Trouble getting a uniform grind

Bfusmc03117

Bfusmc03117

Joined
Dec 29, 2008
Messages
697
Hello again fellas,

So again I was making a new blade and naturally I feel that each blade is getting better and better . Well I felt really good about this last one and I was happy with my grinds until I started getting to a thin edge doing a basic flat grind on a drop point style blade .

As I was getting to almost sharpening edge I noticed either the base of the blade was thicker than the middle and then became thick again Torwards the tip . So I thought I should focus on those areas. I grounded the belly of the blade down to try and match the thickness of the rest of the blade and then noticed the tip wearing thin so I then stayed away from the tip because on a previous knife I got to thin and it broke and I was very upset.

Then I went to attack the base of the blade to try and achieve uniform thickness an I did . In my head I thought once I obtained uniform blade thickness I would just go back and clean up the grind lines to make them uniform. Well to say the least I want to rip my head off now because it became so frustrating between making pretty grinds and uniform blade thickness. The middle edge ended up rolling a little and the extreme ends are both still slightly thick.

Please excuse the long winded post but any suggestions or ideas as to why this is happening? I'm pretty confident I'm applying even pressure through the whole blade on my grind but maybe not.
 
Bfusmc03117,

I'm guessing the blade has been heat treated at this point. If not, you are making the edge way too thin. If this is post HT then it's all about going slowly and carefully. Too fast and you can build up too much heat and ruin the temper. I tend to get thinner sections in the middle sections of the edge sometimes as well. It happens. It could be because we worry about the plunge area and are more tentative there. In any case, when evening out the grind, go slowly. Light passes with frequent dunks in the water bucket. Check the thickness along the whole edge often with a digital caliper. Shoot for ~ .010". If you get too thin and roll an edge you can grind it back a tiny bit to get back to a slightly thicker edge. Then continue to work on getting consistency along the edge. You can always work with hand files and sandpaper if more control is needed.
 
So what I have learned is when your grinding and you start to get frustrated or pissed or whatever, walk away for a bit. Come back the next morning.

I still struggle with getting even grinds. I think one area your trying to get to thin before heat treat. Knock the edge down to about .020 or so a little thinner depending on the blade design and steel used. Once it is ht then come back and do your finish grinding. I think the grinding is easier to control after the steel is hardened.

I also used my bubble jig for a long time before I started doing it totally free hand. Start grinding at the top and work your way down. I take the edge down to just about final HT thickness so say .020". Then I work this grind down the side of the blade. Do it at an angle so your intial grind is about 1/4" down the blade, then go to about 1/2" so on so forth until you get the desired grind height on the blade.

Hope that helps.
 
Do you have a ceramic platten? I found it helps a lot, even at my novice skill level.
 
I do not have a platen and I'm not entirely sure I know what that is haha. Maybe I'm going about my flat grinds the wrong way. I usually take the blank and do an initial plunge cut at about 35 degrees. Then I hold the blade almost flush to the belt and just apply even pressure and slide the knife out. I repeat the process until my grinds are uniform with the initial plunge cut I made. I have no training besides YouTube and me just messing around.

So maybe I'm going about it the wrong way. I'm open to constructive criticism and suggestions.

Thanks again guys you have been more than kind and helpful to a newbie like myself
 
A platen is basically whatever solid surface you're grinding up against. Otherwise you're basically letting the belt flex in against the blade as you grind. What kind of grinder are you using? Another helpful tip which may help you with you're plunge lines (which I still don't do myself because I try to be a hero) is cut you're plunge lines in with a chainsaw file. I'm not a very experienced maker but I will say much like Quint I think Fred's Bubble Jig takes A LOT of frustration and probably wasted steel out of the equation when learning to grind. I love mine, I just wish I had the shop time available to utilize it more.
 
Where is the counts usual response. There are alot of how too's in the top of this forum.

You can do the initial plunge line at the ricasso with your files and get that where you want it. However for grinding the length of the blade it is a ton easier to walk the grind down from the edge. This way your only working on a portion at a time instead of fighting the entire area. Makes for easier grinding.

I dont want to advertise for others and what not but Fred Rowes little system works wonders and for starting out is well worth the money IMHO. If anything look up his instructional videos and see how he does it, even if you dont use his system the practice is still the same. I highly recommend watching his videos. It helped me alot.

Others do it differently and I also recommend finding what works for you, this worked for me.
 
Getting good grinds takes lots and lots of practice.

Keep at it.

I don't know how many knives you have ground but it takes a lot of grinding to do it well.

Go to a few hammer ins or or other knife making events.

Find a local knife maker and ask for a little help, most are very friendly. Just be polite and respect there time.

Practice.

Greg
 
I make a magnetic fixture that is adjustable to any angle needed to grind it blade. I will post a video when I get one made.
 
Last edited:
Jim McGuinn said:
I make a magnetic fixture that is adjustable to any angle needed to grind it blade. I will post a video when I get one made.
Click to expand...

I made my self one but forgot to account for my steel platten. I used a magnet so strong it stopped the grinder, can only use it on my aluminum contact wheels :( .
 
Jim McGuinn - I would like to see the pics and any sketches (dimensions) you have. I may make one.
Tim37a
 
You need some sort of reliable platen. Some prefer hardened steel, most use ceramic. Without it, You're going to have irregular convex grinds at best IMHO.

Following the plunge at the ricasso is problematic at best. You are trying to carry a constant angle across a relatively long horizontal plane from said ricasso, and even the best trained eyes wouldn't be able to keep a constant reliable angle IMHO.

Once you get a reliable platen affixed, scribe your midline where the cutting edge will be. If you are going to cut your plunge by hand, do that next. The rest is just even pressure while moving the blade at a steady, repeatable speed, and adjusting your angle. You can use a bubble jig if you like. Neat little product. Or learn how to walk the grind from the get-go. Plenty of youtube videos on both methods.

The rest is sorta up to you. Everyone does things a little different. You'll find what works for you. I grind edge up and walk the grind to the spine (most do it this way). It's not difficult in theory. You can tell if your holding the correct angle, as well as make minor corrections, just by watching your references (I use grind height in relation to the spine and distance to midline of the cutting edge). My experience is that the more you pay attention to the plunge early on, the more likely you are to mess it up. I use tape at the ricasso as a reference for the plunge and clean it up after the bevels have been ground. IMHO, a large part of knifemaking is watching EVERYTHING that's going on with the grind, and from EVERY angle. Adjustments should be minor and fluid.

I am an amateur knifemaker, and certainly not an expert. Others more experienced than me may offer different or more prudent advice.
 
oic0 said:
I made my self one but forgot to account for my steel platten. I used a magnet so strong it stopped the grinder, can only use it on my aluminum contact wheels :( .
Click to expand...


Yes I use 3/8" aluminum for the platen I also use a 3/8" x4"x 18" work rest. Made of aluminum. So far the aluminum platen has held up well. I could go to non magnetic stainless or ceramic
 
Use fresh, sharp belts.

Dull belts don't cut, so you apply more pressure, only it still doesn't cut. So you mess up. Then you try to even it out by changing where you focus pressure, which creates heat, doesn't cut, and makes you screw up again. And again. And again.

Use fresh, sharp belts. Use belts like they're free. Which is more expensive, using a bunch of belts, or scrapping knives because you're unhappy with the grind?

Is all the stuff the rest of the gang here said true? Yup. But I'll bet your problem is using dull tools. It was the same for me, too, and got worse when I flat ground. Changed instantly when I started throwing belts out after just a few minutes. Productivity increased, grinds were better, mood improved... no down side, other than having to buy more belts. Small price to pay for making what I was trying to make to begin with!!!!
 
Matthew Gregory said:
Use fresh, sharp belts.

Dull belts don't cut, so you apply more pressure, only it still doesn't cut. So you mess up. Then you try to even it out by changing where you focus pressure, which creates heat, doesn't cut, and makes you screw up again. And again. And again.

Use fresh, sharp belts. Use belts like they're free. Which is more expensive, using a bunch of belts, or scrapping knives because you're unhappy with the grind?

Is all the stuff the rest of the gang here said true? Yup. But I'll bet your problem is using dull tools. It was the same for me, too, and got worse when I flat ground. Changed instantly when I started throwing belts out after just a few minutes. Productivity increased, grinds were better, mood improved... no down side, other than having to buy more belts. Small price to pay for making what I was trying to make to begin with!!!!
Click to expand...

Great advice.
 
Check your work often, and don't grind blind. If need be stop after each pass on the grinder and check the grind. Also keep the blade moving over the belt and don't stop on one spot or you take more steel off leaving a dimple.
 
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