Chip breaker - out of square

[Jimmy Thomson]

The chip breaker on my no. 4 plane is out of square with the sides (see photo below). I'm not entirely sure if this really affects things (complete novice here), but if it does, then I'd like to get that edge square with the sides. My question is: how would I go about getting a precisely square end to the chip breaker? I have a grinder, though that feels too harsh. I'm not convinced that filing will do the job as I'm assuming it's hardened steel (I may well be wrong though). I've tried endless wet&dry paper but am getting nowhere.

It looks like there's about 0.75mm to come off to level it up.

Any thoughts on the best approach would be much appreciated.

Thanks,

Jimmy.

 

[AndyT]

It's not very hard steel.
A file is the answer.

 

[Jimmy Thomson]

Thanks, Andy! I was nervous about wrecking a new file on it. Your comment gives me the confidence to give it a go.

 

[ED65]

I'm not entirely sure if this really affects things (complete novice here)

It depends on how much you use the cap iron.

It wouldn't matter much or at all on a traditional jack or fore plane where the cap iron would be set back a fair bit from the edge, it's potentially a big issue with a smoothing plane or jointer where you should use the cap iron to control tearout – that's what the cap iron is for. You do this by setting the cap iron close to very very close to the edge, that's under 1mm to 0.3mm or less respectively.

I'm not convinced that filing will do the job as I'm assuming it's hardened steel (I may well be wrong though). I've tried endless wet&dry paper but am getting nowhere.

Well it should be mild steel, which should abrade with no difficulty at all. But how you do it matters greatly, just as it does doing the same thing on a cutting edge incidentally.

Before you begin you might want to check square from both edges, as these aren't all perfectly parallel-sided. If you find this is so you might stop right there, it's possible you'd be able to set the cap iron okay by just canting it slightly on the cutting iron. Yours seems like it's too far out to make that likely but I wanted to mention the possibility as it'll save you a ton of work; many a cap iron doesn't have its leading edge perfectly square with the iron it's attached to so they're screwed together at a skew.

 

[ED65]

If you do have to correct yours I feel fuller instructions are called for with something like this, where there's a finite amount of steel to work with (unlike a chisel or plane iron where you can mess up and retry almost endlessly).

I would generally use a sharpening stone or diamond plate for this task, but on any a flat abrasive surface the method is the same: stand the cap upright, flat towards you, touch down on the high corner (or high spot if the edge is cambered) and start pushing it back and forth. Hold it very low down to dampen vibration and keep the noise down.

If you're doing it with a file you'll clamp it edge-up in a vice, just below the curve, and then file away most or all of the high spot. It's going to screech! BTW if using a metalworking vice fitted with its original steel jaws pad them with something or you may marr the cap iron terribly.

Either way check periodically as you go so you don't overshoot the mark. This can be very easy to do as mild steel cuts fast, like buttah.

There's no reason you couldn't do this initial squaring task on a grinder if you're careful, and your rest is deep enough to support the cap iron sufficiently and set close enough to stone for safety (less than the thickness of the steel).

Once you are square then you need to re-form the front curved edge, which I think you'll find will prove to be more work than the squaring! Lastly you'll need to fettle the underside of it as per usual.

 

[toolsntat]

I would not touch the outside of the curved side unless not flat.
It's very hard for me to explain but you need to work on the contact side with it sitting on an abrasive whilst the other portion of the blade is on a lower support . While doing this you concentrate on keeping your pressure on the greatest projection on the curve.
This, if the curve is well formed, should result in a co-planar under cut squarish finish.
Cheers Andy

 

[MikeG.]

If the curve hasn't been formed accurately, or has been bent or damaged in some way such that the axis isn't at right angles to the centreline of the cap iron, then no amount of metal removal will ever sort this out. I think Andy (toolsntat) has made the most important point...the flat of the underside of the iron must be in a parallel plane to that of the edge, thus all work on the leading edge should be from the underside, not the top of the curve.

If the geometry of the curve itself is out and this isn't just a case of over-zealous and under-skilled adjustment previously, then you're going to be bashing the thing with a hammer before you take a file of diamond plate to it.

 

[ED65]

It's always a judgement call about what's needed, and how to go about it to a certain extent is a horses-for-courses type of thing, but nobody should be under any illusions that remedial work may necessitate work to the front and the curve. The more out the leading edge is the more necessary this is, and 0.75mm is a lot out.

Maybe it should have been bent first rather than the first port of call being metal removal, but many are very reluctant to even attempt this – to the point of 'advising' this should never be done, as we've seen in posts here in the recent past. However, others have done this successfully, perhaps multiple times, and not rendered their cap irons unusable which kinda tells us something about that position.

 

[D_W]

If the plane adjusts fine as it is, I wouldn't touch it. By that, I mean if you can set the cap iron close and still adjust it properly.

When a plane adjusts fine, squareness doesn't matter, the iron should be maintained to match the cap iron. The iron probably has tapered sides, anyway.

 

[ED65]

If the plane adjusts fine as it is...

That's the key question isn't it?

...the iron should be maintained to match the cap iron

All of us who have posted subsequently presumably would have little difficulty in maintaining a cutting iron with a deliberately out-of-square edge. Not so easy for those with less experience, tough ask of the complete beginner!

And perhaps impossible for most who rely on a simple side-clamping honing guide.

 

[D_W]

I think maintaining a square iron if the iron has tapered sides is out of the question for a beginner because there is no square reference side. The cap iron is the reference, so the job for a beginner is to learn to maintain an iron to that reference unless the reference is unusable.

Skews are seen as difficult to maintain, but probably because people aren't maintaining them to the sole of a plane by eye.

The square should probably be left out in favor of the eye if everything functions.

 

[D_W]

I saw the picture of the cap iron and assumed that it must be to a woody as far off as it is, but see that it's to a common 4. It'll need to be bent to work if it's squared. For someone new, it may be better if the plane can't be set right to just replace the cap iron.