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Need Help - Router Bit Tearout and burning

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Forum topic by Boghog posted 06-06-2017 11:52 PM 513 views 0 times favorited 8 replies Add to Favorites Watch
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Boghog

27 posts in 347 days


06-06-2017 11:52 PM

Topic tags/keywords: question maple router problem technique

Guys, I wanted to share some of my troubles this weekend…

I was attempting to cut a dove tail groove in a piece of maple.

It should look like this model… however, I really struggled with a couple different issues…

I had entry side and exit side tear out:

And at a certain point, the bit started to get REALLY hard to pass through the maple…

and I got a lot of burning like this:

I tried a bunch of different ideas including painters tape and sacrificial pieces to support the wood fibers,...

sigh this shouldn’t be this hard…

Where do i need to start looking to root cause my problem here? bit speed? dull bit?

Thanks for any/all input…

JY

-- Justin Young, Indiana


8 replies so far

View papadan's profile

papadan

3584 posts in 3203 days


#1 posted 06-06-2017 11:59 PM

Blade is dull and speed is too fast. With the angle on the side of the piece, how are you holding the wood to cut the dovetails, could be binding. Try a piece before cutting the angles above the DTs

View Rich's profile

Rich

1976 posts in 424 days


#2 posted 06-07-2017 12:04 AM



Blade is dull and speed is too fast. With the angle on the side of the piece, how are you holding the wood to cut the dovetails, could be binding. Try a piece before cutting the angles above the DTs

- papadan

+1 on papadan’s comment. I’ll add to clean the bit and use a backer board.

-- No matter how much you push the envelope, it'll still be stationery.

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Boghog

27 posts in 347 days


#3 posted 06-07-2017 12:09 AM

So i don’t have a variable speed controller on my router, what speed should i be running at to improve the quality of cut?

@papadan

-- Justin Young, Indiana

View runswithscissors's profile

runswithscissors

2558 posts in 1859 days


#4 posted 06-07-2017 01:25 AM

That is a lot of wood to hog out at one pass (and of course you have no choice with dovetails). Try initiating each cut with a straight bit, wide enough to match the narrowest part of the dovetail. Then follow up with the dovetail bit. Should stay sharp longer and not create as much heat.

You could also make similar cuts with a dado on the TS.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View Madmark2's profile

Madmark2

371 posts in 423 days


#5 posted 06-07-2017 01:25 AM

Stringiness varies by material. Some is inevitable. Light sanding will fix tearout & no one will ever see the burnt sides. The burning suggests you are using HSS, try carbide instead.

M

View Boghog's profile

Boghog

27 posts in 347 days


#6 posted 06-07-2017 01:32 AM

Great ideas guys, thanks a bunch!!!

-- Justin Young, Indiana

View runswithscissors's profile

runswithscissors

2558 posts in 1859 days


#7 posted 06-07-2017 01:39 AM

Dull carbide will burn just as readily as HSS.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View Nubsnstubs's profile

Nubsnstubs

1207 posts in 1564 days


#8 posted 06-07-2017 02:34 AM

Hog, I have a hard time with posts like this. You are concerned with burn marks made from the router bit, but the first picture of your project has burn marks above the dovetail. No concern about your saw? If it can’t be seen in the finish product, don’t worry about it. I would guess that the oils or sap/moisture in different wood species would react differently from a fast moving heat building cutting instrument and burn at different feed rates. I’m surprised that cross grain cut into hard maple only left that little tiny burn you are showing. When you have ashes instead of chips, you need to worry then.

Tearout is just something that is inherent with woodworking, especially with a router on the exit. Learn to live with it. If you can’t live with it, use a thicker piece, and trim off the tearout after the pieces are all routed. Watch out for that burn from the saw, and have some fun. ........... Jerry (in Tucson)

-- Jerry (in Tucson) www.woodturnerstools.com

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