Does anyone flatten the frog side of a plane iron?

[Mike Soaper]

I know that folks flatten and polish the chipbreaker side of a plane blade\iron for sharpness,

and make the face of the frog flat to reduce blade chattering,

but don't recall hearing about flatting the side of the blade that goes against the frog to reduce chattering.

Does anyone flatten the frog side of the plane iron?, or is this a non issue?

I decided to check the frog side of the iron and came across this on an iron from a stanley #3 type 11
frog side of plane iron az.jpgfrog side of plane iron bz.jpg

[steven c newman]

I will flatten both faces, as needed....and IF needed. Don't want the iron to rock while sitting on the frog...It also helps remove any rustiness going on, with the older irons.

IF you find a big hollow where the chibreaker would be going...chances are there is a large bump on the other side...best to level both faces.

[Tom Trees]

Yes you can do it with a soft mallet should there be a large warp.
Just to make note, if it's not a bevel up plane and is indeed a Bailey style plane with thin iron,
should you be inclined to want to lap the face of the frog, have a look and see that there is indeed a gap there as per the design,
should no burrs be present then it is indeed a waste of time, since the cap iron bends the iron,
I done that early on, removed the yoke by way of abrading off the peening, and only just was able to pien it again,
very risky operation for absolutely no benefit whatsoever.

If you want to know how to get the very very best out of a plane, then have a look at David W's youtube channel, specifically for information on the
cap iron/chipbreaker, and don't trust other sources,
Why, you might ask?
It's because most folk, like the popular guru's on youtube doing tutorials or classes for a living... either don't know/refuse to learn how important the cap iron is,
or they know all too well (well, at least nowadays)
and are embarrassed, or even worse.. making it their business to keep newcomers ignorant and in the dark with the drip feed system.


Just to make it clear, I'm suggesting David's videos or articles on the matter of fettling the actual plane itself, mainly you should focus on everything he has to say which is cap iron related, as he has went to much effort to make all this widely known, thanks to Warren Mickley, who frequents here often.

Now, if you want to learn how to use the plane, another David (Charlesworth)
has the very best information you will find on the matter of precision planing.

You likely have to watch/read from Mr Charlesworth to achieve the results you want, should you wish to use the cap iron/chipbreaker
for more than just a blade stiffener,
i.e for the complete elimination of tearout, and NO scraping or sanding afterwards.

Ps make note that lapping is a very bad idea should you think that you can lap a convex (bellied) plane flat on a lapping plate with a larger abrasive area than the plane is,
That won't work and you will abrade off the ends compounding the issue.
A lap which is larger than the plane is for testing only, i.e only to identify the contact points, so you can concentrate on specific removal of those areas
and NOT remove areas where you don't want to, because abrasion on a solid flat lapping plate, i.e float glass/granite will always favour the edges.

You should be able to colour in the sole with a marker, work out the high areas and still keep the ink on the perimeter, where you want to keep as much meat as possible and
not end up with a wafer on both ends.

Three rubs of the plane (on the large lapping plate) when flat, should abrade everything evenly you can note that abrasion favours the edges
More than that though, and you'll be shooting yourself in the foot, abrading where you don't want to.
SAM_3677.jpg

https://postimg.cc/QBDNqb55

Should you be sceptical, just make note that no-one takes out the feelers, nor does anyone do up to three light rubs and no more to prove something is flat
Some videos even suggest to intentionally create a belly by targeted abrading of the edges on a Bailey.
Beware of that, and understand how much work it could take to fix.

Those two David's are where you will find the very best information regarding hand planes.
Make note of what cap iron "influenced" shavings are on dry hardwoods
Note mainly the straightness of the shaving will tell you more than the timber itself, but also the chatoyance of the surface of both shaving and work.
Cap iron influenced shavings will be straight (not curly) crinkly, and waxy looking.
If you can get the hang of that, then you can easily plane any timber under the sun.
SAM_3411.JPG

https://postimg.cc/4Yfs7dTb

SAM_5131.jpg

https://postimg.cc/ygWGNCMS

Good luck


Tom

[Jim Koepke]

A bit of advice, "if it ain't broke don't fix it."

jtk

[Luke Dupont]

No need to touch the "frog side" of the iron. The only instance I can imagine one might is if restoring some really badly warped iron, but then it may get too thin to use anyway.

A bit of advice, "if it ain't broke don't fix it."

jtk

This. Why make your iron thinner than it needs to be, and risk ruining it if it's already working just fine?

A lot of harm has been done to a lot of planes and irons over the years with unnecessary grinding. Many of us with a lot of second hand tool experience have seen plane soles or irons that have been ruined by somebody over enthusiastic with a belt grinder or something.

Preserve as much thickness on the plane sole and iron as you can, and always be aware that you can introduce error yourself even if you're grinding on a stone or something which is perfectly flat. Test often to make sure that you're not rocking and making the problem worse.

But more importantly, things rarely need to be dead flat to work well. Most planes will work just fine without flattening the sole, and/or already have soles that are either flat enough, or have even been ground dead flat by somebody already. Before you start flattening anything, you should have a compelling reason to do so. Does the tool function just fine? Then for heaven's sake, don't try to fix what isn't broke, as the only thing that can come of that is harm and wasted effort.

Wooden planes aside, I've only ever flattened one iron plane sole. The vast amount have come really flat already. And the one I flattened, I only flattened because it was really bad and I could notice something felt a tad off. I flattened it 90% of the way to dead flat, very carefully, and stopped when I felt it was close enough and that removing more material would just thin out the sole and waste time and effort needlessly. Maintain as much thickness in the sole of your planes, and thickness of your irons, as you can.

I also want to observe that many Japanese plane irons, for instance, are hand forged, and very far from flat on the "frog" side -- granted, the wooden dai is generally matched to the iron. But this proves an important point: If you are having problems with the iron in the plane, I would start by investigating the frog and the cap iron and cap iron screw, then maybe the chipbreaker, and only lastly consider touching the iron. But again, I won't touch anything unless I first identify it as the obvious source of a problem.

Don't fix what ain't broke -- it's just asking for trouble. Fix only what you have identified as the source of some problem in use.

[Andrew Seemann]

I will clean up rust on the bottom (frog side) of the iron, and run it briefly on something like a diamond stone to check for high spots, but I'm not going to lap it on a surface plate or anything like that. As long as it seats good on the frog, that is good enough for me.

[Robert Hazelwood]

Usually the frog side of the iron is a bit concave along its length, so that when you rest it on the frog it mainly contacts the frog at the top and bottom. The lever cap will flatten it out, but that concavity helps ensure good contact where it counts, which is right at the bottom of the frog and heel of the blade bevel. If you have good firm contact here the rest doesn't matter too much.

The only thing I might worry about is flatness across the width of the blade down by the heel of the bevel. A hump across the width here could be a problem, and the lever cap is unlikely to flatten it out completely. If you are getting chatter or other strange behavior its something to check. You can make a sort of indicating fluid out of some oil and pencil lead- rub this on the back of the blade at the bevel heel area, and place the iron (with cap iron attached) in the plane and tighten the lever cap. Remove the iron and look at where the pencil lead transferred to the frog. A full width strip of contact is ideal, contacting on left and right sides is usually acceptable, a single spot of contact in the center might be an issue. If you get the latter, and are having issues with the plane, then consider removing the hump from the bottom inch or so until that contact strip looks better.

[Jim Koepke]

Usually the frog side of the iron is a bit concave along its length, so that when you rest it on the frog it mainly contacts the frog at the top and bottom. The lever cap will flatten it out, but that concavity helps ensure good contact where it counts, which is right at the bottom of the frog and heel of the blade bevel. If you have good firm contact here the rest doesn't matter too much.

Interesting theory, my preference has always been to 'tune' the chip breaker so it does its duty without deforming the blade. Solid contact between the blade and the frog helps to dampen any vibrations created between the blade's edge and the surface being planed.

The dampening of vibration from a more solid mounting of the frog was a feature of the Bedrock design.

The folks at Millers Falls even used it as a selling point in their advertising:

The standard lever cap used by competitors applied pressure to the chip breaker/cutter assembly at two points—one at the point of contact with the cap’s cam lever, the other along the lower edge where it made contact with the hump of the chip breaker. The hinged cap was designed to apply force to the chip breaker/cutter assembly at a third point, just above the chip breaker hump. Three points, rather than two—the company advertised the arrangement as a method for preventing chatter.

jtk

[steven c newman]

Whenever a plane comes into the shop, usually for a rehab...I will indeed check BOTH faces of the iron, just as a matter of habit...

Frog face does NOT need to be polished "mirror" bright.....I am just cleaning the "patina" (rust) up.....and a little work doesn't hurt. Needs to balance out from the other face.

Also, IF the frog face is smooth and reasonably flat....it rests on the frog face better, and even adjusts easier.

Might add maybe 5 minutes to the rehab time.....not a big deal. No straightedge and feeler gauges required....as I already have a flat, smooth frog face to check with.

Would be like changing the front 3 spark plugs, and not worrying about the back 3 plugs in a V-6 engine....

[Mike Soaper]

Thanks to everyone for their replies, examples and insights, good things to be considered.

That said, I think I'm in the first give it a few light swipes to clean and assess things camp.

I'm gonna mull over what to do or not to do with the pictured blade as it looks like only about 20-25 % of the blade is making contact with the frog in the chipbraker area. Seems to be a blade thickness vs support decision

Thanks again,
Mike

[Tom Trees]

Should you have adjusted that mouth to be tight, and also the cap set close, then without more work with a file which seems unnecessary to me,
chattering will be very very prevalent, and the plane refuse to cut.
No need to have the frog forward for dimensioning stock or smoothing.

[Luke Dupont]

Thanks to everyone for their replies, examples and insights, good things to be considered.

That said, I think I'm in the first give it a few light swipes to clean and assess things camp.

I'm gonna mull over what to do or not to do with the pictured blade as it looks like only about 20-25 % of the blade is making contact with the frog in the chipbraker area. Seems to be a blade thickness vs support decision

Thanks again,
Mike

I'm confused, the frog and chipbreaker are on opposite sides of the iron. Where is contact not being made?
Generally I would make sure the frog and chip breaker are flat before worrying about the iron. Then maybe check if the iron is twisted or cupped. If the iron isn't obviously misshapen, I don't think extra flattening will be of much use....

[Tom M King]

I own a Bunch of Stanley and Record planes that get used, and I've never had to bother with the back of an iron where it rests against the frog. The all work easily.

[Mike Soaper]

I'm confused, the frog and chipbreaker are on opposite sides of the iron. Where is contact not being made?
....

The dished area of the blade is not making contact with the frog.

Maybe this overdone exaggerated napkin sketch will help.

Sorry about the rotated pic.

blade drawing a.jpg

[Jim Koepke]

Mike's Picture.jpg

If your blade is anywhere near as bad as the image makes it look, you might be better off acquiring a replacement blade.

Do you have feeler gauges to measure the gap?

jtk