unibond prep

[Aaron H]

What do you guys use to prep your wood / boo laminates when using unibond 800?

Also, I have heard of people over tightening their glue ups using C clamps.  What would you say is the proper amount of pressure to use?

[macbow]

Aaron, the only prep I do,with bamboo and Ipe or Cummaru is the surface left from my thickness planer or,sander.

I know others have different views but I have never had a delamination.

As for clamping. I coat both surfaces to be glued. I clamp,very snug but not super tight.

[Aaron H]

And what grit are you using for your thickness planer?

[Aaron H]

I just ran mine through a thickness planer and I used 80 grit, is this suitable?   Would you recommend I use a hacksaw blade or toothing plane on the bamboo?

[Roy from Pa]

80 grit should be fine, I use 60. Don't use a hacksaw blade on boo, use a tooting plane.

[Aaron H]

Anything else work?  I don't have a toothing plane yet

[macbow]

Many do the toothing plane etc. I don't mine are really smooth when I glue.
Most odf mine are light weight kids bows, but even up to 50 pounds haven't had a failure.

Now the reason for using a coarser grit or a,toothing plane is to add more surface for the glue to do it's job. And probably a good safe plan.

[Aaron H]

So maybe rough up the bamboo with 80 grit?  I also have 60

[macbow]

Smaller the grit the better.
Nothing wrong with using double hacksaw blades either. Just be carefull not to catch the edge and,lift a splinter.

[Aaron H]

Got it, thanks Macbow and Roy

[Bowjunkie]

Be careful who you listen to and why. There are MANY requisites.

The grit, tool, and surface prep I choose depends on the glue type I intend to use. The glue I intent to use often depends on the material to be mated. The material to be mated depends on their properties relative to the desired results.

It's not as simple as 'the smaller the grit the better'.

[macbow]

So in this case using 'boo and wood with Unibond what is your advice?

[Roy from Pa]

For best results there, I would use at least 60 grit on the drum sander. Bowjunkie likes 36 grit, but he is a picky perfectionist. For the boo, I would only use a toothing plane. A toothing plane is slightly convex and adds that condition to the boo. I do it that way with unibond800. Bowjunkie uses smooth on mostly.

[Aaron H]

It is a bamboo backed ipe with a maple core and a padauk power lam.  I gave it all a dry run this morning and my ipe belly broke at the glue line at the z splice in the handle.  My form is a deflex / reflex design with the center post being 4", the middle posts being 2 3/4", and my outer posts being 6".  But, I may not have had my shop warm enough a couple weeks ago when I glued the ipe together, it was maybe 60°.   Is it likely that the glue failed because of this, or another reason?

[Aaron H]

I used 36 grit when I fitted the z splice also

[Aaron H]

The middle posts are 13 1/2" from center post

[Roy from Pa]

How long of a Z splice did you make, did you use unibond and did you mix it correctly? How thick is the IPE belly lam? How long is the bow material right now tip to tip? How thick is the maple core lam? 13 1/2 from center post is a good bit of deflex with a 4" center post and 2 3/4 mid limb posts.

But I have had them break early on in bow building, not hardly at all the past 5 years though. Smooth on is a stronger glue for the Z splice.

[Aaron H]

2" z splice, unibond, I think I mixed appropriately, .250 ipe belly,  66 3/4" ttt, .125" parallel hard maple core.  Should I move the middle posts out some do decrease the amount of deflex?  Unfortunately I do not have any smooth on yet, would thin CA glue work better than unibond?  Or maybe glue the splices together deflexed?

[Roy from Pa]

Z splices should be 4 inches.

[Aaron H]

Well that would do it then, thanks Roy