File in plunges?

Mitchell Knives

Mitchell Knives

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Does anyone here file in their plunges by hand? I'm having trouble getting my plunge lines even with a nice radius, and thought that this might help. I experimented with a piece of scrap steel, and it seems to work well. Should I buy a filing jig or just learn to do it on the grinder?
 
You can use a chainsaw file to put them in - it works rather well. In the end, I think you'll be happier if you learn how to do it on the grinder, but many people file them in.
 
Thanks Cap. I think part of the problem may be that I'm not tracking enough belt off the wheel. I should probably use a higher grit belt when cleaning up the plunge prior to HT. Ant tips?
 
I dont finish my plunge until after ht, I use a guide to make sure the plunge is even on both sides and track the belt off the edge about 1/8 inch. I check before heat treat (gind to 220) make sure is good and even. After HT usually just need to clean up.

I know some makers use a file to make the plunge but its easy to be too deep or too shallow and that leave another problem to fix.


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If you're tracking the belt off of the wheel, then you may be running your plunge into the edge of the belt, you might try "breaking" the belt over the edge of the wheel by pushing a scrap of steel into it. If I'm not paying attention, the edge of my belt is usually what screws up my plunges more than anything else.

You also want to make sure that you're leaving the same amount of overhang for each side of the plunge, as the distance from the edge of the wheel to the edge of the belt will change the plunge.

The radius will also be affected by the shape of your wheel at the edges, is it sharp or rounded?

I never have too much trouble with my plunges at 80 grit, it's when I run a 400 grit belt edge into it that I have the problem ;)
 
AcridSaint said:
If you're tracking the belt off of the wheel, then you may be running your plunge into the edge of the belt, you might try "breaking" the belt over the edge of the wheel by pushing a scrap of steel into it. If I'm not paying attention, the edge of my belt is usually what screws up my plunges more than anything else.

You also want to make sure that you're leaving the same amount of overhang for each side of the plunge, as the distance from the edge of the wheel to the edge of the belt will change the plunge.
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That may be part of the problem. Sometimes one plunge will be straight, and the other rounded.
The radius will also be affected by the shape of your wheel at the edges, is it sharp or rounded?
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I'm using a squard shouldered 70 duro wheel. Do you typically round the edges of your wheels?
 
I do mine on the Grinder. I don't radius them until I get to like a 220g belt though, I make them with a 36g or 60g and just plunge strait.

To get the radius I run the belt tracking off the wheel or platen about an 1/8" or so then run the plunge line edge into the wheel/platen(this only works well with softer backed belts). This is how I even up the plunge lines as well. I always leave enough room to run up on the plunge.
 
I prefer the plunge that I get with a square wheel, but as they get older you sometimes have to radius them to make them match. You'll get a sharper plunge and less radius if you leave the wheel square.
 
I think the main thing about the shape of the wheel is that to get even plunge cuts both sides of the wheel have to be the same. They might need truing up. Square or rounded they need to be the same. They don't wear the same, so you need to check from time to time.

I get my plunge cuts close but don't worry to much until after heat treatment. Then you roll a little belt off the edge and take it slow and deliberate. I haven't had much luck filing the plunge cuts or using a guide.
 
If you use a file guide, a parallel round file, it's a bit of work, but they always come out perfectly even. I recommend a file of roughly the same size as the thickness of the steel.
 
Hmathews said:
I get my plunge cuts close but don't worry to much until after heat treatment. Then you roll a little belt off the edge and take it slow and deliberate. I haven't had much luck filing the plunge cuts or using a guide.
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One of my main problems is that I try to make the blade look perfect with a 60 grit. I know this isn't the right way to do it, but I keep telling myself "I'll just take a little more off.", which invariably leads to a mistake. I need to get into the habit of switching belts faster and cleaning up the blade with fine grits.
 
Round file trick works for me, if I want that kind of plunge I prefer to do it with a file, cause on my primitive grinder to put a small radius plunge is very hard to do. If you pay attention to the center scribe and use a simple plunge jig it is always perfect. But try to file it a bit less than reqired, the remaining will be gone while trying to get rid of the file marks...
 
The Otto Frei company carries a BUNCH of Swiss made files in all sizes an shapes, including a number of types that already have the "safe" sides with no teeth. Expensive, but I plan to buy a few different ones in the future.
 
I use the smallest half round Nicholsen file that I could find at the local hardware store, about 8", I guess, to clean up my plunges after I rough grind the bevels. I really like the way it kind of gradually sweeps into the bevel, rather than abruptly going from ricasso to bevel. Makes hand sanding the transition easier, too.

Todd
 
LRB said:
it's a bit of work,
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Using a chainsaw file on 1/8 and 3/16 stock is not so bad, but forget using it on 5/16!!! I know most folks do not use stock that thick but I had to to make sure it was even. Took me almost 6 hours to get it right.
 
I tried some some of the suggestions provided, and was able to improve my plunge cuts using only the grinder. I'm not sure I'll need a file guide now.

I mainly paid more attention to how much of the belt I was tracking off the wheel, and "broke in" the edge of the belt using a scrap piece of steel.

Thanks for the helpful tips!
 
John - the guide for your belts/files is mostly useful to keep you from having a slip-up in later grits, in my opinion. That being said, I made one and use it when I remember, but many of my knives it seems to just get in the way when I'm working or I'll forget to get it out, so I think it's better (for me) to just do it all freehand. Sounds like you're on the right track.
 
Yeah, I forge them in freehand and then file them freehand. It's not hard to do with a little practice and patience.

The main problem some students have is that they hold the file in one spot and cut too deep. You need to feather the radius out into the flat area with a sweeping motion to avoid cutting too deep in one spot.
 
AcridSaint said:
John - the guide for your belts/files is mostly useful to keep you from having a slip-up in later grits
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That's essentially what I was using the file for; a preventive measure. I took a round file and made a slight 45 degree cut on both sides of the blade. This gave me a visual "stop point", and gave a curve for the edge of the belt to settle into. I'll have to experiment further and see what produces the best results.
 
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