Friday, 28 November 2014

Bamboo Backing Build-Along

Here is some stuff about doing a bamboo backing, bear in mind I've only done a handful and the guys on Primitive Archer helped me out with the first.
Five main points about the Bamboo.
1. Bamboo is razor sharp and the splinters are nasty.

2. Be prepared to remove a lot of Boo before you get it down to size.

3. A good sharp plane takes it down nicely in decent sized shavings. Adjust the plane to a finer cut to trim any thick points as you near the final dimensions. Watch each edge of the slat to make sure you are taking it down evenly.

4. Because it's curved on the back, when you think you've made it too thin, there is still plenty of thickness in the middle, (You'll see that when you saw it down to fit the bow).
Use a belt sander only for final flattening, don't use it for bulk material removal... it will take for ever.

5. Boo is V strong in tension and can overpower some belly woods, so I'd say err on the side of thin rather than too thick.

On the glue up, I apply glue to both surfaces despite the instructions on the glue saying only apply to one. Gluing is a one off operation, get it wrong and you have to plane off the boo, (yes I've done it). It's easy to apply glue to one surface and then look back at it and see patches that look dry.
My usual advice for working on bows is "When in doubt, don't"
When gluing, I advise the opposite, if you have any doubt about the amount of glue or that the surface has wetted correctly, go over it.
As kids we all slap on too much glue and then expect it to stick instantly, we get bad results. Then as adults we get too clever and think a very light application of glue is right.
You need to have enough so that you can see it squeezing out... of course the caveat is, you need to strap it tight enough to apply good even pressure and have flat surfaces.
My belt sander doesn't get a huge amount of use, but preparing glue surfaces is a major use and it has earned it's keep. It's only a cheapo belt sander, but with a 40 grit belt it does actually remove wood.

You can see in the pics I've got the bow strapped up with about an inch and a half reflex. Once it's been unwrapped and cleaned up it has less than an inch. that's fine for this bow as it's for target use as a longbow and we don't want some 'rules merchant' objecting that it's a recurve. By the time it's fully tillered it will probably be ramrod straight.

By the way the back of the boo' has been protected with masking tape to keep the glue off it. Poundland masking tape is a 'must have' in the workshop.

No comments:

Post a Comment