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4 posters
New leaf spring prod idea.
Zardoz- Tinkerer
If there is a will, there is a way.
- Posts : 88
Join date : 2010-12-31
Age : 59
Location : New York
- Post n°1
New leaf spring prod idea.
I have an idea for a leaf spring prod that would compensate for the weak area around the center hole. Have a look at this drawing. Do you think this will work?
https://i.servimg.com/u/f11/18/00/01/77/zardoz13.jpg
https://i.servimg.com/u/f11/18/00/01/77/zardoz13.jpg
septua- Tinkerer
If there is a will, there is a way.
- Posts : 76
Join date : 2012-12-02
Location : Ohio
- Post n°2
Re: New leaf spring prod idea.
I have seen many crossbows with what are called center shot
designs. Why can’t a prod with a center hole be adequately reinforced to
accomplish the same end? Is it due to historical correctness or balance
considerations?
designs. Why can’t a prod with a center hole be adequately reinforced to
accomplish the same end? Is it due to historical correctness or balance
considerations?
Zardoz- Tinkerer
If there is a will, there is a way.
- Posts : 88
Join date : 2010-12-31
Age : 59
Location : New York
- Post n°3
Re: New leaf spring prod idea.
I am planning this for a medieval style cross ow
septua- Tinkerer
If there is a will, there is a way.
- Posts : 76
Join date : 2012-12-02
Location : Ohio
- Post n°4
Re: New leaf spring prod idea.
This may be obvious but mounting the prod can done to a
correct medieval style by creative clamping design giving emphasis to the area
across the front of the tiller, and not just at the two zones where the bow
irons pull. Basically I mean using a metal bolster plate that puts adequate
pressure across the front thus preserving the look that you want. The bow irons
would apply force to the plate but the thrust will be distributed more evenly
across than usual. The cord binding method I’ve seen sometimes has a bolster or
plate like this made from wood.

correct medieval style by creative clamping design giving emphasis to the area
across the front of the tiller, and not just at the two zones where the bow
irons pull. Basically I mean using a metal bolster plate that puts adequate
pressure across the front thus preserving the look that you want. The bow irons
would apply force to the plate but the thrust will be distributed more evenly
across than usual. The cord binding method I’ve seen sometimes has a bolster or
plate like this made from wood.

Rizzar- Workshop Savvy
Did you see my tool collection?
- Posts : 194
Join date : 2012-08-11
Location : Germany
- Post n°5
Re: New leaf spring prod idea.
The "bridle socket" you saw on medieval cord bindings is good to dristribute the binding pressure to the center of the prod.
You are right, with clamps and plates you can stiffen the center very good, but the clamps must be very tight and stay this tight which is the difficulty.
Though I think a bolt through the center hole with stiffening plates will do its duty pretty well and you even can hide it unter the bridle socket and cord binding if done properly.
The center shot is not very historical and due to the forces applied to the center not very practical.
Zardoz, to your design suggestion:
Let´s say it simple: every corner in any design is a weakening spot.
There will be a misbehaviour between the fade out and the working area, the material will need to compensate different forces and in my understanding be a very weak spot.
Greetings Rizzar
You are right, with clamps and plates you can stiffen the center very good, but the clamps must be very tight and stay this tight which is the difficulty.
Though I think a bolt through the center hole with stiffening plates will do its duty pretty well and you even can hide it unter the bridle socket and cord binding if done properly.
The center shot is not very historical and due to the forces applied to the center not very practical.
Zardoz, to your design suggestion:
Let´s say it simple: every corner in any design is a weakening spot.
There will be a misbehaviour between the fade out and the working area, the material will need to compensate different forces and in my understanding be a very weak spot.
Greetings Rizzar
Zardoz- Tinkerer
If there is a will, there is a way.
- Posts : 88
Join date : 2010-12-31
Age : 59
Location : New York
- Post n°6
Re: New leaf spring prod idea.
I planned on using a binding block, but I didnt mean to put a corner between the fade and the working section. I wrote in the drawing to blend it in. Would a more gradual transition do the trick?
Rizzar- Workshop Savvy
Did you see my tool collection?
- Posts : 194
Join date : 2012-08-11
Location : Germany
- Post n°7
Re: New leaf spring prod idea.
As I mentioned before I would stay with the stiffened triangular design.
It is easy to produce and you most likely won´t run into trouble.
It
is a bit hard to describe, but regarding to all the information i
collected until now a taper that is more "aggresive" than a triangular
is leaving weak areas.
So if you go from the center of the prod (the
area the limb begins concerning the stiffened area) you should have a
linear taper in cross section.

(don´t forget the complete center is stiffened, otherwise the triangle begins in the middle of the prod)
For optimal force distribution a perfect triangle (100% to 0% cross section) would be the best.
Most medieval bows show values of about 35-40% of the centers cross section at the beginning of the tips.
Greetings Rizzar
It is easy to produce and you most likely won´t run into trouble.
It
is a bit hard to describe, but regarding to all the information i
collected until now a taper that is more "aggresive" than a triangular
is leaving weak areas.
So if you go from the center of the prod (the
area the limb begins concerning the stiffened area) you should have a
linear taper in cross section.

(don´t forget the complete center is stiffened, otherwise the triangle begins in the middle of the prod)
For optimal force distribution a perfect triangle (100% to 0% cross section) would be the best.
Most medieval bows show values of about 35-40% of the centers cross section at the beginning of the tips.
Greetings Rizzar
Zardoz- Tinkerer
If there is a will, there is a way.
- Posts : 88
Join date : 2010-12-31
Age : 59
Location : New York
- Post n°8
Re: New leaf spring prod idea.
I guess it's back to the drawing board. I may just go back to my original plan to use Power Tuff.
mac- Master Weaponsmith
- Posts : 561
Join date : 2010-12-23
Location : Near Philly USA
- Post n°9
Re: New leaf spring prod idea.
Zardoz,
If you do go back to the drawing board, you might want to reconsider the 2" tiller width that you spec in your drawing. As near as I can tell, most tillers were a lot closer to 1" than to 2". A nice thin tiller goes a long way toward making a bow look good.
Mac
If you do go back to the drawing board, you might want to reconsider the 2" tiller width that you spec in your drawing. As near as I can tell, most tillers were a lot closer to 1" than to 2". A nice thin tiller goes a long way toward making a bow look good.
Mac
Zardoz- Tinkerer
If there is a will, there is a way.
- Posts : 88
Join date : 2010-12-31
Age : 59
Location : New York
- Post n°10
Re: New leaf spring prod idea.
2" was just for illustration. The graph paper was 1/4 inch sqares.