Replies

1. 
   hdgis1 | May 05, 2009 08:42pm | #1

   Smaller mouth opening doesnt mean smaller shaving. Tightness of mouth has more to do with how plane holds down fibers. Best way to figure out mouth opening is to set depth of blade ot what you like and then close mouth until it doesnt clog. You will have hard time getting .001 shaving through a mouth opening of .0005!

   Chris

1. 
   MikeHennessy | May 05, 2009 09:03pm | #2

   "then close mouth until it doesnt clog"

   Are you sure that's not backwards? Didn't you mean open the mouth just until it doesn't clog?Mike HennessyPittsburgh, PAEverything fits, until you put glue on it.

1. 
   hdgis1 | May 06, 2009 06:26am | #4

   Start with mouth open and close it down till it clogs and then open up a bit...yeah sounds about right!Chris

1. 
   jeff100 | May 06, 2009 09:38am | #5

   Start with mouth open and close it down till it clogs and then open up a bit

   Actually, I believe it's start with mouth open and close it down till it clogs, then back off one...;-)

2. 
   saschafer | May 05, 2009 09:15pm | #3

   If you're working with reasonably straight-grained woods, the mouth opening is not an issue at all. I can take my smoothing plane (a Veritas Bevel-Up Smoother) and open the mouth as wide as it will go (about 1/8"), and still get clean, "whisper-thin" shavings on well-behaved woods. The ability to close down the mouth is more important on misbehaving woods (e.g., curly grain).

   So don't sweat it unless the wood is forcing you. If you're having troubles, the source of the problem is unlikely to be the size of the mouth, unless the wood is unruly. Much more likely are flatness of the plane's sole and sharpness of the blade, or even just trying to take too heavy a cut.

   -Steve

    

3. 
   RMillard | May 06, 2009 01:12pm | #6

   Greg,

   I will go against the grain (sorry about that) and state that the mouth opening has little, if any impact on how well a plane can handle difficult grain. I have a wooden plane I made, which I strove for a tight mouth. I was too successful and it always clogged with shavings. I then opened the mouth to about 3/32"" wide, and there was no difference in its performance, on highly figured mahogany, curly maple  or on a particularly difficult piece of birch.

    On a typical Bailey type plane, I adjust the frog until the iron is fully supported by the rear of the mouth opening, and pay no attention to the opening. This helps, by supporting the blade down as far as possible and works to reduce chatter. With some of the thicker irons on today's planes, this probably isn't as critical as it is with the thinner irons on some of the Stanley planes. I don't own a Lee Valley plane, but I believe they have a frog that moves forward as a unit so the iron is always fully supported.  On my own 4 1/2, I have the opening at just over a 64th of an inch, judging by a quick eyeball measurement.

   I think the issues determining how well a plane handles difficult grain  in order from most to least important are.

   Projection of the iron

   Sharpness of the iron (really a tie with the first one)

   Bed angle (the addition of a back bevel can do wonders for a plane bedded at 45    degrees)

    Thickness of the iron

   Rigidity of the plane (again a tie with the one above)

   And last and certainly least the throat opening.

   Rob Millard
   http://www.americanfederalperiod.com

    

1. 
   derekcohen | May 06, 2009 03:52pm | #7

   Hi Rob

   I recall a review of the Marcou BU smoother by Christopher Schwarz a year or so ago. He found that this was the first plane where closing down the mouth actually made a positive difference.

   In my experience with gnarly timber, the mouth size becomes increasingly less important at the cutting angle increases. I agree with Terry Gordon (HNT Gordon planes) that 60 degrees represents the point where the mouth size becomes irrelevant. Conversely, the mouth needs to be closed down when planing reversing face grain with a common angle (and even then ..).

   Of course, on end grain the mouth size is totally unimportant.

   Cutting angle is #1 in my book.

   I do agree that a thicker iron is more stable than a thinner iron. Therefore it is preferred. However it does not prevent tearout, only chatter.

   Sharpness is a biggie and, together with a fine shaving, is the next alternative to a higher cutting angle. Another we agree on.

   Regards from Perth

   Derek

    

1. 
   RMillard | May 07, 2009 04:04am | #8

   Derek,

   I did stray from the actual topic, by including the thicker iron.

   I thought for a while, on what order to put the list in; I guess I put sharpness and depth ahead of bed angle, because a dull blade or one sticking out too far won't cut no matter the bed angle. In the end each one is depended on the other so putting a list in order is kind of futile.

   Rob Millardhttp://www.americanfederalperiod.com