flattening chisels backs

[bandit571]

One can polish both faces of a Butter Knife....and can still be only able to cut warm butter..."But, look at how it shines!"

[Timberwolf]

One can polish both faces of a Butter Knife....and can still be only able to cut warm butter..."But, look at how it shines!"

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...IMO, "Polishing" just removes scratches by the use of finer and finer abrasives, to the point where the human eye cannot see them anymore...that doesn't mean the scratches are "eliminated"...it's just because our eyes can't discern them without magnification.. They never can be totally removed..even when our finest abrasive is used..

[Tony Z]

I have Hock's book in my office at my plant (and Lee's book in my other office at my warehouse!). Hock refers to polish in the same way Jack references polish, that being the use of finer and finer abrasives. I think we all can agree a mirror finish does not necessarily mean the sharpest edge and in fact, might be as Steve (Bandito) has just posted, as "only able to cut warm butter".

Regarding what Tom has done with his chisels, is not the same as Two Cherries/Hirsch has done with their chisels-namely dub off sharp edges to achieve a mirror polish (I only had one of their chisels long enough to give it away). Two Cherries buffs to a mirror finish on rounds off edges, though the cutting edge remains sharp.

[AHill]

I have Hock's book in my office at my plant (and Lee's book in my other office at my warehouse!).  Hock refers to polish in the same way Jack references polish, that being the use of finer and finer abrasives.  I think we all can agree a mirror finish does not necessarily mean the sharpest edge and in fact, might be as Steve (Bandito) has just posted, as "only able to cut warm butter".

Regarding what Tom has done with his chisels, is not the same as Two Cherries/Hirsch has done with their chisels-namely dub off sharp edges to achieve a mirror polish (I only had one of their chisels long enough to give it away).  Two Cherries buffs to a mirror finish on rounds off edges, though the cutting edge remains sharp.

I think we can all agree that the flattest edge produces the sharpest edge.

I never tried to equate Two Cherries polished chisels to what Tom showed.  Apples and oranges.  I just reinforced that a mirror polish can be achieved on a surface that isn't flat.  

But I'm going to stick to my guns and say that if your sharpening media is flat, and you're not placing uneven pressure while honing, that a polished surface is flatter than one that isn't.

[Admiral]

But I'm going to stick to my guns and say that if your sharpening media is flat, and you're not placing uneven pressure while honing, that a polished surface is flatter than one that isn't.

That may be, but does it really matter.  I've never polished the back of an iron or chisel, so long as the leading edge, for 3/8" is flat, that's all that matters, no?

[tablesawtom]

I just wanted to say that there is a difference between flat and polish. I have a set of two Cherries chisels and yes they were highly polished. And yes, I like their steel and yes I think they have good edge retention. But I had to flatten every one of them. And yes I agree with everything Ahill was saying about them. Polished  but not any flatter than most. I posted the pictures because I have the availability of using a grinder, and because because i though I would let someone see a different world. When on a surface grinder one get a line where you stop grinding so it is just easier to flatten the whole back than to do a partial grind. And it looks nicer and I like my work to look nice as well as be functional.

Being primarily a die maker I worked with a lot of hardened tools steel. Most of our steel was tempered back to 58-60 Rockwell C scale. In most cases anything harder just didn't hold up for any length of time.  60 Rockwell to me is a good trade off so I bough four  Narex chisels for about $15 apiece because they are advertised at about 60 Rockwell. Flattened them and then I angled the fixture at 20 degrees and made my own dove tail chisels. No land for about 1 1/2 inches. I stoned off the sharp edge so I wouldn't get cut

   


The primary bevel is ground back at 15 degrees and the secondary angle is at 30 degrees. The 15 degree angle lets the chisel go deep without driving the back of the chisel back into the marking gage line. These are not for heavy blows but delicate finish work. But I only have about $60 invested and not over $400. 

I guess I am kind of off the subject but I don't stop with chisels.

   

   

   

   

   

And then there is acme treading

   

   

Tom

[tablesawtom]

And no, a polished surface and a flat surface have nothing in common and polishing the surface usually takes it out of flat. My world flat is measured in tenths, that is shop parlance for 10,000s of an inch and polish is 
surface finish and is measured with a profilometer. A 63 finish is usually what you will find on the backs of Erwin chisels. 

In my origin post I said  For the final cut the depth of cut was .0003 and then there was a total of 3 spark out passes.  0003 is 3 ten thousandths.

Tom

[AHill]

One last post then I'm done with this thread.

If people would actually read what I said, they wouldn't be arguing. I caveated that a polished (mirror) surface using FLAT media is flatter than one that is not mirror smooth. Don't know how it could be otherwise. If you hone to 8000 grit and your stone is flat, then you'll get a mirror finish 99% of the time. An 8000 grit stone equates to around 3 microns or 0.0001 inches. If you follow up with a strop (on the chisel back) or polishing wheel, you may end up getting a more shiny surface, but yes, you are likely making it less flat in the process.

[Joe Bailey]

One last post then I'm done with this thread.

If people would actually read what I said, they wouldn't be arguing.  I caveated that a polished (mirror) surface using FLAT media is flatter than one that is not mirror smooth.  Don't know how it could be otherwise.  If you hone to 8000 grit and your stone is flat, then you'll get a mirror finish 99% of the time.  An 8000 grit stone equates to around 3 microns or 0.0001 inches.  If you follow up with a strop (on the chisel back) or polishing wheel, you may end up getting a more shiny surface, but yes, you are likely making it less flat in the process.

Right up front, I'd like to establish that I have been successfully reading AND comprehending for many decades now.

I understand that your argument makes sense to you, but it is not technically accurate to unequivocally state what you have stated.

It does not follow that the polished surface (given your other constraints) is FLATTER than another similarly processed surface which has not been polished to the same extent.

The former simply has smaller scratches which refract light differently -- it is NOT necessarily flatter.

[Timberwolf]

Right up front, I'd like to establish that I have been successfully reading AND comprehending for many decades now.

I understand that your argument makes sense to you, but it is not technically accurate to unequivocally state what you have stated.

It does not follow that the polished surface (given your other constraints) is FLATTER than another similarly processed surface which has not been polished to the same extent.

The former simply has smaller scratches which refract light differently -- it is NOT necessarily flatter.

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LIL
It looks like this train has gone off the rails.