Replies

1. 
   BossCrunk | May 08, 2006 11:29pm | #1

   The real thing has substantial hand carving and cannot be reproduced with any machine that I am aware of .  The shape is sawn out with a bow saw or band saw and then the edge is carved with an appropriately sized gouge. 

   You might find a router bit with bearing that comes 'close' to the carved portion (say some sort of cove bit) but end the end it will look like poop, IMO.

   
   

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   Edited 5/8/2006 4:53 pm ET by BossCrunk

1. 
   chamfer | May 14, 2006 07:33pm | #2

   I've hesitated quite a while before following up on this question. In part, because my reply, to some degree, is simply a reenforcement of BossCrunk's response. Further, I'm not sure I'm going to be able to make any suggestions which are going to be all that helpful. But, I've finally decided that there is an additional consideration which may make further discussion worthwhile.As BossCrunk indicates, authentic interpretations of this type of gothic tracery really cannot be accomplished with radial cutting tools. Among other things, there are some very tight areas which simply can't be reached with radial cutters. I've attached a small photo of a trefoil I produced some time back in order to illustrate the difficulties. While not exactly the same as a quatrefoil, the characteristics are similar enough to be germane to this issue. (Also, I wanted to include an image to determine, for sure, if we're talking about the same general type of work.)Another, possibly more important, consideration is one of safety. Due to the variety of grain orientations in the pierced areas, there are bound to be areas where blow-out will be almost inevitable, unless one decides to do back/climb cuts. At best, this is tricky when the work or the tool is hand-held. At worst, it can be quite dangerous. So, it doesn't seem advisable to set up a process which necessitates such cuts. I certainly couldn't recommend it with a clear conscience.If you are needing to produce a large number of these, then it might be worth gaining access to ####CNC machine. As I understand it, they can be programmed to do back/climb cuts, and this can be done with some safety when both the work and the tool are mechannically restrained. Even with a variety of cutters, though, there are still going to be areas which will need to be finished up with hand tools for authentic interpretations of these forms.It may or may not be helpful, but I will attempt to briefly describe my general approach to the trefoil shown in the photo [as best my memory allows :-) ]. The layout is virtually all compass work, and it takes a little time to determine the radii which give you the overall size desired, as well as the appropriate relationship of the various parts. Though not completely foolproof, my memory is that the illustrations in Franz Sales Meyer's _A History of Ornament_ proved to be quite useful. I complicated the layout by adjusting the lobes of the pierced areas so that they could be produced by one of the forstner bits I had available. This was worth it, though, as it produced the lobes very accurately, requiring almost no clean-up, while providing ample areas for entering the saw blade for cutting out the rest of the pierced area. I don't remember, for sure, but I think I bored very small "pilot holes" to guide the small lead tip of the forstner bit, while giving me reference points on both surfaces for layout purposes.The thickness and surface dimensions of the material will largely dictate which saw can be used to cut out the bulk of the waste in the pierced areas. A bandsaw will not do, as it cannot enter the enclosed pierced areas without destroying the integrity of the trefoil or quatrefoil. A scroll saw would be great if it would handle the work piece. Thinner stuff could be cut with a coping saw or a fret saw, while thicker/larger stuff would require an appropriately sized bow/turning frame saw. Some care with the saw pays off in less clean-up at the end. A little patience at this stage will save you much time later.Various chisels, gouges, and/or rasps and files can be used to clean-up the sawn surfaces. I won't attempt to describe that in any detail, as that will vary, a great deal, according to your tooling, the size and working characteristics of the material, etc. A significant issue, however, is avoiding tear-out at the "off" surface of the material. This is especially true if you are not going to be carving both surfaces, as with the example in the attached photo.The cove cuts may require a spoon, or front bent, gouge for some areas. In the trefoil in the photo, the remainder of the carving is fairly simple gouge/chisel chip carving. This requires the appropriate sharp tools and some care/patience, but is not all that daunting.Hope this helps a little, at least.Don McConnell
   Eureka Springs, AR

   
1. 
   BossCrunk | May 19, 2006 08:26pm | #3

   Great post.  Great post.