Maple Board Bow Tiller Review

[willie]

Hi Mark,

I will keep working on that inner limb until it is bending more and not take any more weight off until it is.

Actually, if you pull your bow to a bend that is equivalent to say, a 6" brace height, and then remove wood in the stiff areas, you will be taking weight off. The scale will indicate less and less to obtain the same bend. Once all looks even at 6", then pull your bow till you see any unevenness or reach 30# again, which ever happens first. Hope you don't feel I am splittings hairs, but here is a good read on what Badger calls a "subtle distinction"   http://www.primitivearcher.com/smf/index.php?topic=61452.0

An important step is to radius the edges of the back if you haven't done so already, board bows especially will want to raise a splinter with surprising little bend, (a slightly rounded belly is easier to scrape also)   

Yes thats the bow, His has a slightly working tips, as the reflex he added straightens slightly at full draw. It is the inner limb profile that I thought was worth comparing.

simple machine forums are indeed simple, especially the search function.  a google search of       moose bushboy site:http://www.primitivearcher.com/smf/      works in spite of the fact that I didn't even get the thread title correct

[mmattockx]

Actually, if you pull your bow to a bend that is equivalent to say, a 6" brace height, and then remove wood in the stiff areas, you will be taking weight off.

That is true. I should have been more specific and said I will not take any more wood off the limbs overall, just at the stiff spot.

A question - the left limb in the pictures is bending a bit more than the right when I use a straight edge to measure gap along the belly. Do I want to get the right limb bending more to match the left after I go to a regular string or just go by which limb looks stronger and work that one down?

An important step is to radius the edges of the back if you haven't done so already, board bows especially will want to raise a splinter with surprising little bend, (a slightly rounded belly is easier to scrape also)   

Yes, I did that before doing any tillering at all. I am doing most of my scraping with an old pair of scissors that have a slightly radiused cutting edge that scrapes a relatively narrow line and then smoothing/flattening the belly with a straight edged scraper to finish. It is sort of the reverse of a rounded belly, but gives the same effect of easing the scraping work.

Should the edge/corner of the belly have much radius? I've been breaking the sharp edge with the scraper but not ever putting more than 1/32"-1/16" of chamfer on it. I figured I would round it slightly during finish sanding to match the back and be comfortable to handle.

Yes thats the bow, His has a slightly working tips, as the reflex he added straightens slightly at full draw. It is the inner limb profile that I thought was worth comparing.

Good. I will look at the pictures again as a guide.

simple machine forums are indeed simple, especially the search function.  a google search of       moose bushboy site:http://www.primitivearcher.com/smf/      works in spite of the fact that I didn't even get the thread title correct

I tried the google site search but got the site string wrong by leaving the stuff after the /smf/ on the address. I will make a note of that so I can use google in the future, it usually does a much better job than forum search engines.


Mark

[bushboy]

This one may be a better example...

[willie]

the left limb in the pictures is bending a bit more than the right when I use a straight edge to measure gap along the belly. Do I want to get the right limb bending more to match the left

yes, but concentrate on the left inner first and get the left as even looking as the right, even if the whole left limb bends more than the right while fixing that spot. you pretty much have your taper established on the right and getting it to bend more is a simple overall reduction.

Do I want to get the right limb bending more to match the left after I go to a regular string

I would do it on the long string before I pulled further, and would pull it further and keep it even before I brace. when you decide to brace, you might consider a course of action described by jeffp51, a low brace at first progressing to a full brace closer to the end.    http://www.primitivearcher.com/smf/index.php/topic,67447.msg947680.html#msg947680

Should the edge/corner of the belly have much radius?

it doesn't need to like the back, what ever makes the scraping go easy or suits your design, a relatively flat belly design works well for most whitewoods.

[mmattockx]

This one may be a better example...

Many thanks. That looks like a circular arc to me, is that right?

yes, but concentrate on the left inner first and get the left as even looking as the right, even if the whole left limb bends more than the right while fixing that spot.

Will do.

I would do it on the long string before I pulled further, and would pull it further and keep it even before I brace.

That lets me keep working while I track down a string so I will go that way. How much more draw before bracing it? I'm down to 20" with as tight a slack string as I can arrange for and don't want to go too far before bracing.

it doesn't need to like the back, what ever makes the scraping go easy or suits your design, a relatively flat belly design works well for most whitewoods.

A small radius it is then. The belly is dead flat and staying that way as it's the most structurally efficient cross section.


Mark

[willie]

That lets me keep working while I track down a string so I will go that way. How much more draw before bracing it? I'm down to 20" with as tight a slack string as I can arrange for and don't want to go too far before bracing.

as long as you are using parachute cord its going to be difficult to say. I would bring my tips down 10 " or so. Others get by with less, some prefer more. not sure you can go "too" far on the longstring with your design, as it's the tips that give a false read between long string and normal string.
I wouldn’t  go much further than bringing the tips back 12" I guess.  a half a dozen strands of  cheap braided dacron fish line, like is used for fly-line backing or saltwater reels would be an effective temporary substitute for a bow string,  and for making up a decent tillering string. 50# test might be available in your area.

[mmattockx]

as long as you are using parachute cord its going to be difficult to say. I would bring my tips down 10 " or so. Others get by with less, some prefer more. not sure you can go "too" far on the longstring with your design, as it's the tips that give a false read between long string and normal string.

OK, 10" is a ways from where I am at now so that gives me room to work some more over the weekend. I was worried about the tips after reading that thread by DC but if the stiff levers eliminate that problem then I won't concern myself with it.


Mark

[mmattockx]

Today's progress:

Pulled to 24" on the long string, tips at or past 10" of movement. Right limb looks stronger to me and the left limb has a slight twist, which is why the belly is showing more on that side. How do I deal with that?




Low braced to ~4" (I couldn't wait after getting it moving nicely...)




Pulled to 17" draw from the low brace (Only pulled 20lb at that point). Right limb still looks stronger but I also had the string tight on the nock and it wasn't moving properly. I ran out of time to fix that, will sort it tomorrow and take a new picture.




I have found a bow string, should have it Monday or Tuesday next week. Do I brace it to full height and keep going on taking weight off while getting to my draw length target or something else?


Mark

[willie]

Looking nice , Mark, your deliberation is paying off as it's looking like a success on your first.

I wouldn't brace any more for now, as your 4 inches seems to be measured from a rather deep handle. This will do well until you finish it out. I agree the right looks stronger, and needs some more work. I wouldn't pull any further until you even it up. A solid backdrop behind your tiller tree would help the visuals. I would put up something rigid that you can see a tracing of your limb curve on as you go. a tiller stick will enable you to hold it at the point I see it in the last pic and make the tracing, a lot of folks don't care to use a stick, as it is not the best to keep a bow drawn for to long, but long enough to make a quick trace on the backercoard, then you can tack it up behind the tree.  The idea is that you can flip the bow left and right to see differences easier.
another thing to keep in mind is that as you near full draw with your pulls being the desired finished draw weight, you might want to stop 2 inches short. by the time you have shot the bow in (a couple of hundred shots) at the reduced draw length, and finished sanding and any final radiusing, you might find a slight loss of draw weight or need to touch up the tiller somewhere.

twist: http://www.primitivearcher.com/smf/index.php/topic,27206.0.html

Does the thickness run off to one side where it is twisted, or do think the wood varies in the twist area? maybe softer

[mmattockx]

Looking nice , Mark, your deliberation is paying off as it's looking like a success on your first.

I can't believe you said that out loud! That Murphy guy is everywhere, you know.

I wouldn't brace any more for now, as your 4 inches seems to be measured from a rather deep handle. This will do well until you finish it out. I agree the right looks stronger, and needs some more work. I wouldn't pull any further until you even it up.

Will do.

A solid backdrop behind your tiller tree would help the visuals. I would put up something rigid that you can see a tracing of your limb curve on as you go. a tiller stick will enable you to hold it at the point I see it in the last pic and make the tracing, a lot of folks don't care to use a stick, as it is not the best to keep a bow drawn for to long, but long enough to make a quick trace on the backercoard, then you can tack it up behind the tree.  The idea is that you can flip the bow left and right to see differences easier.

I am working on a backdrop, believe me. Just haven't found a big enough piece of cardboard to put up there yet. As a substitute for tracing and flipping would pictures of the bow from each side be worthwhile?

another thing to keep in mind is that as you near full draw with your pulls being the desired finished draw weight, you might want to stop 2 inches short. by the time you have shot the bow in (a couple of hundred shots) at the reduced draw length, and finished sanding and any final radiusing, you might find a slight loss of draw weight or need to touch up the tiller somewhere.

Ok, I will keep that in mind and not go over 26" draw before shooting it some.

twist: http://www.primitivearcher.com/smf/index.php/topic,27206.0.html

Does the thickness run off to one side where it is twisted, or do think the wood varies in the twist area? maybe softer

I need to take a picture from the end so you can see what is happening. After reading that thread I can see I have mislabelled it. The limb is not pulling off to one side, it is much more of a propeller twist that doesn't change from unstrung to braced to drawn. It might get slightly worse when drawn but not by much. I will check the limb thickness to be sure I didn't scrape in a bevel, but I have been watching for that and have kept everything pretty even side to side so far.

Now that it is braced I will take a string alignment pic as well and post it, in case I am missing something there. You will probably be able to see the propeller from that as well.


Mark

[mmattockx]

Since I have managed to get this far I now need to consider what I am doing with the levers. I left them chunky in case I needed to correct anything but they need to be thinned down in the end. Currently they are 3/4" thick full length and taper from the 1.5" limb width to 5/8" at the tips. The overlays are another 3/8" thick on top of the 3/4".

I was thinking of narrowing them to 3/8" or so at the tips and having a nice, smooth arc from the nock grooves to the working limb and having smooth sides on the nocks with the string groove only across the back of the lever in the overlay. Thickness can be tapered from 3/4" at the limb end of the lever to whatever works at the tips.

Something like this:




All thoughts/experiences/ideas are appreciated.


Mark

[willie]

Hi Mark,

As a substitute for tracing and flipping would pictures of the bow from each side be worthwhile?

what ever works best for the guy doing the tillering. Some take a pic, make it semi transparent and flip it in an overlay with photoshop or gimp. I was inspired by DC to paint a piece of underlayment with chalkboard paint. http://www.primitivearcher.com/smf/index.php/topic,64606.0.html

I have been watching for that and have kept everything pretty even side to side so far

the wood might be weaker there somehow. as it is in the same area as the bend that gave you difficulties.  If the limb does not want to roll of to the side excesssively and cause the grip to twist in your hand as you draw, then I would leave it alone for now and continue on. There is a chance that you might not make your intended draw weight if you remove much more wood in that area. shoot it in first at 26" and decide later if there is a pressing need for correction.

[mmattockx]

Despite our annual blast of winter in March (welcome to Canada, eh?) I managed to get some work done today. The handle got roughed to width and I worked on the limb balance. The handle is wider than I expected so I may take a bit more off once I am at full draw in the tillering. Assuming I get to full draw without pieces flying around.

First, a string alignment shot from the left end:




And from the right end:




Pulled to 17" again after I worked on the right limb some:




It looked close enough to me (rookie eye and all...) to start working towards my target draw weight again. After the work above it went to 24" of draw at 30lb and I stopped there because everything flexed so much getting there that I was flinching waiting for the explosion. First time I've ever tried to bend wood like that and it was scary as hell. Still in one piece, though  :




I stopped at that point for a second opinion on the bend (after the big pull that right limb still looks a bit strong to me) and because my toes were dying in the cold. On the plus side, I have about 1/4" of string follow immediately after the bow is unstrung and it recovers to nothing overnight. With only a 30lb draw weight I assume I shouldn't have much string follow, but it is still nice to see.


Mark

[willie]

Canada? must be east of the rockies, well you almost fooled me with the green grass pic until I realized it was another bow. I'm a bit NW of you in Alaska. 4' on the ground and -10 F. in the morning. springtime!! It does warm up nicely during the day though, lots of sunshine.

the limbs look about as even as I can tell from the pic. That twist fools the eye I think. the light looks like it is coming from low and too the left. maybe a pic with the light from high center? (to minimize the underside of the left limb that shines) Tack up something dark to those shelves for a backdrop behind the limbs please, I would hope that some else would comment also, as I am not the best eye at PA, that I know.

[mmattockx]

Canada? must be east of the rockies,

Yep, just east of the foothills in central Alberta. We don't have your snow but it was -20C all day today, which is way cold for us this time of year. March can be a horrible weather month, though, and a huge tease with hints of spring and then lots of snow and blasts of cold.

the limbs look about as even as I can tell from the pic. That twist fools the eye I think. the light looks like it is coming from low and too the left. maybe a pic with the light from high center?

The light is coming from the big shop door, otherwise it is a cave in there. I will try a pic with the door closed and just shop lighting to see if it is any sort of improvement. I will also work on a backdrop. The shelving was super convenient for a solid tillering tree mount with room to move away while pulling the string, but the busy background is a significant problem. My end goal is a large sheet of cardboard painted a solid colour with grid lines on it for comparison but I need the cardboard first.

I do appreciate all the help, I never would have got it this far without your assistance and the comments from others.


Mark