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View Full Version : how do you get crisp plunge lines using a file?



omegaman111
06-30-2010, 07:08 PM
hey everyone, i dont have a belt grinder so on my first knife i used a flat ******* file and i just didnt get the crisp plunge lines i was looking to get. i am going to start another knife soon and i was wondering if anyone knew any techniques or knew of any technical aids that could help me get crisp plunge lines. thanks.

Bssc
06-30-2010, 08:23 PM
use a file guide made out of hardened steel

Justin King
06-30-2010, 10:43 PM
There is a tutorial in the Tutorial Forum on cutting them with a round chain saw file before filing/grinding in the main bevel. This is a good approach if you have a file guide to use to keep from cutting into that pretty plunge when you do the rest of the bevels. If you are freehanding it I think you might as well not bother.
I have a piece of granite with the edge rounded over, that I wrap sandpaper around, and use this to lap my plunges after grinding the bevels in. I have an improvised file guide that I use as a fence to guide the blade as I drag it across the sandpaper. It is mechanically the the same as doing it with a file and guide but I am moving the blade instead of the tool, and this also works effectively even after heat treat, which files usually can't do.

Ernie Swanson
07-01-2010, 04:50 AM
hey everyone, i dont have a belt grinder so on my first knife i used a flat ******* file and i just didnt get the crisp plunge lines i was looking to get. i am going to start another knife soon and i was wondering if anyone knew any techniques or knew of any technical aids that could help me get crisp plunge lines. thanks.

Here is a link to a couple videos, they show how I do my plunge lines with a chainsaw file.

http://knifedogs.com/showthread.php?t=8593

After I get my plunges cut, I then grind the blade up to them. I do everything freehand, unless I am using my grinding jig. but I do not use a file guide.

Doug Lester
07-01-2010, 01:07 PM
You could also use a pillar file. They only have teeth on the flats; the edges are smooth. Another advantage to the file guide is that it allows you to get the plunge lines and shoulders even.

Doug Lester

omegaman111
07-01-2010, 01:31 PM
thanks for the video Ernie it was pretty helpful but when you said that after you made the plunge line you grind down the rest of the blade thats what i was really looking to get. i dont know the term for it but its the line at which the full tang thickness meets the grind. how do i get that line to be crisp when hand filing because on my first knife i got a very rounded line.

George Tichbourne
07-01-2010, 03:19 PM
It is not uncommon for knifemakers to grind all of the teeth off the edges of their files so they will not cut sideways while filing the plunges.

George

Ernie Swanson
07-01-2010, 03:25 PM
If you mean you want a square plunge line then just use a rectangle file.

omegaman111
07-01-2010, 03:59 PM
this is sort of frustrating :P i wish i knew the term for it. basically its where the full tang thickness of the blade, on the sides of the blade where you flat grind, meets the slope that you just flat ground. i want where those 2 sections meet to be a nice crisp line. did i do a good enough job of description or do i need to try again? :P

Kevin Cross
07-01-2010, 04:58 PM
If I understand what you are asking, look for a tutorial on "Draw Filing." This will take time and patience but will reward you with a smooth, flat bevel with the sharp edge that you are looking for.
Kevin

Ernie Swanson
07-01-2010, 05:06 PM
Do you mean like this

http://i186.photobucket.com/albums/x124/bigern26/006-2.jpg
http://i186.photobucket.com/albums/x124/bigern26/045-1.jpg

omegaman111
07-01-2010, 05:17 PM
If I understand what you are asking, look for a tutorial on "Draw Filing." This will take time and patience but will reward you with a smooth, flat bevel with the sharp edge that you are looking for.
Kevin

i could not find a tutorial for draw filing on here nor on youtube so im not really sure whether or not you are talking about what i am trying to describe.

and Ernie, what i believe you are trying to show me in the pictures is not what i am talking about. you ground that knife's edge angle (im guessing at terms :P) all the way to the spine. im trying to figure out how to stop that grind before you hit the spine and end up with a nice crisp line. i know this is easy to do with a flat grinder but i dont have one so i have to use a file. i hope this somewhat got the idea across :P

omegaman111
07-01-2010, 05:41 PM
okay i think that what i am describing may be the point where the bevel meets the full tang thickness, does that match what i am trying to describe?

Ernie Swanson
07-01-2010, 06:34 PM
okay i think that what i am describing may be the point where the bevel meets the full tang thickness, does that match what i am trying to describe?

Yes I think!

I will look for a good pic but I think what your describing is hard on a flat grind.
Most do a hollow grind.

Ernie Swanson
07-01-2010, 06:37 PM
Kind of like these?

http://KnifeDogs.com/gallery/files/2/5/00b1_007935_x_702_thumb.jpg (http://KnifeDogs.com/gallery/showimage.php?i=2110&c=2)

http://KnifeDogs.com/gallery/files/2/7/5/5/p6030327_thumb.jpg (http://KnifeDogs.com/gallery/showimage.php?i=2088&c=2)

omegaman111
07-01-2010, 06:42 PM
Yes! precisely. where the blue tinted area on the lower picture ends near the top of the tang, how do you get such a crisp end to the bevel. and if its hard on a flat grind then can some one please tell me how i would do a hollow grind?

Ernie Swanson
07-01-2010, 06:48 PM
Those were not my pics they are pics of members here.
The top one is One of Bill Coye's Knives and the bottom one is made by
Eddie Gunther.

They are hollow ground, I have not really seen lines that crisp on a flat ground unless it like a scandi grind. or a really shallow grind on a thick blade.

To do a hollow grind you would need a big contact wheel on a grinder, most makers use a 8'' or 10'' contact wheel.

omegaman111
07-01-2010, 07:13 PM
is there any way to get that without the use of a belt grinder?

Ernie Swanson
07-01-2010, 07:31 PM
Not that I know of because of the concave,
Some more experienced makers might chime in here, They might know of a way.

omegaman111
07-01-2010, 07:36 PM
okay well this is just great, does anyone happen to know where i can find a cheap belt grinder new or used? :P

George Tichbourne
07-02-2010, 06:06 AM
I am building them now and can always make up one more for you .

Send me an email for photos and more info.

George

Justin King
07-02-2010, 08:10 AM
A filing jig is probably the only thing that would help you with keeping a crisp line at the top of the bevel when filing the bevels by hand. Check Youtube for Greenpete's knifemaking video, he has a simplistic setup that looks like it works ok. Regardless, you might expect to have to flatten things up on abrasive paper after filing, you will usually be able to get things a little flatter and crisper this way. A hard backing plate and good-quality 60-100 grit paper is where I would start after hand-filing bevels.

Doug Lester
07-02-2010, 07:20 PM
Probably the least expensive belt grinder that has a contact wheel like you need to do hollow grinding with is the Grizzly. Some people like them and some don't. Next in line is the Coote grinder. I have one and it has done everything that I have asked of it but again there are those who don't like it eather. Unlike the Grizz, the Coote doesn't come with a motor, which can be good or bad depending on one's point of view. After that I would say comes the build-it-yourself KMG cones. Tracey has plans for one on his store's site as well as many of the parts that you will need. I don't know of any wood working sanders that can be addapted to hollow grinding and I cannot recommend them.

Doug Lester

James Terrio
07-02-2010, 09:27 PM
You can achieve any grind you want with a rock and a good dose of patience. :D

For the budget-minded maker, I strongly recommend the Craftsman 2x42 belt sander. It runs very fast so you have to use a light touch. Mount a glass platen on it, this will help a LOT in terms of getting truly flat grinds. Total cost, around $125, about like taking the family out for dinner and drinks (OK, maybe two dinners). It's not the best machine on the market but it WILL remove steel. Remind me to show you a couple mods to make it easier to work with. Belt choices are limited; don't settle for the Craftsman brand belts at Sears, they suck for grinding steel (wear out really fast). Better belts are available on Ebay and from sources like Tru-Grit and Super-Grit.

If your wallet is more robust, there are a lot better options out there. 2x72 pro-level grinders range from $400 to $2000 and up with all the cool features.

I think you're describing a saber grind; where the bevel is flat but doesn't go all the way up to the spine. Usually saber grinds have a more obtuse angle on the very edge. A Ka-Bar Marine Corps fighting knife and many other classic hunting/military knives are ground that way. It's a cost-effective way to build knives that have a reasonably keen bevel and are fairly strong. It's a compromise. A fully flat-ground blade with the same or even a more accute bevel, made from thicker stock, will be much stronger and just as sharp or sharper. But of course it will be more costly to produce.

Scandi (scandinavian or "Mora" type knives) grinds are similar, but the bevel goes all the way down to the very edge. This is sometimes called a "zero edge". It is thinner, sharper and easier to hone because all you need to do is lay the bevel on your stone and use that as your guide. Really good for small, thin knives that must be very keen but don't need to be extra-strong.

Regardless of the tools you use, it will take practice and patience to get both sides even and have a crisp line between the bevel and the flat. If it was easy, everyone would do it ;)

omegaman111
07-03-2010, 09:25 AM
http://www.harborfreight.com/review/product/list/id/2776/#customer-reviews

does that look like it would be able to do the trick? haha


the next knife i plan on making has a blade design similar to this knife,

https://www.kabar.com/product/productDetail.do?productNumber=5601&mode=category&categoryId=1,2,7,8&categoryName=Military/Tactical

would it be possible to get that kind of bevel with the machine i posted above? :P

Justin King
07-03-2010, 10:17 AM
I bought one of those and it is seriously under-powered for knifemaking work. I don't know how they figure 3/4 hp but mine didn't have anywhere close to that. I found it to be pretty much useless except for very light work on wood and such. I used a Craftsman 4x36 for a while and it was much better but the Craftsman 2x42 is better for knifemaking in pretty much every respect.

omegaman111
07-03-2010, 10:37 AM
okay, where did you find your Craftsman 2X42?

omegaman111
07-03-2010, 10:45 AM
i found a link for the craftsman 2X42 and some people werent saying many good things about it. what would be the cheapest yet most effective belt grinder for doing what i want to do? thats basically what i want to know lol

RodneyJ
07-03-2010, 11:21 AM
the cheapest grinder for what you want to do would be the grizzley. I have never used one so I cant speak for effectiveness. I have a $40 grinder from harbor freight it is under powered but it is better than hand fileing. I can not do hollow grinds on it. I plan to make a few knives to sell and will use the money to build the no weild grinder. from what I have seen and read that is probably the best grinder for your money.

omegaman111
07-03-2010, 11:59 AM
http://grizzly.com/products/Knife-Belt-Sander-Buffer/G1015

http://grizzly.com/products/Combo-2-Belt-Sander-6-Disc-Sander/H7761

http://grizzly.com/products/Belt-Sander-1-x-30-/H3140

http://www.grizzly.com/products/Combo-Sander-4-x-36-Belt-6-Disc/G0547


which grizzly grinder are you talking about cuz they have a few different grinders :P

omegaman111
07-03-2010, 08:03 PM
http://i394.photobucket.com/albums/pp21/hpiracing111/0703102157.jpg

thats my draw out for the next knife i want to make, 7-1/4" blade, ~13" OAL. what tools/machine would i need to get the crisp bevel lines shown in the picture?