Question re: Draw filing

C

Chant

Joined
Jan 27, 2006
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279
I'm just starting out with knifemaking (working on my first). I have a 4 x 36 belt sander, but it just doesn't do a very good job (rather, I can't seem to do a very good job with it), so I'm cleaning up and smoothing with files. At first, I wasn't using the files properly, but I found a great thread here on draw filing, and now it is going well.

Here is my question: is it normal for the file to become magnetic as it is used? When I started, the grindings fell away, but now the file has become magnetised, and the filings stick to it. It is a nuisance to clean them up. They are standard, new Nickolson flat bastards.

If it is not normal, could it be that, by using a strong magnet to help hold the blade when grinding on the 4 x 36, I somehow magnetised the blade, and it is being transferred to the file? Seems unlikely, as the grindings are not sticking to the blade.

Does anyone know how to "de-magnetise" files?

Thanks in advance -- and you guys have no idea how valuable you have been to me in beginning to make knives -- this forum is worth far more than all the books and videos I've purchased put together. Hopefully, someday (when I know what I'm doing!) I'll be able to start "passing along" this knowledge myself.
 
Its the blade! Ive stuck magnets to blades and magnetized them before. Most likely, the filings you are taking off are themsevles magnetized, and sticking to the file rather than the file being magnetic. Try draw filing a piece of stock you havent used a magnet on and see if they stick. I have a few knives that were magnet pre-HT....

You can de-gauss a magnetic blade using a de-magnetizer you can buy at home depot/sears/lowes, or there are online tutorials on how to make your own de-gausser using a magnet chucked up into a drill. Same method of de-gaussing a tv screen that has been distorted by a magnet....
 
Thanks much - I bet you're right -- it is the filings that are magnetic. I'll test it out tomorrow.

Regards,
Jeff Chant
 
What you're seeing may not be magentized filings at all. It sure could be just the filings that build up in the teeth with normal filing. Go buy a file card (Home Depot, Lowe's) they run $5-$6. Looks like a brush with fine metal teeth. Use it often when heavy filing and it'll make the work easier and the file last longer.
Rick
 
No -- definitely magnetism -- I have a file card.
The grindings are so magnetic they actually form threads that dangle off the file when I try to whack it clean.
 
I just got a new draw file that has a diamond shape to the teeth with a good size gap between them and it flat out does not clog. Even on gummy annealed steel I have not had to clean it yet. I know that won't help the magnetism problem but it is a great help in draw filing.

My entire shop is magnetic, every cutting/grinding tool has a metallic beard growing on it. I have ran a dedicated ground wire from every piece of equipment straight to my well casing and it did nothing. Although we just had a very cold dry spell and I had no problem with static so it was not a completely wasted effort.
 
B Finnigan said:
I just got a new draw file that has a diamond shape to the teeth with a good size gap between them and it flat out does not clog. Even on gummy annealed steel I have not had to clean it yet. I know that won't help the magnetism problem but it is a great help in draw filing.
Click to expand...

Where do you find draw files? Aside from the gap between the teeth, are there any other differences between these and an ordinary bastard file?

-d
 
I got mine from a local specialty tool supply that has the best selection of every type of file you could imagine. I am not even sure that it is a draw file perse' but it does the job. It might be slower but it is really hard to screw up a blade with a file. You get alot of time to notice a problem and correct it. For those of you that are having a hard time mastering the grinder just use it to take of the big stuff and do the rest with a file and sandpaper.

The best remedy for bladesmithing frustration is to finish a knife and have it turn out half way decent. Who cares what tools you used or how long it took, just do it!
 
deker, IIRC, an important consideration is that it be a single cut file. A mill file is excellent. Clean it frequently. If a filing sticks you can gall a blade in one stroke to that, "Oh, crap" stage. :( Seek out Tai Goo's work and you'll see stuff finished entirely with a file.

Another tool that doesn't get a lot of press but works well is a "sen", a Japanese drawknife for steel. You can make your own. You can read about them searching Fogg's forum and his website.

Chant, it's not at all uncommon for filings to get magnetized on their own. I can't explain the physics, sorry, but it's a known phenomenon. A good example is gravers. They get magnetized in use, too, from the impact. The solution is periodic demagnetizing on a 110V toolroom demagnetizer, which you can get from industrial supply houses. You turn the power on and draw the tool across it several times.

Hope that helps. :)
 
Whatever you do, do not wipe the file or the blade with your hand, you leave a fatty deposit from your skin on the steel and your next stroke can just skate along the surface, absolutely no bite. Especially with finer files.:eek:

Just regular filing can cause a bit of magnetism to build up too.

Mike.
 
I forgot one thing: get some chalk and keep your files chalked. It helps reduce loading.
 
Looks like we posted at the same time Fitzo.
Sorry to repeat the bit about filing causing natural magnetism Chant.

Mike
 
Hey, Mike, your post made me think a wee bit: what about actually fatting it up on purpose at the end to get a slicker "bite"? Sorta like a Mazola party for a blade and file? ;) Do you think it could actually produce a slightly finer finish?
 
I will try it and let everyone know. If it works we will have to coin a new phrase. Lipo-filing? Fat bastard? I may have just created a forum monster.:foot:
 
from Decker

"Where do you find draw files? Aside from the gap between the teeth, are there any other differences between these and an ordinary bastard file?"



Draw filing is a technique used with a file not a specific type of file. Now that I have said that, I have seen one file actually called a draw file in my life, and it is in the Brownell's catalog, it looks like a second cut mill file (I am looking at mine right now and trying to describe it lol) with more rake on the teeth, short, fat and 5/16" thick. If you want to take metal off in a hurry, get something like a 14" long angle lathe file.

As for files and their differences Decker, there are many different types, the most common being mill files (single cut), and hand files (double cut) these each typically come in bastard (most aggressive), 2nd cut, and fine. The smaller the file, the finer the tooth spacing all other things being equal ie. 8" bastard file is more coarse than a 6" bastard. single cut is a file where all the serations are in one direction only ie mill file. Double cut is where there are two sets of serations making a cross hatched pattern (diamond checkering appearance) ie hand file. There are many other types of files out there but these are the most common. Best place I have found to purchase files is MSC supply either online or in their stores. Spend your money on Nicholson don't waste it on cheapy foreign import crap. Hope this helps a little bit.
 
Proper draw filing is a finish filing technique and uses a single cut file . the file is held at 90 degrees the the filing direction. Keep the file very clean !!
 
Thanks all. Thinks I'll get a demagnetizer (eventually) and chalk. It is difficult to keep the files clean when the grindings keep sticking, and when I don't I end up with deeper scratches than I want to sand out.

Mike - thanks for the info on the "sen". I did some research. I think I could probably use a lee valley drawknife the same way (the angle is probably different, but I'll experiment)

bigbcustom - thanks for the info on files. Especially the part about "the smaller the file, the finer the tooth spacing". I didn't realize that (duh), and should probably be working down in size as I approach completion -- so that sanding will go easier.
 
I knew all that gunsmith training with files would be good for something :D you are more than welcome to any information I may have that could be of help.:)
 
Thanks for all the info from everybody. I've done a fair bit of draw filing, I just had never heard of a file specifically referred to as a draw file. I didn't know about a single-cut cutting faster when draw filing. I'll have to find one or two on my way home tonight before I start draw filing the blade I forged out this weekend.


Thanks!

-d
 
A single cut doesn't cut faster than a double cut when draw filing, but it will leave a smoother surface.
 
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