More dead horse questions, this time, power lams

[skeaterbait]

I have searched a lot of threads about power lams and I get the basics of the function, but nobody really talks about the design. Length, thickness etc. For instance, should the lam extend a certain amount past the fades? Are there guidelines for thickness? Should there be a bit of parallel before it tapers to nothing? Is it ok to kiss on a first date?

Just trying to learn here 

[Roy from Pa]

Ya.

[Bvas]

My take and my $.02.

Power lams do two things. Help protect riser fades and make limbs bend more further out(midlimb and tips).

Length and thickness can vary depending on what you want to achieve.

I make sure there is a constant taper in any part of the powerlam that extends past the riser fades.

Kissing is highly promoted on the first date. Unless your dating my daughter

[BMorv]

I know power lams from an all wood bow perspective, but the concept should apply to gwass. 
You want the PL to be longer than your riser, I would say at least an inch past the fades, so 2 inches longer as a minimum.  It serves a few purposes.  One it takes some stress away from your fades.  You can get by with a shorter riser and steeper fades if you have a PL. 
Second, it minimizes the working limb of your bow, which means less overall vibration in the limbs, and the bow should be more efficient.  Granted, you want to make sure the bow is designed to handle the shorter working limb. Your mid limbs are now handling a larger portion of the load. 
All else being the same, it will add weight to your bow. 
On my tri lams I normally do .25" thick, 16" long, start fading 2" from each end.  But I have done them as short as 10" depending on my riser, and lately I've incorporated a forward handle and PL in one. 
I like to think of them as tip wedges for your inner  limbs.  You can control the bending shape and strength of that area by adding a PL.  And add some color and shape. 

[skeaterbait]

On my tri lams I normally do .25" thick, 16" long, start fading 2" from each end.  But I have done them as short as 10" depending on my riser, and lately I've incorporated a forward handle and PL in one. 
 

I am surprised to see .25", that is significant. Not doubting mind you, I just did not expect it.

As far as the forward handle/PL in one, would you be opposed to sharing a pic of that, I am intrigued.

[BMorv]

I go a little thicker or thinner depending on the shape/look I'm going after.  The fade part is basically the same no matter which middle thickness I pick.  So the effective part of the PL is the same, if that makes sense.
This one is 15" long, about .3" thick in the middle

This is the forward handle one.  I guess you all would just call it my riser, but it's 16" long so it functions as a PL too.  If I didn't care to strengthen the inner limbs, I would only make it 12" long.

[skeaterbait]

Gotcha, thank you.

[Roy from Pa]

Well I guess we use em here too.

I'm getten just like them gwass bow guys.

[Buemaker]

In this three lam the powerlam is 7/32 thick in the middle, 19 1/2 long.
Glued on riser is 12 and bow is 65 ntn.

[skeaterbait]

Thanks Bue and nice bow.

[Roy from Pa]

Interesting, Bue.

I'd like to see that at brace and full draw sometime.

[Shredd]

   Here is my 2 cents and some guidelines to go by...     I am assuming you are talking for glass bows... 
   
     Coming from some other bowyers that I have talked to and my personal experience...  The thickness of the PL at the fade is around .020 to .025" and extend 4"-6" past the fades down to nothing...  Maybe start at about 5" past your fades and go from there... You are gonna have to experiment to see what works best for your design... To much PL and your limbs are gonna stack...  This is where a accurate DFC, measuring string tension and accurately measuring arrow speeds comes into play and can be very helpful on improving your performance...  Think long and lean...  On an overall limb thickness every .015" can gain you 5lb...  So when you think PL, think that with .015" added to the base of your limbs you are theoretically putting a 45# limb  base on a 40# limb...  You want the base of your limbs at the fades to hardly flex at all and then gradually flex more and more when you go out on the limb...  You might have to make 10 to 15 bows to get it just right and get optimal performance from your bow...  .005" plus here and or minus there can make a difference...  It is a War of Thousandth's of an inch...  If you are gonna get into this make sure your your tapers are very accurate, that way when you change things around your changes will be more consistent and accurate...  You can make a fast bow with un-accurate tapers but when you find that magic recipe you better stick to it and don't move a thing...  Another words don't go sliding your tapers around...

   I think it is ok to go parallel up to about an inch past the fades but no more...  But that is my personal opinion...  It could work differently on different or other bows...

   If you have a short draw go a little longer on your PL  (1/2 to 1 inch)... If you have a long draw you may want to go a little shorter... (1/2 to 1 inch)

   If I were you I would start experimenting with Hyper Lams (super lams)... I believe that is the way to go...  They are easier to work with and in my opinion they will be more consistent and accurate in the end results...

  Always try to get to second or third on the first date...  She'll appreciate it...   

[skeaterbait]

Thanks Rich. I may have to go with the superlam. Frankly I can't afford to build that many bows to chase down one aspect. Maybe after I win the lottery...

[BMorv]

I'm glad a glass bow builder chimed in.  The more I think about it, although the concepts are similar, the dimensions will be very different for glass bows. 

Bue is that ipe?  If so, I bet that was a good board.  Very dark= very dense=very good bow= Roy itching.

[Buemaker]

No, not Ipe, but Lignostone. That is resin impregnated, heat compressed Beech wood. Very strong in both compression and tension. Heavy, twice the weight of ordinary Beech.

[Roy from Pa]

Heck Mr. Ben, even I knew it was Lignostone:)

[Crooked Stic]

I would be willing to bet that most of the bowyers that do it for a living are not too concerned about PLs and PWs. Just too many extra parts to worry about. Not saying they dont have their design optimized with a special ground lam.

[buddyb]

Ok not trying to change the subject or hijack the thread but what is a superlam???

[Forwardhandle]

I like the supper lam concept for the reason Mike mentioned less parts when I use one it's usually at least 2" beyound the riser fade for the PL portion ,I guess it would depend on where you wanted your limb to bend to ,I suppose if you didn't want a wedge in it , it could be made with out it !

[Forwardhandle]

Sorry Buddy I posted at the same time as you but a supper lam is a PL ,lam & wedge built in a solid lam the lam portion could be taper or parallel !