Frank asks...

> On 13 Jun 2020, at 14:10, Frank Filippone  wrote:
> 
> Is this because the usual result it to saw straight down, and therefore leave
the least possible mark on the bottom wood of the miter box?
> 
> Frank Filippone BMWRed735i@g...
>> Backsaws need a perfectly flat tooth line, i use a level (fro
>> flatness), and i check for flatness with a feeler gauge. I usually try
>> to reach b/w +- 0.2mm to +- 0.1 mm.
>> 
>> Chris  


Well, yes, but more importantly, when you cut a joint - say even a tenon - and
are trying to intersect another saw cut, that cut will be straight, and you want
to meet it perfectly, with out overcutting at any point.


A feeler gauge seems a strange choice though.  Conventionally, you run a file
along the teeth lengthwise, and when the top of each tooth shows contact, it
will be flat.  Sharpen to ‘just’ remove the glint of reflected light.



Richard