heavy elm bow, advice for measurements

[Aksel]

Hi all, I have a nice slightly reflexed, absolutely knot free, pipe straight wych elm stave, 76 " long 1,1" thick. I am considering making a heavy bend in the handle bow around #100. Just for fun.


I made one heavy bow of elm many years ago. It shot decent I think, but I made the belly slightly rounded and it developed chrysals in a couple spots eventually. Maybe was it also slightly too narrow for a heavy draw weight. Think it was 1,3 or 1,4" wide at the grip. Lesson learned. Will make the belly flat this time.

But to anyone who has made a successful elm bow of higher draw weight, how wide would you recommend I make it?

[RyanY]

Those dimensions don’t sound far off. I’m not sure I’d go much wider than your previous measurements. Maybe try for a flatter belly this time and keep it the full length.

I recall Marc has made a couple elm warbows with smaller dimensions. If you can find those posts they would be a good reference.

[Aksel]

Thanks Ryan, I´ll see if I can dig up those threads

[willie]

your stave length fits well with some mary rose profiles

http://www.primitivearcher.com/smf/index.php/topic,61640.msg862289.html#msg862289

[Aksel]

Thanks willie, just what I was looking for.

My stave holds a 3 inches of reflex and specific gravity is .68. Quite good for whych elm

[Marc St Louis]

I have made a few Elm warbows.  One that I made for a guy that was around that draw weight was damaged during shipping, one tip was crushed, so I made him a replacement and he shipped the damaged one back.  The damage was repairable and I still have the bow.  It's not a full D section bow such as you would see with Yew, more flattened but still rounded belly.  If the Elm is good quality it will handle a round belly if properly tillered

This is a picture of the replacement bow at it's full draw of 32"

[Aksel]

Thanks for your reply Marc, that´s a very nice bow. How tall / wide/ thick was it? Actually I re´read your chapter on heat treating in TBB4 last night

This 76" stave has dried into 3" reflex, is pipe straight and knot free. Specific gravity is .68 and my experience with my local elm tells me it is of very good quality.

I know you heat treat your bows, but if I won´t, - would you recommend other measurements or precautions than 1,4 -1,5 inches max width for a starting point for 76" 100 lbs @ 32" ?

If it comes out low set and good tiller at 100 lbs I might try and pike it to see if I can push it. One thing at the time..

The picture included is of my old heavy elm bow from 2006. Estimated 90-100 lbs on the results I got distance shooting.  I think the tiller was decent, but probably not good enough as it developed a couple of chrysals on a rounded deep belly. Maybe was the tiller too elliptical..?

[RyanY]

Not the best angle to tell the tiller. How much of the limb has chrysals? If it was localized to the mid/outer limbs, I’d suspect a tillering issue. If it was along the whole bow, I’d suspect the rounded belly was the issue.

[Aksel]

 The chrysals were like thin hairs on 2 spots upper limb and one on lower. Both limbs chrysaled on inner mid limb. Was nothing major but I soon threw it away afraid it would kill me if it broke but in hindsight it could probably have kept shooting for a while. But since I was a "green" bowyer then, I´d suspect tillering flaws.

Here´s the stave btw.

[superdav95]

I’ve not made an elm war style bow yet myself.  On my list to do as I wait on my elm stash to dry.  Looking at your bend compared to Marc’s bend it looks like more bend in handle perhaps may have been better???   Hard to say with the angle of the photo but possibly more bend they handle may have resolved some Chrystal issues. 

[willie]

http://www.primitivearcher.com/smf/index.php/topic,69818.msg980227.html#msg980227

the "120%"  bend formula came from a study of the mary rose model linked earlier.
the first elipse drawn was for comparing the bend at about half brace

more discussion on "proper" bend
http://www.primitivearcher.com/smf/index.php/topic,70269.0.html

[Aksel]

Thanks for all the links willie, very helpful, just what I am looking for. I think the reflex together with the heavy draw weight will be the biggest challenge for me.

[Marc St Louis]

I took some measurements of that bow and it is 72" long by 1.375" wide and 1" thick at the center, longer bow would need a bit more thickness for the same draw weight.

I also made a slightly heavier bow for Jaroslav many years ago, well maybe a bit more than slightly.  It turned out to be in the 150#+ range at 32".  This is that bow

[Aksel]

Thanks for the measurements and pictures Marc! This together with the links and advice offered by others will give me something to start with. Thanks all.

[Badger]

     I would monitor the set very closely and not hesitate to drop weight at the first sign of set. At 1" wide elm you will be lucky to get 60# without over-straining. Just my guess here.