May be your feed rate.  Be sure and let the blade do the cutting without excessive feed pressure.

 

Check to see that the blade is as vertical as possible and that you are feeding straight and not pushing to the side.

 

I have used #5 ST blades on 3/4" African ebony which is VERY hard and dense, and did not have a problem.  Just took an hour to cut a small 2" snail.

If anyone wants to hear what a properly tensioned blade should sound like- Judy Gale Roberts and Jerry Boocher have sounds bites on their website at

http://www.intarsia.com/ScrollSawTension.html  Listen to all the sounds and read the explanations of each.

 

Other than that, Richard, I would have to think that your problem would be your feed rate and direction as Terry stated above. You shouldn't really have much of a problem with cutting 3/4" cedar as that is a pretty soft wood.

 

Tom

Thanks for the feed back. I just might be feeding the wood a little too fast. I'm new to this hobby and I am basically learning as I go, just like most everyone. Thanks again-- Richard

Richard

 

One other thing to look for is blade slippage in the clamps either by clamp is broken or oil left on the blades due to the manufactoring process. If it is an oil problem then the ends need to be cleaned by either using some sandpaper or some Mineral spirits or I like to use acetone and just dip the ends. The other thing may not be enough tension. When blades slip in their clamps the up and down motion cause the blade to snap back and it will break.