what's happening here (grind line)

[Txcwboy]

I was working the blade back to get a wider grind line and this appeared. I can see the belt is doing it but why the little runners ? How to correct it ? Those are hard to get out too when I try to finish the blade. Thankya !!

Dave

[mike koller]

are the two runners 2 inches apart?

[Osprey Guy]

Where I believe Mike is going with that...

The lines being about 2" apart is the clue...
Read this thread...should help explain:
http://www.knifenetwork.com/forum/sh...ct+wheel+crown

Make sure you read the entire thread.

Dennis

[Txcwboy]

its flat ground and not 2" apart.

Dave

[AUBE]

Its hard to tell but judging by the glare you didn't hold the bevel perfectly flat against the platen and rocked it back slightly towards the spine...which creates multiple angles or a slight convex grind. The runners appear to be due to slightly high spots on the belt or slightly high spots on the blade (probably the belt) that hit before the rest of the blade did. To prevent this try to hold the blade bevel at the perfect angle on the belt (easier said then done), and use a new/sharp belt. It does happen often at the edges of the belt, especially if the blade is thin and flexes when you apply pressure to it. Also the coarser the grit the more chance of this happening. I only have it happen with coarse grits like 60. When I fall back to 120 or higher it straightens up the grind line a lot.

[mike koller]

Thanks Dennis... that was where i was going.

Dave- has this just started?

[Ed Caffrey]

Heres what I see: First of all, how thick is the stock?

OK, First the "runners"....those are caused by laying the blade at too shallow of an angle. A few stray grits on the belt caused those "runners". Next, There are three distinct "flats" near the ricasso, and two towards the tip. There are a number of reasons that you get a number of flats, rather than a single one. More often than not its due to your position and stance not being solid.

Is the grinder set at the correct height for you? When a grinder is set at the proper height, you should be able to stand in front of it, with your elbows or wrists loosely locking into your sides/pelvis. With your elbows bent 90 degrees, the center of your platen should be right there. If you have to reach up, down, or side to side, your in the wrong position. When making a grinding pass, start in the middle of the blade, with little or no pressure, then moving only at the hips and knees, move the blade towards where you want the plunge cuts. Once you are there, thats when you apply the pressure and torque and make a complete pass to the tip of the blade. When the grinding pass reaches the "belly" of the blade, you will need to very gentle torque the blade towards the spine....this will cause the grind to follow the edge profile and run out the spine.

Now, back to the stock thickness issue. If the steel is 1/8" or less, it is very difficult to achieve a nice smooth flat grind....its just physics....theres just not enough meat there to establish a good plunge cut, without running into/over the spine.

[Txcwboy]

It is .125. SO too thin to get a nice high line on. I wont try anymore. Im just almost getting the hang of grinding.I will check the ginder height but I just set it up and all so I hope I was close.I dont think its done it before but I havent used steel this thin before for this. Its O1 and I thought I would buy some while I learn folders making and blade grinding. I want to be able HT the blade myself . Belt is fairly new and it is a 60.

thanks guys !

Dave
.

[AUBE]

It's not too thin to get a high line on....its just too thin to easily get a high line on

With more practice you will be able to get a high line on it, and on even thinner stock.

Most of it is practice/muscle memory but using a sharp belt really helps and dropping your grit to at least 120 will really help. For example if I have a 1/8" thick blade thats 1 1/2" wide and I want to grind the bevels back 1 1/4" wide I will first use a 60grit belt to grind them about 3/4" back or so then switch to a 120 to get them to nearly the final dimensions then either finish it off with a 220 or hand sanding. If I were to try and take it back close to the final dimensions with a 60grit I get the runners and a nasty looking crooked line at the top of my bevel the majority of the time. That grit is just too coarse for such work...at least for me it is.

[doublearrow]

I hope I can make this understandable. I had the exact problems with you and I mainly use 1/8 stock. I'll show you two pictures one is before I figured it out and the other is after. Before I could only get the plunge about halfway up the blade before I couldn't control it enough and had the runners with multiple bevels trying to stretch the grind. When I figured it out I could easily get the plunge to go where I wanted without the runners.
I grind edge up. After the blade is profiled I make the center line of my blade edge. I use the coarse belt and knock the square edge off and from here I do this:
Put on a fresh 60 grit belt. Run the belt to the exact edge of the platen. Set you grinder to a very fast speed. I have the 3 step pulley system and I set it on the fastest setting. I then start very close to the plunge and I grind using the edge of the belt ONLY. I do not lay the blade against the platen I have the point sticking out away from it a few degrees. After going up the blade about a 1/4 of what I want the height grind to be I start at The edge only (with the point out at an angle) and by the time I'm to the point I have the blade laying flat against the platen. When the grind is about 1/2 to 3/4 the height I want it at I switch to an 80 grit norax (I don't remember the X number of the belt for Norax) and make a few passes with the blade flat all the way across never at an angle. From here I go to a X100 grit norax which I think is 120 or 150 grit I can never keep them straight. At this point I'm running the belt over the edge and cutting in the plunge cuts like I want with the blade being flat against the platen the whole time. Usually by the X100 belt I've slowed the grinder down some.
Hopefully I didn't confuse you and you can actually understand this. On the part about starting just on the edge of the belt and before the pass is over the blade is laying flat against the platen the trick is just to be smooth and deliberate with your motions. For some reason when I was grinding on the edge of the belt I didn't rock the blade as much causing the runners. I know it sounds bassackwards because the edge provided more stability than the whole platen width but I was very please with less work and better looking grinds.
Both are 1/8 thick with about 1 1/4" wide blades. On the lighter handle if I kept going across the platen I would have multiple runners and chasing them made me make more bevels than I could ever erase so I stopped halfway up with the plunge. On the dark handle I did the above mentioned trick.
Sorry so long winded and hopefully this will help you out. One more thing doing this if I had not hand rubbed the grind line out and used a flat platen I would have had a straight distintive grind line straight across the blade like a hollow grind I just chose to sand it out.

[Txcwboy]

I ll keep reading that and maybe I ll get it. Im not a read and do type of guy . I am a watch then do type
Thanks !

Dave

[doublearrow]

I know exactly what you mean. If I can get the wife out there I'll get her to take some pics of me holding the knife like I'm talking about. Also I don't know how for Melissa texas is from pampa but your more than welcome to come up and i can attempt to show you.

ok just for grins I looked and it's 345 miles to pampa offer still stands but that's a heck of a drive for me to screw up everything you already learnt.

[Txcwboy]

Only reason I bought some 1/8 is my goal as a knifemaker is to make folders. I have many in the process but the sending off the 440C to HT delays my drive to finish one. So I bought some 1/8 01 PG to make the blades out of while I learn. I ll just by a thicker piece for making fixed blades. Thats the easiest way to fix that Thanks for the offer though. At 3.25 a gallon Melissa aint close enough !
Dave