another flat grinding thread

marekz

marekz

Joined
Jun 16, 2008
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hello and thanks for reading. First off ive read alot about flat grinding through the search. I have made a jig as well. 1. the problem is when i free hand i always seem to grind deeper in different areas of the blade.2. the jig seemed to work but i also dont get an even grind......When i freehand i tried the push stick method and ended up grinding into the spine( the blade flat against the platen). Then i freehand without a push stick and kept the spine totally off the platen about a cm.this method also is causing dips and grooves.I know it takes lots of practice but this has been my 12th attempt on some lowes steel and nothing came out to my satisfaction.The only blade i liked was when i started on the platen and the awitch to the slack belt attachment. at that point i was slowly moving upwards (spine up) at an angle and ended up half good.Can anyone add or give me some more insight or technigue. thank you-marekz---besides the slack belt i usually do edge up.---thanks again
 
Freehand, light pressure, let the belt to the work. If you want a true flat, stay on the platen. No gloves, sticks, etc. If it burns your fingers, it's too hot. Quench in your bucket often and remove in small passes. Longer blades, do it in sections for hogging, smooth and even full runs at 80 grit or higher. Just my thoughts, they work for me but may not work for anyone else :D
 
Keep at it. Learn to grind freehand, without any jigs or push sticks.
I think it was Jerry Hossum who once said, "The teaching is in the grinding dust at your feet."
-Persevere!
 
With time and more blades, you will start to learn what movements or techniques cause what to happen to the steel. Pretty soon, you'll be able to know that you made a mistake when you feel it happen without even looking. Use all your senses. Feel, sight, sound. I can hear when the belt isn't grinding correctly. I grind completely freehand without a rest and I flat grind on the platen. Until I was able to really smooth things out in my flat grinding, I would mostly flat grind and then blend things together with a very slight convex on the slack belt. It actually makes for a very nice looking finish and hides those mistakes well.

However, a true full flat grind is fairly tough. There's no groove to follow as in hollow grinding, just a flat. Some people pull the handle away from the platen as they work towards the tip, others rotate the handle down so that the grind marks are always parallel to the edge. I do a bit of both. You've got a pull the handle towards you a bit as you move towards the tip in order to get a distal taper. I use my hold body to do the movement, keeping my elbows tucked into the side and kind of rocking to the side. Work lightly on the belts until you get the hang of it, then you can increase your pressures. I don't use push sticks or gloves. Like Erik said, dunk the blade if it gets hot. I do use a plunge guide (filing guide) on most blades to keep the plunges even and it also gives me something to hold the blade with while adding a buffer from the heat. It takes some getting used to for control, but works well until you've got your blade established. Keep in mind, the grind isn't going to be perfect looking the whole way. You will make mistakes and have uneven flats. You will have uneven grinds on each side. The skill comes in learning how to correct those mistakes and make the finished product look perfect.

Good luck, I'll post more tips if I come up with them.

--nathan
 
The three P's Practice, Practice, Practice
When I first started I was lucky to have a teacher to watch, and he can flat grind almost without looking at the steel. The one thing he told was he could "feel the flat" when flat grinding.
Many belts and scrap pieces of steel later, I finally got what he was talking about. It is just a matter of building the muscle memory to repeat a process every time.
I agree with what has been said learn to grind freehand and use your fingers instead of push sticks, when your fingers get hot dunk the steel. You will get some nice calluses real quick :)
Hang in there you will get it.
 
Something that works for me is to do the heavy grinding on the platen. When the majority of the flat is finished, do some draw filing to get things completely flat and any dips out. With a file, I can get things clean and flat in about 5-10 minutes per side. When I try to correct my mistakes with the grinder I usually end up worse off than I was. Now I even occasionally grind a blade that doesn't need the file to clean it up. If you do need to draw file, once things are flat go back to the grinder and clean up with finer grits.

-Mike
 
silver_pilate said:
Keep in mind, the grind isn't going to be perfect looking the whole way. You will make mistakes and have uneven flats. You will have uneven grinds on each side. The skill comes in learning how to correct those mistakes and make the finished product look perfect.

--nathan
Click to expand...

This is very true. At least it has been for me and I'm still learning. Be very patient and keep practicing. You will find what works for you. I find that I often will use platen to mark my plunges then hit the rest of the blade in sections like Erik to mark the flat and then use the disk grinder to true it up. After that its nice sweeps on the platen moving up the grits and then maybe back to the disk at a high grit if I feel it's needed.
 
I would like to see a picture of the problems you are having to get a better idea of how to help. The first thing to understand is what ever problems you have with your grind is pretty much a non-issue until you get to the last couple of passes.

The way to start a flat grind is to grind a 45 degree angle on both sides leaving a final edge thickness, for me this edge is typically about 0.04". The next step is to start grinding the top of the 45 where it meets the flat of the blade. If you can see a small gap between the belt and your edge (o.o4 part) you wont be grinding away your edge and should be off the spine.

Most likely the uneven parts are where you are grinding with the edge of the belt, make sure your platten is just a little narrower than the belt. Carefully place the blade flat on the belt and move across, all the way across with one even pull. If you stop or slow you will overgrind that area. Thats ok until you get to the very last couple of pulls because that is where your final flat is, you can remove any mistake as long as they are not too deep. If they are deep watch how carefully you place the blade on the belt,, slow even and pull across in one movement.

I have 5 to flat grind this week, let me know if you need some pics. I have been thinking about trying to do some anyway just to explain the process.
 
Also, make sure the sparks are coming from the center of the belt. If not, then you are grinding on the edge of the belt instead of the entire surface.
 
WOW thanks again--wonderful advise. i love this forum. i dont have the capacity to post my pictures---hopefully i will be able to. thanks --marekz
 
The thing I always watch is the shaddow between the edge and the platen. When it gets too small to see thats when on the next pass I'll move the grind height UP the blade......wait till the shaddow (new gap at edge and platen) disapears and repeat as needed :)
 
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