Need advice on matching platen corners, raduising glass, etc.

My grinder is home made, and I made the platen out of angle iron. It works well for the most part, but I've been fighting the edges since day one. The angle iron had a slight radius on the corner and I've tried matching the radius on the outside edge by filing it down.

They look like a match, but it seems no matter what I try, the plunges have a slightly different look side to side. One side seems sharper and the other rounder. How do you guys have your platen edges? Should I just mill the whole thing down to sharp corners on both sides? I like the look of a slightly radiused platen on the grinds, but I'm sick of them not matching.

Or, I was thinking about adding the ceramic glass to my platen. Hopefully the edges of the glass would be the same. Or, do you have to radius the glass too when you buy it? Advice and opinions?

Anthony

I have a KMG grinder and I fight this problem also. I am interested in seeing what others have to say about your inquiry. I have been leaning heavily on the glass platen idea. I just have not pulled the trigger yet. I guess I am a little hesitant about the connection of the glass to my platen. In my mind, I just seeing it flying through the air after it is rip off the platen.

I'm going to follow along and take some notes.

DeMo

I had the same problem with my platen a while back. Picked up a piece of ceramic glass from boss and it made a world of difference. I threaded a 1/4-20 socket head screw below it to act as a shelf for the glass to reference, and then used VHB tape to hold the glass on. Been attached for about 1/2 a year now with no issues. I had left overs of the tape from work. We use it to permanently adhere grids to windows.

-Aaron

I feel your pain Anthony. I have also had the same problem. As it is with many things in this hobby we all love so much, it seems to be the little things that make a difference. Having a solid piece of steel is better than the angle iron, IMHO. In either case, the corners need to be exactly the same to get the desired results. Pay attention to your belts too. If your belt is worn more on one edge than the other it will make a difference in the final product. Be sure to extent the belt past the edge of platen the same, and I do mean the same, when you grind each side of your blade. New belts are a must, but even then the outside edges can become different just by how you grind; more to the right or left, pressure used, etc. Quality and type of belt is also a factor.
You can also use a file guide and a file to the radius on each side, then finish it on the grinder.
Don't get me wrong, I am no expert on this subject. Ed Caffrey has a good video on his website, if you haven't seen it yet. Good luck, and practice, practice, practice. They say that's what makes perfect.

Glad I'm not alone! Last night, with a brand new belt and 1000% concentration on matching the shapes of the plunges, they still look different. I'm not having that problem when hollow grinding on a wheel, so I don't think it's me. The difference probably wouldn't even be noticed by a typical customer, but it screams at me, I hate it!

Glass platens are a wonderful thing. Here is how I attach them. I rough up my platen with a 36X belt, clean it and the glass with denatured alcohol, & use JB Weld to attach it to the platen. I let the JB Weld build up at the bottom of the platen for a shelf. I lay it on its side on a piece of wax paper to keep it square and so it wont stick to the bench. After it sets up, I put a 120X Silicon Carbide belt on the grinder, clean up the excess JB Weld off the sides and then radius the edges until I get them like I want them. I like nice crisp plunges so I only radius the edges to about 1/32" or so. Once the belt wraps around that its good to go.

Thanks Darrin, I'll order a piece of glass from Boss tonight. I guess I'll be sure both edges are the same that way.

What I have found is to true up the plunges with the finer belts. Sure try to get close with the 60 or 120 but if you put the attention on say the 35 and even 16 it doesn't seem too difficult. I drift the belt a bit over the side to get what I want. Amazing what those belts will do. I will point out I do have a ceran platen.
Frank

Frank, not sure I'm explaining my issue well. I'm not talking about lining plunge lines up with each other. I'm talking about when you look down the cutting edge, and focus on that little triangle where they meet. I have one side of the triangle with an almost square corner look and the other side has a nice curved radius. It even shows on the sides where the plunges turn out and go down the blade. One side makes a sharper turn than the other. I just ordered the glass from boss, we'll see how that goes.

I use a ceramic glass platen liner as well, and it's leaps and bounds better than a steel platen. Less friction, less wear, more uniform, etc...

As for radiusing, you could try a slack ceramic belt, but I'm not how to ensure an even radius. Personally, I just leave the edges as is, and run the belt off the edge a little bit for a small plunge radius.