rotated it to the ends and served it together to make the loops as usual. it worked out great, but it's also a lightweight string since my crossbow is only 75#@8".

i also haven't had a dry fire yet, but doubt it will blow apart like my first one did, due to only having 15 strands on each end. i have yet to find the string that blew off to see what exactly happened to it. the new reenforced string would look a little better if i had stagger cut the ends so it wouldn't have ended so bluntly. you can see the nock end fairly well in the pics i posted today of the crossbow it's strung on.

it definitely beats having to use double the strands through the whole sting, unless you need the extra thickness in the center. i'm clueless as to how it will work on draw weights over 200#.