Router chipout problem

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Forum topic by SuburbanDon posted 11-09-2010 11:45 PM 2624 views 0 times favorited 6 replies Add to Favorites Watch
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487 posts in 2416 days

11-09-2010 11:45 PM


I have a router problem I can’t solve. I’m routing a roman ogee around the edge of a 1” piece of cherry. When routing the first edge at a corner I can use a backer block to prevent chip out.

The problem is when I rout into the corner from the other edge. It seems I need a backer board with the mating image of the first ogee.

Is my only choice to rout a mating backer board ?

Thanks, Don

-- --- Measure twice, mis-cut, start over, repeat ---

6 replies so far

View NBeener's profile


4808 posts in 2596 days

#1 posted 11-09-2010 11:53 PM

I can’t be sure if it’s your ONLY choice, but it surely seems like the BEST choice.

Half the time I’m routing profiles, I’ve clamped two scraps—one at leading edge, and one at trailing edge—to the work piece.

Very little downside….

-- -- Neil

View PurpLev's profile


8523 posts in 3071 days

#2 posted 11-09-2010 11:53 PM

route the edge that is across the grain first with backer board, then rout the other edge that is with the grain to minimize tearout.

Another thing you can do is before routing the 2nd edge against the rotation of the router (normal operation) approach the mentioned corner with a climb cut – just to touch up the corner itself not the entire length of the edge. this will let you shape the corner with the rest of the edge acting as a backer board. then address the rest of the edge in a normal manner and as you reach the corner it is already shaped out so you don’t have anything to worry about.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View wwbob's profile


111 posts in 2297 days

#3 posted 11-09-2010 11:59 PM

Route in the wrong direction. I don’t know the exact terms, but there is the safe way to route wood where the router will not grab and pull the wood away from you and there is the other way. I was routing red oak and had lots of chipping issues. Here’s what the instructor said:

“Carefully, CAREFULLY, route in the wrong direction taking a series of passes. With each pass, increase the depth of cut.”

I was creating a raised panel using the router and made 5 passes, all going in the wrong direction without chipping.

Routing the wrong direction will cause the router to want to pull the wood out of your hands.

Be very careful, but it is possible.

-- "I like the quiet I hear." - Channing, age 4

View NBeener's profile


4808 posts in 2596 days

#4 posted 11-10-2010 12:02 AM


Climb cut.

See … you can DO it, but may not know the lingo.

I know the lingo, but … usually can’t DO it ;-)

Takes all kinds to make this site great :-)

If you have a minute, Pat Warner is kind of a Router God.

Here's his article about tearout.

Actually, I made it a TOUCH easier to read, and think it should be useful posted here, in its entirety:

I believe more than 95% of tearout (chipout) produced by routers can be eliminated.

In fact most of the routing I do is “tearout-free” and the little that I do encounter is usually traceable to crummy wood, (invisible checks, poor drying schedules, wild reversing grain, etc.), not to technique or tooling.

Let me list some ways for you to get better results.

1. Dimension and prepare your stock well. Try and waste away cup, crook, and bow as much as possible, as each of these defects can present the stock to the cutter out of square or at some unintended angle. Most cutters are designed to attack wood at 90º and if the stock is dimensionally compromised it can be fed poorly (on the router table) or the router can rock as it travels down the work causing tearout.

2. Regulate the depth of cut. A good baseline for the maximum depth of cut on good wood (using 1-1/2 H.P. or more) is about 3/8” x 3/8”. Depths greater than that will often tearout. If you think you can take that much wood (or more) in a single pass, take a few swipes on some scrap stock of the same origin first. If you are tearing out try and do the cut in stages. I usually use two routers with similar cutters to do 2-stage cutting. Say I want a 3/8” x 1/2” rabbet. I might cut more than half of the profile with 1/4” rabbeter set to a 3/8 vertical depth of cut. This may tearout but the finish cutter will often erase the tearout produced on the first cut. Light cuts substantially reduce tearout.

3. Use sharp cutters. Sharp cutters tearout far less than dull ones and antikick back tools tearout less than standard tool bit designs. Cutters with some shear angle also reduce tearout but may I caution you against the aggressive use of spiral ground cutters. Deep side cutting with spiral ground cutters can unexpectedly lift the router or force the work out of your hands on the router table. On-shear cutters are just as good and a lot safer. Incidentally a lot of tools bits are designed to cut on the bottom of their flutes as well as on their sides, (e.g. rabbeters, slotters, straights, dovetail bits). The sides of the flutes have had a lot more technology in their grinding procedures than the ends of the flute and consequently tearout is often worse on the bottom of the cut. This is especially true on resharpening as the bottom of the flutes are rarely touched on the regrind. Because of this phenomena, if I can, I’ll rout the cut on the router table to full vertical depth but only a fraction of the side cut will be taken for each pass. This maneuver minimizes the end cut but takes full advantage of the more efficient cutting design of the side of the flute.

4. Control your feed rate. A fast feed rate, even though the cutter can handle it, can aggravate tearout. There is an optimum feed rate for any cutter/router combination. Try and figure out what it is on scrap. Too slow and you’ll burn wood too fast and you may chip out. Experiment with the climb cut. The climb cut can virtually eliminate tearout but always at some risk. Climb cutting is that practice of routing in the direction of the cutter rotation, (right to left on the outside of stock with the hand router and feeding stock left to right on the router table). Climb cutting is less efficient than anticlimb cutting and therefore takes more energy. That coupled with tendency of the work or router to self feed can lead to an unexpected loss of control with the hand router or the work being pulled from your hands on the router table – both potential disasters. Very light cuts are permissible but if “light cuts” turns into everyday heavy hogging you should consider using the router table exclusively and only with a power feeder. For a further discussion on tearout please see the authors’ “Getting The Very Best From Your Router”, a Betterway Book, Chapters 5, 8 and 10. 1.

Finally, buy good stock. Straight grained, well seasoned material will provide you substantial immunity to tearout. Crummy bent up stock with ever changing grain patterns can be extraordinarily difficult to rout. Knotty stuff with interlocking or rowed grain and pronounced figure (birdseye or quilted maple e.g.) can be quite striking but not much fun to rout. Use only the sharpest of tooling to rout figured material. I use all of the aforementioned techniques to rout without tearout and usually I’m successful. Practice as much as you can on scrap material as the key to good cuttings is experience. If I have to have a flawless cut I always commit the entire procedure to a test or two even though I’ve been doing it for 25 years.

-- -- Neil

View wwbob's profile


111 posts in 2297 days

#5 posted 11-10-2010 12:12 AM

Forgot to mention, I was using a router table. Important for climb cutting. The table makes it much simpler to control the work piece.

NBeener, Thanks for the correct term and the article.


-- "I like the quiet I hear." - Channing, age 4

View SuburbanDon's profile


487 posts in 2416 days

#6 posted 11-14-2010 10:37 PM

Great, thanks for the responses !

-- --- Measure twice, mis-cut, start over, repeat ---

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