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Core material advice request

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Mesophilic:
Are modern wood laminations suitabe for a horn bow cores?  Say the lams Binghams sells?

My Grozer biocomposite looks like it has a core of two bamboo lams.  Was wondering if it would work out if I ordered some or if I'm just flirting with disaster.

If doable, what species would be appropriate?

I ask because I'm trying to find a way to work on something indoors as my knife and bow making space is currently burried in snow.

ETA: not trying to be a purist yet.  When I figure out how to make a few good shooters then I'll work on authenticity.   For example, I'm using epoxy to glue up the horns but will eventually lean the art of grooving and using fish baldder glue.

bownarra:
You will find that it's not really about being 'authentic' more that all the best ways have already been worked out :) Do not try to reinvent the wheel! Even if the old bowyers had had modern epoxy I don't think they would've used it, the reason being that virtually all hornbows need heat correction when tillering. Collogen glues can take it but you need a specific epoxy to do the same job. Sometimes areas need to be repeatedly heated and that is the killer for modern glues in this application.
There is no magic with using collogen glue you just need to learn its properties and how they can be used to your advantage. The grooving isn't hard either and doesn't need to be matching with the core grooves. The grooves filled with glue act as a 'core protector'.
As for cores......Binghams lams - no way! Grozers bows made with multiple lam cores need specialised jigs etc for glu-up. The old way is to benbd your core when still thick. This way the core acts as it's own form for horn gluing. The wood is the stiffest part of a composite and gives the bow its shape. Try gluing horn strips onto a thin core.....it isn't happening!
Again I highly recommend you follow the 'old' methods.
You need a diffuse porous wood, with medium density like maple/hornbeam/elder etc . The wood must accept glue well and be able to be steam bent into shape. If you can't find anything then contact wood mills in areas where there is a lot of maple and ask for perfectly straight grained wood, with absolutely no pin knots and ideally flatsawn. Wood is stiffest laterally in this orientation which is important in a core.
Boo will work but be careful on the node placement and good luck finding thick enough culms.

DC:

--- Quote from: bownarra on January 17, 2020, 02:21:02 am --- the reason being that virtually all hornbows need heat correction when tillering. Collogen glues can take it but you need a specific epoxy to do the same job. Sometimes areas need to be repeatedly heated and that is the killer for modern glues in this application.

--- End quote ---
Can we talk about this for a second or two. The Book says to never heat the bow above 150-160°f. I'm assuming that's the temp that hide glue will take. Any epoxy I've used will easily take that. Is there something I'm missing?

That said, there is no problem using hide glue. You're going to have to use it on the sinew anyway. Learning to trust it is the big thing :D

Mesophilic:
Just to expound on DC's question, this is from West System...they make the epoxy I use on knives and bows.


--- Quote ---"We have glued two blocks of mahogany together with WEST SYSTEM® epoxy, allowed it to cure for one week at room temperature, and then exposed the whole assembly to 200°F for 3 hours before forcing a chisel into the glue line to fail the joint. When the joint was examined closely, we found that the primary failure was in the wood and not the epoxy. Experience has also shown that while heat tends to soften epoxy while it remains warm, if WEST SYSTEM epoxy is not exposed to damaging heat (exceeding 230°F for extended periods), it will return to full strength when cooled to room temperature."
--- End quote ---

simk:
the data sheet of my cheap liquid and ready to use fishglue says:

The curing time is approx. 12 - 24 hours. The cured adhesive is stable from minus 34 °C to + 260 °C.

(translated with deepl)

+ 260 °C is about 500°F

I tested that and gave a full heat treating to a laminated bow....I then reglued it after it delaminated 8). Still I'm convinced that glutine-glues are more heat resistant than standard epoxy.

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