I-Beam construction

[katalyzt]

I've tried the search feature to try and find a description of how this I-beam situation is constructed but I'm having little luck.  What I have learned is that if you make a riser out of curly maple or walnut then you should think of reinforcing it with glass, phelonic, I-beam.  It so happens that I'm in the middle of making a TD riser with those two woods when I read that so I'm trying to educate myself on how to do the i-beam thing   

So how does this go down?  Is the i-beam basically just a piece of material (phelonic, glass, G10) laminated between the pieces at glue up or can an I-beam be added after the riser is basically all assembled and glued up (which is my current situation )? How would I make the slot if adding it after the fact; maybe a router? Any thoughts on getting a reinforcement in there would be super helpful because I'm kind of scratching my head here, I've spent some resources on getting it this far, but I certainly don't a weak bow. 

I can still add glass over the ebony accents and that should help some.   

Have a blessed day!

[Mad Max]

The way you have it laminated together will help a lot, 2nd picture.
What pound of bow are you making?

You are to far into it to do a I beam

[beachbowhunter]

That's a beautiful riser and with the flare laminations it should be pretty solid for a lighter weight (45 or so max?) set of limbs. Yes, too late for an I-beam. To add some strength you might want to take off the short piece of material on the outside of the grip and replace with a couple of layers end to end (right at the limb butts).

[Kirkll]

I have to echo Max's sentiments. You already missed the boat on an I-beam construction on that riser unless you pulled the pins and inserts. Even then... it would mean a lot of extra work.

The way you have that riser footed, and using an ebony overlay on the back, she'll most likely hold together just fine up to low 50's draw weight. But like Beach Hunter said. it should go limb pad to limb pad covering the end grain. Just Capping the end grain on the back of the riser helps a lot and adds strength.  I don't think a glass overlay will be necessary myself.

Something else about an I-beam.... You are better off using a good hardwood I-beam than G-10 or any type of glass composite in the long run. The G-10 has a tendency to not move at all, and the wood will move with different climate changes and MC level.   I still use a lot of G-10 in my risers for extra strength and added mass weight, but i have had to refinish quite a few where the G-10 has separated a fuzz from the wood after it acclimated.   A wood I-beam works just fine and you wont have that issue.   

Same thing is true using glass for accent lines in a riser. Often times those accent lines will stand proud after the wood acclimates. Better off using wood accent lines on footings.   .02 cents    Kirk

[Appalachian Hillbilly]

That will be gorgeous! Maple and Walnut arr mu two favorite woods!. I keep all my bows around 40-45lbs.

Please post up the finished results!

[katalyzt]

Well that went better than anticipated thanks guys.  Although it's too late for the I-beam it sounds like it wont be necessary on this build as I'm aiming for 45#'s.  I think I'll pull the ebony on the back and put a piece that's end to end as Beach Hunter and others have suggested will give me the peace of mind I am looking for.

Kirk Thanks for the info on I-beam material and using other materials alongside wood. That's good info 

Appalacian I just made some limbs that came out at 36 when I was aiming for 50. Yeah a new press and a couple tweaks in the design really threw off my estimate so I now have perfectly good limbs that are making me a bit sad. I guess they're good for a target bow or something?  I dunno I'm new at this.  Anyway, if I were more accurate I would be hitting 45-50 preferably but like I said I'm new at this so that's pretty emotionally based and the fact that I'd like to hunt with them and the min requirement here is 45.

Thank you all for the kind words and I'll definitely post finished shots.  If i don't screw it up along the way... or even if I do I guess 

[Appalachian Hillbilly]

Don't sweat the light limbs! Just make you another riser for them! My first ones( and I am nee at this as well) came out at 30. And that was after  I made another riser for it with shallower lim pad angles!

It was a maple and walnut riser  as well.

[Crooked Stic]

I say if your wood is moving it was not dry enough to start with. Sooo if you got any problems against using wood and composites in a riser then use stabilized wood.
Lots of times MC is a guess at best.

[Kirkll]

If you live and build bows in a dryer climate you have much better luck mixing composites in a riser lay up. Unfortunately... I'm in Oregon and all my wood stays at 12 percent in my shop 9 months out of the year. July-August - September things dry out a bit. 

So i gotta really watch MC levels before i finish the bows. On my G-10 I-beams i like to get it finish sanded and leave it in my spray booth at 80 degrees for a day or two before i squirt it just as a precaution. If its going to seperate a bit or shrink it will, and is easily taken care of.    Kirk

[katalyzt]

I currently live in Utah where it's pretty darn dry all year but I did live in Maui for 6 yrs where you're constantly fighting rust and warp 

[Bow Bender]

  I realize that design and the way the back of the riser is shaped has a lot to do with the strength of a riser.   With a riser of the design of the one in question what woods do you all recommend for the I-Beam to give a riser the necessary strength in 55 lb or higher bows?

[beachbowhunter]

Definitely build another riser for the extra limbs. At 36# that bow would be great to give to someone to get them into archery.

[Kirkll]

  I realize that design and the way the back of the riser is shaped has a lot to do with the strength of a riser.   With a riser of the design of the one in question what woods do you all recommend for the I-Beam to give a riser the necessary strength in 55 lb or higher bows?

Pretty much any kind of hardwood will work for an I beam. Even using the same Black Walnut or Curly maple will do the job. But you need to consider the grain of the wood and cut it thick enough to still have a portion of it left when you cut out the shelf.  3/8" is a good thickness for cutting a shelf just past center, or you could use a thinner I beam and off set it so it doesnt show at all.

Here is a figured Black walnut riser that has a radius footing and a 1/4" G-10 I-beam that is off set so it doesn't show. This bow is 55# and has lasted for quite a few years. but the same could be done with, Bubinga, Wenge, Bocote, Ebony, Shedua, etc...etc...   (Click on links below photos for album photos)

https://goo.gl/photos/mxuQUGwQuUK9GAbq9

These are wood I-beams

https://goo.gl/photos/vugN1Dk4bTbPgfZS7   

Kirk

[katalyzt]

@beachbowhunter 

@kirk Thanks for sharing.  Beautiful and informative with ALL the different shots.