Face or back

[Flem]

I'm a big fan of Smooth-On products, but I would not put much stock in what information the "tech" folks
give out. They are not inclined to admit anything will work. They were dubious about me using Epoxamite as an adhesive. They told Big Jim they would not recommend using dye in their epoxy without testing first. They sell dye to use in their epoxy's! And then they told you the thinner "might' weaken the epoxy. If it does, what it amounts to is irrelevant.

I use Epoximite exclusively for lams and glueing up bows. I have used both the Epic thinner and the flexiblizer with success. You have to make some adjustments from using EA-40. It's not a gap filler, so lams need to be ground finer and you need pressure distributed evenly over the entire blank during glue up. Might not be appropriate for clamping or wrapping methods.

[williwaw]

Let's go ahead and post them up.

Thanks

Flem,  I agree on the thinner stuff and maybe I'll go against the tech support advice and try the epic with the EA40 or maybe use Epoximite if you think it will hold up in a bow.

smooth-on does not seem to have technical spec sheets for their products on their web site. I use system three, and will compare in principle.

Straight resin has the highest strengths. it is usually supplied in viscosities suitable for laminating fabrics. additives such as fumed silica can be added to prevent runout when the resin is used for an adhesive or for overhead fabric layups. Fumed silica may well be what gives Ea-40 it's extra body . If so, then adding a thinner to Ea-40 would be conbining two additives at cross purposes. Any/all additives weaken strength of straight resin, although they can improve other specific qualities.

Flem mentions closer control of gaps as a option to needing a thicker product. Avoiding vertical joints when curing may also help if you wish to work with a thinner mix.  I also use heat and cold to good effect when using laminating resin as an adhesive and add minimal amounts of fumed silica when neccesary.

[Roy from Pa]

poorly tillered/shocky bows and full draw pics of bows that  get it right

That says it all, hand shock comes from poorly tillered bows.

I tiller for equal limb timing and there is no hand shock in them.

[williwaw]

poorly tillered/shocky bows and full draw pics of bows that  get it right

That says it all, hand shock comes from poorly tillered bows.

I tiller for equal limb timing and there is no hand shock in them.

Lol, my bad. I meant poorly designed instead of poorly tillered. went back and changed that, thanks.

I have read the hill style or asl has inherent handshock.  Is this a myth or are there design challenges to making a damp in the hand bow? Of course any bow can be tillered poorly with unequal limbs. I was hoping for pics of asl's of varying designs, to better understand the issues of building a pyramid bow with glass.

[onetone]

EDB - Thanks for the instructive demo. I favor Locktite CA too. Do you have any experience w/ System Three G2 epoxy? I think it is a good product and it has a lower viscosity than EA-40 - good numbers too.

[EvilDogBeast]

No worries, happy to help!  We use 3M and Henkel/Locktite almost exclusively for our aircraft.  All of their adhesives and resins are bomb-proof.  I have not used G2 but I have heard good things.

On the topic of ASL's and set:  It seems most are built with two or three very thick core laminations tops.  Would a higher number of thinner laminations reduce set?

[Stagmitis]

It doesnt Evildog.

But Carbon and Woven glass on the back does to a degree. Shredd noted that linear glass stretches when applied to the back and I am tending to beleive that. The odd thing with a hill bow is that it will take a set (Lose preload,backset) when strung and shot  even for a short period of time. However once unstrung and at rest for a short period it recovers what was lost. I have to think the back material dictates that not the belly.



Flem have fun with this one:
https://www.sakimarchery.com/en/diy-bows/195-2476-still-tech-laminations-.html?fbclid=IwAR09ibtjU8Coj0IGMvJ2fdNO6LH1KgpFEpL_khv_OUDTpJ4-Y9juafgS85I#/241-larghezza-45_millimetri/243-length-920_millimetri/244-finish_color-red_kevlar

[Longcruise]

I used the Evil Dog method on this sample and think it worked well.   Decision now is pre-preg or glue up at lay-up. 

Looks like air in there but it's tape residue.

[Stagmitis]

Loncruise I have done it both ways with smooth-on and found that heating both parts before mixing together helps alot with wet-out and eliminates air bubbles-I use a roller

However smooth-on is not as strong (doesnt provide the stiffness) and is more viscous than other thinner laminating epoxies. So I prefer a pre-preg






 (

[Longcruise]

Loncruise I have done it both ways with smooth-on and found that heating both parts before mixing together helps alot with wet-out and eliminates air bubbles-I use a roller

However smooth-on is not as strong (doesnt provide the stiffness) and is more viscous than other thinner laminating epoxies. So I prefer a pre-preg

I'm leaning toward pre- preg if only to allow knowing exactly what will be inside the bow. 

Also thinking Huntsman glue because it is said to be thinner.

Anyone have experience with EA40 and Huntsman who can describe the difference in viscosity??

[alaninoz]

Now that this thread has quieted down I'd like to thank all those who contributed to it. I've learned a lot from the discussion. I'll never use most of what I've learned but knowledge is never wasted.

[Flem]

   Discourse is a good thing!

[Roy from Pa]

  Discourse is a good thing!

Depends on the opponent:)

Just sayen...

[Shredd]

The thread went off in different tangents... Which can usually happen and good can come from it... The most important thing is whether Longcruise got his questions answer to his liking...

  Well Buddy...   Did you find out which side of the bow should be optimized??  Or summarize your findings from all this...  Curious what you are thinking...

[Longcruise]

The thread went off in different tangents... Which can usually happen and good can come from it... The most important thing is whether Longcruise got his questions answer to his liking...

  Well Buddy...   Did you find out which side of the bow should be optimized??  Or summarize your findings from all this...  Curious what you are thinking...

As was said,  the topic took off in several directions.   Not a bad thing at all.

So the original question addressed which side of the bow should be the more heavily reinforced for best performance and retention of form.  There seems to be a consensus that performance is more related to tension (the back)  as opposed to the belly (compression). 

I was/am more interested in retaining form or IOW, preventing set in an ASL  build. 

Still wondering why tension is thought to be a greater contributor to performance than compression.   Indeed,  if one is pulling (tension) then the other is pushing (compression) is it not?  Both wood and glass are typically stronger in tension than compression so what is the best way to make both do equal work?

[Mad Max]

Put masking tape on the whole limb Belly and brace it and the tape will be wrinkled .
Put masking tape on the back when braced, then un brace, wrinkled

[Roy from Pa]

It all hinges on where you place the neutral plane determined by the coefficient influence of your back and belly wood choices.

[Mad Max]

coefficient
whats dat

[Roy from Pa]

Look it up Einstein...

 

[williwaw]

I was/am more interested in retaining form or IOW, preventing set in an ASL  build. 

Still wondering why tension is thought to be a greater contributor to performance than compression.   Indeed,  if one is pulling (tension) then the other is pushing (compression) is it not?  Both wood and glass are typically stronger in tension than compression so what is the best way to make both do equal work?

the takeaway i am getting from this discussion is...... if you can strain the back harder, it is storing more work.  Set most likely comes from the belly side core, as wood is susceptible to compression damage sooner.