Is there a tiller check limit here?

[skarhand]

Hey everyone! I am working on an ash backed ipe bow right now. It is a bit on the smaller side and will probably go to my wife because she keeps commenting on how much she likes it and I can take a hint. 1-1/4" wide at the fades tapering to 1/2" tips

It is 52" NtoN and so far I have only pulled 15" off a 4" low brace. That took me to a hair over #30. I am shooting for somewhere in the  #40 pound range. What I am not sure of is what would be a safe draw length to take it to? I don't want to over do it. Is there a "rule of thumb" for draw length? (n2n/2 - x" or something)

Here are a couple pics of it at low brace and 15" draw. Right now at rest it has 0 set but I think I see some slight hinges mid limb, more so on right then left. My plan for tomorrow is to leave the mid limbs alone get the tips bending a smidge more and a bit more out of the fades.  Any other suggestion/criticism would be greatly valued.

Joshua (Skar)

[adb]

Your tiller looks pretty good so far. Brace looks nice too. Have you measured your wife's draw length? It's likely 24" -  25" or even less. You should be safe pulling it that far. At 52", I wouldn't pull it to 28" or anything, especially without a bendy handle.

Get the fades moving, and then bring the tips around. Don't worry, ipe is tough, and can take a lot of bend.

The right outer third is a bit stiff, but I don't see a hinge. The left limb is brilliant.

[skarhand]

Your tiller looks pretty good so far. Brace looks nice too. Have you measured your wife's draw length? It's likely 24" -  25" or even less. You should be safe pulling it that far. At 52", I wouldn't pull it to 28" or anything, especially without a bendy handle.

Get the fades moving, and then bring the tips around. Don't worry, ipe is tough, and can take a lot of bend.

What is the best/easiest way to measure draw length? I'd just have her draw mine and measure but she can't pull it far enough. Or can I just have her hold it unstrung and measure her mock drawing it?

[adb]

Find a bow light enough for her to draw fully. Get her to draw it to her anchor point... wherever that is. Make a mark on the arrow shaft beside the BACK of the bow, and measure from the valley of the arrow's nock to the mark. That's her draw length.

To make it easier, I have a nocked arrow shaft with no feathers, and inch mark increments made with a fine point sharpie, from 20" to 32". I get the shooter to come to full draw, and look at the measurement.

Before I start building any bow, I have the final goal in mind. Desired draw weight, measured draw length and design. Speaking of design, what is the back profile of this bow? Is it a continuous taper pyramid type flatbow?

[skarhand]

Yes, continuous taper 1-1/4" down to 1/2". Also, have been meaning to ask, when referring to "pyramid bow" is that in cross section similar to "traped back" or in profile like a loooong pointy pyramid as opposed to a steady width for a portion of the limb then a taper for the rest?

[adb]

A 'pyramid' flabow has a continuous profile taper from fades to tip. The limbs have no parallel sections. Your final tiller shape with this design should end up as round as possible for the best results. Keep thinking 'round' when you're tillering it.

You're on the right path. Once the fades move well, get the tips to come around and you should be good. Of course you can't make it as round a tiller shape as a bendy handle ELB, but you get the idea.

With a pyramid bow, you'll find your thickness taper to be almost constant from fade to tip. In other words, the bow's belly will have almost the same thickness from fade to tip.

[mikekeswick]

Good advice above.
Taking it a step further - when trying to decide what the bow should bend like it always comes back to wether the limbs have any thickness taper. If (as on the bow you are making) you have a pyramid width taper then there will be little if no thickness taper. So if each section of the limb is the same thickness each bit should/can bend as far as it's neighbour - this results in a 'circular' tiller.
If you made a bow that had parallel width limbs for most of their length and then tapered to the nocks say 8 inch from the end of the limb. Then that limb design would have to have a thickness taper (because it has to taper somewhere). Thickest near the handle tapering to the tip. The thicker wood can't bend very far without taking set. The thinner the limb gets the further it can bend. So the tiller should be elliptical eg. each bit bending a little further than the bit next as you move along the limb to the tip (but leave the last 8 inches or so stiff).

[mullet]

Your Tiller doesen't look far off to me either. The left limb I'd give some nice, even, full length scrapes and the outer 3ird on the right limd and then check the weight and draw length.

[skarhand]

Thanks guys for the advice. Now I just have to try to get through work so I can get back to working on it, lol.

[skarhand]

Ok, update. I decided to try for 24" draw, but after pulling it to 20" I have chickened out, lol. Now it pulls #40 @ 20" and I am thinking that I may just stick there. As of right now immediately after unstringing it it returns to 0 set. Any thoughts? Should I push it (pull it rather) and keep going? Or is my chance of breaking high? My Ipe and Ash supply is very limited, so I'd rather have a working bow that pulls shorter then I wanted then 500 ipe toothpicks, lol.

[adb]

Get those tips moving a bit more, especially the right side and you can easily get another couple of inches. Ipe is tough. It'll bend. As long as your backing is sound, you'll be fine. Your tiller looks great so far. I think you can easily get 24", and 50# should be no problem either.

The fact that it's taken no set is also an indicator it's not overstressed.

[Ifrit617]

I agree with adb. You should have no problem getting 24". Here is a Osage shorty I made that had the same specs as yours and pulled 45#@24".

Jon

[Pappy]

What adb said on the right limb,and depending on your wife's draw would be the
decision maker on how much more I went, no need in going any more than you need for her to shoot it confrontable.  24 shouldn't be a problem if you need that much.  Looking good so far.
   Pappy

[skarhand]

Thanks guys. I measured her draw length again last night on my full sized bow and came up with 22". So I'm going to work on the tips and then take some off both limbs, I need to get it down around #40 at 22" and even that may be a lot for her to pull. But I figure it would be better to have it a bit heavy and let her work up to it.

Hopefully I'll be able to make some good progress on it tonight and have some finished tiller pics later. Then to my favorite part....shaping the handle and finished sanding. I love to see a rough piece of wood turn all smooth and curvy. Two months ago I would have never imagined I could make things like I am now. Thanks all for your help!