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Thread: Shooting board limitations.
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17th August 2004, 01:33 PM #16SENIOR MEMBER
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It distributes the wear across the blade.
Dan
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17th August 2004 01:33 PM # ADSGoogle Adsense Advertisement
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17th August 2004, 01:42 PM #17
Wouldn't that depend on the size and shape of the stock? If it was square, then the blade is still going to wear in one spot more than anywhere else...
Not saying it's not the case, just wondering if that's the only benefit."I don't practice what I preach because I'm not the kind of person I'm preaching to."
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17th August 2004, 02:02 PM #18SENIOR MEMBER
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Originally Posted by silentCDan
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17th August 2004, 02:38 PM #19
Don;t know about heat, The sole wasnt hot that's for sure.
It's bloody hard work though using a shooting board, I can tell you that much.Cheers,
Adam
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I can cure you of your Sinistrophobia
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17th August 2004, 04:36 PM #20
Adam
What do you find hard about using a shooting board?
Regards
Derek
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17th August 2004, 04:58 PM #21
It simply takes a lot of manual effort to plane the end grain of a 40.40mm piece of pine.
By your comment though, I'm starting to think that I havent got the blade sharp enough.Cheers,
Adam
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I can cure you of your Sinistrophobia
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17th August 2004, 07:48 PM #22
OK first of all: I am still to master the planing bit (got the book and a #4.5 from dad but it stops there). But I do work with geometry on a daily (well OK: weekly) basis.
But I did some drawing after reading the posts here and I'm with Dan regarding the impossibility of a skew cut with this shooting board. In order to do that you would need to move the plane forward and sideways at the same time (see attachment for picture). I don't know of any shooting board contraption that can do this (there's a great jig to be build here people!).
On the other hand I'm with SilentC regarding the distribution of wear. By ramping the shooting board you get more of the cutting edge in contact with the wood, BUT at the same time you make the central part of the cutting edge work longer. Picture the 45 degree ramp again: the outside edges of the plane blade only go through wood very shortly, the central part however now has to go through the diagonal of the wood (which is about 1,4x longer than the width). In the attached picture (wear_distribution) the red area symbolizes the length of wood that each part of the cutting edge has to go through. In short the central part of the cutting edge gets more wear when using a ramped shooting board. Since you have to sharpen again as soon as any part of the cutting edge is dull, you end up sharpening more often .
As to the jig: how about making the ramped shooting board and putting the plane on a sled to hold it horizontal again. While the sled is moving along the ramp, the cutting edge is always vertical while the plane moves forward and downward.
Jasper
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17th August 2004, 09:17 PM #23
To repeat points I made earlier: the ideal plane for cross-grained cutting is one with a low cutting angle (typically 20 degrees). A plane with a skewed blade simply reduces the effective cutting angle.
This is not to say that a high angle plane cannot cut across the grain – the HNT Gordon Try Plane(60 degrees) can do a great job. But the cut is not as clean as a low angle plane, all things held equal (such as inertia and momentum – later).
A shooting board is mainly used to cut end or cross grain. This is either to accurately trim ends of boards, or to trim mitres.
A ramp on a shooting board is there to reduce the effective cutting angle by fooling the board that the plane has a skewed blade. As an illustration consider the technique we use in planing long grain: the plane is skewed at an angle and pushed straight ahead. The blade is not cutting across the grain (as one might if using a scrub plane) but rather the skewed blade is slicing at an angle. It is this skewed cutting action that we are talking about.
Have a look at the Lie Nielson #140 Skewed Block Plane as an example of a low angle set up.
http://www.lie-nielsen.com/tool.html?id=140
OK, so what are the best planes to use on a shooting board. Basically something that has heft and weight so that it carries enough momentum through the cut. Yes, end grain cutting is hard work and a dinky block plane is not the way to go. A #6 or #7 will do far better in this regard. But wait a minute! They have 45 degree cutting angles! Too high? So why not reduce the cutting angle with a ramp to simulate a skewed blade? What a good idea.
An (available) preferred plane would be something like a LN #62 (I use a Stanley #62) because these have both the size and the low angle set up. Then you do not have to ramp the shooting board.
Regards from Perth
Derek
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17th August 2004, 09:19 PM #24SENIOR MEMBER
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Jasper,
I was thinking of it this way. The edge to be planed has a certain area that will be cut on each stroke, if you can make the cut by using as much of the blade as possible (by ramping the board) then the blade should last longer (you can share the load a bit). The blade will get more wear in the middle but at least the edges will be doing a bit of work as well. With no ramp the same section of the blade does all the work (same area of wood but less blade to cut it with) which leaves a blade with a big blunt spot (usually towards one end) and the rest of it not having touched wood since the last sharpening.Dan
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17th August 2004, 09:31 PM #25
Jasper
I think your on to something there (and who ever it was that suggested it first).
Running the plane on a ramp doesn't give a you a skew cut it just changes the cutting direction (like planing diagonaly across your timber).
The plane is still going straight ahead, just at a (down) angle.
To produce a skew cut you'd need to hold the plane perfectly horizontal, then run it down a ramp.
Or....
Hold the plane on an angle, then run it horizontaly.
See??
Your blade wear maths sounds right too.
Ben.Last edited by Ben from Vic.; 18th August 2004 at 12:29 AM. Reason: removed line that could have sounded a bit insulting :)
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17th August 2004, 09:41 PM #26SENIOR MEMBER
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Derek,
I agree that a skew mouth plane will lower the cutting angle. I also agree that a square mouth plane can be made to act like a skew mouth plane if its axis (from heel to toe) doesn't match the direction of travel (ie, its skewed). However, the same square mouth plane cannot make a skew cut on a shooting board, ramped or flat, because its axis will always be parallel to the direction of travel, the timber being cut doesn't come into it because it's just wood and all it sees is a square mouth comming toward it (the blade edge is always 90deg to the direction of travel).
Even if the ramp did produce a skew cut, with the ramp at 5deg or so the effect would be bugger all.Dan
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17th August 2004, 11:31 PM #27
I made another picture.
The pictures show a couple of plane positions and a piece of wood (not moving) the motion is from light grey to black (right to left).
The top figure is a normal square mouth plane on a normal shooting board. Concentrating on the centre of the wood, you can see it moves straight up the blade. Because of this the angle that the wood sees is the angle that the blade has in the plane (45 degrees).
The middle figure is a skew mouth plane on a normal shooting board. Concentrating on the centre of the wood, you can see it moves at an angle across the blade. Because of this the angle that the wood sees is lower than the angle that the blade has in the plane. For a 90 degree skewness (unrealistic of course) the angle will be 0 degrees and for a skewness of 0 degrees (normal square mouth plane) it will be 45 degrees again.
The lower figure shows a square mouth plane on a ramped shooting board. Again concentrating on the centre of the wood, you can see it moves straight up the blade. Because of this the angle that the wood sees is the angle that the blade has in the plane (45 degrees).
I really do think that the only way to make a square mouth plane work like a skewed mouth plane is by holding the plane perfectly horizontal and running it down a ramp or as Ben said "hold the plane on an angle, then run it horizontaly".
Ben's option is of course much easier to build (why didn't I think of that).
Jasper
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17th August 2004, 11:48 PM #28
Should have included a picture for a straight mouth plane on a sled moving along a straight shooting board of course. So here it is.
Jasper
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18th August 2004, 12:47 AM #29
The angle of attack/presentation of the plane wont matter at all when planing endgrain on a shooting board save for anomolies in the grain. Changing the angle is the same as rotating the stock on the board.
The blade angle, as Derek points out, will. Terry Gordon explained the angled shooting board as using more of the blade width and distributing wear which I think would be beneficial if you had say 20 pieces of the same size hardwood to true up.
A sliding wedge under the board would be interesting allowing you to use the whole blade width....Or you could have several positions for the stop block?? provided it stayed square...
Cheers
BTW Has anybody made a shooting board for a Makita power planer??Squizzy
"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all" {screamed by maths teacher in Year 8}
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18th August 2004, 07:28 PM #30
I stand corrected about the amount of skew imparted by a ramp. It is not much. The real advantage of a ramped shooting board is that is distributes wear on the blade. So the best plane is a heavy, low angle if you have one, or a heavy one if you don't.
I received the following message from Jeff Gorman, whose opinion I value highly:
I think that the usual ramp angle would have little effect in this regard.
Please see my web site - Planing Notes - What Happens When You Slew.
The problem with the common shooting board is that the wear is restricted to
just a narrow section of the blade, hence rapid wear. In fact, a significant
notch will soon stop the plane working altogether.
The idea is therefore to lengthen this section, though of course the
thickness of the workpiece comes into the equation.
For my own idea of a lightweight ramped board intended principally for end
grain, please see - Projects - A Ramped Shooting Board. I do believe that at
least one person has tried to make one!
Jeff
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Jeff Gorman, West Yorkshire, UK
Email: [email protected]
www.amgron.clara.net
Regards from Perth
Derek