Author Topic: Crushing the inside of a recurve  (Read 1586 times)

0 Members and 1 Guest are viewing this topic.

Offline DC

  • Member
  • Posts: 10,396
Crushing the inside of a recurve
« on: June 26, 2018, 12:03:58 pm »
This is a test bend on a piece of scrap Douglas Maple with the opposite of the usual cracking on the outside. The wood crushed on the inside. A first for me. I used steam and a strap. It's 1 3/4" radius. Is there something I could have done or not done to avoid this?

Offline Del the cat

  • Member
  • Posts: 8,291
    • Derek Hutchison Native Wood Self Bows
Re: Crushing the inside of a recurve
« Reply #1 on: June 26, 2018, 12:11:36 pm »
Maybe a gentler radius.
It's fixable by rasping it down thinner and the bending a tin piece of maple and gluing it on.
In fact that possibly a good way to do very tight hooks, make 'em thin so the will take the band and then glue on a pre-bent thinner patch.
I've used this trick on the belly.
https://bowyersdiary.blogspot.com/2013/05/radical-recurve.html
Del
Health warning, these posts may contain traces of nut.

Offline High-Desert

  • Member
  • Posts: 876
Re: Crushing the inside of a recurve
« Reply #2 on: June 26, 2018, 01:22:31 pm »
I've had this happen with thick yew sapwood. I just scraped it down till it couldn't be seen. If your curve is thick enough afterwords, you're good to go. The other time I did it, I did what dell said, glue on a lam, if its too thin.
Eric

Offline leonwood

  • Member
  • Posts: 762
    • Leonwood Bows
Re: Crushing the inside of a recurve
« Reply #3 on: June 26, 2018, 01:47:50 pm »
I had it with yew and a tight radius too. Cut the radius of the form a little bigger and shortened the bow a bit. Bigger bend went fine, just tillered it to brace today actually

Offline DC

  • Member
  • Posts: 10,396
Re: Crushing the inside of a recurve
« Reply #4 on: June 26, 2018, 02:17:06 pm »
It was just under 1/2" thick. I tried another, same thickness, but I loosened the strap a bit. It wrinkled the inside and lifted a splinter on the outside. I made one 3/8" thick. it's cooling now.

Offline BowEd

  • Member
  • Posts: 9,390
  • BowEd
Re: Crushing the inside of a recurve
« Reply #5 on: June 26, 2018, 03:43:00 pm »
That happens DC on many different types of wood over here too DC.Does'nt affect anything negatively really though after heat tempering.
« Last Edit: June 26, 2018, 03:46:57 pm by BowEd »
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline Hamish

  • Member
  • Posts: 1,473
Re: Crushing the inside of a recurve
« Reply #6 on: June 26, 2018, 06:26:42 pm »
It could be partly due to the type of maple, and whether it was air dried or kiln dried.

Offline DC

  • Member
  • Posts: 10,396
Re: Crushing the inside of a recurve
« Reply #7 on: June 26, 2018, 06:57:26 pm »
It's air dried.
 I kerfed one that is a half inch thick and bent it over the same form. Look at how much difference there is in length. It's no wonder it splinters and crushes. If it was not kerfed it would have to stretch and/or compress 1/2" in six inches.

Offline BowEd

  • Member
  • Posts: 9,390
  • BowEd
Re: Crushing the inside of a recurve
« Reply #8 on: June 26, 2018, 09:00:34 pm »
Good demonstration DC.Now you can just glue that kerf together and then there's no need for tempering with a heat gun...but you have that glue yet though.
BowEd
You got to stand for something or you'll fall for anything.
Ed

Offline DC

  • Member
  • Posts: 10,396
Re: Crushing the inside of a recurve
« Reply #9 on: June 26, 2018, 10:44:37 pm »
I like the kerfing method for that reason. Once it's glued it's there forever. I like to put my recurves in early and I never seem to get the kerf centered.

Offline Bryce

  • Global Moderator
  • Member
  • Posts: 3,125
  • Pacific Ghost Longbows
Re: Crushing the inside of a recurve
« Reply #10 on: June 26, 2018, 10:48:47 pm »
I use that same kerf method with laminate bows and recurves. Just slide in a matching curved piece and you can’t even tell it’s there.
Clatskanie, Oregon

Offline DC

  • Member
  • Posts: 10,396
Re: Crushing the inside of a recurve
« Reply #11 on: June 27, 2018, 11:36:34 am »
I wish my glue lines were that good. I have to use contrasting colour wood to hide them. :)

Offline Del the cat

  • Member
  • Posts: 8,291
    • Derek Hutchison Native Wood Self Bows
Re: Crushing the inside of a recurve
« Reply #12 on: June 28, 2018, 12:44:13 am »
@ DC
That photo showing the movement when done with kerf is great :)
Easily worth a thousand words.
Del
Health warning, these posts may contain traces of nut.