Router keeps changing depth

[Eddie Ormerod]

While making mortise and tenon breadboard ends, my router lowered on me while routing the tenon. I've made several of these and haven't had any issues until yesterday.

I thought it was my old ryobi plunge router causing this so I went out today and bought a dewalt router. Put the motor in the fixed base and it dropped depth on me again.

Am I taking too much off, making vibration which is causing the bit to vibrate out? I go about 7/16 deep on my rout. It's alot but I've never had this issue.

Thanks
Eddie

[Jim Becker]

Replace the tooling...if the cut is changing with two completely different routers and collets, it's most likely the tooling that's worn. If it's a down cut bit, that can be adding stress to pull it farther down into the material, too.

[Mel Fulks]

Ive always liked Porter Cable routers. They can be hard to lock. I tighten as much as I can without straining ,then use pliers to tighten just
a bit more . All the old guys I worked with did that. And all had a “I thought everybody knew that” opinion of the practice. The way
liability is these days I think it would be wise for the mfg. to include a pair of pliers with non- marring jaws.

[Adam Herman]

I have had this happen if the collet or shaft of the bit are dirty, the bit slips in the collet no matter how tight you think you have it. after the first time, that bit has some kind of wear or something and will keep doing it. even after a good cleaning.

[Mel Fulks]

Op might be adjusting router depth in wrong direction. We were told to always adjust up not down.

[John TenEyck]

If you bottom the bit in the collet it is likely to loosen. FWIW, a 7/16" cut is massive. 1/4" is about all I ever take, usually less.

John

[Tom M King]

The bit is not keeping up with the motor rpm's, so it's moving in the collet. Try taking 1/4" bites.

[Adam Herman]

7/16 deep with a shallow cut or 7/16 cut at some thickness...

i have edged 3/4 thick stock no problem, but never taking more than maybe an 1/8 depth of cut. radial to the bit

[Ken Fitzgerald]

When I have had this problem, I first clean the shank of the bit, cleaned the collet with a solvent and retry the cut on a similar test piece. If it still moves I have lightly scuffed the shank of the bit to eliminate the problem.

[Mel Fulks]

Yeah, have to go slowly ....with 2 flute bits. Single flute is MUCH faster!

[Eddie Ormerod]

I'll try cleaning the bit shaft. Might even buy a new bit. Disappointed. I'm trying to fix the mistake but I think the top might need to be redone.

[John TenEyck]

I'll try cleaning the bit shaft. Might even buy a new bit. Disappointed. I'm trying to fix the mistake but I think the top might need to be redone.

If the tenons are too thin now, you can glue some new stock to what's left and redo it. Worst case, cut off the tenons, route mortises in the ends of the top, and glue in new tenons.

No need to build a new top.

John

[Lee Schierer]

Find some micrometers and measure the OD of the shaft. Some bits have metric shafts and won't grip well in a single split collet.

[Thomas McCurnin]

I always practice on similarly sized scrap before making any cuts. Indeed, when I order wood, I usually order some alder or poplar in identical thicknesses and use those for test cuts. Often, I end up with an identical project piece made from the scrap, because I didn't ruin it all. Also for mortises, try an upcut bit which removes more material with less stress to the bit or router,

[Jim Dwight]

Do we know if it is the collet in both cases or could the routers depth control be an issue in one or both of the cases? My old Ryboi R500 had a good collet that I don't think ever slipped. A DeWalt should also be good. Otherwise I agree with the other comments, too much of a cut and make sure the bit is not the culprit. If I was still doing mortises with a router I would probably use one of the straight bits with a bottom cutter - or a spiral upcut if I decided to spend more.