Starting Thickness

[Wooden Spring]

I was talking to someone the other day about tillering, and as I'm about to start my first stave bows, my one unanswered question was how to go about starting the bow's thickness...   Basically what we talked about can be seen in the sketch I drew below...  Is this right?

1) Basically, the drawing shows a cross section of a bow at 1 1/2" wide. Start the limb out at 3/4" thick, parallel to the bow's back.

2) If you want the bow to be less than 55#, then come up from the back 1/4" and scribe a line.

3) Then connect that line to a centerline along the belly, forming a triangle in the cross section.

4) Begin rounding this out to tiller the bow to the desired poundage.

(If you want a bow greater than 55#, start by offsetting 3/8" rather than 1/4" and tiller as before.)

Is this even CLOSE to how you pro's do it?

[okie64]

Ive never done it that way but I guess that method could work. I just work my limbs down to about 5/8" thick or so while floor tillering. Once the limbs are bending nice and even on the floor go to low brace and remove wood from flat spots then to regular brace height and finish tillering. I probably made that sound a lot easier than it actually is sometimes

[Badger]

  I don't thin pros measure the thickness unless they are kind of mass producing board bows.

[IdahoMatt]

I do a 1/2" to 3/8" thickness on harder word (denser) and 3/4" to 1/2" on less dense woods.  This is just to get them bending.  Then there is still quite a bit of wood that still needs to come off.  Just be sure and mark your line accurately.  If using a ban saw DONT CUT TO CLOSE TO THE LINE, rasp down to it.   In your sketch, cutting at an angle is the way I do it so there is a peak in the center of the belly.  Every now and again I will cut the peak off with the ban saw.  Hope that helps and wasn't too confusing. 

P.S. These are general dimensions that will very but they should leave you with enough wood to play with.  They are also for stiff handle section bows.

Matt Kulchak

[George Tsoukalas]

What wood will you be using, Wooden Spring? What is your draw length? What weight?
Jawge

[SLIMBOB]

+1 okie and Badger.  I couldn't tell you the what the starting thickness is on any stave bow I have ever built.  Eyeball it at 3/4 inch or there abouts and then Floor tiller till it's bending good and then get it to low brace and finish it.   Don't over think it would be my first advice to you.  It's far more simple than that.

[Pat B]

When I'm cutting out a bow blank from a tree stave I reduce it on the bandsaw to about 3/4" to start. I test the bend. If still rigid I'll reduce the thickness to 5/8" and check the floor tiller. If still too stiff I'll reduce it to 1/2". All of the reduction to this point is done with a farriers rasp. From this point on I only use a scraper with some light rasp work where necessary.
  When the limbs bend evenly and together and you've hit your intended draw weight at your intended draw length, that is how thick the limbs will be.

[missilemaster]

if you build enough bow you start to know what looks right. I thing its more of a feel thing than an actual measurement. Every piece of wood will be different so the starting thickness will vary.

[GB]

I rough mine out the same way that has been described, 3/4" at the fades to 1/2" thick at the tips just to be sure I have plenty to work with.  That leaves quite a bit of rasping on a 45# bow, but better to start too thick than too thin.  Jawge raises a good question about the type of wood you're using.  You might start narrower than 1 1/2" if it's a dense wood like osage or go wider if it's lighter wood like maple or erc. 

[bushboy]

What M/M ,badger and pat said.i like to have 1/4" thick on the edge. Regardless of the crown for a wide limbed bow and 3/4" for a very narrow one.i never like to reply to a thread when the word expert is mentioned, cuz i'm not even close!lol!

[Wooden Spring]

In response, this is for a hickory bow. I just felled a tree and got 8 good staves out of it, so I'm hoping to turn them into bows maybe by Summer. I'd like to be in the 50# range, but as this is a learning experience, I realyy don't care where it actually ends up, so the 1 1/2" width is really arbitrary.

My main concern is technique. How is thickness on a bow done, and where's the best place to start???

[bushboy]

Reduced,flex at floor tiller,repeat.

[DLH]

Honestly I haven't made enough bows to give great advice but I think Gordon's build along gives the best visual example of intial thickness to start. Check out his build along where he is laying out his thickness taper. That's what these guys are doing by floor tillering they are bending their bow on the floor and removing wood as needed to establish their taper. I'm assuming they lay out their intial thickness taper some how? You can set up your intial taper like gordon does in his build along or free hand it with a pencil but it's just a starting point. Also the width taper effects the thickness taper as well. This is what little info I have picked up. I struggle with how far to floor tiller checking how it feels on the floor with another bow to have a refrence with weight. I hope someone else will chim in on this that knows more than me or will correct me if I'm wrong.

[DC]

It's not done by thickness, it's done by bend

[Wooden Spring]

It's not done by thickness, it's done by bend

True, but you don't start out with a 16" thick bow either, and to the untrained such as myself, 3/4" might as well be 16" if you ain't got a clue about how to start.