Author Topic: Recurving board bows? Kerf cutting for recurve?  (Read 19442 times)

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Offline bubby

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #30 on: February 22, 2016, 01:52:12 pm »
One bow, it will work on any wood but is especially effective on woods the don't like to bend with heat, epe and other tropicals, I don't do recurves till I get the bow to about 18" of bend so whatever you have dimension wise at that stage. A pullsaw will work but whatever you use be precise in your cuts. I don't think adding a recurve to offset set helps because it actually adds more stress, and if the wood will manipulate with steam or dry heat i would just use that and not add all that extra work, hope that helps ya, Bub
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline Onebowonder

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #31 on: February 22, 2016, 03:22:20 pm »
Thanx Bubby.  I appreciate the input.  I'll keep researching and see what I can find.

A build along is unlikely to address many of those questions. There seems to be a real resistance to learning by doing these days.

What is crawled up inside you Pat?  I told you I plan to use this method this weekend.  I'm not resistant to anything.  I am trying to read and research some before I try so as not repeat the errors of others needlessly. 

A build along may not have the answers to some of those questions, ...but then again it may.  It is infinitely more likely to have some of those answers than the first page of the thread, which is all that you suggested.  Have you EVER DONE THIS?  I'm guessing not.  If so, and IF you have any input you'd like to share to help, please feel free to speak up.  If you are just as ignorant as I am, please feel free to not comment.

OneBow

Offline PatM

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #32 on: February 22, 2016, 04:27:04 pm »
Sure I've done it. I prefer other methods.  I guess posts asking for every single detail in a short period of time  rather than hitting all the stepping stones along the way have worn out my patience.
   We see more and more of that on here now.

Offline bubby

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #33 on: February 22, 2016, 05:11:41 pm »
Onebow can I suggest that you take an 18"-20 pc of wood and make some practice cuts and even do a glue up to see how everything goes and what you need to do
failure is an option, everyone fails, it's how you handle it that matters.
The few the proud the 27🏹

Offline Onebowonder

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #34 on: February 22, 2016, 06:08:58 pm »
Onebow can I suggest that you take an 18"-20 pc of wood and make some practice cuts and even do a glue up to see how everything goes and what you need to do

Very good idea!  I'll give that a try.  I actually have a couple old bow limbs from bows that exploded that I might use for that testing.  Beats throwing them into the burn pile...  :-\ :)

OneBow

Offline bradsmith2010

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #35 on: February 22, 2016, 08:30:08 pm »
after you put the recurve in the exploded limbs, then splice them together and continue shooting them :)

Offline Dances with squirrels

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #36 on: February 23, 2016, 06:24:31 am »
Onebowwonder, I'll try to answer some of your questions. I don't know of any such build-along, but I don't think it's necessary.

1] Are there particular wood species this method is best suited for?

Not really. I've used it on various bow woods and in various designs and construction methods... d/r, hybrids, recurves, in selfbows, bamboo backed bows and trilams.

2] What approximate range of dimensions will it work for?

I'm not sure I understand this question. What dimensions? Do you mean thickness of limb prior to kerfing? If so, the best suited thickness depends on how drastic of a curve you intend to inflict on it upon glue up. If you're going full recurve, it should be nearly working limb thickness prior to kerfing. And of course it could be a wee bit thicker if you were simply inducing some reflex. It will behoove you to do this with outer limbs that have neither much ring or grain runout. If they do have runout, I would opt for reflex rather than more radical recurve shapes.

3] Are there any particular suggested precautions when doing this method?  (i.e. - ...things that might have gone wrong before for someone that has used the method that they might be able to advise another on as a forewarning.)

See above ;^)

Also, use a method similar to what I mentioned in an earlier post about finding the proper thickness lam dimensions, because if you you force the lam down into the kerf, it can easily cause a split starting at the bottom of the kerf and running into the limb.

4] At what point in the build process should this method be implemented?  (i.e. - ...at floor tiller?  ...completed tiller?  ...untillered blank stave or board perhaps?)

I've done it in all of those instances... as long as when kerfed, each individual piece is able to make the bend you intend.

5] Can this method be utilized to recover some of the effect of set that has occurred in an older bow?

Sure. Though, depending on other factors, it may cause it to take more set elsewhere.

6] A bandsaw was mentioned as the preferred tool for the work.  What TPI blade is suggested for this work? 

This isn't a critical factor. I've used blades as course as 3/4" with 3 teeth per inch. Cutting accuracy and tool familiarity is more important.

Will a Japanese pull saw work as an effective substitute?

Perhaps. I've never tried.

7] What-ever-else tips might be locked away in the mind of someone that has actually used this technique a few times previously that they might be able to share.

When everything is ready, glue is applied, lam slid into place, and you're ready to pull the pieces down into the jig to effect the bend..... The FIRST clamp should go right where the kerf ended BEFORE any bending is done. I had one crack there one time when I pulled it down into a recurve jig and I'm convinced that wouldn't have happened if I had placed a clamp there first.

Any other questions or concerns.... fire away.
Straight wood may make a better bow, but crooked wood makes a better bowyer

BobbyO

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #37 on: February 23, 2016, 07:16:27 am »
Whoa there fellas,
This link is to a two page posting on paleoplanet; quite nice pics and a drawing.

http://paleoplanet69529.yuku.com/topic/14941

Offline Onebowonder

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #38 on: February 23, 2016, 11:24:07 am »
Thanx for all the input guys.  I'll post my results if they are worth seeing after this weekend...

OneBow

Offline Springbuck

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #39 on: February 24, 2016, 11:17:47 am »
Ok bad is this sounds I not sure what those saws are so I will have Look further into those.

Doesn't sound bad.  That's exactly what google is for....

Offline Springbuck

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #40 on: February 24, 2016, 11:28:53 am »
  My input is this..... TB III is strong enough to do a kerf-and-splice recurve, but I have had a lot of failures anyway, because the hardest part is getting the cut even, smooth, and consistent size.  My best luck has been with a pull saw.  MAKE PENCIL MARKS!  It helps.

You CAN simply thin that limb down and recurve it, then add a belly splice overlay, too.  Not hard, looks good, and the thinner the wood, the more you can recurve it.

Pat's method is awesome, too.  I was afraid of it, but learned that if you make careful marks and cuts it works super.  when I did this, I layed up multiple lams over a tight curve, cut it in half and used them for the siyahs.  Get the alignment level on the back of the bow so you don't have to sand into the back to make it nice, then work the belly to fit and add another la, or wrap it with cord at the joint.  The glue will take it, though.

The best thing about adding recurves is that you CAN make the limbs pretty thin, so they will bend for you, because the recurves raise draw weight dramatically.

Offline Onebowonder

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #41 on: February 28, 2016, 09:40:19 am »
I will post pictures when I get back to my PC. However; we tried this yesterday and had a very bad time of it…  :( :( >:(

OneBow

Offline Onebowonder

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #42 on: March 01, 2016, 01:01:36 pm »
Well - Here is the pictorial of the doomed effort Patrick and I made at doing a kerf style recurve.

First mistake was that we talked ourselves into trying this out on a bow blank that was still promising to become a bow instead of one of my old blown-up bow limbs.   ::)

Patrick laid out the lines to cut the kerfs.  Then he cut them while I took pictures.  Up to this point, we were still pretty hopeful...

OneBow

Offline Onebowonder

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #43 on: March 01, 2016, 01:06:04 pm »
Next we tapered the inserts out of some walnut I had on hand.

...Then we used the heat gun to 'pre-bend' the hooks into the tips prior to glue-up.  Also, Patrick sanded the back side of each hook to accommodate the brush nocks he had planned for this bow. (...did not get a picture of this step.)

OneBow

Offline Onebowonder

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Re: Recurving board bows? Kerf cutting for recurve?
« Reply #44 on: March 01, 2016, 01:08:41 pm »
...and then fainally, the fail, which came during the glue-up and insertion into the caul step.  The hooks shattered badly and and were not at all readily bent.

OneBow