bastard cut mill files

[dan sherman]

I purchased my first scraper over the weekend, and I think I need to get a file especially for it. I have a few mill files already, including a baster cut. However they are all cheap ($5-10) Nicholson's that aren't very flat. They all have enough bow to be noticeable when I lay them on my surface plate.

What brand files are you using on your scrapers, or doesn't it really matter?

[lowell holmes]

I have the Lee Valley Jointer Edger that I use on saws and scrapers. The 8" file that came with it is flat. It does matter.

I will joint my scrapers on a diamond hone when sharpening.

[glenn bradley]

Nicholson. Inexpensive and pretty solid manufacture.

[Paul Murphy]

Dan, like you I had a mill file hanging around that really wasn’t all that flat. I ordered an 8” from Lee Valley, and it turned out to be a Nicholson, and although not all that flat, the edges I file clean up fine on my coarse DMT plate.

I have since seen these files, and wonder if they might be better:
Grobet files, 8" Mill File
http://www.toolsforworkingwood.com/Merchant/merchant.mvc?Screen=PROD&Store_Code=toolshop&Product_Code=MS-MF.XX&Category_Code=CGB (http://www.toolsforworkingwood.com/Merchant/merchant.mvc?Screen=PROD&Store_Code=toolshop&Product_Code=MS-MF.XX&Category_Code=CGB)

If you get the Grobet file, let us know what you think of it.

FWIW, I have been amazed at how useful a simple scraper can be. I have since bought a cabinet scraper, also a really wonderful tool. I also bought a dedicated burnisher, because the length helped me hold the angle better, giving me a more consistent hook.

[george wilson]

Just about all files will have some curvature to them. Since they are packaged in the annoying plastic now,you can't examine them like you used to.

Unless you are going to joint the scraper straight across its length,the curve shouldn't matter. If you ARE going to flatten the scraper,you are stuck using the convex side of the file,and testing your scraper's edge against a straight edge,unless you do have a stone to flatten it against. I hope no diamond powder is picked up in this process,and embedded in the steel. Usually hardened steel doesn't pick up dust,but a scraper is only partially hard. Wipe it off carefully. Those diamonds can fracture,and escape their nickel plate medium. They are about the most brittle stuff there is.

Since the scraper is always BENT in use anyway,sprung between the thumbs,or against a screw in scraper planes,do you really need it dead flat?

[Tony Shea]

I would think that the slight curvature of a mill file should not effect the edge of the scraper to a noticable degree. Especially where people use a jointing jig and you're able to keep the edge on the same plane of the file across its' length. Even by hand it shouldn't have a huge effect. I actually have an old file larger file that I use that is almost dead flat. But before I came across that at the Tool Barn I used a cheap Nicholson that worked just as well. I've never seen a real difference between the two files in all honesty but I also hone the rough edge on a fine diamond stone.

[george wilson]

Files often warp badly when hardened due to the teeth on their surfaces. Makers used bending jigs to straighten them by hand. This is a personal skill based job. As with so many such skills,they seem to vanish over time.

I bought some very old files years ago. They had never been used. Since I had bought about 20 pounds of files,and was quite tired out at the end of the day,when I selected these,I only noticed later that they were twisted like a propeller!! They were,I suppose,slated to be discarded at the factory,but somehow made it out,probably in someone's lunch box.

Files used to be somewhat curved on both sides,especially pillar and "hand" files(a special type of pillar file) to help avoid going hollow.

The worst files are those that assume an "S" shape when quenched. You have no side to choose from. return them at once. A machinist will use the convex side of a file to good effect when filing a flat surface. You can selectively file the high spots off a surface you are generating with a slightly convex file.

I must have spent thousands of hours filing when young,and without machinery. Those skills I still use today for detail work.

You can straighten the very hardest steel tools that would snap like dry twigs if bent normally. What you must do is heat them up to about 400 degrees,and quickly straighten them before they cool. I have straightened half round,long tuning peg reamers I made like that. A long(or even short) half round reamer warps like crazy when quenched because of the difference in surface area that the quench acts upon. Similarly,plane irons that are to be hardened should NEVER have the bevel ground on them first. They will invariably warp across their width if pre beveled. It's better anyway,to grind away some of the edge of a new tool since the metal near the surface will have possibly lost some of its carbon from being heated very hot.

Remember the old adage"If you would a good edge win,forge thick and grind thin."

So,how are the teeth of files not ruined by the heat of hardening? They are coated with a substance that shields them from being burnt. In the old days,Stubbs used "beer leavings." A thick sludge that melted into a coating of carbonaceous material. It flew off when the files were quenched.

I have tried old recipes of flour,yeast,salt and water mixed into a batter. Dip the tool in it,heat and quench. It leaves a clean,gray surface like a new file. More often I use Brownell's "PBC No Scale". Sold by Brownells Gunsmithing Supply in Iowa. Google them.

[dan sherman]

Since the scraper is always BENT in use anyway,sprung between the thumbs,or against a screw in scraper planes,do you really need it dead flat?

I'm still a newbie at this, but I have seen several people say that the edge needs to be jointed strait with as file, and then polished on a stone. I would assume that some curve is acceptable, but how much, I have no idea.

[george wilson]

The scraper is BENT when you scrape with it. Unless you file a pretty big curve into the scraper,you'll bend it more than the filed curve. Then,only the central area of the scraper will still touch the wood. Just don't let the hollow curve in the scraper get too severe and it won't really matter.

There is a LN Stanley knock off scraper plane(I have 1) that needs the scraper to be flat. I don't keep track of the model #'s. it's the narrow model.