help with cracks in riser on shrew samurai

[ozy clint]

gday guys, my brother in law has a problem with his shrew samurai. there are some major cracks in the riser. it's a 2 piece with a bow hinge. not sure who installed the bow hinge and i suspect this modification is the root of the problem, since i just read that shrew use a bow bolt.

the pictures aren't the best but the riser itself has cracks on both sides and the overlays and bamboo back lamination on the top end of the hinge is starting to delam on both sides. i imagine the shelf material is covering up some of the damage too.

any possibility of a sound repair?

the cracks are big enough that the corner of a sheet of paper will fit in there when the bow is braced. goodness knows what they're like at full draw!

   

   

[JamesV]

Clint...............

Those cracks can be repaired but would they hold long term is the problem. I would say 50/50. I repaired an old Pearson (1967) that was really bad and my wife is shooting it 3 years later. I would get a bottle of Locktite 420 and fill the cracks. That stuff is really thin and will wick completely thru the crack to the other side. The repair should not even be noticeable if the bow is refinished afterwards. That would be my suggestion, let me know if I can be of help.

James

[ozy clint]

thanks james. i thought loctite too but they seem more serious than that. he would consider turning it back into a one piece if it meant the bow is saved. i thought maybe that the hinge could go and some better way of strengthening it as a one piece?

[LittleBen]

That's a real nice bow.

If it were me I would use thin super glue. Loc-tite or whatever brand you prefer but it's needs to be thin like water. I'd mask off near the crack just to limit how much of the finish gets sh***** up and drop in the glue one drop at a time until it wicks through to the other side of the crack. I'd let that dry for an hour or so then repeat until no more glue will go in. May take a few rounds.

If you're not comfortable doing it, then this might be a job for a professional, or a knowledgeable hobbyist bowyer.

I think the best thing to do it probably leave he hinge as it is. If anything I might remove the screws for the hinge and check if there's cracking in the screw hole as well. I would put just a drop or two of thin glue in there as well if there is visible damage.

[mikkekeswick]

Sure you could try to fix it but what you've got to ask yourself is WHY it did this in the first place? Without handling it myself I can't say the exact cause but what I can say is that the area supporting the hinge is simply not strong enough to do so....so once you 'fix' it what is to stop it simply starting to crack again? Even if you do a good job of getting glue in there then it is already seriously compromised.
Personally for me it would be a wallhanger from now on.

[SportHunter]

In your second picture above the arrow it looks like there is a space where the lams and glass end and a strip behind the bow hinge begins with a gap between the two. If so it is probably a weak spot that is transmiting pressure to the wood in that area.

[yaderehey]

I think it was a seriously botched installation of the connexion hinge.  It looks like they chunked out not only the overlays and bamboo but the backing glass as well to try and get a "flush" fit of the whole hinge.  I believe they should have just cut out the half moon for the actual hinge. Then rest of the hinge mechanism would normally go over the lams and have the screws to support and prevent lifting/delamination.  It's not supposed to be perfectly flush and it's actually cut deeper than flush on the top end of the hinge.  There is nothing supporting the ends of your lams where it was cut out and it's at a high stress area.  The cutting out probably didn't help the glue lines any either.  They did add some sort of black material under the whole hinge but it's hard to tell what it is.  My sense is the hinge needs to go and you can try to  fill in the area of chunked out lams and then add additional strong overlays on the back of the riser to hopefully hold it all together.  I think it would have to be a one piece again as I don't think a bow bolt would work at this point.  There are others on this site who know a whole lot more than me, but I don't think I'm too far off. I think your work is cut out for you in any case.

[LittleBen]

Yeah I agree as above. This is not a simple fix. I think you're right on with the fitting of the hinge yadereh