Plane iron getting "wrecked" when shooting: what can it be?

[MikeAnblips]

So I am building a box using oak. This is the first time with this type of wood, sofar I've planed/sawn soft: pine and spruce/fir.
I've sawn, resawn, dimensioned thicknessed and the whole procedure on the sides, I did not notice anything special behind of course the different texture and "reaction" of the wood under the tools. Yesterday I started shooting the miters, I use a Veritas low-angle Jack and a home-made shooting board, here with the mitres 'add-on':


In the pic you see one of the long sides, which came out after one of the short ones: both without problems, at least I could recognize.

When I got to the second short side, I sensed something was happening, but I could not understand what it was. Some black-ish strip was appearing in the mitre, but I didn't pay much attention to it and went on planing. As I got to the second mitre, the cut was coming out unexpectedly bad, and shortly after, the plane started making a "grinding" sound, insead of cutting

I had a look at the plane iron, and it was completely destroyed! Basically, there was a notch, where the blade contacted the wood (it's a small portion of the blade, due to the geometry of the setup). I don't have a grinder, so bringing the edge back to life on my 200 grit diamond wasn't exactly quick... Anyhow: I sharpened again and went back to shooting.

In a matter of a few strokes (which cut - say - normally), I was back to square one! This is a pic of the edge just after regrinding/sharpening and using it for a few seconds:


This is the black ribbon which appeared first on the edge I managed to shoot:



And this is a close-up of the edge I'm not finished with... Yet:



Even the sole of the plane got scratched...


Now, before I go on and grind again (actually, I've already done it ), re-sharpen and then go through the same experience again, I thought I'd stop for a minute and try to understand what's going on...

What can it be, and how to go about it?

Thanks,
Michele

 

[Peri]

Well, only something as hard as the the blade (ie steel) is going to cause that damage. I'd run a magnet over the jig and the wood to make sure there's no lumps of swarf embedded somewhere.

Obviously check fixings (if any) you used to make sure they're well below the surfaces - but to be fair, damage that wide looks like it'd need an entire screw head to be sticking up (edit: although It could be a small point and due to moving the plane across it at an angle it'd be a much wider bit of damage).

 

[MikeAnblips]

Thanks @Peri - a magnet could not reveal any lumps around the wood or the jig.
I have used the same setup time and again, and also with this project for a few sides already, so I'm really wondering what could have gotten trapped between wood and plane, without me noticing anything

 

[Pete Maddex]

Do you have a second blade to try in your plane?

My guess is the blade is to hard and is chipping.

Pete

 

[CHJ]

My guess is the blade is to hard and is chipping.

Pete

If it is, then not helped by the straight chopping presentation to the endgrain that results with a conventional hand plane, a skew blade presentation providing a slicing action is more forgiving.

But few of us have the luxury of a skew plane for the occasional use on a mitre board.

 

[Trevanion]

You might benefit from a slightly steeper angle on your plane iron, so that you have a higher pitch angle at the cutting edge once inserted in the plane. This will make the edge more durable but also make the plane lean more towards a scraping action rather than a shearing action, which works better for dry hardwoods typically.

 

[MikeAnblips]

Alright gentlemen,
mystery solved - but quite disappointingly so

That oak piece is a small slab I got roughly one year back from a local joyner - at the time I wasn't really sure how to do my first attempts and I didn't want to start with a whole slab I didn't know how to manage.



This very kind professional had some pieces lying around, actually much more than what I wanted... So he cut and thicknessed this and another piece of European ash for me.

I never looked at it super close, after all he put it in the thicknesser and sawn the edges too...

But today, at the third attempt/swing of the plane, the black strip went away, leaving a small crater with a shiny object underneath. Maybe a diamond?



Then I got curious, and looking at the other side, the one I managed to mitre, but had this blackened strip nevertheless, I could see it even more clearly:



Was that a nail?? How so? I never did anything like this!

I grabbed the "full" slab shown above, and... After a closer look...





So, basically (not sure why), the joyner had shot some mini-nails into the slab, and probably forgot he'd done that, when he gave me the slab.
I got lucky in a number of instances, but then hit the bad spot :-/

What could I do?

 

[Pete Maddex]

Wow that’s some bad luck to hit one right on a miter.

Pete

 

[MikeAnblips]

Wow that’s some bad luck to hit one right on a miter.

Pete

Actually, on two Pete!
It's just that the first one wasn't catastrophic enough to stop me and make me think!
Also, I planed that face too... So it was just really on the edges!

 

[CHJ]

Really bad luck, make sure you remove all traces of the iron particles if at all possible, oak, iron and moisture have a habit of providing some serious stains.
Time for a basic metal detector methinks, especially if using reclaimed wood, surprising how many times a supposedly removed staple, nail or screw has left evidence of it's past presence.

 

[Mike G]

No, no.....you've got it all wrong. It was obviously a question of a right handed plane being used by a left hander.

 

[CHJ]

No, no.....you've got it all wrong. It was obviously a question of a right handed plane being used by a left hander.

That's rather a sinister remark

 

[MikeAnblips]

No, no.....you've got it all wrong. It was obviously a question of a right handed plane being used by a left hander.

That might well be... I saw with my left and plane with my right, but shoot again with my left hand. Plane must have got confused. Rightly so.

 

[Trevanion]

Most likely it’s a piece of staple left over from the timber supplier as they staple on pieces of paper to designate packs to certain buyers on the yard and lorries. If a pack gets rejected they tear off the paper and staple a new one on to send it elsewhere until someone accepts it and sometimes you can have planks riddled with staples.

Once had a load of pre-fab oak newel posts which were absolutely riddled with staples, I don’t know who in their right mind decides to staple a finished item with a steel staple right through the face but that’s likely why they were rejected so many times. Fortunately, they were going from 90mm to 80mm so all the staple holes and tannin stains were removed.

 

[Woodbloke]

I'd tend to agree with Trevanion above. There's no logical reason except for the explanation given for the oak to be contaminated with so much steel debris. I've come across those staples before and they penetrate a long way into the wood and even if you think that you've extracted the whole thing, a bit may have been broken off and left behind - Rob

 

[Peri]

And the magnet didn't find it?

I have a small metal detector thing, but it's a bit of a flaff - I tend to use a small, super strong neodymium magnet that you can feel 'grab' the smallest bits of metal.

 

[Cabinetman]

That was unlucky and a pain and time consuming, in my half century (+) of doing woodwork I’ve never come across any foreign objects in new wood. Just fortunate I suppose.

 

[MikeAnblips]

And the magnet didn't find it?

I have a small metal detector thing, but it's a bit of a flaff - I tend to use a small, super strong neodymium magnet that you can feel 'grab' the smallest bits of metal.

I couldn't find my neodymium ones
so I went for a standard ferrite torus and that couldn't reveal anything. As you see in the pics, once I got triggered, I could spot some of these metal nightmares showing off the surface of the rest of the slab... There could be more under it, maybe? (I mean thin nails/staples which just buried themselves below the surface).

 

[Steve Maskery]

I've got one of these (not this particular one, I don't think, but this type of gadget). It is excellent and worth its weight in gold.
Metal detector

S