C'est la vie

[Pat B]

I've only used elm a few times, each time I used the wood right under the bark. I was quite impressed how good of a bow wood elm is. I built 60" selfbows and maybe one sinew backed.
 The reason I asked about the wood is this looks like a tension failure across the back which usually means unsound wood. Was the trunk dealt with correctly after cutting the tree? I had a hickory log given to me that laid on the ground for 2 weeks before putting it in a garage, off the ground for 2 years. The first piece I used failed. That little time on the ground allowed fungi to infect the wood and even 2 years in the dry didn't prevent the infection.
 Trying to figure out the reason for failures can be a real problem. I don't see and reason for failure from your pics so I suggested the possibility of fungal infection.

[simk]

Thanx for your thoughts Pat - I got the staves from a expirienced bowyer and have also seen pics in our club house of a whole group cutting and splitting that huge elm - they did it together, event-like. So I cannot imagine the staves have been laying around long time on the ground. There have already been done successful bows of that tree and mine was a success until I overdraw it. I'm not blaming the wood but only myself...

[bradsmith2010]

 did you check the moisture content

[PatM]

It does seem  like that elm isn't quite the wood our better stuff is.    Also smaller trees seem to be relatively stronger wood.

[AndrewS]

May be the elm had the dutch elm desease (Ophiostoma ulmi / Ophiostoma novo - ulmi). On a big elm, it is possible that only a part of the tree was infected.
Had the stave some dark points or stripes in it ( or some white spots like a salt flake) when you worked on it?

[backtowood B2W]

Oh sh..!
I agree with you simk, it was build right on the edge und you overdraw it!
61" is not really long for this design imo (- i never worked with elm, and never made such a design)
How long are the levers, how much reflex did you have and did you heat treat?