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What am I doing wrong, or is there something else?

4K views 20 replies 11 participants last post by  collinb 
#1 ·
Building 3 corner shelves. Giving each a profile.
The first two went fine. But the third .... The bit grabs and tears it up.
(Doing three passes to try to avoid the problems associated with hogging out too much.)


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#3 ·
RT???
bearing guided???
freehand??
 
#5 ·
Router table. Bit is a Craftsman 25474, carbide with bearing. The edge curve is intentional.

So far what I have gathered is that I was going against the grain. But the other two came out perfectly cut.

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#6 ·
I can't find any reference for the bit you mentioned - perhaps it's old?? However I'll presume that it has a bearing at the top. You said you made three passes so, are you using a fence? Is the tear out at the end that went through first?

Still assuming here - if you are not using a fence, is it possible that the corner of the board hit the bit and caused the tear out - did you feel the grab or just see it?

So if that board is ruined, try flipping it over and send the other end through first and see if you get a smoother cut.
 
#7 ·
Typo. It's # 25454 cove and bead.

It happened two times on the same board.
After the first time I trimmed the bad part off with the band saw and tried it again with less angle. In neither case did the bit hit the end of the board.

What I think happened -- the larger boards had enough grain in both directions that I was going off the end grain toward the grain so there was nothing loose to grab. Like going around a circle on a larger piece of wood. This problem was on the smallest of the three so there was nothing like the end grain starting point to physically absorb board's stress.

Looks like the best solution will be to make the third, smaller shelf a large shelf then trim it down after the rest is done.
 

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#8 ·
Are you using the fence on the RT or are you freehanding on the RT...?
 
#9 ·
Did the grain have a swirl pattern where it tore out? I've seen wood that close to a large knot do similar to that before.
 
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#11 ·
You have a very good chance of getting blow out when cutting across end grain. When milling all 4 sides of a rectangular piece, you go across the end grain, with the long grain, across the end grain, then the long. This allows the cut across the long grain to clean up anything blown out on the end grain pass.

Since you are doing a triangular piece, you have continuously varying grain. The suggestion of using a backer board is probably the simplest and best way to prevent this. Another easy way is to keep your piece long, so you can trim off the last 1/2 inch.

If you can post a picture of the entire shelf piece, I might be able to offer another suggestion.
 
#12 ·
Looks to me like tear out from cutting into end grain. Looks like the grain runs from the corner at about 45 degrees.
 
#13 ·
So tonight I picked up another piece of wood just to get the process going again. Restlessness.
This piece worked just fine, like the first two.

And wife has been using Golden Pecan stain on oak around the house so she tried it on the poplar. Looks good and will be a suitable tone match with other things in the house
(As much as possible I eliminated the green parts of the poplar.) So don't just paint poplar.

The Craftsman bit remains sharp. I do wonder who's product they private labeled. It's not a bad unit , not like the stuff from HD.


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#14 ·
Looks good. I happen to like poplar--I have some with pretty dazzling purple in it. I've also found that dark walnut or chestnut stains work well with it--but I use a sealer first to avoid blotching. My favorite of the times I've let the poplar show--Minwax Pickled Oak...like a thin whitewash effect which allows the green & purple to show but mutes them a bit.
earl
 
#18 ·
Looks to me like the bearing ran out of bearing surface when it came to the end. Can't explain why it didn't do it on the rest of the pieces,unless you did the ends first then the sides. The sides are supported by the fence, the ends are supported by the bearing and if the side is already cut then as the bearing comes to the corner it runs out of any surface for the bearing to run on and digs in.
Just saying,
Herb
Herb
 
#19 ·
I'm not a fan of poplar in general b/c of how easily it dents. But these will be out of the way and not hit. Plus polycoat protection.

The tear-out was at the beginning of the cut.

It seemed to be just this piece. Replacing it solved the problem.
 
#20 ·
Now I got it...after seeing the other pictures.

For this kind of application (profile on the diagonal - bearing guided - no fence) I typically profile first and cut second...saves me the headache of figuring out how to apply a backer board or deal with start and stop...and the corners come out really crisp and clear after the cut... (decorative cleats, outside furniture trim, etc...)

Nothing new...guessing you already know that...

How did you get rid of the poplar green...?
 
#21 ·
Next time I do this, backer board it is.

To get rid of poplar green
(1) I was amazed to find one piece with no green in it for the replacement unit.

But for the other two
(2) I ripped the boards to remove all or most of it and re-joined them.
 
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