Further to the article recently published in the Australian Wood Review, here are some tips on keeping your blade sharpened at 30 degrees.
Your blade bevel angle can easily become greater than 30 degrees from repeated sharpening especially right at the tip of the blade where the naked eye can’t see the increased angle. The picture below is showing how to re-hollow grind at 30 degrees with a standard bench ginder. Just take it easy and cool your blade as you go. Grind as close as you can to the edge just leaving a small line of the polished edge. Wet grinders are another very good way of doing this and take away any issues with burning your blade and you can grind right to the edge.
You can also use honing guides to maintain your 30 degrees, however if you don’t hollow grind (particularly on thick blades) it will take you a lot more time to sharpen than if you had a hollow grind. As a guide, if it takes longer than 2 minutes to get your blade perfectly sharp on waterstones then you need to re-hollow grind.
My experinence clearly tells me that grinding blades to reset the correct geometry has great benefits in saving sharpening time and gettting better results with edge tools. If you are concerned about burning blades get hold of an old blade or chisel that you don’t use or buy one at a boot market and practice grinding the bevel, that way if you do accidently burn the blade it is of no consequence, and you will learn how hard you can grind before the steel will burn. Also if you are using HSS blades you can grind and have some minor burning and it doesn’t effect the harden and temper of the blade.
If you are purposely sharpening your blade at 50 degrees to change the blade pitch of the plane to handle cranky grains then you will have to accept that the blade will blunt very quickly effecting the performance of the plane and the results you will achieve. If you are trying to deal with cranky grain I can only recommend that you acquire a plane that is purposely designed for this without the inherent problems of sharpening blade bevels at greater than 30 -31 degrees.
For the last 22 years HNT Gordon has been making planes specifically for dealing with difficult Australian hardwoods. Try one of our smoothers and you will clearly see the benefits of our blade geometry for planing these woods and you will also be pleasantly surprised at how well these planes handle all sorts of softwoods.
The next article in the AWR will be on blade Clearance angles which will highlight problems with planes that have very small clearance angles. So if your plane is tending to jump out of the cut or you have to force your plane down on to the wood to make it cut this article will be of interest to you.
NEW!! Front Vice - No racking!
Our new front vice is available to purchase off the website here.