On Fri, 23 Feb 2007 16:44:37 GMT, Phil-in-MI NO wrote:

{Snip}

Phil, thanks. Lots of wisdom here. First of all, I get satisfactory
holes now, after switching to a thinner scroll saw blade and getting a
little more practice. I will look out for even smaller blades that
allow for sharper turns (are they called fretting blades??? Any
suggestions?)

These holes are guides for plasma cutting of steel. I would lead my
torch along the plywood. Plasma cutting, itself being a relatively
medium accuracy process, does not require perfect holes (since it
would produce imperfect result anyway), so I think that if I stay
within 1/2mm or so, and the hole is relatively smooth, I will be
fine.

I made a hole yesterday and I will try using it as a template tonight
to see how it works.

Ideally I would like to find 7/16" or even 3/8" thick MDF instead of
the crap plywood, though 1/2" plywood will also work.

I think that plasma cutting profile cuts, using scroll sawed plywood
as a guide, is a good start for decent hole and profile cutting.



In scroll saw work we number the blades. Such as #5, or #7 or #2. Also we
describe the blade's tooth system such as skip-tooth, double skip-tooth,
reverse-skip-tooth and so forth. (Most of this tooth stuff has to do with
the old bandsaw blade rule of 3 to 5 teeth in contact with the wood.) We
also WAY prefer to use plain end blades as opposed to pinned end blades like
you are using. Once you try a plain end, you will never want to go back.

You seem to be using coping saw blades, which if they work, and you get the
Job done, fine.

Most scroll saw blades you find in local store shelves are of medium
quality. There are much better blades by mail order. Pegas, and Flying
Dutchman are two brands. Please don't use Sears brand scroll saw blades.

(aside: as a personal favorite, for thick plywood I like
double-skip-double-tooth with reverse blade configuration, but them's
fightin words in the scroll saw hobby world. Man the Flame Throwers!)

IMHO: Best explanation of blade types is http://www.scrollsaws.com/ just
scroll down on the left hand side. There are other web pages that explain
scroll saw blade types and sizes, but they are associated with selling their
brand of blades.

As with any project, it is more important to get the project done than be a
"purist" of the craft. You seem to be well on your way to making do with
your templates. Therefore a hearty WELL DONE!

Now for the bad news. A scroll saw blade with too many teeth, will cause
you all kinds of grief because the gullets between the teeth are too small
and close together to remove the chips and saw dust. The chips not removed
will remain in the kerf and cause friction, which results in heat. This
heat dulls the blade. The end result is broken blades, burned wood in the
kerf, and just bad news.

Keep at it, you are doing great. The object is to make templates, not to
get confused with some obscure hobby world word play.

Good Luck.

Phil



Thanks Phil. I will see which blades work best, out of what I end up
having.

i