redoak & tb3

[willie]

I was thinking of laminating two  3/4" thick pieces of red oak and gluing with tb3 for a large  elb design the "handle" or glueline needs to go to midlimb.

I have never brought myself to use pva glue for limb laminating before, always used epoxy,but I cannot ignore all the good things I hear about tb3 and want to give it a try.


any tips for red oak prep for tb3?

anybody use weldwood plastic resin glue anymore?

thanks
willie

[bowandarrow473]

I would prep it like any other wood, but I have only used it for handles and overlays back when I made a lot of board bows when I was 10 and 11. Ed oaks not oily so you should have an easy glue up.

[Pat B]

Either TB or Weldwood Plastic Resin will work. TB needs flat, well matched glue surfaces and the Weldwood is a gap filing glue. You want the surfaces well mated but I'd use course sand paper or the edge of a hack saw blade to score it first.
 An ELB isn't a good design for red oak. IMO

[DavidV]

I'd agree that red oak wouldn't be my first choice for an elb, you may be wasting two good boards if it chryshalls. Hard maple is decent though.

[willie]

Thanks Pat and David

I seemed to remember reading something about red oak not working well with certain glues, but a search turned up nothing.

red oak is not my first choice either, but I have never made an ELB before, and it seems that I need one to be able to fit a big guy for the real thing, so this is sort of a practice/experimental bow in many ways.

willie

[bradsmith2010]

I agree it is not the favorite for long bow,, but if you adjust the length a bit,, it should work,, it just might no be the rocket launcher a choice wood could be,, but will probably shoot an arrow in a respectable way and accurately as any bow,,,,

[bowandarrow473]

Red oak is not well suited to an ELB as previously stated but I have seen several made with width and length adjustments, and they reportably shoot well without excessive set.

[PlanB]

......I seemed to remember reading something about red oak not working well with certain glues, but a search turned up nothing.......

That would be with the old resorcinol glue. The tanins were the problem if I remember correctly (former boatbuilder).

[willie]

why thanks PlanB

It just so happens that I have a boat building project underway, and as I have been doing research on line for the boat, It was probably where I saw it

[RBLusthaus]

It's not red oak where some have had problems, it is white oak, and I thought the problems were sometimes had when using epoxy, not TB.  Your glue up should be fine.  Russ

[PlanB]

Russ, Weldwood, the manufacturer of resorcinol glue at the time specifically noted oak on the can as inappropriate when I had a boat shop in the 70's. I was an early user of W.E.S.T System epoxy, and I (and innumerable other boat builders) have used it many times for successfully gluing white oak laminations. I wrote a technical design column for WoodenBoat magazine for three years.

Gluing hardwoods successfully with epoxy requires an understanding of a lot of different factors re. both glue resin type, admixtures, hardener type, hardwood thickness, moisture changes, surface roughness, etc.

Rules of thumb work, as long as someone has experience with the particular epoxy resin in a similar glue up used for a similar purpose. But just because one bow builder has a failure with one unnamed brand of epoxy with unspecified thickness and moisture content white oak, doesn't mean "epoxy" doesn't work with white oak. It probably means one or more of the above weren't appropriate.

Likewise when a manufacturer like Weldwood (re. resorcinol glue) specifically advises against a particular kind of wood, it's probably based on wide experience and testing. Most won't recommend against using a product they sell, unless there's a very good reason not to sell it for that purpose.

If I were laminating red oak for a bow, I'd probably reach for my W.E.S.T. System cans. Laminations should be thin. The Gougeon Brothers have always pointed out that moisture changes in thick hardwood laminations (ie over 1/4" thick) can exceed the peel strength of the wood at the glue line. That is, by the way, the weakest link in the chain, not necessarily the tensile strength of the epoxy itself.

[JoJoDapyro]

Willie, Take it for what its worth from a fairly new bow builder. the only failure I have had with Tightbond was in a handle build up, and the wood itself delaminated and left the glue line untouched. It was red oak on red oak.

[Badger]

  I have used tightbond on a lot of white oak backings and red oak. I don't think I would use red oak for an elb. I have made several and they all took more set than I like.
As mentinioned above hard maple can make a nice elb, An elb calls for a rounded belly but I would minimise the roundness as much as I could.

[PlanB]

Willie, Take it for what its worth from a fairly new bow builder. the only failure I have had with Tightbond was in a handle build up, and the wood itself delaminated and left the glue line untouched. It was red oak on red oak.

The peel strength of the surface layer of wood where it meets the glue line on thick hardwood is usually the weak link in the chain for any good glue up, not just epoxy.

It's often over-stressed by changes in dimension with humidity. The local forces of expansion with high humidity in hardwood can be tremendous. Thick hardwood isn't very flexible. Swelling is proportional to thickness. Thin laminations aren't often bothered. Heavy pieces are more iffy. If a glue line is damaged by swelling, it won't often show up until stressed by bending.

The W.E.S.T System for boats used thin layers of wood laminated to locally isolate each layer from humidity changes, and coated the exterior with epoxy barrier as well to minimize it further. Not saying this is appropriate for primitive bow making, just information about how this works, and why it happens.

I do know that there are ways of chamfering the fade area to raise the glue line that can reduce handle pop-off, but that's a different topic.

[RBLusthaus]

Plan B - I did not say that White oak and epoxy are a problem - only that some say that it is.  I too am a boat builder and frequent the wooden boat  forum.  As I am sure you know, there are many discussions over there about white oak and west systems.   I myself have had no issues with West systems and white oak, having laminated many a canoe stem from it, but a quick search over there will turn up many such discussions and claimed incompatibility issues.  I agree they are likely due to some other factor.  I am not able to comment on the use of resorcinol glue as I have no experience with it.    The Weldwood Urea glue I use often, and have no issues with it - but do not think I ever used it with either kind of oak - I use it with bamboo backings and ipe in place of the now discontinued URAC.  Russ