Oak as core?

[stuckinthemud]

When I started building bows I was told European oak was not a good bow wood. This does not mean it is not a good core wood.  North European medieval composite crossbows seem to have used it extensively as a core wood but of course it could have been misidentified. Any thoughts?  Does European oak make a good choice of core wood?

[bownarra]

No.
You want a diffuse porous wood not the most ring porous wood you can find like our oak! Maple, hornbeam and elder would all be better.
It actually does make a good selfbow but you must trap the back heavily. The reason most people are down on the oaks is their strength in tension exceeds the bellies ability to resist compression. Heat treating and trapping take care of a lot of these sub par bow woods. It is just a case of identifying the woods strengths/weaknesses and designing accordingly.

[stuckinthemud]

Thanks, that is pretty much what I thought, but, I am starting a new crossbow project and want to be as authentic as possible.  I am fairly sure that many of the bows identified as containing oak are mis-identified, some one in antiquity going oh, its a strong, dark timber, most likely oak then....

[bownarra]

Yes that is certainly possible.
I would plump for hornbeam if you can find a piece. It is nigh on perfect for a core, especially for a crossbow.
I found a perfect section a few years ago and it became a core for my now 'go to' Turkish bow. It has definitely more than proved its durability.

[DC]

Have you ever had a core break without the horn or sinew breaking?

[sleek]

I've had a core chrysle without a problem on the belly or back. I used a very soft wood as a core and a bamboo back. I dont know what I used on the belly, but the belly developed a hinge right there. Which came first, idk?

[stuckinthemud]

Hornbeam is nigh on impossible to get here, what about hawthorn?

[bownarra]

Have you ever had a core break without the horn or sinew breaking?

Yes It happens when the sinew isn't thick enough or the back sized correctly and the correct thickness of glue.
After making lots of wooden/sinew bows I thought I had the sinewing process totally down and hardly even thought about it....it's just like sinewing a wooden bow right? Wrong my first few failures were all down to sinew lifting on the back and the core then failing. The interesting thing is the bows can still just about be shot....which goes to show just how bombproof a good sinew backing is.
To avoid these problems treat the sinewing job as carefully as you treat the core to horn joint (getting a perfect sinew job is not easy).

[bownarra]

I've had a core chrysle without a problem on the belly or back. I used a very soft wood as a core and a bamboo back. I dont know what I used on the belly, but the belly developed a hinge right there. Which came first, idk?

Sleek a hornbow core is undergoing quite different forces. Comparing a core on a wooden bow and a hornbow core is a bit like comparing apples and oranges. They would break/fail for different reasons.