Starting the next tri lam

[Ice Mike]

I've got the lams just about ready. On the last one like this I tapered the backing and core Lams. On this one I'm going to keep the backing lam straight and taper the core a little more. This is going to be pecan/pecan/walnut in that order for backing/core/belly. This one will have a 16" riser section (not sure on the wood yet) with 4" fades so I don't have to go so thin on the walnut belly to make the transition like I did on the last one. I'm going to put a final backing on this one with sinew before I start tillering to try to end up at 50-55@28 with no splinter pops. The specs are:

65" ntn
1.5" width to midlimb tapering to .5"
5/8" thickness from fades to 3/8" at tips.

Here is a pic of the lams and form I'll be using.

 

There are a few more adjustments I need to make on the core before I start initial glue up. I have marked the thickness on each side of the pecan core and have put the amount I still need to reduce between the numbers in a circle. I'm going to try to get it as perfect as possible this time before I even pull out the scraper.

 

[LittleBen]

Mike, I lke your plan but I would recommend not using walnut as the belly. It is not very strong in compression. Pecan would be much stronger.

Walnut is light weight and better suited to being a core.

[Ice Mike]

Thanks for the advice Ben. You know, come to think of it, I think the layers would compliment each other much more color wise in the configuration you are suggesting as well. Now is the best time to change that. I'll work on it tomorrow evening and post the results.

[Bowjunkie]

I concur with putting walnut in the center.

[Roy from Pa]

Me 3..

[Black Mockingbird]

Me 4...and no need to sinew that either to hit your weight...learn how to tiller to a specific weight instead....plus it doesn't need sinew...hickory is more than capable as a backing(as long as u chose an acceptable piece with acceptable grain)...if wanting to keep splinters at bay just use rawhide..but again if you chose a good piece you shouldn't have to worry about it

[Ice Mike]

Originally posted by Black Mockingbird:
Me 4...and no need to sinew that either to hit your weight...learn how to tiller to a specific weight instead....plus it doesn't need sinew...hickory is more than capable as a backing(as long as u chose an acceptable piece with acceptable grain)...if wanting to keep splinters at bay just use rawhide..but again if you chose a good piece you shouldn't have to worry about it

Herein lies my issue...I have a 1.25" thick slab of pecan about 18" wide and 12' long that I picked up from a sawmill in Natchez, MS for 25 bucks. You can see some of it in the pic above beside and underneath my form. This is all the material I have on hand for honing my bow building skills so I don't have the liberty to select a "perfect" piece. I have to use what I have on hand and I also have a bag full of Elk leg tendons I can process into sinew. I know the grain violations will require backing for keeping splinters down if nothing else. I also need the practice in processing and applying sinew. I know it's probably overkill but I'm really more concerned at this stage about what skills I can learn rather than having a foolproof building process.

Not sure if I'm making any sense with that statement? LOL

[Roy from Pa]

18 wide by 1.25 thick? I would cut that board out so I had a 1/4 sawn piece of wood for my bow.

[Ice Mike]

Originally posted by Roy from Pa:
18 wide by 1.25 thick? I would cut that board out so I had a 1/4 sawn piece of wood for my bow.

I'm still learning here, so please excuse my ignorance...but could you elaborate on what steps you would take to do this? I understand what 1/4 sawing at a mill is, but I'm not sure I understand how you mean to turn an 18" wide by 1 1/4" thick plain sawn board into a 1/4 sawn peice??

[Roy from Pa]

A lot has to do with the grain the board has, but if possible I would orientate my cut so the bow slat would be 1/4 sawn if possible, or at least rift sawn. Here is what you want the end of your board for the bow to look like if possible. This board is closer to rift sawn than 1/4 sawn. 1/4 sawn the grain would be running straight vertical.

 

What I am trying to say is, your board is 1.5" thick, which is what the width of your bow is going to be, so therefore you have enough thickness in your board to cut it in a manner to get rift or 1/4 sawn material..

[Ice Mike]

Got it. Thanks Roy for explaining that. I was thinking more of the technique of how the wood was sawn from the mill, and not so much how the grain lines up in the board as a result of that sawing technique...

Classic case of OVERTHINKING it!

[Roy from Pa]

Yupper, here is what I strive for, Mike..

 

Then I run them through the drum sander to even them up and or taper them if needed.
https://www.youtube.com/watch?v=jjSbwgKB7FA&feature=youtu.be

[KenH]

Interesting form, Mike. Glad to see I'm not the only one who uses a non-firehose type form.  Mine is  pressure treated 2x8 with dowels spaced every 2" and bicycle innertube bands:

 

[Ice Mike]

Originally posted by KenH:
Interesting form, Mike. Glad to see I'm not the only one who uses a non-firehose type form.  Mine is  pressure treated 2x8 with dowels spaced every 2" and bicycle innertube bands:

   

Thanks Ken. That's a nice looking form you got there yourself!

[Ice Mike]

Well I went and picked up some more walnut today to remake the core. I decided to try and find a better and more accurate way to taper the lam, so after a little brainstorming,  I came up with this.

   

It's a jig for clamping the handle area and one limb flat down and running a router with a straight bit set at 1" depth. I thought it was a great idea and it actually produced a perfect evenly shaped and even thickness taper all the way down until I got to the tip area. I didn't anticipate the effect of a high rpm cutting bit inducing torque on the wood that it is cutting, thus producing a nice explosion when the thickness of the wood is too thin to handle the vibration and can no longer hold its fibers together.

 


Long story short, I ruined a perfectly good walnut lam and I just have enough wood for one more. I may use the jig and router down to with 6 or 8 inches of the end then finish it off on the belt sander. I may just do the whole taper on the belt sander just to be safe. I'll try again tomorrow evening when I get off work.

[Roy from Pa]

 

[LittleBen]

Doing glue ups at 6am Roy?

Sleep in once and a while man, you're retired!

[Ice Mike]

Well I think I finally got over the "can't make a tapered lam blues" and built a solid jig that spit them out consistently.
Here is a pic of the jig. It sits on the platform of my Ridged belt/spindle sander.

   

I also took Roy's advice and made my tapered core in two pieces and then spliced them. Got the splice done and clamped down. After the glue dries, I'll test the joint and and glue up the core and backing lams. Then it's just making the riser and gluing that up with the belly lams.

   

 

[Roy from Pa]

Don't go testing that glue joint too much, it will be fine once everything is glued together! I have already not even glued the core lam into a splice. I just lay it in there at glue up between the belly and backing. The backing, belly lam, and riser will be all the support it ever needs. What's the little piece sticking up for?

[Ice Mike]

That's a fine strip I put in the joint to make up for the kerf of the blade where I cut the angles.

Also, I am going to put this in my form to make it a reflex deflex. I usually glue up the core and the backing and then use the result to make the riser section conform to the curve. Then I glue the riser on with the belly lams going up the fade.