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Getting to full draw without losing thickness or gaining set?

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stuckinthemud:
I am copying a historic yew bow from Scandinavia. The thirteenth century original was compression wood and cold climate yew. My yew is less knotty stem-wood but mild climate and so much less dense.  I am currently on the mark for width and thickness and am starting to show signs of set as I get close to brace height. The original had a little more set than I am showing, but It was a working bow and I am only at brace height.  Any advice on how to get to full draw without increasing set and without loosing too much thickness?  Gizmo shows good even bend on both limbs

Pat B:
As long as your tiller is even you can continue to pull the bow towards full draw.

mmattockx:

--- Quote from: stuckinthemud on June 28, 2023, 07:19:52 am ---I am copying a historic yew bow from Scandinavia. The thirteenth century original was compression wood and cold climate yew. My yew is less knotty stem-wood but mild climate and so much less dense.  I am currently on the mark for width and thickness and am starting to show signs of set as I get close to brace height. The original had a little more set than I am showing, but It was a working bow and I am only at brace height.  Any advice on how to get to full draw without increasing set and without loosing too much thickness?  Gizmo shows good even bend on both limbs

--- End quote ---

Getting to brace on a flat bow normally puts about 1/2 the strain on the limbs that you see at full draw, so you are going to pick up a bunch more set getting to full draw. There is no way to stop this aside from using a better piece of wood that will withstand the strain level of this bow. You have two options. You can either opt to keep the thickness and live with however much set you get or you can remove thickness from the limbs and minimize the set, at a cost to limb thickness and draw weight.

If you have a nice bend going on then you need to just reduce thickness evenly along both limbs to drop weight while keeping the good tiller.


Mark

superdav95:
I agree with what has been said as well.  The other thing that could be done is to reduce width.  I know that this may ruffle some feathers but it is an option to help with reducing the amount of set.  I find that on a narrower bow limb that is slightly thicker will often take less set then wider thinner limbs.  Many factors come into play here but this has been my experience.  If all things being equal such as how well a bow has been tillered and laid out as far as design goes then generally I find that slightly narrower thicker limbs can take less set.  Now this opens up another conversation… does this always translate into better performance in the end?  The short answer is, Not always.  A little Set is not always a deal breaker as far as performance goes.  Minimizing set is the ideal for wood bows and some set is I believe inevitable.  Quality of wood such as density, mc, type/species, grain and ring quality all play a role among others in set as well.  Not trying to make a general statement here about width and thickness layout but it’s been my experience so far.  The game of controlling compression failures or even compromised belly seen or unseen is often overlooked I feel.  In tension strong woods such as hickory for example thinning too much on wider bow will likely show compression issues and or set.  Things can be done with hickory to limit this like heat treatment but still can be an issue.  Osage for example is obviously different then hickory.  It’s density is gonna be better for the most part depending on quality of Osage and such but is generally better in compression then hickory.  This dose t mean that compression issues won’t surface on an Osage build but one could get away with a little more on a good piece of Osage.  Anyway I’m rambling on here but I hope my point I’m trying to make is that sometimes narrower thicker can translate into less set and sometimes better performance if done well.  Hopefully this is not too general of a statement in this context but gives you something to consider when doing your build.    Cheers. 

stuckinthemud:
I don’t have any margin for thickness but I did factor in 10 percent extra width to compensate for the difference in density, I think cutting out that extra material makes a lot of sense

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