File jig angle

C

cainethirdmortal

Joined
Jul 14, 2013
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Before I started my first blade I looked into how others were filing their blades. I came across a few different jig setups. At first I wanted to make an advanced fancy jig but my wife suggested making a simple on until I made a few blades and was sure it was somthing I wanted to do. I took her advice and held off on order the parts for a fancy one as we are on a tight budget to begin with. I decided to tape my file to a lenght of 4130 cromoly tubing I had left over from a bike frame project. I clamped the blade on the edge of my bench and laid the file on top of it. I place a piece of angle iron under the tubing and moved it away from the blade until i got to the angle I wanted using my square machinist protractor to measure. It was then that I realized that the further I filed and closer I got to my edge line the steeper the angle would get. I searched google for bevel geometry equations for a full flat grind knowing it would bring me here as well as a few other places. I came across trig equations, a nifty chart, and the general answer of this is why using a jig for filing or grinding isn't the best option. None of which were the answer I was looking for. So I drew a rectangle being my blade blank and 2 angled lines being my file. One went to the center of the edge of the rectangle the other to the top corner of the edge to show my wife the angle would change as I filed and that I wasn't crazy. I then thought, why not just figure out the angle I needed to start with to give me the end angle I needed for the full flat grind. There was the math and precise drawing I didin't want to try and do. As I sat here looking for other answers on the internet I noticed the icon for my CAD program and then it clicked. So correct me if I'm wrong. This is what I came up with.

zv80.jpg
 
While some people seem to like file jigs, I see so many problems with then=m, I can't recommend one.
File by hand and either lift or lower the file handle to change the angle :) Smooth straight and full strokes with a slight lift off the blade on the return stroke will make fast and efficient filing.
 
All I did when I used to use my file jig, (pretty much like that one) was in order to account for the angle change once the steel was all filed off to reach the edge, I just layed the file on something (sitting next to the clamped blade) like a piece of scap steel for instance, that was half the thickness of the steel that my blade was, and set the angle according to that. Say my blade thickness was 1/4" , I used a piece of 1/8" steel to set the angle.

As for angle chats, here is the best one I know of, it's in PDF form..... http://www.bladeforums.com/forums/showthread.php/562593-Chart-of-Blade-Angles-for-Flat-Grinds

Hope that helps :) If you have any questions, just let me know. I have some very simple to understand "cad" drawings I made of my jig, as well as a video of me using it.

-Paul
www.youtube.com/Lsubslimed
 
Thanks for the input guys. Glad you replied to this coldsteelburns. You and your sugarcreekforge knife build along videos were my inspiration to try making a knife. I have all the stuff to build your jig just haven't gotten to it yet. It's good to meet ya.
 
If you are looking for an easy 'newby' grinding guide, try Fre Rowes 'Bubble jig" system. It is like training wheels on a bicycle. Not really a jig, more of a teaching aid on grinding. I am a big fan. ...Teddy
 
Haha , What are the odds of that!? That's cool though man, I'm glad my vids helped inspire you to get into knife making :) Like I said if you have any questions about my jig like how it's built and/or how I used it just let me know. I have had a few people in the past ask me how I made it as well as how to set/measure the angle of the jig.. I'll just go ahead and post some CAD pics that I made up for them cause it can't hurt ;)

Here are two CAD drawings I made up trying to show one guy how to measure/set the angle using this jig (remember that I set the angle using a piece of metal (or w/e) that is half the thickness of the blade stock):





And here are a couple I made up for a guy that show details on how I built/assembled "my" jig:





Anyway that's all I have ta add. Nice ta meet you as well. Do you have a youtube account, and if so what is it? I'm always curious what bladeforums members youtube accounts are.. (that would make a great sticky!!) :cool:

-Paul
www.youtube.com/Lsubslimed
 
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I've had a youtube account for a while but just started my channel tonight or this morning. I don't have anything up on it as of yet. I've never been one for taking any videos and I always forget to take pictures. Going to try and work on that. Those are some nice clear drawings. Thanks for the help and info.
 
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