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Sharp Inside Corners - How do you cut?


Fred Wilson

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So there I was, cutting away on one of Susan Landry's patterns and contemplating my techniques.  (I usually contemplate something whilst I cut)  

 

This project has some rather sharp inside corners throughout the.  Corners like " < " with inside angles less than 10 degrees.  As i was contemplating it occurred to me that I didn't have to think too hard when I was cutting them.  And then a light bulb turned on and I wondered how sharp the end of that corner would be and how did my scrolling buddies cut their sharp inside corners.

 

Species of wood?  Size of blade?  Skill?  Luck?  Experience?  Type of blade?  Sharpness of blade?  Etc?

 

Let me know what y'all think about my contemplations regarding sharpness of that 5 degree angle inside cut.  I'll put my revelations out there in a couple of days.   Promise  :P

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No, Harry, I understand ur way. That's the way I go for those.

As for me, that's the way.  If the corner - like a real tall "V" with a corner less than, say, 3-4 degrees, I will back up, turn the piece around, back up into the kerf, turn the piese slightly and then cut my way out.

 

A far as how sharp the "V" can be?  The blade width is the answer.  If the corner is greater than 90 degrees, it then becomes an "outside" corner and the rules change.

 

Thanks for joining the conversation, Harry andf John

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Fred

I usually run into the corner, then back up enough to turn my blade. Back into the previous cut and continue. I know there are quite a few ways to do this, but this is my "prefered" way. Blade size depends on the wood I am cutting. The softer the wood the larger blades I use. Ex. Pine #5UR hard woods. #3UR. I have been known to go to a #1UR to accomplish the task at hand. Different angles, different woods = different blades and approaches. There is more then one way to skin a cat :)

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There are several ways to do that tricky inside corner.  One method I have seen done is to drill a #65 or #70 hole at the apex of the angle ( the point ) this allows you more freedom to make the turn.  Another method I have seen is to plan the cut in such a way that you come at it from both sides of the angle.  Yet another way is to cut as normal and rotate the work when you reach the point.  Another way would be if there is enough scrap area overcut one side and circle around and come back to the opposite side making what looks like one of those support ribbon shapes.  This will give you a very sharp angle.  I have done all of these at one time or another and they all work ... just not all the time for every situation.  It varies.  Hope this helps.


DW

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  • 4 weeks later...
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59 minutes ago, oldbutnotinthewayyet said:

Didn't see anyone mention spiral blades.   If you want to test your cutting skill, or see if you have a steady hand, that's the ticket since they cut no matter which direction you're going.   

 

 

Hey Old, that spiral you talk about is a great invention in many applications isn't it? I love spiral router bits too, seems that spiral design has made its way around somewhat, in many ways, and it sure is nice to use. Great suggestion by the way.

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1 hour ago, oldbutnotinthewayyet said:

Didn't see anyone mention spiral blades.   If you want to test your cutting skill, or see if you have a steady hand, that's the ticket since they cut no matter which direction you're going.   

 

 

Using spiral blades is next on my list. I may have to try them on a pattern I'm working on.

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On 8/16/2016 at 9:33 PM, oldbutnotinthewayyet said:

Didn't see anyone mention spiral blades.   If you want to test your cutting skill, or see if you have a steady hand, that's the ticket since they cut no matter which direction you're going.   

 

 

No, Harry, I understand ur way. That's the way I go for those.

As for me, that's the way.  If the corner - like a real tall "V" with a corner less than, say, 3-4 degrees, I will back up, turn the piece around, back up into the kerf, turn the piese slightly and then cut my way out.

 

A far as how sharp the "V" can be?  The blade width is the answer.  If the corner is greater than 90 degrees, it then becomes an "outside" corner and the rules change.

 

Thanks for joining the conversation, Harry andf John

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OK, guys and gals - y'all wanted pictures - I know - worth a thousand words - well, haw many words does it take for a video ! ! ! ! !  Thought it might be easier just to show you how I cut them.  I believe, that by reading the entire thread, that others are doing it the same way.  As far as spiral blades are concerned, I use them on occasion but find that I can not get a sharp enough inside corner since the point of the corner wil be only as tight as the kerf of the blade.

 

Anyhow, here is the link to the video.  Enjoy (or not)

 

https://youtu.be/PLLFNky6OZY

Cutting inside corners video

 

 

Edited by Fred Wilson
tried to put the insert in the post
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As far as the inside  corners, I will drill relief holes (1/16)at strategic locations (close to but not touching the cut lines). This way I have a location to turn the piece around without putting any side pressure on fragile fretwork. Depending on the pattern and the material being cut, I do the same thing for outside corners.

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11 hours ago, Wichman3 said:

As far as the inside  corners, I will drill relief holes (1/16)at strategic locations (close to but not touching the cut lines). This way I have a location to turn the piece around without putting any side pressure on fragile fretwork. Depending on the pattern and the material being cut, I do the same thing for outside corners.

Sorry the video didn't work for you.  Harry didn't have trouble seeing it.

I agree with you on "no side pressure".  That is why I use the methods I do.  "go to the corner, back out make cut to the other side and into the corner" or "go to the corner, back it up to where I can turn the piece, back into the corner and then continue the cut". 

Hope this helps everyone out.

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