Shooting Boards
#20
  Re: Shooting Boards by Large Wooden Badger (I'm fixing to embark...)
Derek,

Would my math -- or is it geometry? -- be wrong in assuming that the donkey's ear placed on the 5 degree slope of the shooting board will yield a compound mitre, not at 90 degrees?

Greg
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#21
  Re: Shooting Boards by Large Wooden Badger (I'm fixing to embark...)
Hi Greg

No compound angle. The ramp allows the blade to enter the work at a 5 degree skew, cuts with this slight skew. Think of skewing a smoothing plane as you push it down a board.

The advantage of this slight skew is to reduce the impact from a straight blade. It is not affecting the quality of the cut, per se. Also, a ramp does not "save" the blade in terms of widening the part of the blade use. Again, the skew is too little.

It a ramped board worth the effort to build? In my experience it is ... if using a straight blade. I began making these boards about 20 years ago. However I mostly use a Stanley #52 shooting board with a Veritas shooting plane.

Regards from Perth

Derek
Articles on furniture building, shop made tools and tool reviews at http://www.inthewoodshop.com
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#22
  Re: Shooting Boards by Large Wooden Badger (I'm fixing to embark...)
Thanks Derek that is helpful, I do not yet have a 51 so I should incorporate a ramp.
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#23
  Re: Shooting Boards by Large Wooden Badger (I'm fixing to embark...)
Yes, thanks Derek.  I was picturing it all wrong.  My shooting board has the ramp tilted, too, and I saw in my mind's eye the creation of a compound angle rather than a meeting at 90 degrees.  For many years I've used the shooting plane I built while studying with Krenov.  We also built the shooting boards in class, of plywood with lignum vitae ramps.  I recently splurged and got the Veritas shooting plane.  The pure heft of that beast produces nice fish scale shavings.  I am thinking that the keeper on your ramp might make the use of any plane on the shooting board run more true.

Anyway, thanks for sharing your infinite knowledge and experience.

Greg
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#24
  Re: RE: Shooting Boards by Derek Cohen (Hi Greg No compou...)
(10-30-2019, 09:28 PM)Derek Cohen Wrote: No compound angle. The ramp allows the blade to enter the work at a 5 degree skew, cuts with this slight skew. Think of skewing a smoothing plane as you push it down a board.

The advantage of this slight skew is to reduce the impact from a straight blade. It is not affecting the quality of the cut, per se. Also, a ramp does not "save" the blade in terms of widening the part of the blade use. Again, the skew is too little.


Skewing a smoothing plane as you push it down a board does (at least) two things: it reduces the impact of the blade's initial contact with the wood (as you note), but it also changes the effective angle of the blade by causing the blade to move at an angle relative to the slope of the bevel. Think of this latter effect as causing the wood to drive up a slight swithcback instead of straight up the steeper slope. 

A ramp on a shooting board has only the first benefit (lessening the impact from the blade making initial contact with the full thickness of the board at once), it does not reduce the effective cutting angle since the motion of the blade is still parallel to the slope of the bevel. The ramped shooting board would be more like changing the orientation of the board while still using the smoothing plane in a straight-ahead orientation. A skewed blade in a shooting board has both benefits.

Whether there is any real-world benefit to the skew over the ramp I can't say.
''How can we ever hope to understand atoms?'' Heisenberg had lamented that day.

''I think we may yet be able to do so,'' Bohr replied. ''But in the process we may have to learn what the word 'understanding' really means.''
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#25
  Re: RE: Shooting Boards by Derek Cohen (The style of shootin...)
(10-30-2019, 08:00 PM)Derek Cohen Wrote: As a counter to Hank’s flat board, there is a 5 degree ramped board (in Jarrah and quartersawn Tasmanian Oak) ..
Derek, with the angle of that shooting board I am imagining the cutting force is pushing the work piece up as well as into the fence. would reversing the angle so the plane blade travels down and forward help hold the work piece in place? Or is this just not a problem?
Proud maker of large quantities of sawdust......oh, and the occasional project!
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#26
  Re: Shooting Boards by Large Wooden Badger (I'm fixing to embark...)
Kyle, if there is any up force, it is either theoretical or so minor that it is irrelevant. Don't sweat it.

Regards from Perth

Derek
Articles on furniture building, shop made tools and tool reviews at http://www.inthewoodshop.com
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#27
  Re: Shooting Boards by Large Wooden Badger (I'm fixing to embark...)
The workpiece will never get lifted up as a hand is placed on the workpiece to keep it down and against the fence.

Simon
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#28
  Re: Shooting Boards by Large Wooden Badger (I'm fixing to embark...)
Thanks guys for answering the question. I do know that moving the plane sideways a little as pushing it forward really helps on end grain. My experience comes from trimming end grain flush on box joints with my trusty LV block plane.
Proud maker of large quantities of sawdust......oh, and the occasional project!
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