Edge chipping with drawer lock bit on router table

[Gabriel Marusic]

I'm building some drawers and am trying out one of these drawer locking bits for the first time and am having a bit of trouble with some chip out that I'm getting. For reference, I'm using the Whiteside 3347 https://www.whitesiderouterbits.com/products/3347 on my router table to make the cuts and am cutting half inch maple ply. When I'm doing my passes with the workpiece face flat against the router table face they're coming out flawless. When I'm doing the opposite cut and running the piece vertically against the fence I'm getting some pretty substantial chip out here and there along the length of the cut. I wish I had a picture here, I forgot to take it when I left the shop and should be able to grab one tonight when I'm back there. Just to be clear this isn't tear out along the edge of the ply but rather some large chunks here and there. I solved my earlier tear out issue with a zero clearance insert for the router table fence.

The router bit is brand new and making perfect cuts on the other face so I don't see that as being an issue. My router is a bosch 1617 and is at about 4 on the speed setting which is about 20,000 RPM. The wood is 1/2 maple ply, possibly too soft? I'm running the piece fairly slowly across the fence, possible I have a little wobble in my technique or still too fast?

[glenn bradley]

I use this joint and that bit a lot. A smooth continuous pressure / feed rate is your friend. I have a tall fence doo-jobber that I use for the vertical cut. It has a replaceable ZCI for the bit which solves most of those problems. It is unused in these pics. Normally the bit would protrude through it.

461926461925461924461922461923

I run a large blank cut to length and then rip the drawer box sides from it. If you have some material that is particularly chip-out prone, a razor knife strike along the cut line should solve your problem. One benefit of using this joint with ply is that the chip-out prone area is mostly inside the joint when you glue up.

[Gabriel Marusic]

I use this joint and that bit a lot. A smooth continuous pressure / feed rate is your friend. I have a tall fence doo-jobber that I use for the vertical cut. It has a replaceable ZCI for the bit which solves most of those problems. It is unused in these pics. Normally the bit would protrude through it.

461926461925461924461922461923

I run a large blank cut to length and then rip the drawer box sides from it. If you have some material that is particularly chip-out prone, a razor knife strike along the cut line should solve your problem. One benefit of using this joint with ply is that the chip-out prone area is mostly inside the joint when you glue up.

That is an awesome setup Glenn! I will definitely try scoring the cut line before making the actual cut when I do it again tonight. Most of the chips coming out aren't visible but I am getting the occasional one at the end which will show. My challenge there is it's been tough keeping the sacrificial piece tight behind the one I'm cutting when it's vertical. Do you have any suggestions there?

Also, who makes those featherboards? They look perfect for the job.

[Ralph Okonieski]

Sometimes my lock mitre bit creates chip out. Then, I will score the piece with a utility knife at the appropriate place. The piece comes out nice and clean.

[Mel Fulks]

Gabriel, one thing that will stop that tear out is to first use a round over bit (climb cutting) and of appropriate size to get rid of the sharp corners. Then when you do the “real” cuts all will be well. Old trick not much seen in print because of liability concerns….of your insurance
salesman.

[glenn bradley]

Those are older stackable Rockler feather boards. They may still make them. Stacked for greater control is the way to go IMHO

[Lee Schierer]

The quality of the plywood has a lot to do with it. My son recently built a plywood cabinet for his shop and one piece of plywood he purchased from a regular lumber yard had a lot of veneer facing failures as he was cutting pieces from that particular sheet. Apparently the manufacturing process didn't apply the glue consistently across the sheet. There were small areas of the veneer that would lift right off the substrate.

[Rich Engelhardt]

one thing that will stop that tear out is to first use a round over bit (climb cutting) and of appropriate size to get rid of the sharp corners.Can that be done with a handheld router & then move over to using the table?

[Tom Bender]

Attach the sacrificial piece with tape or glue