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24th August 2012, 12:23 PM #1Rank Beginner
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Flattening hand plane soles (again)
The time has come for me to flatten the soles of my handplanes.
From what I can discover, including from previous posts on this forum, there are three methods available to the average woodworker to flatten the sole of a plane.
The first is sheet abrasive lapping, i.e. sticking a bit of sandpaper to a reference surface and then having at it with the plane sole, in a figure 8 pattern, and being careful to frequently remove the swarf with a brush or magnet. I don't like this idea. The only relationship my tools have ever enjoyed with sheet abrasives ended badly, with mutual intervention orders and a contested, acrimonious divorce. And the children of that unhappy union suffered, too; it took hours to fix the dubbing on one of the bigger chisels.
The second option is taking the plane to a machinist.
The third is filing and scraping. I prefer this method, primarily because it is an opportunity to learn a new skill.
As I understand it, this involves applying a very small amount of Prussian blue (a non-abrasive pigment suspended in oil) to a reference surface then applying the plane sole to it, wiggling it about a bit and then lifting the plane straight upwards. The Prussian blue adheres to the high spots, showing the areas where metal removal is required. A hand scraper with a hardened steel or carbide tip is then used to "shave off" the blue areas. The process is repeated until the surface is dead flat, or at least as flat as the reference surface.
Because scraping is so deadly slow, bulk metal removal is achieved by hand filing (say with a 10" 2nd cut mill file). Personally I wouldn't be game to try this, but none of my planes are sufficiently wonky that they need it (hopefully). I would use sheet abrasives for very rough work if needed.
I was originally considering using a carbide-tipped scraper, as I believe that these are usually preferred by machinists. However, I've not got the equipment to sharpen them. Instead, I've settled on a hardened steel scraper like this: Engineers Hand Scrapers Flat - Faithfull Tools, to be had from eBay for around $15 with postage.
As for the reference plate, I had intended to use thick glass. However, my own experience is that plate glass often isn't particularly flat at all (I use it to flatten ceramic waterstones). Instead, I'm planning to spend $55 on a 12" Carbatec no-name granite plate. This probably isn't flat to machinists' tolerances, but should be just fine for woodworking.
Prussian blue can be had on eBay for $15 a tube.
So that's $85 in total, which all in all, isn't so bad (as I wanted a surface plate anyway).
My main question is:
Will the small size of the surface plate (only 12") make it an inappropriate reference surface for larger areas? My jack plane, try plane and jointer plane are 14", 18" and 24" respectively. How can I flatten these using the scraping technique I've outlined?
Otherwise: what do you think of this harebrained scheme, oh wise ones? Has anybody else tried scraping a plane sole flat, and if so, how did it work out?Cheers,
Eddie
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24th August 2012, 12:40 PM #2
Hi Snafu might be wise to post this thread on the metal work forums where all the scraping happens.
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24th August 2012, 02:09 PM #3well aged but not old
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The scrapping method sounds far more risky that using a reference surface to me.
My age is still less than my number of posts
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24th August 2012, 04:33 PM #4Rank Beginner
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Well, you still use a reference surface with scraping. I guess that the worst thing that could go wrong with scraping is getting a bit over-excited and taking a deeper shaving than intended. But, since I'll be practising on a junker first, and a scraper with a large radius only allows a very shallow bite, I can't see this as being too catastrophic.
I recently flattened the back of a chisel using a small circular grindstone mounted on a hand drill. After that, scraping doesn't seem so bad.
I've pretty much convinced myself to have a go at this now, I'll give it a crack and report back. I think that a reference surface shorter than the sole I'm flattening will be a problem for the #8, but shouldn't be too much of a biggie with the #5 and #6 provided I rely upon a straightedge too (in my case a bit of angle iron).Cheers,
Eddie
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24th August 2012, 05:00 PM #5
Eddie, you are amongst a bunch of metal workers down that way who will help you out if you get in touch with them - there have been courses run in the recent past.
I am self taught but have done a bunch of planes by scraping. Once you have experienced a super flat plane you will never want to flatten it any other way. But do not think you will be able to use thick glass, unless it is a glass surface plate. Any glass other than one made as a surface plate is a recipe for frustration when spotting for scraping, it is just not flat enough! Borrow some time on someone else's if you have to. Don't mess around with anything but tungsten scrapers, it is just not worth the time.
The problems with lapping are well known and while some have success, I'm yet to see someone spot their lapped soles to show how flat they are. Additionally if you have an old plane that has been "rehabbed" before and the sole is convex, it is practically impossible to flatten a convex sole by lapping.
There are some horror stories about machinists and handplanes - I have one. One machinist took off so much meat he went right through some of the thinner parts of the sole. The one I had done came back less flat than it began. Handplanes are notoriously hard to clamp sufficiently for machining without distorting the sole.
good luck with it.
Forgot to say McJings have reasonably priced granite surface plates
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24th August 2012, 07:23 PM #6Rank Beginner
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I just picked up a $55 granite surface plate from Carbatec.
I don't want to use a tungsten carbide scraper because I can't sharpen it, and they cost much more. I only have a few planes to scrape, so hardened steel would be alright, don't you think?Cheers,
Eddie
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24th August 2012, 07:39 PM #7
That is where it'll help you to contact some of the scrapers down that way, they'll be able to show you how to sharpen so you can try both and see for yourself the difference. While I use diamond powder on a cast iron lap, I have also used a fine diamond plate. You may even have one.
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24th August 2012, 07:44 PM #8
Hi,
Firstly have you read my thread here: https://www.woodworkforums.com/f65/sc...-plane-153138/ i am also fairly new to scraping, and like you i do not yet have the ability to sharpen carbide, but one sharp insert should do all your planes. As it is, a cheap diamond wheel from CTC tools will go on a grinder and you can sharpen all the carbide you like. The Carbatec plates are flat to 2.2 micron (so it seems from the few reports i have seen). They are really only long enough to do a no5 properly, although you could get away with your 6 but certainly not your 7.
You will also need something to spread the blue, a brayer etc.
Watch Nick Muellers Vids, best scraping vids bar far. Kanal von MuellerNick - YouTube
Post this in the metalworking section, there will be plenty of guys that can help you in Melbourne.
You will be blown away by how much better a scraped plane feels over a lapped one, i know i was.1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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24th August 2012, 09:50 PM #9SENIOR MEMBER
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Scraping is really difficult, thats why milling machines and surface grinders were invented IMHO. Life is too short
I can remember our apprentices trying to fool their TAFE teachers by using machine tools and then adding some scraper marks, the teachers didn't fall for that though
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25th August 2012, 02:48 AM #10well aged but not old
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I was wrong. Apparently this is a well established method of flattening soles of planes. I might have a go myself.
My age is still less than my number of posts
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29th August 2012, 09:39 PM #11Rank Beginner
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I have now ordered (or already own) all of the necessary bits and pieces, which are:
A flat 8" hardened steel engineer's scraper from eBay;
A tube of Prussian blue (bearing blue);
A Carbatec surface plate;
A 12" second cut flat file.
I've already got the bits and pieces for sharpening the scraper.
Aside from flattening plane soles, apparently scraping can be used to mate surfaces to an extremely high degree of accuracy (i.e. the frog).
I'll start on this project in a week or two once the bits arrive and report back.Cheers,
Eddie
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30th August 2012, 08:01 AM #12
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5th September 2012, 10:16 AM #13Rank Beginner
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Although the scraper I ordered hasn't yet arrived, I tried scraping using a Tungsten carbide paint scraper from Masters.
Although this worked quite well, removing nice even shavings of steel, it quickly became clear that I'd be at it for three or four hours. Scraping, it appears, is best for those situations where you are making a flat thing REALLY damn flat. (And besides, the carbide blade on the paint scraper was at too small an angle to hold an edge for very long working in steel). The handplane I'm working on has already been lapped "flat" on abrasive sheets, checked with a straightedge and so on. But a single round on the reference plate with the blue made it very clear that it's got no contact around the mouth, and is instead resting on a spot at the toe and a long section along the rear right of the heel (a typical wear pattern on old planes). This looked like a lot of work.
So instead of the scraper, I using a small diamond file (a few dollars from eBay). Using the very tip of the file as a scriber, it's possible with a little practice to "scribble" away the blue spots, using a cross hatch pattern. This works much more quickly and in about forty minutes I have a plane that is genuinely co-planar at the heel, toe and along the width of the front and rear of the mouth. The diamond file allows a remarkable degree of control - about the same as using a pencil. It's rather like colouring in. And I dare say I could get the surface even flatter, if I felt so inclined, without resorting to a scraper.
To give you an idea of how delicate the diamond filing marks are, it's possible to remove them in about one minute using a very fine sandpaper, say 400 grit.
The accuracy of the bearing blue depends upon how much is used. A very very thin coating - achieved by applying the blue and then rubbing it all off again with a rag - shows that there are slight variations within the surface that I've diamond-filed away. These variations are too slight to make any difference to the function of the plane, in my opinion, but I'll nevertheless attempt to remove them when I get a proper engineer's scraper.
I'll post photographs when I can.
In the meantime, I was surprised at how easy this was, and how far away from being flat the plane was after lapping. It was certainly less boring, and much quicker, than lapping. What do you guys think of this method?Cheers,
Eddie
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5th September 2012, 10:47 AM #14SENIOR MEMBER
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I am fascinated to watch your progress on this task but as an Engineer used to dealing in minute tolerances, where appropriate, I have to ask Why?
Will your hand planing be more accurate?
How many decimal places are you using when measuring your wood?
This is not meant as a criticism and I wish you well
I have spent many years explaining to Engineering graduates that you don't have to specify 3 decimal places on absolutely everything you design as accuracy costs money and time, as you are well aware by now.
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5th September 2012, 05:06 PM #15Rank Beginner
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Well, of course you're right, in the sense that this will not improve my woodworking in the slightest. It's certainly difficult to justify from a functional perspective.
However, from what I can tell (having only done one plane), this method doesn't take as long as abrasive sheet lapping, is cheaper (excluding the surface plate, which is handy to have anyway) and is almost impossible to screw up. It removes the element of trial and error. So it seems to me to be an improvement on all fronts.
At the least, it will hopefully start a useful argument.
However, at this stage, I am not even close to machinist's tolerances; as I mentioned, when I use only very light blueing, I can tell that some spots within the filed areas are slightly higher than others. The only reason why I'll be using a scraper to reduce this difference is curiosity; I'm perfectly happy with the result I've achieved scribbling away with the diamond file.
I've added a photograph, so you can get an idea of the sort of accuracy I'm talking about. It's a long way from a universally flat, shiny sole. (And again, you'll notice I've used the blue quite heavily).Last edited by snafuspyramid; 5th September 2012 at 05:11 PM. Reason: Attachment added
Cheers,
Eddie