Building a hunting crossbow (Not Medieval)

[Ivo]

Hello everyone!

Thought I'd make a new post as the one I posted in wasn't exactly fresh nor had enough relevance to what I'm doing.

I'm half way finished with my crossbow and am making the limbs at this moment leaving stock, trigger, scope/sight rail.

As everyone already knows NJ included crossbow in the fall hunting season. I want to finish it soon so I could get plenty of practice.

Any one built one lately?

Ivan

[Balistarius]

Hi
Go to my web site there are two pages on building a prodd.
www.thecrossbowmansden.com
if you need more help e-mail me

Robin

[Ivo]

few more posts to go...want to post pics

[Ivo]

last one....

[Ivo]

Sorry about the nonsense...needed 5 posts to posts to post pictures.

Hi Robin,
I've been to your website and read almost all the articles. I believe the prod on your website has 18 inch limbs, in my case I pushed the limb design down to 14 inches in lenth.

Profile is a recurve which I modified by moving/compressing the recurved tips towards the end to provide the limb with more "working limb"





Would that cause a problem or can I still get 100/150 lb at 14.5/15 inches of draw?


Ivan

[Balistarius]

Hi Ivan

I understand what you are doing, yes my prodds are 18" but when you cut the string nock they are now down to 17 1/4", so when have cut your string nock you will be down to about 13 1/2" now to draw that back to 14 1/2" or 15" it will not be able to bend back that far without breaking, it will break at the riser as this will act as a pivot, I have found after building and breaking many many prodds that the 18" at 14.5" draw works out, now if its power you want for hunting just use more lams in the prodd, using the 18" 14.5 draw I can get up to 200 lbs with no problems, your drawing looks good for a prodd but two things more lenght and not so much hook on the recurve,
remember you can only push wood and glass so far before the stress force will take over.
Kind Regards
Robin

[Ivo]

Yeh, You got me there Robin...forgot about the nocks completely, good call!

I'll make a new form for the 18" limb. About making the tips less recurved.
Would this do?


As for the wedge...would a good dence piece of oak heartwood do the job? Or can I stick with bamboo?
________________________________
Is the form I made lost completely or I can flaten out the recurve a little and make smaller crossbows for my younger brothers so they can come to the range with me. Does 11.5" draw length sound good for 14" limbs.

________________________________
I've seen your casting videos ... I myself cast for a dental lab and have had it as a hobby for a little while, but that's non-precious rings and small aluminum parts. Only recently I moved up to the biger stuff...crossbow riser was a toughy.



First go didn't go at all...the second was a tiny bit better.




Still needs work before final paint.


Thanks for all your help and a great website...I'd love to see a section on custom stocks(non adjustable rifle like stocks).

Ivan

[Ivo]

Good call Robin!

I forgot all about the nocks!
Must agree with you on how sharply curved the tips are as I tried to press a lam and it almost broke.
I'm going with the 18 inches now.
What do you think about this profile...should do right?


As for the 14" form that I made...may be I can still get something out of it.
I'll flaten out the curve more at the tips and should get a similar profile. Would 11.5" draw length be proportional?


The reason for me asking this is that I have two younger brothers who are in the shop with me helping me build this thing...thought I'd make each of them a crossbow, so I can bring them to the range for reasons other than to watch me practice.

I've been doing research for two years before attempting this build...and most of the things I ended up figuring out myself as there isn't much out there about crossbows as if it's a highly classified piece of government equipment, so Thank You for all your help.

Ivan

PS. Your web site can really use a section/video on building a custom stock(non adjustable - rifle like) or if you can recommend some literature or other resources on the subject I would greatly appreciate it.
I ordered a few books that promised a "custom stock" that ended up being about checkering...good read, but still not what I'm looking for.

[Balistarius]

Hi Ivan
That prodd shape should work well, and if you make it 18" it would draw to 14.5", as for a video on stock building I have been thinking about this, I have some done on target match crossbow its about the same as a hunting crossbow, if you P.M. me your mailing address I will send them to you.
Kind Regards
Robin

[BatGeorgeone]

Hello there,

Ivo, I am making a crossbow too, please bear a minute with me while I go downstears to make a few shots of it...

At the moment I am struggling with the string...

[Ivo]

+++Check your inbox

Non articulated version of what my stock will be (I know that the cheek piece needs to be moved way back towards the shoulder).


I have some general knowledge on building a stock. Got it here...page is in Russian thou.
http://arbalet.info/make_art_loge.php

Russians building crossbows...this one was the last spark needed for the flame to ignite.
http://arbalet.info/gl-self-phoenix-3.php

Any one heard of Pyankov?
http://crossbow.ru/pictures/

Ivan

[BatGeorgeone]

Sorry for the many post that I am about to write but need them in order to post pictures

So, I made it when I was in high school.

I used piece of walnut-tree for the butt, actually I used two pieces because I was not able to find one good and long enough for the job...

However after the years I have lost the second piece, so from the wood you will see on the pics I am about to make a new butt...

For the shoulders I used a leaf spring from the Russian legend car MOSKVICH

As it is now on the pics I used metal string which is bad idea, as it breaks after 5-6 shots and when it breaks sometimes it hurts a lot

[BatGeorgeone]

Cheers for the LINKS Ivo!

For the butt I am using my little trick, I got a few air rifles so I just take the measures from the one that fits me the most...

[BatGeorgeone]

Ivo,

What trigger mechanism you are going to use?

I used a few my self and still do not have a preferred one...

[BatGeorgeone]

Ivo,

How do you estimate the power of your bow?

I wish to believe that mine is about 70-80 KG but still did not have a chanse to measure it...

[BatGeorgeone]

Ivo, thanks for your understanding

I hope now I will be able to post some pics...

Here they are, for the trigger...

Maybe I will do this one, as it is easy to make at home http://kamko.bg/pics/1.jpg and http://kamko.bg/pics/2.jpg

And there are my crossbow:

[Ivo]

I was going to use this design
http://arbalet.info/image/gallery/se...enix_2/010.htm
http://arbalet.info/gl-self-phoenix-details.php

And just cast a nice thick housing for it out of aluminum.

What worries me the most is the lack of a safety switch, but by the time I get to building the trigger I'll have it figured out.

Ivan

[BatGeorgeone]

Ivo, that is very clever design - http://arbalet.info/image/gallery/se...etails/010.htm

I always knew that I need to use some sort of a small bearing in my trigger mechanism...

Not too much to worry about the safety mechanism - the lack of arrow is the best safety

I am joking of course, from the Russian design we could work out someting pretty quickly...I think...

However I do have on remark on this design - http://arbalet.info/image/gallery/se...etails/010.htm

As you can see on the top of the trigger mechanism, where the string goes, there are sharp edges...

I do believe that my string brakes only because of this type ot sharp edges so I am planning to do this...(see drawing)

[Ivo]

Check out the link I posted as well as Robin Allen's website www.thecrossbowmansden.com
Use Bacron B50 for the string.
It's time for bed and my eyes are as heavy as lead, there's always tomorrow.
Good night and good luck.
Ivan

[BatGeorgeone]

Thanks Ivo and nice dreams

[Ivo]

Don't mean to be rude, but what are you planning to do with that crossbow?

There is an old story...
A young man came to a philosopher and said "Teach me! I want to know what you know!"
The philosopher answered "You really want to know what I know, come back in ten years..."
Young man got angry and walked out kicking everything in his way.
Ten years later....a man walks in to philosophers house. The used-to-be young man introduces himself to the philosopher and asks the same question yet a different tone is in his words "Ten years have passed since we last spoke, I'm ready to be your student"
The philosopher took him in as a student.

The question stands...Why? Simply because now he knows why he want s to learn and not just because Philosopher sounds like a cool word.
Same goes for the crossbow. If you’re building it to shoot holes in plywood in your back yard that’s fine with me…and the law is not my profile…just sometimes people do things and then can’t forgive themselves for the rest of their lives.

__________________________________________________ _______
About your string

There is more to it than thinking that the steel cable should hold.
If you did your homework you would have known that when a bow is fired and the string comes back to it's original position...in that split second moment the string tension multiplies by five(if your bow is 80kg the string must have breaking strength of at least 400kg.)

You are lucky that cable broke near the trigger and not where it attaches to the bow. If it breaks at the limb tip it will probably slash you across the eyes.

I was at a hospital once and saw a sign saying “Doing something without knowledge is the same as committing a crime”

Sorry for being so grim, but that’s how I see it.

Ivan