Splice gaps

[HanibalLecter(InnerSmile)]

With regards to V-splices and the like, I've often heard that it is advisable to hold your joint up to a light source to determine if it has gaps. If no light shines through, it is assumed there are no gaps.

However, that can't always be true, because the surfaces might not be perfectly level.
Meaning, they may only be blocking out visible light because the surfaces of the joint contact for a mere 10 microns along the surfaces in some places.

For example, I've got a V-splice. There's no light shining though when I hold it to the light. But I can stick my thumbnail in to the joint on the belly side of the bow. I can't do this on the back side, meaning there's still a gap in that joint.


Does this mean the joint is no good and needs to be leveled, or can hot hide glue fill up a gap that small?

[HanibalLecter(InnerSmile)]

Sorry to be redundant, but I just wanted to re-emphasize that I'm only talking about natural protein glues here, like hot hide glue, sinew glue, fish bladder glue, etc.


Also, does anyone here have experience with mixing wood flour/wood pulp with the glues mentioned above, to get a thixtopic gap-filling effect? Is there any record of ancient cultures doing this?

[Del the cat]

I think a thumbnail gap is fine.
I remember reading an article about mixing hide glue too different consistencies for different applications...I'll see if I can find it.
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Can't find anything about additives... but there are warnings to avoid making the glue too thin as it will starve the joint... so I guess, get the glue fairly thick for better gap filling.
Del

[sleek]

Soak it in water for a few hours, put the splice together and clamp it tight iluntil dry. Then unclamp it and the gaps will be all gone.

[HH~]

Use better glue. Some glues expand upon curing then shrink to size. Regular wood glues are not best for splicing.

HH~

[HanibalLecter(InnerSmile)]

I think a thumbnail gap is fine.
I remember reading an article about mixing hide glue too different consistencies for different applications...I'll see if I can find it.
.
..
...
Can't find anything about additives... but there are warnings to avoid making the glue too thin as it will starve the joint... so I guess, get the glue fairly thick for better gap filling.
Del

Your post was very reassuring, thanks for it. I guess a fingernail joint isn't so wide with thick glue.

Soak it in water for a few hours, put the splice together and clamp it tight iluntil dry. Then unclamp it and the gaps will be all gone.

Thanks for your input, really appreciate the help. I will try this to see if I get a bit of a tighter fit for even more reassurance.

Use better glue. Some glues expand upon curing then shrink to size. Regular wood glues are not best for splicing.

HH~

Point taken.


Thank goodness the primitive archer community!

[bownarra]

I'm sorry but if you really get into it there probably isn't a better glue for splices than a collagen based glue. Strength isn't an issue, nor really is water resistance. You might be surprised how long you have to soak a hornbow in water before it will come apart.... The splices will be the last thing to release. But the real winner winner is that these glues gel before drying. You only have to hold the parts together until the glue gels and then if needed you can clamp the joint. The gelled glue will hold everything together even with clamping pressure. No epoxy or wood glue has this amzingly useful property. Watching an epoxy loaded splice slide apart when you put the clamps on can be ....a pain! I know all the ways around this problem but....its still a problem that you don't have with collagen glues. Collgen glues can be used to glue splices with no clamps anyway. As the glues dries it contracts and pulls the pieces together. I don't use clamps most of the time because I get the splices perfect
Do NOT think it can fill gaps.......all these glues work best with perfectly mating surfaces and a smooth finish to the surface.
Do not mix anything with it other than 5% alcohol for better wetting of oily woods.
Size with a few coats of 5 - 10% glue. Do your actual glue-up with 25 - 30% glue.
To make the joint a perfect fit do what Sleek recommended. You can also boil the parts for 10 minutes instead of soaking to make the wood more pliable.

[Eric Krewson]

If you have a heat gun use dry heat to warm your splices to the point you can barely touch them your then clamp them, the wood will bend to conform and tighten the splice.

[Marc St Louis]

Soak it in water for a few hours, put the splice together and clamp it tight iluntil dry. Then unclamp it and the gaps will be all gone.

Actually you can clamp the splice and use dry heat and it will do the same, just tighten the clamp as you apply heat.

[PaSteve]

Some really helpful advice given on this topic. Thanks for the info.

[bownarra]

Soak it in water for a few hours, put the splice together and clamp it tight iluntil dry. Then unclamp it and the gaps will be all gone.

Actually you can clamp the splice and use dry heat and it will do the same, just tighten the clamp as you apply heat.

Umm....I prefer my method It softens the actual surfaces of the splice and is easier than holding a heatgun

[Eric Krewson]

I use a reflector when I heat with a heat gun, I could do a splice heat and clamp in a minute or two or less. I have probably made close to 100 spliced billet bows and heated and clamped at least a dozen or more. On really bad brain lapse splice cutting days I have had to add shims to the splice to fill the gaps, over 27 years I have only had to add shims 3 or 4 times.

This is my aluminum reflector, I can cut heating time by 2/3rds by using it.