Help, I cracked a riser.

[chefrvitale]

Hello all, I need some advice. I am building a matching pair of bows for my best friend and, we turn 40 this year. They are looking great, but I pulled mine back to look at the tiller and heard a small pop. The pressure made a small crack towards the back of the arrow rest.
I poured some CA glue in it and tomorrow I plan doing something else to help reinforce. Any suggestions would be much appreciated, thanks for the help.

[Crooked Stic]

What' wood. Also corner needs radius to.

[kennym]

Looks like it cracked along grain, might have been a hairline crack to begin with?

About all you can do is fill it with CA and hope IMO

[Kirkll]

It happens sometimes.... It's amazing how much pressure there is on those risers, and when they do crack its usually right where yours did from compression.

 I'll echo Kenny's response. I would use water thin super glue first and let it soak deep into the crack a couple times until it wont take any more. then put the string on the bow and let it set overnight at 60+ degrees.  Bring it in the house and keep it warm over night and keep it strung up.  Hopefully that will do the trick....

Stic mentioned a radius transition from shelf to strike plate. That's very important. Sharp corners have a lot more tendency to split.

There are a number of ways to accomplish this. i cut my shelf depth a bit shallow, then use my palm sander with 80 grit to sand the radius into the strike plate. Or you can do it with a round rasp and a chain saw fie too if you like.     .02 cents worth     Kirk

[Kirkll]

What types of wood are you using in that riser? Can you give us a side profile of your grip/ shelf shape? 

The farther you bring that shelf back over your hand, the more likely you are to have issues like this with softer hardwoods.   Kirk

[garyschuler]

Agree with everyone’s thoughts. And yes, on wood Sharp edges, corners are never a good thing at transition stress areas. Kinda like a waterfall, on a sharp cliff the water falls off sharply. And on a smooth surface radiuses edge. It flows off with hardly a ripple.
Just an analogy.

[chefrvitale]

I appreciate the comments.
The wood that cracked is black and white ebony,it's usually pretty tough. Thanks for the advice on shaping the strike plate radius. I typically do put a slight radius after I rough tiller, but I always thought it was strictly to help arrow flight. I had no idea it would help prevent a crack like this...... live and learn. It's a brand new design and form, kenny just mailed me my hardware for the form. I shoot heavy, this bow will be 70#s and i took the shelf back further than my other bows..... I'm sure that didn't help things. It's soaked in CA, tomorrow morning I'm going to cut across the crack on my band saw and tap in a shim of rosewood covered in EA40. Between the two I think it will hold.

[Smguinnip]

I don’t have the experience to offer any advice, but I hope ya can save it. It’s already shaping up to be a beautiful bow. Would like to see pics when finished.

[jess stuart]

Could you cut crescent shaped piece out of the riser and fit another piece in?  I have done that a few times with success.  Not sure if it would work with the shape of your riser or not.

[chefrvitale]

The patch looks good, but the crack is still visible.
I'm going to string it and hope.

[chefrvitale]

NOPE! Just put a string on it...... she is about to blow! Big pop and is twisted to the left, towards the cracked side.

[jess stuart]

I would try cutting a crescent out if the riser and fitting another piece of wood.  Not much to lose at this point.  Really bad as that is a great looking bow.

[chefrvitale]

I think you are correct. That will be my game plan when I'm finished whining about it........ you guys think it was a bad piece of wood or my design?
This is my first bow out of this form.

[jess stuart]

Take your time and fit the pieces.  Don't want a thick glue line.  Good luck.

[OldRawhide42]

It looks like it might be cut pass center. I would I beam the next one.

[Kirkll]

I think you are correct. That will be my game plan when I'm finished whining about it........ you guys think it was a bad piece of wood or my design?
This is my first bow out of this form.

I don’t see anything wrong with the riser design. Most likely a deep check in the wood that went unnoticed during the build.

The thing that would concern me at this point is that you said after it popped the second time, the limbs twisted to the left…

Looking at that footed riser, I find it hard to believe that riser itself has twisted. But what ever your plan of attack is, I think I’d check my form out real close for twist before I do anything.   You are going to need to put it back in the form to keep the limbs straight while strategically rebuilding the riser from the inside out.  That’s going to be a tough one to pull off successfully.

But you can always cut the limbs off and build a TD bow out of it. I’ve done a few of those years ago after a riser fail that couldn’t be repaired.   Good luck.    Kirk


What kind of draw weight are you working with here?

[Crooked Stic]

As bad luck would have it my guess is a bad piece of wood. I am thinkinking if you could cut it out past the Crack and shape a new piece to fit back . Or chalk up to bad luck .

[Mad Max]

One other thing is you want the high part of the arrow shelf in line with the deep part of the grip for better shooting.

[bownarra]

That should've had an I-Beam.....
Black and white is a pain in the ass.....I bet it wasn't fully dry. No I-beam and a huge stress riser...
Chances are it won't move more but to find out get it warm for a few hours.....
Never cut corners as sooner or later it will bite you in the ass....
I-Beam    I-Beam    I-Beam

[chefrvitale]

You are right, I didn't want to see the beam so I didn't do it. That one extra step cost me bow..... kicking myself, I had even cut 2 strips of that ebony to beam the riser with and decided against it.