Using Dry Heat to Reflex a Bow: Lessons Learned

I recently bent reflex into an Osage stave and learned a few lessons. These may be obvious to the seasoned bowyer, but I want to share my growing pains in case the reader is interested in trying to bend wood with dry heat themselves. The lessons are stated in bullet points at the end of the post for those not interested in my rambling.

The Osage stave in question was roughed from a small diameter tree and has a slightly crowned back. It’s 52″ tip-to-tip and tapers to 1/2″ over the last 8″ of each limb. I most likely wouldn’t have reflexed it had it not demanded it. But after roughing it out I was left with one limb reflexed about 2″ and the other dead straight. I hadn’t had much luck reflexing bows before, but it was time to face the music: this bow would be reflexed, or it wouldn’t be a bow. After reviewing the Bending Wood chapter in The Traditional Bowyer’s Bible, Vol. 2, I cut a form out of a 2×8, fired up the heat gun (pun slightly intended, sorry), and set to work.

I always read that the successful bowyer exercises extreme patience when heat bending wood. Take your time, heat slowly and thoroughly, and wait until the wood is too hot to touch before clamping it to the form. Wait until the wood is too hot to touch before clamping it to the form. Heat. Touch. Heat. Touch. Heat. Touch. “Ow! I can handle a bit more…” Heat. Touch. Heat. Heat some more. Too hot to touch! Clamp.

A selfbow clamped to a reflex form.

The bow stave is clamped to the reflex form and left to cool.

It didn’t quite work. The straight limb was mostly still straight, but with a bit of a flip at the end where the full width of the limb tapered to the tip. I considered the possibility that the “too hot to touch” rule only works where the limb is sufficiently thin. By the time a thin portion of limb is hot to the touch, it is hot all the way through. This is not necessarily true for thicker limbs. I suspected that the heat had not penetrated to the interior of the limb’s first and middle thirds, leaving a cool, rigid backbone that resisted bending.

Then next day I tried again, only working with the straight limb. I did a few things differently. First, I soaked a bit of vegetable oil into the wood before heating (worth it for the smell alone!). Then I heated longer portions of the limb at a time. After the wood was too hot to touch, I heated for another five minutes before clamping. I ensured this using the timer on my cell phone.

This time I had success, and was glad to see an evenly reflexed bow come off the form.

A reflexed Osage stave.

The stave after a second attempt to heat reflex into it proves successful.

My euphoria was quickly tempered when I inspected the wood. Small cracks formed along the grain on the belly. Even worse, two big cracks formed on the back in an area already hazardous due to some seasonal ring violations. While this doesn’t necessarily kill the bow, it does make it a bit more challenging. This stave will need to sit in the garage for a week or two to let the humidity return some moisture to the limbs. Then I’ll seal the cracks with super glue. I’ll also wrap the damaged area of the back in sinew when it’s close to final tiller for extra safety. Osage is very forgiving, so I still hope to make this a sweet shooter.

Troublesome areas on the back growth ring of an Osage stave.

Troublesome areas on the back growth ring of an Osage stave. Seasonal rings are violated, and cracks formed when heating reflex into the bow (right picture). Red X’s show corresponding areas before and after heating, and the brightness/contrast of the images were tuned to accentuate anomalies.

So what lessons did I learn?

  • Thicker portions of the limb may need heating past the “too hot to touch” point to allow time for the heat to penetrate into the core of the limb.
  • Some form of grease or oil may help dry heat distribute more evenly throughout the wood. This is inconclusive for me so far, and other bowyers report mixed results.
  • Wood cracking from too much heat is a very real possibility. To combat this, I need to try holding the heat gun further from the wood in the future and heating the wood slowly.

If you have anything to add, feel free to leave a comment or reach out to me at fieldandflood@gmail.com.

2 thoughts on “Using Dry Heat to Reflex a Bow: Lessons Learned

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s