I experienced something this afternoon in the shop that I have never had happen in the 20 years I have owned my RAS. I was making a cross cut on a 4/4 walnut board to cut it down to manageable size and the blade climbed up on the wood and stalled the saw out. After careful inspection I discovered that I had the wrong blade on it. I had a Freud 50T thin kerf blade on it with a positive hook on the teeth. I should have had one with a negative hook. Oh well, no harm done this time, but maybe I will pay better attention from now on.
I also discovered that my 10″ Jet bandsaw is not the optimal tool for resawing…just an observation.
Harry
Following the path of least resistance makes rivers and men crooked.
Replies
harry , I don't use any thin kerf blade on the RAS , but a 50 t blade normally will cross cut lumber easily on the RAS . My guess is that the blade gaulled because it was fed too fast in too thick wood , it happens , I don't think the hook of the teeth made it happen .
regards dusty
It's the hook. You should always use a blade with a negative hook angle on a RAS. Positive hook angles are very aggressive and since the RAS is performing a climb cut it is aggressive by its very nature. A negative hook angle is necessary on a RAS. It's the nature of the beast.
in , So then should you use a positive rake on a scms since it is the opposite cutting direction as the RAS ?
Is it the hook or is it the rake angle ?
regards dusty
Edited 4/14/2008 8:15 pm ET by oldusty
With the SCMS, it's not a climb cut, so the rake angle is much less of an issue.
-Steve
Dusty,
Good point. I know blade manufacturers recommend using a 0 degree hook angle or less on SCMS. I think that is for two reasons. First, the blade is above the workpiece and the spin of the blade would tend to lift the board off the saw if you were using a positive hook angle. Second, not everyone uses a SCMS properly and they will pull the blade through the workpiece instead of pushing it through. In this case the action is the same as the RAS.
I have an old Sears RAS saw with a positive hook blade (the reason - I don't have a negative one for it right now.) It stalls all the time. I have to be very careful when sawing thick or very hard wood to avoid it. Had the saw almost fifty years and it is exhibiting its age somewhat. If I'm going to keep the saw, I must get the proper blade.
Edited 4/13/2008 9:13 pm ET by Tinkerer3
This is why I got rid of my RAS long ago! That thing always scared me and I'm not exactly "Mr. Safety".
http://www.ithacawoodworker.com/
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