Eucalypt Planing Drama

[homesy135]

I get black marks like you have if I rub steel over wet timber. For example, thicknessing wet timber will have lots of black stuff on the underside of the board that was in contact with the thicknesser table. Since your knife is just riding the surface (i would imagine it would be difficult to plane wet timber, though i have never tried it), it will be slightly compressing the surface of the timber, squeezing out any moisture and then the sole turns it all black. Also, thinking back to one of your recent threads about lapping the plane soles, the black stuff can be leftover crap from the lapping, give the plane sole a good clean with whateva solution you r comfortable with, I use acetone.

I'm with Kuffy here. That black stain is iron tannate - iron from the plane reacting with tannins in the wood. The same sort of thing that happens if glue, wood and an iron clamp are in contact. I'd check the moisture content of your boards.

[Luke Maddux]

I firmly believe in closing the loop on my "cry for help" posts. Unfortunately, these loop closer posts are typically a bit embarassing, as the problem often turns out to be extremely simple and kind of discrediting to me...

And this is a good one, fellas.

Even after my "I think I fixed it" post last night, I wasn't having good results. I basically just had a (expletive, expletive) moment and threw my hands up. In that moment, I had already decided that I would be buying a powered jointer, it was just a question of how wide.

I then sat down on my bench and thought about what was happening. This is physics. I like physics. I'm GOOD at physics. I can figure this out. The blade was DEFINITELY making contact, but it wasn't cutting. What could cause this? Something is happening within a millifractionth (TM) of an inch of that cutting edge that is causing the blade to touch the wood but not cut.

And then, as is often the case, it hit me.

I sharpen by hand and, when I sharpen, I am always feeling for the wire edge. That's my cue to move from the coarsest grit stone onward to the other two. Over time, the microbevel broadens and in my case, apparently, steepens. I know...This is something I need to work on in my sharpening technique. I was unaware of it before today.

I had reached a point where I had steepened the microbevel such that instead of the tip making initial contact, it was the HEEL of the microbevel. This made perfect sense. The blade was hitting the wood, but instead of cutting, it was skimming along a surface which was not sharp at all and, as a result, was only removing the highest, most jagged undulations in the wood and then no longer cutting when it came time to remove the last few subtle undulations (which was the initial problem). It also made sense that it would have worked alright on an extremely tame wood for planing, such as silky oak, which has a much straighter grain and is softer, thus more likely to compress very slightly under the plane and expose a fresh surface for my oh-so-slightly-high cutting edge.

I (hollow) ground the blade and resharpened. Totally fixed.

Man... Just when I think I've got this figured out something so incredibly minute and simple totally derails me for like a day and a half. Frustrating, to say the least, but I guess it's safe to say that eventually I will have all of the minutiae sorted out. The question is how many more times will this happen before I'm there...

Ok. The project is back on track. Thanks for all of the help.

Cheers,
Luke

[IanW]

Don't feel too bad Luke - lessons learned like that tend to stick with you for life! You may have helped someone else avoid discovering clearance angles the hard way.

'Bevel creep' is something hand sharpeners need to be aware of. We all like minimising effort, so the tendency is to lift the blade a fraction when re-forming the primary bevel, which gets your edge back quicker, but steepens the bevel quite a lot over a dozen or so heavy re-sharpens. Adding a secondary bevel to an already steep primary bevel eventually eliminates your clearance, as you amply demonstrated to yourself. I seem to remember it took a few incidents like yours before I figured this simple fact out....

Cheers,

[auscab]

The question is how many more times will this happen before I'm there...



Cheers,
Luke

Ha Ha Luke , it never ends !

Well solved though on the tiny curve in the blade , It acts like a little ski .

And how right , it cuts softer woods but skips over hard stuff.

Ive taught a few young fellows and come across this plenty , their holding the plane up frowning saying

"I just sharpened it and it wont cut"

Holding a cabinet scraper as a straight edge to the blade with light behind it shows it up, with the blade still in the plane . with glasses on now, for me .

Im still wondering about the black marks though ?

Are you saying this was caused by the blade curve as well ? It looks like a moisture and steel contact stain . An iron oxide stain .

Rob

[Luke Maddux]

Im still wondering about the black marks though ?

Well I'm thinking that there's some legitimacy to the whole "metal rubbing wood creates blackness" line of thought which has been mentioned above. I don't think it's a result of the wood being moist. This was kiln dried and then sent to QLD where it has been sitting for four months.

I think maybe it's just oil and grime rubbing off of the bottom of my plane. Because the plane wasn't cutting, I was taking stroke after stroke and wondering why. I think that by the time I ultimately decided to give up and take a photo of that (particularly blackened) board in the post above, I had probably taken twenty or thirty ghost strokes, which would've likely just deposited a bunch of oily blackness.

Some of it may have been out of the gum veins. I suppose that's a reasonable assumption.

I'm willing to bet that if most of us went into the shop, retracted the blade into our plane completely, and then took thirty strokes on a light colored board then there would be some of it on there.

Bottom line: I think the black stuff appeared because of the plane strokes which weren't cutting, as opposed to the plane strokes not cutting because the black stuff was present.

Does that make sense?

[auscab]

Yeah , sounds right .

[planemaker]

Luke. Its good to hear you got it all sorted. I would still recommend you watch the full Paul Sellers video. Also take the time to make yourself a pair of winding sticks.

regards Stewie;

[Robson Valley]

Finely divided particles of most metals are black: the iron from honing a gouge or chisel, the silver in an old, analogue black & white photographic negative. Iron oxides (aka "rust") is normally some shade of orange through red to brown, not black.

[auscab]

It going black, must have to do with the Tannin in the wood . An iron oxide stain is made by dropping steel in a jar of vinegar , I use steel wool . A drop of that on the woods that react to it is a jet black spot , when it's a strong mix . A iron nail or key left in a pool of water will leave a black stain , know as a iron oxide stain . Reversible with oxalis acid .

[auscab]

Oxalic acid . I can't see an edit button on this phone ?