Jimping

T

tim37a

Joined
May 18, 2010
Messages
1,057
Hi all,
I have been doing some jimping but it looks terrible. Those of you who do jimping always have the grooves uniformly deep, spaced, and clean looking. How do you do it? Is there some special grinding wheel or a special set of files? Any and all help would be appreciated.
Tim
 
I don't know about others but for the few knives I've made I've used either a needle file or a file similar to mr Moore's but mine has one of the sides rounded depends on the style I'm going for
 
It is sheer folly to attempt evenly-spaced jimping or filework without some kind of guide or tool that is already precision-ground to specific spacing.

On the rare occasions that I put jimping on my knives, I use a thread-cleaning file to lay it out, and triangle files to deepen the grooves, before HT. If I did it more often, I would invest in a nice hardened checkering file and still do it pre-HT.
 
A 20 lines per inch grobet checkering file and a good file guide makes jimping quick and easy. There are certainly other ways to do it but this makes nice clean results.
 
Proper layout is half the battle. Blacken the part to be jimped, lay out the lines with a scribe to whatever spacing you desire. Start with a sharp-edged file (a triangular needle file works good for this) and make an indention where the major grooves go. Set the angle of the blade so that it is measurable and consistent, as you will want to be able to work both sides from the same angle. Have the blade clamped so that you will be filing horizontally. I start with the round cuts first, then fill in the others, the round cuts are usually the deepest and widest, every thing else just fills in around them. Use a sharp file. Take one steady stroke and check. If you are off to one side a bit, adjust your next stroke to put you back in line. Keep your file horizontal, use the same amount of force each stroke, and keep track of how many strokes put you at the proper depth... if the steel is soft and the file is sharp, it should only take a couple of strokes to get the depth you want. If everything looks good, go on to the next one, and finish with all the grooves of the same type on one side of the blade before starting on the next side.

Proper layout, consistent angle, guide cuts, and consistent pressure... and fix things as soon as you see they are off... practice on mild steel until you feel confident. I had a batch of 9 sgian dubhs to be jimped, and by the time I got to the last one I was getting pretty good at it... :)
 
For file work, and the occasional jimping I do, I start by marking the spine with a fine tip sharpie. If it isn't right, a wipe with alcohol makes the spine a clean slate for a second attempt.
Once the marks look right, I take a 2/0 jewelers saw and make VERY SHALLOW cuts. Just barely nicking the surface of the spine. A misplaced line can be re-cut as needed.
Once the lines are cut, I use needle files to make the file work or jimping. I like Valtitan round and triangle files for this work. Use 0/cut needle files for the first cuts, and clean them up with 00/cut files. As with all similar processes, start with shallow cuts. You can always make them deeper/wider, but can't put the metal back when it is gone. Do the whole pattern several times, making it a little deeper/wider each pass. This will allow you to "push" a line a little on way or the other as needed to keep things even. DO NOT TRY TO CUT ANY LINE IN ONE STEP UNLESS YOU WANT A POOR LOOKING JOB.


TIP:
When doing file work, the biggest problem is often getting it evenly spaced. I start by laying a ladder pattern of lines along the spine with a sharpie. I make the lines get closer together as they approach the tip ( especially important with a large blade having distal taper). Once the grid is laid, I use the jewelers saw to make the shallow cuts as above. These cuts will be my reference lines when doing the file work. Depending on the pattern, I usually start with a triangle file and make shallow cuts at 45° to the spine, on each side at the reference cuts, all the way down the spine. These cuts are the starting points where I will make curves, notches, line cuts, etc., to create vine and thorn, bramble, barbed wire, vine, arrows, diamonds, etc. patterns. Any left over marks from the saw blade cuts will be sanded out in the final sanding before HT. Using this method, it is very hard to drift off your pattern spacing. The tapered pattern to the tip makes for a very professional look.
 
I assume you mean something like this, but executed much better?

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For myself I also mark how deep to make the lines, and use clear nail polish from the dollar store to fix the lines in place. (Plus the remaining colors in the pack are a great present for my 7 year old daughter!)

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Yep, that's pretty much it. The side lines for depth are a good idea, too. The shallow saw cuts will negate the need for coating it in nail polish, which may tend to gum up the file teeth.

I didn't mention that before picking up the steel, you should make a scale drawing of the patter desired with notes on the order of cuts/filing and such ( Do first, cut at an angle, file from the side, etc.). I like to make the spine drawing about 1/2" wide to allow plenty of room for the sketch. Reduce it in the scanner to the actual knife spine size to see how it will look on the knife.
 
Thanks for the input, guys. I'm talking about the lines at 90* to the blade you put on to keep your finger from slipping when skinning or gutting an animal. I have a Grobet checking file, a Grobet pillaring file, and Grobet knife files, but the jimping still looks pretty rough. Maybe I just need more practice.
Tim
 
Jimping is still file work, just in its simplest form, and as such Stacy's advice for doing filework still applies.

In my very limited experience, to do some basic jimping I started by marking 5 or 6 even spaces with a fine tip sharpie. For comfort, I tend to spread them out where the raised flat of the spine between the jimping is as long as the notches are wide. For example if I plan the round valley to be 1/8 inch across, I make my spacing 1/4 inch. I then score each mark with a small triangle file to keep the round file from skidding off course. Then I make shallow round notches with a chainsaw file. I work my way down the spine working each one until they are even.

If it is consistency in size and depth that you are struggling with, perhaps intentionally make them different sizes. Make 4 to 6 even spaces as before but starting away from the handle, make each valley progressively deeper than the last. You would want to make minute differences and also be careful not to bring the flat of the spine to a point between the deeper valleys for comfort reasons.

Good luck,
Chris
 
This may seem like a stupid question, but is there a practical purpose for jimping besides a spot for your thumb to gain traction?

I ask because sometimes I see jimping that travels an inch or more down the spine and I'm not seeing the connection.
 
The original purpose was traction for the thumb. Now it is minorly that and mostly for looks. In truth, it servers very little function.
 
+1 for "Salolan's" way of doing it... plus a couple tips that have helped me get mine even. I also use a 1/8 chainsaw file for my jimping. i measure out 5 evenly spaced out lines with a sharpy exactly 1/4" apart... this gives you exactly 1/8 space between 1/8" grooves when finished if you file carefully and it looks really sharp (to me). I only picked 5 because it seems to give a great thumb "feel" and i like the way it looks as well.. IMHO too many gets tacky and too few just doesn't give enough grip. Once i measure out the lines with the sharpie I place my blade in a vice with 1/8" of the spine left above to give me uniform depth across the grooves. I start my grooves with a hacksaw so the spacing is easier to control then move onto the chainsaw file until i am filing flush with the top of the vice on both sides and this ensures that my grooves are uniform depth as well as even on both sides. this method has gotten me the results I wanted and it's the easiest way i know to get professional looking jimping consistently. I hope this helps.
 
Thanks rustyrazor. Great idea to control depth by placing it in a vise. I'll try that with the knife file after using the pilar file to set the spacing.
Tim
 
No prob chief... it was the easiest way i could come up with to keep things consistent. good luck
 
Isn't there a bloody grinder wheel for jimping? I saw it somewhere, now I can't find it...
 
Its my opinion that jimping - unless its purely for utility, such as a better thumbgrip, etc - is a sign of quality craftsmanship, and should not be made with a grinding wheel or the like. Filework is a good way to increase your skills but it does take a while to learn. My best advice is to take your time and leave yourself room for errors. Never make cuts that will be too dramatic too quickly. Take little bites at it and make everything even, then deepen it up evenly.


 
I understand your perspective and respect the ability to do file work by hand. You guys are artists. However, I have had requests for genuine functional thumb or fore-finger traction on the spine of work knives. I'd love to have a serrated wheel for that.
 
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