Nicks in Jointer Knives. Worst offender?

[Rick Williams]

Looking for your experience as to what seems to be the worst offender in nicking your jointer knives. Over the last couple of weeks, I've ran several bdft of air dried cherry, walnut & white oak, on my 8' Grizz, all of which I scanned with a metal detector with negative results. Today, I was running some Borg poplar for drawer sides through and noticed a ridge. Checked my knives and have a nick not only in the knives but a scratch running the full length of both the infeed & outfeed tables. Not a typical scratch but a shiney line about a 1/16 of an inch wide like a serious rub occured.

Any thoughts on the culprit? I did run some cherry with a pretty serious knot in about the same position (2 & 3/4") off the fence?

TIA

[Russ Massery]

Most likely the knots did them in.

[Lou Ferrarini]

The only time I ran into something like this was when I ran some knotty pine through my jointer. I'll never do that again.

[Mark Singer]

I did it with a screw in a 2x4! Runed the knives...ohhh! I make occasional big mistakes!

[Jim Becker]

Knots or occasionally a grain of sand on rough lumber will do it in my shop. Fortunately with the Tersa knives, it's darn easy to shift one over a skoosh to deal with a nick.

[Ian Abraham]

I'd guess that you got a tiny pebble embedded in the surface of one of your boards, that would account for the mark on the tables and of course it's not gonna do the blades any good either :(

Ian

[Rick Williams]

That's kinda what I figured, something imbedded in the wood given the marks on the table. Figure the 'big guy's" got a sense of humor knowing how much I hate messing with jointer knives:D

[Tyler Howell]

Hi Rick.
I run a brush over rough sawn and the metal detector before planing. If it's real yucky stuff I'll skip plane it with the drum sander first. paper's a lot cheaper than blates.

[Mike Parzych]

A bullet in some walnut. Makes one heckuva nick.

[Dennis Peacock]

Nails, barbed wire, imbedded rocks, mud, sand/grit, and very hard knots will nick the knives. I've got nicks in mine right now, but sooner or later, I'll pull them off and run them across my Tormek and put a new edge on them.

[Rick Williams]

Dumba$$ me didn't think about lead not setting off the metal detector. Wish I had a drum sander, sure would make cleaning up some of this real rough stuff easier. I do brush off with a whisk broom but obviously have missed stuff. Used a 6" jointer for about 10 years and constantly nicked knives. Up graded to the Grizz 0586 recently and thought I had really focused on cleaning up the material before jointing but obviously not. Have thought about the Tormek for awhile and that may be the direction I go. Just ordered a shop heater yesterday so it's gonna be awhile before the budget allows a Tormek.

Thanks for the comments.

Rick

[Bob Spare]

The only time I ran into something like this was when I ran some knotty pine through my jointer. I'll never do that again.
Considering a planer, been working with 1851 barnwood.
But getting request for pine. Your post makes me wonder what course to take with knotty pine and the planer. Suggestion, as still in the learning curve.

[Jim Becker]

Most often it's either dirt on rough timber or knots. I just adjust one knife laterally slightly and move on.

[Laurie Brown]

I did my knives in with 3 bdft of hard maple. Didn't take much...

[glenn bradley]

I'm with Ian. I dutifully checked a board for metal, ran it through and it slipped a bit during the feed. I thought that was odd and so cleaned up my rollers and kept going (same side up). Theknoves survived but a small piece of grit (rock?) put some serious scratches on my bed ;-( I don't know how I missed the first set of scratches during the roller cleaning exercise; I was just too focused I guess.

[Dan Gill]

Lead ought to set off a metal detector. For that matter, plain lead (like an unjacketed .22 bullet) is very soft and probably won't knick the knives. It's not really GOOD for them, but not too bad. Now, a steel-jacketd slug like the military 7.62 x 39 AK bullets would probably do the knives in.

The last time I chipped mine badly, it was a screw in the wood. But little knicks do happen over time, and I suspect they are embedded grit.

Grit happens.