Power Lams - function?

[Bel007]

I have been reading a few threads about using power lams and how-to-make power lams, but I am not at all clear about their function.

What are they supposed to do for ya?

[kennym]

They manipulate where the limb bends, moving the bend away from the fades of riser.

Tip wedges do the same on the end of limbs.

[Crooked Stic]

Kenny has it right. I will add that they also take some of the stress off the fades. Why move the working part of the limb toward the tip you ask? You will be moving less mass on the power stroke = more arrow speed.
The tip wedge stiffens the tip to keep a better string angle and prevents early stacking.
You have to remember first is a good design. ThePL and TW may enhance performance.

[Buemaker]

Is it used much in a glass laminated bow? I thought it was mostly used in an all wood or wood- bamboo laminated bow to stiffen the handle section to keep a glued on handle from popping off. Bue--.

[PV]

I use them in all of my bows glass or natural Bue.As Kenny and Mike stated they manipulate the bending of the limb. My drum sander grinds a  more precise fade than shaping them by hand.

[bjansen]

I especially use a power lam where I have a very short riser and a steep fade (think of a Herter's 46" bow for example).  Its a little added protection to keep stress off a short fade.

[coaster500]

Brian you got my curiosity up so I found a few answers...  Just a few as there were many more. These are from some members and sponsors.

Dick in Seatle...power lams are short, tapered laminations that serve to extend the very thinnest part of the fades so that the bow doesn't curve too close to the riser. In other words, it moves the power up the limbs. They're a complication in a simple build and I resisted using them, but Kirk (who is a sponsor here) kept telling me to try them so I did. I extend the pl's 3" to 4" past the end of the fades, so with the 18" riser I use on bows for myself, I use a 24" to 26" pl. Depending on the weight of the bow, these will be from .100 to .130 in the center with the taper going to zero at the ends.

Sixby...I build for short or long draw by adding or adjusting power lams in the stack. This allows you to use a conventional length riser and shorten or lengthen the working area of the limb so that it performs best at the draw length you want it to. You will never get a short draw to perform like a bow with several inches more string time but you can get a short draw to perform at the best level for that draw. A bow designed to draw 28 inches does not cut the mustard for a 24 in shooter compared to that same bow designed to perform at 24 inches. A really good bowyer can make the difference for you. God Bless, Steve

Apex Predator... A power lam is a short lam that extends just a few inches past the riser fadeouts, which serves to move the bend in the limb out from the riser.

[Buemaker]

Okay. Let us say that on the back of a RD bow you have a glass laminate and two wood laminations before the riser, is it then advisable to lay the power lam between the two wood laminates? Bue--.

[PV]

I've not found any difference where you put the PL in the glue up Bue. In my tri lam wood bows I place it as you suggested. My glas bows between the lams and the back of the riser although I have run it on the belly of the riser as well. The power lam is essentially your fadeout.

[Crooked Stic]

I put mine on the belly side of the riser. Beside taking some fade stress when moving your bend toward the tip you will have less mas weight moving back to brace = some better performance. You just dont know how much untill you try it. To see the results you have to build idetical bows changing the power lam only. Prototyping takes time and $$ so it may not be for everyone.