Blade movement question

[jscott2]

With the discussion going on in golfman's post http://stevedgood.com/community/index.php?topic=17127.0 about back and forth movement, I thought I'd ask my own question.

Some saws have no back and forth movement of the blade.  If there is no (zero) back and forth movement, how does the sawdust get cleared out of the cut, especially when cutting pieces that are thicker than the length of the stroke?

Not trying to debate that various saws, just wondering?
Jim

[scrollgirl]

Technically, the only saws that have "zero" front to back movement are saws with a piston action, like the Eclipse. Most of the higher end saws are "near -zero", but by the nature of the arm movement, they do have a small amount of front to back movement.

   Sheila

[jscott2]

Thanks, Sheila,  Now the engineer in me is asking "how much is near zero?",     even though I know the answer is probably not available - unless someone gets out with micrometers, dial gauges, etc., etc.

Thanks again,
Jim

[scrollgirl]

Well, most of them are parallel or c-arm linkages, so there HAS to be some movement. But there are ways to minimize that movement at the table level. Different methods for different saws. I certainly don't know how to do it on ALL of them! But some have adjustments that you can do to make the movement as minimal as possible.

Sheila

[pddesertrat]

Darn, just the other day I watched a video of the Eclipse scroll saw in action.  It was taken at a trade show and they had one set with the sides cut away so you could see it working.  Sorry I can't find it on the internet right now but when I get more time I will look again and post it.  If I remember correctly it the dust was blown from the top and sucked from the bottom with vacuum, which is probably what removed it from the kerf along with the up and down action of the blade.  I don't think they specifically mentioned that, but it would be my guess.

[TheCamMan]

as mentioned in another post even is the movement of the blade holders are exactly straight up and down, If you don't put the blade in exactly inline with the movement you will still get some front to back action on the cutting edge. so while some say zero or approaching zero that is still just the saws mechanical movement. you still have to be careful how you put the blade in.