Flattening back of plane blade

[justin sherriff]

I just picked up an stanley no3. I am trying to flatter the back of the blade and it is going slow.
Here you can see the high spot in the middle if that was a hollow it would of been a easy job.
415781

how should I go about getting this thing flat? Is there a short cut or is ti just going to be a long time at the diamond stone.
I have a coarse diamond stone, 1000 and 8000 shapton stones.

[Jim Matthews]

Search David Charlesworth, "ruler trick".

[Ralph Boumenot]

Use 80-100 grit sandpaper on a flat surface. That will be a lot quicker than using diamond stones. Once it is flat than use the diamond stones.

[Jim Koepke]

Search David Charlesworth, "ruler trick".

Whether or not you employ the ruler trick, the hump may cause a bigger problem with the chip breaker.

If the blade is properly hard, a file will likely not cut much.

David Weaver once posted about a set up he made to hold a blade while working the back. It was a piece of wood he could attach to the blade so he could apply preasure to the area being worked.

What one wants to avoid is rocking the blade side to side while trying to flatten the back. Some suggest only working the back by going back and forth along the long axis of the blade across the sharpening media.

You may want to preserve your stones and use a coarse sandpaper on a flat surface for the rough part of this job.

jtk

[Mike Cornwall]

For me it seems like the belly in the middle rolls and perpetuates itself, I’ve had good results hollowing very lightly between lapping on the coarse diamond plate. If you have a way to hollow the iron just enough, staying away from the leading edge, it might save you days of agony.

[Derek Cohen]

Justin, I would hang in there until it is done. You only have to do it once.

Unfortunately, the high area means that the more you do, the more you need to do. And then, finally, it is over. This is the situation where one would use the side of a Tormek or CBN wheel. Assuming that you do not own these, work with 120 grit (80 grit leaves deep scratches). I have a 1m long glass-on-MDF plate for such purposes. The long strokes are less fatiguing.

Depending on the length of the blade and whether it was laminated, you could turn it over and bevel the other side.

Regards from Perth

Derek

[Mike Cornwall]

Justin, I would hang in there until it is done. You only have to do it once.

Unfortunately, the high area means that the more you do, the more you need to do. And then, finally, it is over. This is the situation where one would use the side of a Tormek or CBN wheel. Assuming that you do not own these, work with 120 grit (80 grit leaves deep scratches). I have a 1m long glass-on-MDF plate for such purposes. The long strokes are less fatiguing.

Depending on the length of the blade and whether it was laminated, you could turn it over and bevel the other side.

Regards from Perth

Derek

For some reason, using the side of the tormek gives me a lapped back that I can’t swipe the wire edge off on my diamond plates or oilstones. After honing, I go to swipe the burr off the back and the flat area from the tormek doesn’t reach the front edge of the iron when lapping on the stone. I think it must be due to the geometry of the high spots and hollows on the back, but the best idea I could come up with was to lap on the surface I’ll be lapping on when I sharpen.

[steven c newman]

A bad "hump" like that? I lay the iron on my bench, with the high spot facing up, and marked.....then a few whacks with a large ball pean hammer, checking as I go, until the worst is flattened.

Beltsander, clamped in the bench vise, with the top handle in the vise. Have a cup of water handy. Stand to the side of the sander, lay the back of the iron on the spinning belt....count to 3, dunk the iron, check the back.....100 grit belt, and it helps if it is worn a bit. Repeat as needed, until the back is flat....then just polish it up.

Use your fingertips to hold the iron to the belt....when the fingers say they are too hot, dunk the iron.

Also, check the chipbreaker. Lay it on a flat surface ( BEFORE you do anything else to it) and see if it rocks. Either the curved section has a hump in the middle, or it is the inside of the hump.
same as the iron, lay it with the high spot up, a few taps, and check for any rocking....sometimes, the ends are lower than the middle, to where the corners only will contact the iron. Goal is to bring the high spot down, so the edge is a straight line across. Also, sight down the length of both the iron and the chipbreaker....sometimes they have sat wat too long, clamped down too tight...and soon have a bow along the length. Both can be hammered out...BTDT. Do NOT clamp an iron in a vise, and try to straighten it by hand.....cuts from when it snaps take a while to heal.

get both flat and straight, first.....then you can sharpen however you please ( Millers Falls called for a single bevel, @ 25 degrees) just remember...even a butter knife can be polished like a mirror, and still not cut cold butter....
415797
Craftsman #3 ( Sargent # 408)....single bevel, angle is 25 degrees. Had to fltten the iron and the chipbreaker, first. There are no gaps between the iron and chipbreaker.

[justin sherriff]

A bad "hump" like that? I lay the iron on my bench, with the high spot facing up, and marked.....then a few whacks with a large ball pean hammer, checking as I go, until the worst is flattened.

Beltsander, clamped in the bench vise, with the top handle in the vise. Have a cup of water handy. Stand to the side of the sander, lay the back of the iron on the spinning belt....count to 3, dunk the iron, check the back.....100 grit belt, and it helps if it is worn a bit. Repeat as needed, until the back is flat....then just polish it up.

Use your fingertips to hold the iron to the belt....when the fingers say they are too hot, dunk the iron.

Also, check the chipbreaker. Lay it on a flat surface ( BEFORE you do anything else to it) and see if it rocks. Either the curved section has a hump in the middle, or it is the inside of the hump.
same as the iron, lay it with the high spot up, a few taps, and check for any rocking....sometimes, the ends are lower than the middle, to where the corners only will contact the iron. Goal is to bring the high spot down, so the edge is a straight line across. Also, sight down the length of both the iron and the chipbreaker....sometimes they have sat wat too long, clamped down too tight...and soon have a bow along the length. Both can be hammered out...BTDT. Do NOT clamp an iron in a vise, and try to straighten it by hand.....cuts from when it snaps take a while to heal.

get both flat and straight, first.....then you can sharpen however you please ( Millers Falls called for a single bevel, @ 25 degrees) just remember...even a butter knife can be polished like a mirror, and still not cut cold butter....
415797
Craftsman #3 ( Sargent # 408)....single bevel, angle is 25 degrees. Had to fltten the iron and the chipbreaker, first. There are no gaps between the iron and chipbreaker.

The ball peen hammer sounds like a good idea I will try that tomorrow if I have time. belt sander I would try on a junk blade first.
The chip breaker just needed some cleaning and a little time on the stones now I think it my be the best one I have.

2 side questions
you sad about the chip breaker being clamped down to tight. On this no3 there is a nice bit of spring (compression) befor it is tightened all the way down. Should I stop befor it bottoms out? I can go all the way down with just finger tightening.

Is the knob on a no3 the same size as a 4 or 5?

[steven c newman]

#3 #4 #5 are all the same....the only thing that changed was the height of the knobs....they went from a "Low" knob, to a taller knob, and finally a shaped to fit the ring around the base of the tall knob....

When these older planes sit for too long, and someone had torqued things down tight....then things get a bit "curvy''.....Tighten enough that things do not move on their own...like when you use a plane....just a bit past snug. Tighten the bolt between the iron and the chipbreaker until you can move either....

[Mike Cornwall]

I broke a few irons trying to whack a belly out of them. I should have put a piece of wood or something on the belly and whacked that instead.

[Charles Bjorgen]

Whether or not you employ the ruler trick, the hump may cause a bigger problem with the chip breaker.

David Weaver once posted about a set up he made to hold a blade while working the back. It was a piece of wood he could attach to the blade so he could apply preasure to the area being worked.

You may want to preserve your stones and use a coarse sandpaper on a flat surface for the rough part of this job.

jtk

Here's my adaptation of David Weaver's plane blade back flattening system. It uses 80 grit self adhesive sand paper on a granite surface plate. This jig allows concentrating pressure directly over the plane back and saves your fingers. I've never experienced a hump on a blade as shown by the OP though.

[Derek Cohen]

A dozen years ago I posted this photo of flattening the back of a blade ...

http://www.inthewoodshop.com/WoodworkTechniques/Lapping%20the%20Backs%20of%20Blades_html_m569096a8 .jpg

http://www.inthewoodshop.com/WoodworkTechniques/Lapping%20the%20Backs%20of%20Blades.html

Regards from Perth

Derek

[Prashun Patel]

Do you by any chance have a Worksharp? That and a diamond lap blade would make quick(er) work of this.

If you do not, I'd probably save my diamond stone for less drastic work, and use a few sheets of coarser grit sandpaper lubricated with a fair amount of patience.

[lowell holmes]

If you lay wet or dry sandpaper wet on your table saw table, it makes a good sharpening surface. Afterwards, wipe the surface with a thin coat of Johnson floor wax.

[Roger Nair]

What I have done with success is to alternate with a coarse diamond bench stone, to define the high spot, then go to the bench grinder or better yet a die grinder and LIGHTLY grind the high spot only and return to the bench stone for a nice long session, then repeat as necessary. Never bear down when power grinding and never go near the edge and keep the blade cool by using the mass of the blade to absorb the heat, the edge and sides are low mass areas. If you feel the blade heating up a little, you have to stop grinding. If you feel the need to quench, then you have ground the blade too aggressively. By alternating you can speed up removal greatly but aggressive dry grinding will result in harm to the blade.

[Robert Hazelwood]

Fresh 80 grit sandpaper will cut much faster than any diamond stone I've used. But keeping it fresh is important- you can remove more material in the first minute or two of use than you can in the next 10 minutes. So try to arrange the paper you stick down so that you can use every bit of it, and once every part is used don't hesitate to change it.

The prominent hump makes things more challenging. The safest way to lap is to only go in one direction instead of back and forth, and don't try to go too fast. You want to keep the pressure centered over the hump, and you do not want to let it rock side to side about the hump. Once you can develop a decent sized flat spot on the hump, that will sit stably on the lap surface, you can try going back and forth and increasing your speed.

Once I've gotten the back flat with 80 grit, I use some worn out section of 80 grit to remove the deepest scratches, then move onto 220 grit sandpaper. Then onto a 1000 grit waterstone, and arkansas stones after that.

[ken hatch]

At some point you should say to heck with it and buy a new Japanese, Hock, Veritas, or even a new Stanley cutter and get on with life. Unless rubbing iron on sandpaper or stone is how you get your jollies there are better ways to spend your time in the shop.

Of course YMMV,

ken

[David Bassett]

... there are better ways to spend your time in the shop....

Yeah! You could be building another bench! ;)

[ken hatch]

Yeah! You could be building another bench! ;)

David,

You have been reading my mail :p.

My next build is a kick wheel for MsBubba. After that is a toss up between a tarted up shave horse (my current one is a prototype and pretty ugly) or a new bench with an Oak base and slab TBD. Whatever life is too short and there are too many options with respect to cutters to spend hours rubbing iron on stone unless the cutter is a really old forged steel that shouldn't/or can't be replaced.

ken

[steven c newman]

Don't need to be a Blacksmith with the hammer. Instead, use the same amount as you would use on a handsaw plate.....

I usually use the ball end of the hammer....if the iron "hops" went you hit it, back off a bit on the swing. You are not trying to do a horse shoe operation....think of it as more of removing a dent in a fender....

All that sanding to get a perfectly flat back on the iron....results in a thinner iron, ..unless you are simply looking for an excuse to go out and buy a new iron ( that costs more than the plane your are working on..)

Been rehabbing planes for a long time....and I go with what I find to work best.
415836to415837
Both needed flattened...once the crud was removed...Spent about 2 hours or so, not counting the PBlaster soaking...
415838
Once the bolt for the rear handle is repaired, it is ready to go to work...

[justin sherriff]

I got the back flattened now.
415875
I still need to spend some time on my 8000 grit.
Hammered down the hump and then I grinded about 1/8 to 3/16 inch off the end to get to the nice flat I had.

A quick sharpening and was making nice shavings.
415876
so far I am liking the feel of the #3 vs a big #4 1/2

[Steven Mikes]

I'm with Steve Newman on this one. Actually I don't even have a ball peen hammer, I just used a soft-faced hammer (one of those yellow/red ones). Paul Sellers has a video somewhere doing this, I recommend it. He puts the plane blade on a piece of softwood (pine) and whacks it on the high spot a few times. The pine has enough give to allow the metal to flex. You stop when you end up with a very slight convex surface on the back. Worked great for me.

[Jim Koepke]

so far I am liking the feel of the #3 vs a big #4 1/2

The #3 is a nice sized plane and gets used more than my #4-1/2. The bigger plane is handy when knocking down a large hump on the face of a board or panel.

jtk

[Doug Dawson]

I just picked up an stanley no3. I am trying to flatter the back of the blade and it is going slow.
Here you can see the high spot in the middle if that was a hollow it would of been a easy job.
415781

how should I go about getting this thing flat? Is there a short cut or is ti just going to be a long time at the diamond stone.
I have a coarse diamond stone, 1000 and 8000 shapton stones.

You could try shaving it off with a sharp carbide scraper. Blue up the back to check your work, and repeat as necessary. Me, OTOH, I'd just buy a replacement blade (not necessarily new BTW) and go on about my way.

[Charles Guest]

At some point you should say to heck with it and buy a new Japanese, Hock, Veritas, or even a new Stanley cutter and get on with life. Unless rubbing iron on sandpaper or stone is how you get your jollies there are better ways to spend your time in the shop.

Of course YMMV,

ken

Yes! After having read the responses in the thread it's just bizarre that people would go to the lengths they go to for a cutter easily replaced. I get the mental image of wailing and the gnashing of teeth over a bellied cutter, all in the midst of thousands of dollars in other woodworking equipment, and some extraordinarily arbitrary line being drawn in the sand. It doesn't make sense. It's a Stanley plane iron, made in the hundreds of thousands if not millions, it's not a vintage Aston Martin.

[Derek Cohen]

I agree about getting a new blade. Frankly you really could upgrade your plane by getting a PM-V11 blade. Over at WoodCentral Hand Tools forum David Weaver has been describing his exhaustive testing with a series of steels, and PM-V11 came out on top ... not just for being longer lasting, but producing a better finished surface than all other steels.

Regards from Perth

Derek

[steven c newman]

These last 3 posts sound more like a "Message from our Sponsors"......OP has already FIXED his iron....

[ken hatch]

These last 3 posts sound more like a "Message from our Sponsors"......OP has already FIXED his iron....

Steven,

If you go back and read the original post that the last few posters were responding to it was posted well before the OP posted he had fixed the problem. I stand by my post, there is no "Message from our Sponsors". Unless you just enjoy rubbing iron on stones there are better ways to spend your shop time with little cost, replacement cutters are cheap, much cheaper than my time.

ken

[david charlesworth]

I think we should be much more willing to send back any blade or chisel which has belly, in width or length, to the vendor or manufacturer.

It can be a huge amount of effort try and correct this fault.

I had a student once who came with a set of Sorby chisels. All had belly in the length. We had to send them back twice before the problem was dealt with.

It was only after I had spoken with the workshop foreman that anything was achieved.

Best wishes,
David Charlesworth

[lowell holmes]

I have diamond hones to rub on. Try them, you will like them.

[steven c newman]

Rather hard to send back...when the Company no longer makes that iron.....

I don't worry about "belly in length" on chisels.....as I only USE the first inch or so....of course, any belly WOULD raise ones knuckles high enough not to scrape the wood...

Fancy stones are..ok..if all you do is sharpen edge tools all day......I prefer to get back to work as FAST as I can. One can polish a butter knife to a flat, mirror-like shine...and it would still barely cut cold butter.

Been rehabbing planes since before the 90s....soon found what works, and what is just..hype.

The hammer trick? Which would you prefer...3-5 whacks to get a bad iron close to flat, where sandpaper & stones can finish up, and be planing wood the same afternoon? Or...spend more money than the plane costs, on an iron they may not even fit, wait until it arrives by mail...and hope the depth adjust tab can even reach through the "new" iron to get to the chipbreaker?

I hold the iron onto the top of the bench's leg, so there is no bounce. I want to use only enough force to flatten the hump down, to where the rest of the sharpening can begin....
I also sight along the iron, to see if it is curved/bent...a few taps to correct that.

There was a name for workers that took hours to do a simple 10 minute job.....we called them "Milkmen" because they seemed to milk the time clock,....they usually were either shipped out to another job site..or..fired.