I-beam ?

[critter69]

I have had two risers crack recently. I have looked at adding a 1/4 of phenolic I-beam but I dont want to see it,in the sight window or along the back or belley of the riser.I read to off set it from center so as to not see it in the window. But iam afraid that when I shape the grip area even with over lays it will be seen. So Iam thinking of using either an 1/8 piece of phenolic or a piece of .060 glass. Would this work and if so wich one would be better? (three piece take down long bow)I have built a few with out it that have not had problems yet.I just want to build them with out having to worry as much.

[Crooked Stic]

Here is an idea that I done. Saw your riser piecs so you glue three pieces back together using the same wood. Say for a 1 1/2 riser width use three .500 pieces. You can start out with your block 2 in. longer than needed and drill 1/4 holes in the extra inch on each end. Then when you glue it up use 1/4 dowells to keep everything lined up. There will be two glue lines but the grain will match up good. Look at this pic you can see it above the grip overlays. If you have to use a composite glass would be my choice.  

[Sixby]

If the phenolic shows in the grip it just says to the owner that the bow is built right. I never have anyone complain about how my bows look. Ever.
god bless you, Steve

[T Folts]

What about a double I beam equal in the riser closer to the outside to give a ballanced look?

[**DONOTDELETE**]

Reinforcement of a riser can be done in different ways and the strength depends on the riser shape and length.

There are pro's and con's using fiber glass accents vs phenolic too. it doesn't expand and contract the same as wood in different climates when the MC level changes.

i think the I-bean is the strongest. if you don't like the looks of a phenolic I beam, use a dense hardwood instead.

every lamination you do in a riser has the potential for more strength or added weakness depending on your joinery skills.

[rmorris]

Jeff, I looks like you are attempting to make an I-beam riser for a three piece take down and as far as I have tried there is not a great way to do it without being able to see the reinforcement on the back or belly side of the riser. the best I have come up with is something like this

 

All the white lines are fiberglass and the Boliviam rosewwod along with the limbs will cover any I-beam pieces in the purple heart and the same is true for the belly side of the bow except for at the ends where you would see your reinforcement.

If you are looking to I-beam reinforce a one piece bow here is one i did. I took two 1" pieces of leopard wood and glued them together with fiberglass in between. I then had a riser block that was 2" thick so I only cut the wood off one side to get it down to 1.5" now you cant see the black fiberglass reinforcement because of the laminations all along the riser and the crescent insert covers it up where there is not lamination. if you do this I would recommend putting an "x" on the side you are going to cut the shelf or you will have the joint running in the middle of your shelf.

 

[rmorris]

Also, if you can show a few pictures of you riser cracks and there is a good chance someone has had the same problem and many have a solution that does not involve a re-design of your riser.

[critter69]

Iam going to try and get my son to help me try and post a pic. Just that I have to wait until he has time. Thanks guys for your help. But to try and explain it. I believe I had a glue joint in a bad spot (right were the bottom of the top limb met the riser.)The riser was an inch and a half (belly to back) wide at that point ,narrowest spot.I am going to make it one and three quarters thick there and change the glue joint location. I was reading that the i-beam construction was the strongest, so Iam thinking of trying it.Iam new at this, but totally addicted. Have to wait until I can get some new woods to try, with out the wife finding out how much it cost.Again thanks