Cutting in a plunge line

[Fletch Helical]

Alright what's the secret to this? I only cut one in on an actual knife with a grinder and while it's not bad it's not great either. I have a length of mild steel I cut pieces off of and then attempt to cut line after line in to get them even and straight. Closest trick I've come up with so far is taking a marker and marking the narrow part of the stock so I can try to get the cuts in line with one another. I'm guessing I can also try taping it off and going that route but I noticed Silver Pilate's on the blade he forged and I have nothing that looks even remotely close to that. I'm getting a line that basically runs the whole width of the steel. Which is a result of just mashing the whole piece of steel up against the edge of the platen obviously. So can anyone shed a little light on how to go about making good plunge cuts?

 

[silver_pilate]

My plunges form as I grind the bevels rather than all at once. If you can use tape or marker to indicate the location of the desired plunge on either side, that can keep you symetrical. I either use the marks to keep me lined up and then start grinding my bevels (starting with a 45 degree bevel and gradually walking it up towards the spine), or I use a quick and dirty little guide I fashioned out of some 440C I had laying around. Here's a pic:

This can help keep me fairly even on my plunges when they are formed as I grind the bevels. I usually use this while rough grinding, forming my plunges a little bit ahead of where I actually want then, and then I work the plunges back using careful grinding at the edge of the platen and blend then into the bevel. I didn't start making decent plunges overnight (and mine still pale in comparison to many of the makers on this site). It took a lot of blades and a lot of practice. It's something that will develop as your grinding skill improve and you understand more and more about what to do with your hands and grinder to get the effect you desire.

Also, if you want to avoid the "step" plunge as I call it that runs the entire width of the blade and creates a step from the blade to the ricasso at the spine, you have to gradually work the bevel line up closer and closer to the spine, sneaking up on it, if you will. All it takes is a split second of incorrect pressure on a low grit belt to take your plunge up past the spine, so as you get close, switch to a fresh higher grit belt (finer grit, that is). This allows to you to more slowly remove the metal and gives you a *bit* more forgiveness, though you'll be surprised at how fast a fresh 400 grit belt can remove metal. Later on you'll be able to do more work with the course belts before you switch to a finer grit.

Hope that helps some.

--nathan

 

[Troop]

I got the idea from Harvey Dean's DVD to use a brightly colored masking tape....that and PRACTICE!
Works great. My advice is not to rely on jigs and gadgets; learn to do it freehand.

 

[Phantom Steelworks]

I tried free handing my plunges and I could get them straight, but its hard as hell to get them lined up on both sides.

Take Nathans advice and make a file guide/clamp. You will be amazed at how much a difference they make.

Also, look into Fred's bubble jig and clamp. The man is a genius.

Best of luck and keep practicing. I am very new to this but get better every time I try. Just got to keep your eye on your work and go slow:thumbup:

Chris

 

[Troop]

You guys are cheating using jigs, you know that, right?

 

[Phantom Steelworks]

I need all the help I can get brother...haha

You guys are cheating using jigs, you know that, right?

 

[Gene Martin]

Go to freehand, you'll have to learn it anyway.

Bob Ebgnath taught me to scribe a cou[ple of centerlines about .030 apart, then scribe where you want the plunge cut. Use a worn 60 grit belt and break the edge off both sides of the blade. When you get close to the plunge cut, pull the tip back a little to create a divot at the plunge cur. From there, use that divot as yopur stop point. Don't try to use it as a bump into it stop, because that will create a 2" mark on the blade.

After a couple of passes at about 45%, then start reducung the angle on the passes, widening the grind line. Don't invade the space between the lines. You'll need it later.

As you start working into the grinding, change from the worn belt to a sharper belt. Those passes to break the edge will just shear abrasive off the new belts, so use old ones to do that.

Keep a uniform pressure on the blade as you grind. Thumb pressure towards the edge, whilke grinding edge up, will make a deeper cut toward the edge. More pressure towards the spine makes a broader grind line.

Gene

 

[Phantom Steelworks]

Gene,

Not to hijack the thread, but thanks for taking the time to offer up some tips for us newbs!

I will give this a go this weekend.

Chris

Go to freehand, you'll have to learn it anyway.

Bob Ebgnath taught me to scribe a cou[ple of centerlines about .030 apart, then scribe where you want the plunge cut. Use a worn 60 grit belt and break the edge off both sides of the blade. When you get close to the plunge cut, pull the tip back a little to create a divot at the plunge cur. From there, use that divot as yopur stop point. Don't try to use it as a bump into it stop, because that will create a 2" mark on the blade.

After a couple of passes at about 45%, then start reducung the angle on the passes, widening the grind line. Don't invade the space between the lines. You'll need it later.

As you start working into the grinding, change from the worn belt to a sharper belt. Those passes to break the edge will just shear abrasive off the new belts, so use old ones to do that.

Keep a uniform pressure on the blade as you grind. Thumb pressure towards the edge, whilke grinding edge up, will make a deeper cut toward the edge. More pressure towards the spine makes a broader grind line.

Gene

 

[silver_pilate]

Good tips, Gene. I like the divot idea.

I've done it both ways. Freehand and using a jig. I just find it faster to use the jig many times. After the bevels are established for the most part, I take the jig off and freehand it from there, and I work without a jig to push my plunges back where I want them and clean them up.

I read the smiley, Troop, and I know you're just joshin, but there are many people out there that do view using a jig or guide as cheating. This argument has been hashed out many times here before, so I'll not get into it beyond this. I guess I could walk to work, but it's a lot faster in a car. I could get out the dictionary and look up every word that I put down to make sure it's spelled correctly, but it's a lot faster to use spell check. I could have made a charcoal forge, but for me, propane was more conveneint to my knifmaking habbits.

The thing to remember is that, with enough training/practice, I probably could run to work pretty quickly. If I spell the same words over and over again, I won't have to use the dictionary, and if I had a coal forge and used it, it would be like second nature after a while.

When I was having difficulty keeping my plunges even, I started using the guide. The more practice I got, the better my control got, and now I don't have to use the guide unless I want to. I see the guides as something similar to Fred's bubble jig. It doesn't completely substitue for skill, but it sure helps train those skills along, and eventually you wouldn't need it. Kinda like grinding on a work rest. I can do either, and neither way is wrong.

--nathan

 

[Troop]

Good tips, Gene.

I've done it both ways. Freehand and using a jig. I just find it faster to use the jig many times. After the bevels are established for the most part, I take the jig off and freehand it from there, and I work without a jig to push my plunges back where I want them and clean them up.

I read the smiley, Troop, and I know you're just joshin, but there are many people out there that do view using a jig or guide as cheating. This argument has been hashed out many times here before, so I'll not get into it beyond this. I guess I could walk to work, but it's a lot faster in a car. I could get out the dictionary and look up every word that I put down to make sure it's spelled correctly, but it's a lot faster to use spell check. I could have made a charcoal forge, but for me, propane was more conveneint to my knifmaking habbits.

The thing to remember is that, with enough training/practice, I probably could run to work pretty quickly. If I spell the same words over and over again, I won't have to use the dictionary, and if I had a coal forge and used it, it would be like second nature after a while.

When I was having difficulty keeping my plunges even, I started using the guide. The more practice I got, the better my control got, and now I don't have to use the guide unless I want to. I see the guides as something similar to Fred's bubble jig. It doesn't completely substitue for skill, but it sure helps train those skills along, and eventually you wouldn't need it. Kinda like grinding on a work rest. I can do either, and neither way is wrong.

--nathan

Nathan, it's a sound idea to use a jig until you develop the proper amount of skill. It's about creating the best of your Craft that's inside of you.
For me, it was a personal thing to develop my skills at the grinder; that's my temperament....I guess I'm just real stubborn.
The flip side is.... I ruined a real lot of nicely forged blades during the (still) learning process.
In retrospect, I'd do it all over again. Those ruined blades made me learn FAST!
- Mitch

 

[Fiddleback]

You could always cheat. Put a little choil at the base of the plunge to hide how effed up they are. I mean, thats the point of the little choil right? Because skin and cloth get cought in there, so it doesn't improve function.

 

[Gene Martin]

If you go to a hardware store and get some paint stirring sticks, they work great for practice. They get eaten by the belt pretty fast until you learn to use a lighter hand, but immediately tell you what you need to do fifferent.

If you know someone with a table saw, get a 2x4 and rip it into 3/16 and 1/4 wide pieces. That's thicker than the paint sticks so you'll get more experience with wider stock.

When I bought my grinder a long time ago, I got a BurrKing with a 1.5 hp variable. I ran it about half speed the first 6 months and 3/4 speed the next since months. I figured it's harder to make a serious mistake going slow.

Gene

 

[C_Kyle]

File guide and chainsaw file.

 

[Mike Quesenberry]

I grind off of a table and use a stick on the blade to control where I want pressure. I agree with Gene on the initial 45 degree grind. The stick applies pressure and the other hand just pulls the blade straight inline with the platen. I mark on edge where I want the plunge to start. Then come up to the platen pararallel with the blade about 1/2" from the plunge and shove into plunge then apply pressure with the stick and pull with the other hand.
Fiddleback, the choil hiding your inadequacies at grinding is far from the truth. If it does anything it it makes it worse. If you are off even a hair it will show when looking straight down on that plunge.

 

[wordsmith]

IF you can already get them straight, I'd suggest going freehand with the painters masking taper to keep them even. If lined up the same on both sides it'll help a lot. It also provides just enough of a different feel so that you can tell when you hit the tape. Best trick I ever learned for plunges.

 

[Fletch Helical]

You could always cheat. Put a little choil at the base of the plunge to hide how effed up they are. I mean, thats the point of the little choil right? Because skin and cloth get cought in there, so it doesn't improve function.

I was always under the assumption that a choil is put in to have to do with sharpening the knife. So you don't mar up the ricasso when sharpening it. Then there is the thing about using it to catch an opponents blade in a knife fight but c'mon.....

 

[gixxer]

I have started using a belt grinder attachment like what Nick Wheeler uses. He has a small wheel attachment and a platen directly behind it. You hold the knife lengthwise with the belt and let the bevel ride on the platen, let the wheel cut your plunge. Another method is to use a piece of steel with a radius on the end facing you instead of a wheel on top, let the belt ride over it and do the same as mentioned above.

I could be mistaken but I think I saw Kyle Royer using the same type deal in his sub hilt fighter build vids on youtube.

Maybe Nick can post those pics he has posted sometime ago of his attachment.

 

[Fletch Helical]

See I think I did it kind of awkward for me. I basically pit the bevels on and then I added the plunge cuts, rather than put them in as I was grinding. I spoke a bit to Fred when I got his bubble jig and he said he puts the plunge in after he gets his bevels. Maybe I went too far with my bevels or didn't leave enough meat on the blade where the plunge lines were going to be. I kind of like the idea of developing them as I grind... Should I be able to accomplish that.

 

[Gene Martin]

If grinding on a work rest or with a jig makes you comfortable to start with, do it. You'll find that you'll be freehanding before long. A jig or work rest actually becomes a restriction on what you can do.

For the best grind lines and stability for you, while freehanding, stand close to the grinder with your feet about shoulder width apart. You'll need to reposition as you switch blade sides, standing slightly off center from the platen, left or right. Make one pass on each side and you'll understand what I'm saying.

Keep your elbows tucked in and your wrists against the sides of your stomach. It makes for more control and fewer bobbles in the grind line. This belly so many of us have is actually an organic work rest. It's a kegger, and really solid for keeping your hands and arms steady. The guys with the 6 pack abs are really screwed in this department.

If you find yourself reaching out, move closer. If you smell something burning, it's your shirt tail. I grind with the blade about 1" in front of my stomach, maybe closer.

If you use a push stick, the non stick hand becomes more important for straight grind lines. Drag the blade across the platen with an even pressure, pulling the tang toward you slighlty as you near the tip. This helps with distal taper.

When grinding edge up it is really easy to see where you are grinding. Watch the sparks coming off the blade. If they are not centered on the platen (or wheel if hollow grinding) then you aren't using the full width of the belt. When grinding edge up, stand slightly right of center for the left side of the blade, and slightly left of center for the right side. I use a rocking motion sometimes from side to side to more easily keep on track.

The off center body position gives more stability as you bridge the gap between hands.

I usually grind a bunch of blades at a time, so I start with one side and do them all, then switch sides. It saves a lot of setup time between sides. I finish one grit size on both sides of the blades, then move to the next batch. That way there are only two setups per belt, rather than a new one for each blade.

I'm tired tonight and starting to ramble, so if I'm not making sense send me a PM and I'll try to explain it better.

Gene

 

[Will Leavitt]

One thing to add to the very complete explanation of grinding.

Sway, don't move your arms, sway your body.. it's called the knifemaker's waltz