Knife Grind Problems

[jamb52]

HELP!!! I'm using a jig for knife grinds and having problems lining up the recaso ( May not be spelled right) the second time for finish grind. Also when I want to do the second grind the grinding starts at the top of the first grind and goes down not up. ANY SUGESTIONS FROM ANYONE????

[jimmontg]

I'm trying to understand you, do you mean when you switch the blade in the grinding jig the blade is in a different orientation other than right and left?

Also lining up the plunge line is a simple as making a scribe line as a guide and to mark both sides. You can attach a guide onto the grind jig too.

When you say the grind goes down and not up is confusing, up from the edge? up from the spine? you see why I'm confused.
In other words what kind of a jig are you using? There shouldn't be any change in the up & down position. Your jig should have the edge up with the handle sticking out in opposite directions for opposite sides of the blade.

[Ray Rogers]

As Jim said, that's pretty confusing but that's OK. My first inclination is to suggest you put the grinding jig aside and learn to grind free hand. Unless you mean the jig is for setting the plunge cuts only in which case its hard to see why you have any problem.

The clearest method I have to answer your questions is some DVDs I made about grinding. I have moved the links to them to the top of this forum so you can find them. The plunge cut information is in the Hollow Grinding DVD, the part about doing the plunge cuts works the same even if you are doing a flat grind.

The problems you seem to have with bevel grinding would be covered by the Shop Chef video if you're flat grinding or by the Hollow Grinding video if you're hollow grinding. The videos are cheap and they could help a lot. Or, you can do a few more posts until you're allowed to post pictures and then show us what you're having trouble with. It will take longer but we'll get there .....

[dtec1]

i agree with ray LEARN freehand.....trust me i tried all sorts of jigs the first year of making knives...that was a year wasted i didn't learn freehand at all after that year i started to really learn how to grind first off things looked better i can do things i cant with a jig and i learned a whole lot quicker than a year so i wasted a lot of time in the year with jigs....the only thing that i use sometimes and this could solve your problem is get a "file guide" it clamps on the blade right on the plunge lines and you grind up to it and it makes the plunge lines even...but even still you should learn to do it without even that....what happens if you don't have your jig and you cant do free hand then you cant do anything.....you don't need to waste good steel get some mild or scrap steel and practice on that

[jimmontg]

But proper use of a good grinding jig is very consistent when used properly. I will use a grinding fixture for small knives in particular and double edged blades for consistency. I have tried to do a double edged knife freehand, but I never get it as close than when I use a jig.

I've been doing this since 1992 and started freehand with a 3x21(?) belt sander clamped to a table. LOL I don't see an issue with using a jig to start, IF it's a well designed fixture. I used one at the machine shop where I worked for hollow grinds and they were nigh on close to being perfect. I will start a knife freehand, but depending on its configuration I may end the grind with a jig, just depends and may go the other way. Start with the jig and finish freehand. Yes and no. LOL

Yes I can freehand and I do on my 2x48 grinder, but my 1x42 gives better results with a grinding jig sometimes and especially with the 600 grit and higher polishing belts.

To each his own I guess.

[epicfail48]

Originally Posted by jimmontg

But proper use of a good grinding jig is very consistent when used properly. I will use a grinding fixture for small knives in particular and double edged blades for consistency. I have tried to do a double edged knife freehand, but I never get it as close than when I use a jig.

I've been doing this since 1992 and started freehand with a 3x21(?) belt sander clamped to a table. LOL I don't see an issue with using a jig to start, IF it's a well designed fixture. I used one at the machine shop where I worked for hollow grinds and they were nigh on close to being perfect. I will start a knife freehand, but depending on its configuration I may end the grind with a jig, just depends and may go the other way. Start with the jig and finish freehand. Yes and no. LOL

Yes I can freehand and I do on my 2x48 grinder, but my 1x42 gives better results with a grinding jig sometimes and especially with the 600 grit and higher polishing belts.

To each his own I guess.

Im with Jimm on this one. Yeah, you can do a lot more freehand and its worth spending the time to learn how, but jigs are a handy little cheat to make the process easier. Sure, you wont be doing any internal curves like a kukhri or fancy variable angle grinds, but unless you need to make those sorts of grinds, well, easy can be good.

As for getting the plunge lines lined up and symmetrical, it just takes practice. Going off the description, sounds to me like the angle of the plunge changes from side to side, i.e on side 'A', the plunge line is 90 degrees to the edge, but on side 'B' the plunge is 80 degrees? If thats the case, sounds like something is either wrong with the jig or the grinder. Either the blade isnt secured at the same angle to the jig for both sides, or the belt doesnt run square to the table of the grinder

[M&J]

I make that first plunge cut about 1/4-1/2" earlier on the blade then after it is all ground go back at a slower speed to do that final plunge-clean-up. This is where I've found doing the clean-up on the plunge works well on a variable speed grinder. The slower speed is easier to manage. For those times I come in slightly off, the slower speed doesn't turn the blank into an "oh ____!!!" moment.

Early on I was attempting to grind a particular line on the blade and duplicate to the other side. That was when my mentor relayed to me to not do that because it brought more challenges in those early days, just grind/wash it up to the top. Had enough thin ones along the way. Comes with practice and you'll develop the feel for how the steel is being removed to sense it. Muscle memory too, you'll develop a position that works for you to be accurate.