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post #1 of 7 (permalink) Old 06-21-2015, 05:55 AM Thread Starter
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I used a cove but as a design I am putting on a guitar. The bit is brand new but still left a nasty burn on the end grain... I do not want to disrupt the shape the bit made, but I want to clean up the burn marks... What do you guys suggest?

Also it bums me out the the glue line is visable because prior to using the cove bit the seem was perfect.
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post #2 of 7 (permalink) Old 06-21-2015, 05:55 AM Thread Starter
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post #3 of 7 (permalink) Old 06-21-2015, 06:55 AM
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whose bit is it other than yours???...
does the bit have a guide bearing???...
you know that maple and cherry are notorious for burning...

reasons...
feed, speed, depth of cut not matched up...
bit not sharp...
bit loaded w/ glue or resins...

how to avoid...
1. Too much speed. Fast-turning large bits generate wood-searing heat. Back off on the speed.
2. Heavy passes. Take off no more than 1⁄8" of material with each pass—less on the final one.
3. To avoid heat build-up, feed stock as quickly as possible without leaving chatter marks.
4. Dull bits. Replace or resharpen bits that have lost their edge.

fixes...
sanding...
another pass w/ the bit cleaned and verified sharp...
find a fractionally smaller bearing and recut... you may end up at a bearing wholesaler to do this....
if you, do get a selection...

hints...
put a single layer of masking tape where the bearing rides..
do all of your cutting....
peel the tape and do one last pass...
if you are burning really deep use two layers of tape...
peel on layer and cut...
peel second layer and do a final pass...

if you are hogging use several bearings of decreasing OD's so that the cuts are minimal...
make a cut... change to a smaller bearing... cut... do this several times...

now for the glue lie...
accent it and make it a feature...
''V'' groove it...
color it...
inlay it...
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If only new layers hadn't been added....

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post #4 of 7 (permalink) Old 06-21-2015, 12:42 PM
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The best tools for sanding coves smooth are dowels of the same or very slightly smaller radius than the the r of the bit you used with a wrap of sandpaper glued to them. Go to the hardware store and buy a set of those cheap 3' long dowels they sell so you can cut pieces off and glue whatever grit paper you need onto them.

By angling the very curved scraper from Lee Valley you can also use it to smooth various radii without changing the profile. Super-Hard Curved Scraper Sets - Lee Valley Tools

Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.
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post #5 of 7 (permalink) Old 06-22-2015, 12:04 AM Thread Starter
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Thank you guys for the input!
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post #6 of 7 (permalink) Old 06-22-2015, 12:06 AM Thread Starter
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Quote:
Originally Posted by Stick486 View Post
whose bit is it other than yours???...
does the bit have a guide bearing???...
you know that maple and cherry are notorious for burning...

reasons...
feed, speed, depth of cut not matched up...
bit not sharp...
bit loaded w/ glue or resins...

how to avoid...
1. Too much speed. Fast-turning large bits generate wood-searing heat. Back off on the speed.
2. Heavy passes. Take off no more than 1⁄8" of material with each passóless on the final one.
3. To avoid heat build-up, feed stock as quickly as possible without leaving chatter marks.
4. Dull bits. Replace or resharpen bits that have lost their edge.

fixes...
sanding...
another pass w/ the bit cleaned and verified sharp...
find a fractionally smaller bearing and recut... you may end up at a bearing wholesaler to do this....
if you, do get a selection...

hints...
put a single layer of masking tape where the bearing rides..
do all of your cutting....
peel the tape and do one last pass...
if you are burning really deep use two layers of tape...
peel on layer and cut...
peel second layer and do a final pass...

if you are hogging use several bearings of decreasing OD's so that the cuts are minimal...
make a cut... change to a smaller bearing... cut... do this several times...

now for the glue lie...
accent it and make it a feature...
''V'' groove it...
color it...
inlay it...
I think to much speed was the problem... I lowered it significantly and the burn was much less... Still a little on the maple.
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post #7 of 7 (permalink) Old 06-22-2015, 06:35 AM
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Even with the correct feed, speed and a sharp bit, some woods are still prone to burning as Stick pointed out. There are a couple of options for sanding profiled edges - sandpaper wrapped around a dowel is one, but I like the little shaped rubber blocks sold by Lee Valley Contour Sanding Grips - Lee Valley Tools I also found this option for those having a Fein Multi-Tool as I was doing a quick search for the Lee Valley blocks []http://multifitblades.com/profile-sanding-kit.html - the price is low enough that it's worth giving them a try as that's going to be much easier on arthritic hands.

Tom
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