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Issue Lapping back of plane iron

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Forum topic by RD87 posted 04-30-2016 03:46 AM 693 views 1 time favorited 16 replies Add to Favorites Watch
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RD87

16 posts in 268 days


04-30-2016 03:46 AM

Topic tags/keywords: lapping plane iron diamond plates flatenning sharpening

I bought a Stanley #3 at a local flea market, mostly to learn how to rehab cheap planes. However, I am having a very difficult time lapping the back of the plane iron flat. I don’t know if this is user error (quite possible), an issue with the plane, or (hopefully not) and issue with my diamond plates not being flat.

I have been going at it on my extra coarse and coarse DMT diamond plate, but I keep on getting the same results. I have even gone down to 80 grit sandpaper on plate glass, and it looks like it’s flattened. When I put it back on the diamond plates though I still have hollows in the same spots, so it seems the sandpaper is “mushrooming” and making it seem like the iron is flat. That is my best guess at least.

As you can see, there seems to be a nice big high spot right before the plane edge that I cannot remove. I have put over 2 hours of work into trying to flatten the high spots, but haven’t seen much progress.

I don’t have a grinder or belt sander or anything with a motor to use in this, so I am stuck with hand techniques.

I am open to any and all suggestions, and I hope someone here has been able to overcome a similar issue and can shed some light.

Thanks,
Rob


16 replies so far

View bandit571's profile (online now)

bandit571

14606 posts in 2149 days


#1 posted 04-30-2016 04:07 AM

Someone had used the ruler trick a bit too much….before you got it.

Only worry about the first 1/4” or so, just where the chipbreaker will be sitting. After a few sharpenings, you’ll soon be back to the newer flat area. Just make sure the chipbreaker sits without any gaps…

-- A Planer? I'M the planer, this is what I use

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TheFridge

5765 posts in 952 days


#2 posted 04-30-2016 04:07 AM

Focus on the last 1/4” or so at the edge.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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BigYin

347 posts in 1882 days


#3 posted 04-30-2016 07:52 AM

Paul sellers showing plane iron sharpening

https://www.youtube.com/watch?v=vvTcReENk9g

-- ... Never Apologise For Being Right ...

View Don W's profile

Don W

17971 posts in 2033 days


#4 posted 04-30-2016 11:00 AM

That’s a common problem. Personally I’d just use it and work it out as you sharpen it. You won’t get full width shavings for a while, but what you loose isn’t worth worrying about. You’r probably going to camber slightly anyhow.

-- Master hand plane hoarder. - http://timetestedtools.net

View rwe2156's profile

rwe2156

2198 posts in 946 days


#5 posted 04-30-2016 12:23 PM

I know its frustrating, but remember a plane iron is not like a chisel where flattening the back is an absolute.

I agree with bandit I would elevate the blade and sharpen it to get the last 1/2” or so flat then go from there. As long as the chip breaker is in good contact it will work.

-- Everything is a prototype thats why its one of a kind!!

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unbob

718 posts in 1369 days


#6 posted 04-30-2016 03:00 PM

Yes, sandpaper does not get things flat, It rides up and rolls over the edges. Lapping with a diamond plate or a cast iron lapping plate will get things flat. Lapping using a figure 8 motion usually cuts faster.

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RD87

16 posts in 268 days


#7 posted 04-30-2016 11:11 PM

Thanks for the tips, I will try just focusing on the last 1/2 – 1/4 inch on the blade and see if that gets me where I need to be.

The sole of the plane also has a nice long hollow behind the mouth and a slight low spot at the very front edge of the sole. Do I need to get the sole completely flat, or do I just need to flatten certain important areas like before and after the mouth…etc?

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bandit571

14606 posts in 2149 days


#8 posted 04-30-2016 11:25 PM

Toe, both in front and in back of the mouth and the heel need to be “coplanar” , everything else? Not so much.

The hollow is from many years of just plain wear. How much time you wish to invest to get it perfect ( they never were) is entirely up to you. Get those three areas on the same level, try it awhile with a sharp, well tuned cutter, and see how it goes.

-- A Planer? I'M the planer, this is what I use

View OSU55's profile

OSU55

1062 posts in 1455 days


#9 posted 04-30-2016 11:40 PM

Flattening plane soles. Paper backed sandpaper is good for roughing in the back of the blade, but it “gives” too much and rounds the edges. My DMT plates aren’t flat enough to get the final flatness required. I finish them off with 25 um 3M polishing film with mylar backing which doesn’t flex. As others have said, you only need the last ~1/4”. Use a shim to raise the blade a bit, and you can continue to use the same shim for the life of the blade (or not). A piece of plastic milk jug held in place with masking tape works fine.

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RD87

16 posts in 268 days


#10 posted 05-02-2016 11:44 PM

UPDATE:

Using the suggested method above, I was able to get the last 1/2 of the blade flat and ready for sharpening. After sharpening the blade cut through paper like butter… Just have to wait on the rest of the plane to be tuned up to try it out. Thanks for all the help!

I did run into another issue trying to remove the frog. I was able to get one of the frog screws out easily but the other is not budging. I sprayed a bunch of wd40 on it to try and loosen it up but to no avail. The screw has started stripping so I’m not sure how to go about removing it. Any suggestions?

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bandit571

14606 posts in 2149 days


#11 posted 05-03-2016 12:30 AM

PB Blaster, and let it soak, or ATF-4 and just soak it over night. Use a thick enough blade on the screwdriver, and tap on the handle of the screwdriver as you try to turn it. Some here will also apply a bit of heat to it.

-- A Planer? I'M the planer, this is what I use

View OSU55's profile

OSU55

1062 posts in 1455 days


#12 posted 05-03-2016 12:48 AM

Use a hollow ground screwdriver tip vs the typical angled type, along with the PB Blaster

View Don W's profile

Don W

17971 posts in 2033 days


#13 posted 05-03-2016 01:17 AM

Heat it with a torch, and give it a couple good smacks (use a punch to get to it) then tap the screwdriver as you turn it. A perfect handle screwdriver works well, or an impact screwdriver works as well. I typically put it in a vise so I can keep it hot without burning up the bench.

-- Master hand plane hoarder. - http://timetestedtools.net

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Don W

17971 posts in 2033 days


#14 posted 05-03-2016 01:19 AM

Oh, and an FYI, wd-40 is not a penetrating oil. The first attempt should be with a penetrating oil like pb blaster, kroil or one of those types.

-- Master hand plane hoarder. - http://timetestedtools.net

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ColonelTravis

1192 posts in 1360 days


#15 posted 05-03-2016 01:28 AM

I’ve got a #4 Bedrock and the screw holding the little frog adjustment plate to the frog would not come out. I tried every method listed here over and over and over, plus a homemade penetrating oil concoction. Eventually I gave up because it wasn’t necessary to remove and it was getting mangled. That’s the only screw I’ve never been able to extract from anything in my life. Still ticked off about it, but just have patience because you don’t want to damage the screw any more. Good luck!

showing 1 through 15 of 16 replies

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