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Cutting Along the Line


Rockytime

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I was cutting my grandson's portrait with a Penguin Silver Reverse #3 blade. Before this I cut a pattern with a Pegas MG #5 blade and was impressed with how well it tracked the line. Today I put in the PSR #3 and noticed it tried to drift. I remembered someone suggesting sanding the right side of the blade which I did. I was surprised at the difference it made. I was delighted because I really like the PSR blades. They cut very smoothly. I just attached 220 sandpaper to a piece of wood with spray adhesive. I placed it next to the blade and ran the saw for only a second or so. Worked like a charm.

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Some of the reason the PSR #3 blade cuts smoother than the MG #5 is because it's a smaller blade with more teeth.. The more teeth or smaller the blade.. the smoother the cut's edges will be.. This is one reason I like the MG blades as they are slightly faster or more aggressive cutting.. where I normally would use a #5 blade with a different brand.. I can cut with a #3 blade with the Pegas MG blade...

 

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Well now I am very confused.  I have read somewhere in my beginning days that the drift is caused because the teeth points protrude slightly to the right of the blade..... This is caused by the way the blades are made.  In fact it is one of the ways I was taught how to tell which way was up on a some blades, run the blade between the thumb and forefinger, and you will feel the slight roughness on one side.  Mount the blade with that rough side on the right an the blade will be mounted right end up.  This was a long time ago, maybe it was in a dream or something, but I remember it.

Now if this is true, and you sand the side of the blade, wouldn't that sand the points of the teeth off and make the blade dull??😕🤔

 

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I stone the back edges of scroll saw and bandsaw blades using this stoning tool, made for this purpose:

https://www.highlandwoodworking.com/bladeroundingstone.aspx

For bandsaw blades, I just hold it against the back edges and rotate it while it is running.  A few small sparks fly off now and then, but generally a very tame operation.  I am careful to not rotate it far enough to ever touch the teeth (same for scroll saw blades).

For scroll saw blades, I first mount the blades upside down and stone the back corners, and move up and down to be sure to get the entire length of exposes blade as it oscillates up and down.  Then I turn the blade over and repeat.  This is to ensure the entire usable length of the blade gets stoned.  I do this for the two reasons stated earlier, to reduce drift and for making tighter turns. 

I used to use stones from my father's machinist tool box, but the above stoning tool is substantially coarser and handier to use. 

Rick

Edited by Rick Kr
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I don't sand the back of my blades as I have not had a problem making very tight turns but I do sand the right side which helps me cut straighter. On the #1 blade, because it is so small, I clamp the blade with sandpaper on the right side and a plain piece of wood on the left. I just run the saw and lightly pinch the two together. Only  for about a second or two.

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I sometimes do this, as well as round the rear edges of blades, but I prefer using a sharpening stone for this and dedicated a small one to use with my scroll saw. It holds up way better than sandpaper. Don't use the stone that you use to sharpen your knives and plane irons though, because you want a perfectly flat stone surface for these uses and one used for the scroll saw will become slightly grooved over time.

 

Charley

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In the process of making most scroll saw blades, they are stamped out of sheet steel. In that process they leave the right side with a burr because of the direction of the stamping. If they were stamped from the right to the left, the burr would be on the other side and they would drift to the left because of the added drag. By doing what Les is saying, the small burr is removed only from the right side of the teeth. Not the front. That would ruin the blade for sure. Just a tiny bit is all that is required. I have also done the bandsaw rounding of the back side edges for years. That makes a big difference too. I hope this is understandable. I know in my mind what I'm saying but putting it into words is not always doable. 

 

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