efficiently flattening chisel backs ?

Re: efficiently flattening chisel backs ?

Dan Clermont in Burnaby

>Hi Chris,

I wouldn't use a belt sander to flatten a chisel back.

Some people such as David Charlesworth say a "hollow" or concave chisel back is a nice thing to have as a convex back is very difficult to flatten due to the roundness.

You need to make sure your stones stay dead flat during the flattening process and must spend most of your time on your 800 or 1000 grit before moving up to the higher stones.

Hope that helps.

Dan Clermont

Re: efficiently flattening chisel backs ?

Jack Guzman from Maine

>I charge my 400 grit diamond by rubbing a 220 grit water stone over it.It works.I figured that out while trying to flatten A-2.That is tedious.---Jack

Re: efficiently flattening chisel backs ?

Fred Krow

>Yes, heavy pressure does ruin the DMT diamonds.

I visited a WW show and spoke at lenght with a DMT salesman in January, he showed me how light the pressure should be for honing. He also stated you will easily and quickly wear out a DMT with hight pressure. The force was in ounces,,,,maybe 2x the weight a small chisel or plane blade.

Regards,

Fred Krow

Use a belt sander...my technique

Bryan in Broad Ripple, IN

>When I need to do gross flattening of chisel backs, I use a belt sander. It's fast, but your touch must be light.

First, put the sander upsaide down in your vise. Next, position yourself on the end of the sander with the belt spinning away from you. I NEVER use the platten. Rather, I grind only on the middle of the wheel where the crown is located. This allows you to focus the action of the belt sander in an area maybe 1/2" wide by 1/4" or so long. I then lightly grind the back of the chisel for a few seconds. I start about 1 inch from the tip of the blade, lower (very lightly) the chisel on the edge of the wheel at the crown, and pull the chisel towards me...stopping about 1/16" from the blade tip. If you grind all the way to the tip, you will dub the edge for sure. The last 1/16" inch is easy to lap out anyway.

I do this one or two times, then try lapping the back on my scary sharp system (using 60 grit) to check the progress. If it is not flat, I repeat as necessary until it's close. After a few minutes, you will get the hang of it and can be more aggressive, if you like. I can usually rouhgly flatten the back of a chisel in just a few minutes using this technique.

Good Luck!

-Bryan

Re: efficiently flattening chisel backs ?

mikew

>Hi Chris,

I use a stationary belt sander all the time for initially flattening the backs of chisels and plane blades.

The platen on the larger sanders is different, though. I wouldn't worry about a slight hollow at all. Keeping it flat on the sander is the prime concern so the chisel doesn't end up trapazoidal in cross-section.

After grinding on the belt sander, a little work on the DMT will further refine the back, and once the edges of the back begin to errode the hollow you can move up to higher grit stones or sandpaper to bring them to a finer finish.

Take care, Mike

Re: efficiently flattening chisel backs ?

Tony Zaffuto

>I bought coarse and medium India stones from Joel/Tools for Working Wood. Although my 200 grit waterstone cut faster, the total time including flattening of the waterstone was longer than the India stones.

Re: efficiently flattening chisel backs ?

ThomD

>My experience with the DMT stones since they originally brought them out is that everything ruins them. Mostly money down the drain as far as I am concerned. All the more true with the fabulous improvements in sandpaper and laping compounds over the same period. In fact, I have individual pieces of sandpaper that seem to have held up better than DMT stones.

Re: efficiently flattening chisel backs ?

ThomD

>What does that tell you about DMT cutting power. rubbing on water stones is another thng that can wreak DMTs.

Re: efficiently flattening pick one

ThomD

>To a certain extent the problem is that efficient flatening is what most of us own the DMTs etc... to correct. Someone at a factory tried this already and botched it up, or maybe the flatness settled, though I haven't seen evidence of that myself.

So if you want efficient, I think some form of belt sander with a flat platen is the ticket, or even sandpaper like 220 on a flat surface. This is what they seem to do at the factory, and it usually needs tweaking.

If you want flat then something like an Iron Kanaban is an option. Maybe aluminum would work since it is easily bought nice and flat, and is soft... Hand flatening takes an eternity. Look up the various meanings of the word "grind". Try to get in a peasant non-self-important state of mind, and gut it out. They call it wood"working".

In a lot of applications, an flat back is not necesarry. If your old chisels look used...

Re: efficiently flattening pick one

dave caudill

>First you need a little luck in getting chisels that aren't too badly convexed. Next you need a good flat piece of glass or stone and then some good sandpaper and a lot of elbow grease. I start with 80 or 100 grit and move up two or three steps to 320 before I go inside and hit the stones. If you don't get them fairly flat before going to the stones you are going to spend a lot of extra hours getting nowhere other than prematurely wearing out your stones. I won't say the guys that use the sanders are wrong I just know I can't get them flat on a sander and would likely suffer a serious injury putting a sharp chisel on a spinning belt. I've had good luck with this method but it is just one way and not the only way.

Dave

Re: efficiently flattening chisel backs ?

Jim in Burlington On

>Flattening the backs absolutely kills DMT's. I use 220 grit then move up till I get to 400 grit then onto my Norton stones.

Re: efficiently flattening chisel backs ?

Fred Krow

>I have two 12" DMT diamond hones purchased in the early 1970's,,,,,still very functional and cut well.

Regards,

FK

What I do

Derek Cohen (in Perth Australia)

>As stated by others, a hollowed back is actually a bonus since there is less to flatten. Look at the Japanese chisels. The important sections of the back of the blade are the edges and the leading edge of the bevel. These must be in a single plane.

Getting rid of a rounded back is difficult since it is possible to maintain it when lapping to remove it (as one can do when jointing an edge of a board that is higher in the centre). So it is helpful in these situations to paint the back of the blade with engineer's blue or a permanent marker pen so that you can see exactly where you are working.

For the back of blades I prefer using sandpaper. I have tried a stationary belt sander but find that it is difficult to maintain an even grind - just not precise enough.

For sandpaper I will start with Zirconion Oxide belts, first 80 and then 120 grit. These are glued to a float glass plate. I use a light contact glue spray (designed for posters). This is easy to remove - often with just hand pressure, sometimes with a heatgun. Most of the time I can re-use the same glue surface, otherwise a quick wipe with acetone leaves the glass gleaming. My glass plate is 1m long, which makes for less effort and faster lapping.

Once this is flat I move onto my waterstones.

Regards from Perth

Derek