Ozbow

Howdy folks,

I've always been an admirer of the excellent joinery skills of the glass bowyers here and abouts. I'd like to try my hand at some similar work.

In particular, the practice of having an arc of thin contrasting wood within a riser/handle. Like this:
(image taken from http://www.buildyourownbow.com/five-com ... bow-grips/)

I realise of course that this has several lams within each arc, and I'd start simple.

Does this kind of effect/process have a particular name? How do you guys do it and how might someone else learn?

Cheers,

Dave

speaking for myself, with some of my designs I use a template to draw required curve, cut out and sand square, then match other piece to it, along with any narrow trim pieces I might use.It is mainly a process [ sometimes tedious] of sand and fit. It is important that it is an airtight fit as endeavouring to 'remedy' any discrepancies with clamps etc is usually a recipe for disaster. There is a school of thought that using different materials in this curve such as 'glass , phenolic, etc can cause problems due to their different expansion and contraction rates compared to the chosen wood used, in varying weather situations. I do believe there is merit in that supposition.

I have seen People make up a Jig so they could cut a repeatable curve using a Bandsaw. Check this link out it has pictures of similar home made Jig to what I have seen used. I made a small scale version years ago that worked very well. You can even adapt this type of Jig to cut different width Riser or Limb Lamination's.

http://tradgang.com/cgi-bin/ultimatebb. ... 2;t=000072

and another

http://piratesofarchery.net/bb/viewtopic.php?p=18938

Thanks Perry, good link! Wouldn't you just know it, my new bandsaw (http://www.machineryhouse.com.au/W955) has a built in adjustable circle cutter (http://www.machineryhouse.com.au/W9495).

I've not yet tested it thoroughly to see if it's consistent enough to do the tidy kind of work in your link.

I guess in those designs where the join is not an arc of a circle, that cutting one and carefully machining the other to match as BigBob said is probably the best/only way to go. I guess it helps to have the right kit, eh?

Any others with insights?

D

Hi Dave,

The bigger the bank balance the easier the task becomes because you can lash out with big amounts of cash to purchase specialised machinery to carry out the various tasks.

bigbob wrote:............It is mainly a process [ sometimes tedious] of sand and fit.........

Unfortunately I am stuck with a bandsaw and various grades of sand paper and sanding sticks.

Depending on the accuracy you get off the bandsaw there can be several hours of hand sanding to get a neat fit with the mating components.

The task can become more difficult and tedious when the desired profile does not conform to a set radius.

Daryl.

[Your new bandsaw looks at though it will serve your needs very well.]

greybeard wrote:Hi Dave,

The bigger the bank balance the easier the task becomes because you can lash out with big amounts of cash to purchase specialised machinery to carry out the various tasks.

bigbob wrote:............It is mainly a process [ sometimes tedious] of sand and fit.........

Unfortunately I am stuck with a bandsaw and various grades of sand paper and sanding sticks.

Depending on the accuracy you get off the bandsaw there can be several hours of hand sanding to get a neat fit with the mating components.

The task can become more difficult and tedious when the desired profile does not conform to a set radius.

Daryl.

[Your new bandsaw looks at though it will serve your needs very well.]

As Daryl says re bank balance, Sse of the bigger makers in USA use CNC to cut out risers. There are jigs as mentioned to use on bandsaws but again as mentioned unless desired curves as uniform they won't properly follow an elliptical or non typical course. Some have rub collars fitted to their spindle or belt sanders to make a pattern sander where work piece is clamped to template and brought down to lines of template. Great idea and very time saving if one has the ability to go that way.

Using circular arcs is by far the easiest and looks good too. The benefit is you can use emery tape on one piece to sand the other and vice versa until they fit really well, given you take the time to square up your bandsaw table. I find if you want the accent to be fairly thick (like a mosaic strip or such) that you need to make the radius of the convex part smaller than that of the concave part. For thin accents I just rely on the thickness of the emery tape to set the gap. Templates the key. Mark your parts with templates and for the case with two contrasting blocks, make sure you bandsaw the same side of the line on both blocks to give you as close a fit as possible. I used 5 mm acrylic for my templates so I can see through them and gets where certain features may fall in the finished riser (I also have the finished riser marked on the templates. Cheers, Rod

That's terrific Rod, very helpful!

I like the idea of alternating the sanding medium between surfaces to marry the fit.

Cheers,

D

i use a jig similar to the one on trad gang for different sized semi circles