Osage Belly knot cluster - chrysals - PATCHED!

[PatM]

With a very sharp chisel.

[mikekeswick]

The scallop method is superior because those butt joins eventually fail. I've done four in total and every one has creased at the edges. When you fit a new patch it hasn't been compressed, once you get the patch to fit perfectly and then carry on tillering the patch gets compressed and it's no longer a perfect fit.

[Del the cat]

Personally I prefer a longer shallower scallop. Not sure I'd like a square edged insert, although I've done it in a grip so I could introduce a bend more easily. (Cut out a section, bent it and then glued in a block).
Del

[Eric Krewson]

I have done 3 of these patches, one held 3 years, one a couple years and one about 6 months but all eventually failed.

[Jim Davis]

How do you remove a perfect square of wood from a bow limb?

That "square"  patch extends through the left edge of the limb.

 As far as the new wood not being compressed, not so. I made the patch a tight fit with the limb flexed backward a little bit. You can do the same with a round/dowel type patch--flex the limb while drilling  the hole and while inserting a tight dowel. Then the dowel is compressed when the limb is in the unstrung mode.

Just have to think about the dynamics when planning such a repair.

The  bow is still shooting after three years with no issues around the edges of the patch. There are also two round plug patches in the limbs. I turned the plugs in the lathe such that the grain runs straight across the diameter of the plug so the grain could be oriented in line with the grain of the limb.

[bubbles]

Well, if it lasts a year, ill be happy, then if it fails, ill just re-do it. How did they fail on you Eric? Was it slow or sudden and catastrophic?
Ash arrow -  so when you install the patches, you're flexing the limb slightly backwards? That way the limb is exerting compression on the patch at all times correct?

[Jim Davis]

...

Exactly.  I make the plug a very snug fit with the limb flexed back slightly--it's a bit subjective about how much flex.

[Eric Krewson]

My failures started with a cracked patch which eventually started breaking out and led to a hinged limb, nothing catastrophic. Superglue wouldn't stop the crack.

[bubbles]

I assume the cracking was the glue line?

[bow101]

I have done 3 of these patches, one held 3 years, one a couple years and one about 6 months but all eventually failed.

Do you know of any that survived.?  Makes sense to me for a patch that size,  kind of like taking someone elses skin graft

[Eric Krewson]

Here is my most radical patch on an bamboo backed osage elb, this one only lasted a few months. I patched the bow for a friend who loved the bow and wanted to save it from a failure around a huge knot.