Concave finish to my chisel bevel?

[DeanDodsworth]

Hi Guys
I have just purchased a t-4, and like a excited child, set straight up and tried to re bevel one of my 1" wood chisels.
I appear to have a slight concave to the bevel, with a straight edge 
I have not trued the stone and have ordered the TT-50 to take that out of the equation. 
I can't see this problem online so I know it's down to me..what am I doing wrong?
Thanks in advance
Dean

[Ken S]

Welcome to the forum, Dean.

In the past, I have answered questions, only to find out later that I misunderstood the story and answered incorrectly. In the interest of accuracy, let's take a closer look:

The ideal edge for a chisel, of course, is straight across. When you say that you have a slight concave to the bevel, do you mean that the edge is not straight (curves inward in the middle)? Or, that your bevel has what we call a hollow grind? A, inwardly curving edge is a problem. A slight hollow grind in the bevel itself is normal when grinding with a wheel instead of a flat bench stone.

If your problem is a concave inward curve in your edge, are you moving your chisel from side to side while grinding? I suspect that you may have a grinding wheel with a high spot in the center. In roads, we call this a crown, to help rain run off to the sides. Moving side to side should correct this. If you place your support bar against the grinding wheel and see light on both sides, this is your problem.

The handbook discusses hollow grinding. If, by chance, you have not read your handbook, this is an excellent opportunity.    Make sure you register your new Tormek on the Tormek website. While you are doing that, download the online handbook. I reread it on my ipad when I do not have wifi access.

Truing your wheel with the TT-50 is essential. You must master this skill. It is not difficult. Allow some quiet time with no other sharpening plans. Make sure you have good light. Set the microadjust to make a very fine cut, just kissing the highest spots on the wheel. Listen to the sound of the light cut. Watch the effect on your wheel and learn the feel.
After the first cut, assuming that only parts of your wheel were in contact with your diamond, lower your diamond very slightly. Half a microadjust number is plenty. Keep listening, watching and observing the feel. Continue with fine cuts until your cut touches the entire wheel. At that point, stop. Beyond that all you are doing is wearing down your wheel. As you become more comfortable, you may make deeper cuts if you wish. Frequent and light truing will keep your wheel running optimally with minimal wear.

Keep us posted, whether this helps or not. Your problem is definitely solvable.

Ken

[DeanDodsworth]

Hi Ken...
Thank you for replying and making me feel a fool (in a good way )....
Whilst waiting for my TT-50, I picked up the instructions, obviously having never read them..!
Anyway the TT-50, and my newly discovered knowledge work a treat!!
Thanks again for the solid sound advice!!
Dean

[Ken S]

Dean,
Welcome to the club. As Benjamin Franklin said, "Experience keeps a dear school, but a fool will learn in none other."
I'm glad the suggestions helped.
Keep learning and keep posting.

Ken