Hemlock Branch Bow

[PlanB]

Day 3:
1043 grams. Curve 3-3/4"

Day4:
1025 grams. Curve 3-1/4"

Day 5:
1014 grams. Curve 3-3/4" (measured with springback after 20 min.)

[PlanB]

Today I drew a center line down the back, following the grain, and then marked out widths to trim the butt end down to almost the same width as the branch end. I also trimmed some of the belly off at the thick end. Then I weighed it before lashing it back down. Weight is presently 912 grams, which means I trimmed off 102 grams of wood. The heartwood is quite hard, and the sureform rasp tended to skid over it. A sharp low angle block plane worked better for me.

[Fox]

 

[PlanB]

Thanks Fox.

Day 6:
904 grams. Curve 4-1/4"

Curve increased possibly because of wood removal altering the drying rate of part of the limb. But the curve is now in line with how I would string the bow to keep the handle in line with the tips, instead of sideways, which is a gain. I doubt lashing down will reduce the deflex further at this point, but I'll continue to dry it that way.

Change in weight due to drying, in grams has been:

Day 2, 71
Day 3, 20
Day 4, 18
Day 5, 11
Day 6, 8

[PlanB]

I took another 100 grams off the heavy end, bringing the limb to 804 grams before putting it away for the day.

[willie]

Curve increased possibly because of wood removal altering the drying rate of part of the limb.

I have found that the reddish compression wood takes longer to dry than the whiter wood, and it will also shrink longitudinally as it dries, causing "reaction wood" type internal stress. 
as you tiller, if you remove more of one kind (and expose proportionately more of the other) the limbs will move.

[PlanB]

Hey, Willie.
I guess we'll find out what the problems are when we start tillering.
Day 7:
784 grams (drop of 10), Curve 4-1/4" (no change)

Even though the each limb curves out and in in opposite directions (S Curve) the tips and handle center are all in a line.

[PlanB]

Day 8:
786 grams (gain ?)
Later..... noticed a small check starting through the center of the belly near the butt end. I put the branch outside to slow the drying.

[PlanB]

Day 9
799 grams.

The branch picked up 13 grams on the porch in damp weather, and the check at the bottom end closed up again.

I brought it back indoors. Indoor humidity today is 33%. That's pretty low.  I'm putting a coat of linseed oil on the whole bow, Let's see if that helps slow the drying rate.

I'll have to to think about that check. It was hairline and about 2 inches long between two very small pin knots on the belly side about 8 inches from the tip. Gone today. If it opens again so I can find it, I might try a superglue repair.

[PlanB]

Yesterday I superglued the belly check and linseed oiled the whole bow. I weighed it in the evening afterward and it was at 787 grams. This morning I weighed it and it was at 788 grams and the filled crack is unchanged.

This crack is very fine, and it looks like it might be fairly shallow. It's near the end of the bow, which is presently 7/8" thick and may get worked off when tillering the belly down.

[PlanB]

I did some more wood removal on the branch. That brought it to 752 grams. I'm bothered by a side bend in the butt limb. I was going to just orient the bow to let that be compensated by the upper limb giving an S-shaped bow with the handle centered. But it just bothers me. And I do wonder how it will affect the arrow flight. And it's going to make tillering hard. I think I'm going to try steaming the curve out. That's a big question mark here because I don't believe softwoods are as amenable to that. And hemlock branches are a further unknown. But well, that bend bothers me, and this is an experiment, so lets just try it and find out.

[PlanB]

I gave it 40 minutes of steam, and the curve actually straightened over the pot. It was probably a drying warp. I nevertheless strapped it down bending in the opposite direction to prevent it from returning, and to allow for spring back.

[willie]

PB,
sideways bends are tolerable if tips and arrow pass line up where you want,  and the reddish wood is high in lignin, which makes it very amenable to heat bending

nice experiment.

[bownarra]

Don't worry about sideways bends until the bow is braced. Only then do you know for sure how the bow will 'line up'. Even with the string outside of the handle it isn't really a big deal (it will still shoot just fine) and almost to be expected when trying to make bows from small saplings like this.
your small check will be long gone by the time it is a bow. To avoid this happening (or at least reduce the chances) rough out the thickness taper to a stout floor tiller. The tips needn't be anymore than 1/2" thick.

[PlanB]

No problems here fellas, I just didn't like the curve and wanted to see if steam would do anything on a hemlock branch, and it did. I've been gradually working it down over the last couple days. We're at 602 grams and ready to brace. There's a fair amount of deflex, but that's intentional, as mentioned early on. Brace height will have very little tension.

This couple of old videos from John J Riggs was what got me interested in my own attempt at a softwood branch bow, plus having a cut hemlock with waste limbs to dispose of. Plus nobody saying hemlock was a usable bow wood.

https://www.youtube.com/watch?v=Ga6LCxd8zk0
https://www.youtube.com/watch?v=C1F7cT7s3LM

His bow is a 48"  ttt and draws an arrow to the low 20's.
I'm at 71" ttt so far so I think I have a reasonable shot at 27" draw. Performance will be modest, but so what? The goal is to see what can be done, and how good you can make it anyway.