Shooting edge joints

Everything I've read on preparing for an edge glued joint with hand planes shows the board clamped with the edge facing up. Assuming the board is short enough to fit on your bench, why isn't shooting with your plane sideways on the bench the preferred way? It seems easy to place another board under the one to be joined so you end up with an open space on the bottom. Plane one face up and the other face down and you should cancel out any slight variance from 90 degrees. I know I read about this somewhere but it certainly doesn't seem to be common practice. What am I missing? The only thing I can think of is that maybe the majority of planes aren't machined at exactly 90 degrees from sole to side. You would also abuse a single section of your iron I suppose, making sharpening necessary earlier.
Thanks, Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Since we don't know the setup used to do either, a milled surface is more likely to be square simply do to the nature of the setup required. A great deal of "ground" surfaces on consumer products are produced on a belt sander with no reference to a particular angle other than the original surface. It is likely though, that the usual way of producing plane bodies would be to mill them to clean up the casting then belt sand them for finish. Due to the handwork, this would introduce errors but would be so slight as to be insignificant for the intended use. Top of the line planes, such as the Lie-Nielson, are surface ground.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
It seems that most production metal planes are cast. When I was on the shop floor, and admittedly that was some time ago the next part of the procedure to true the casting up would be to mill the necessary critical surfaces for precision performance . As production milling operations generally produce a true but relatively rough surface the final operation would be to grind the milled surfaces to a fine and even more accurate level. The setup for the grinding operation probably amounts to simply placing the casting on the grinders magnetic bed.
If you are going to belt sand the item then why not just take the basic casting and sand that rather than destroy any accuracy imparted by the milling process.
Examination of many of the mass produced items by the likes of record ,stanley et al shows the final grind is on a relatively coarse stone and the steel seems to have a somewhat coarse grain structure . The grain structure on the more expensive planes appear to be finer the same being true of the grind and in addition the castings appear heavier and might have been green sand castings .Given the difference in prices this is understandable. Of course basically the same results can be obtained with either, it all ends up depending on the skill of the operator, and a little patience ....mjh
-- mike hide

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Cast iron should have at least .015 to clean up to ensure full clean up (more is better and is the norm). You can easily mill to a 63 microinch finish. To clean up the milled finish, you would only have to remove a few .0001s. To clean up the rough casting, you would have to sand off .015 or more. Removing a few tenths by hand is not going to effect accuracy to any meaningful degree for this purpose. Sanding from rough cast, there is little chance of any kind of accuracy. In addition, sand castings are not very accurate as to form and they are intentionally cast with a draft angle to enable the form to be extracted from the mold. The difference in finish you see between high end planes and production line one is the difference between surface grinding and belt sanding. The stones used for surface grinding cast iron are very course to avoid loading. A fine surface finish is easily achieved with a course wheel in machine grinding where the machine controls depth of cut. In freehand grinding, you would need a much finer grit to achieve the same finish. Someone good with the belt sander could do five planes in the time it would take to surface grind one. A very good example of this process is a shop I worked in about a year ago. We turned out thousands of "ground" parts. They were all milled to size and belt sanded for finish. We had people that did nothing but sand all day. They were very good at it. They had a horizontal belt sander that took about a twenty foot belt. Three people at a time used this machine.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tell that to the group that grind their plane irons to a one micron tolerance at times and 5 microns all the time . Personally in my view the only reason to beltsand a milled surface is for the very reason you mentioned you can do 5 in the time it takes to grind one . Thus what appears to be a fine accurate ground surface is actually is a hand beltsanded one with no where near the accuracy of it's ground counterpart and quite liklly less accurate than the milled blank that was started with.
I am probably wrong here but I thought one of the virtues of cast iron was it did not load up
mike hide

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If you start with a 63 microinch surface finish and you sand just far enough to remove the milling marks, you will achieve an accuracy level as good as most do when lapping. If you think about it, it is nothing more than lapping. Only difference is instead of you pushing the plane across the abrasive paper, the paper is moving and you are holding the plane to it. This is not being done by Joe Monkey Weekend Hacker on an $85.00 dollar Black an Decker. On an 80 grit belt, you would have to work quite hard to remove .001 over the width or, harder still, length of a plane sole and if you did, that amount would mean nothing for what a plane does. Yes, cast iron will load a grinding wheel quickly. I once decided to regrind a cast iron surface plate We didn't have grinding wheel for cast iron as we did nothing but steel. I thought I could probably get away with it. The grinder (surface grinder) left burn marks at each stroke. I tried dressing the wheel very course(think Tormek). It was better but still left burn marks. Went next door and barrowed a wheel for cast iron. Quite course with an open structure. That worked. A five micron grind (grit size. No one is holding 5 micron tolerances) is way overkill. While superfinishing is quite effective in some applications, this is not one of them. There are other points of edge failure that far override the superfinish. It does give them something to do however so it is not a complete waste of time. I have read about everything I could find on the subject of sharpening for over thirty years and there is only one thing that is universal. No one will ever agree on the best way.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi, Chris,
As another poster mentioned, shooting boards used to be fairly commonplace before the advent of machine jointers. I still have mine, although it's seldom used now.
Mine is made from a piece of 1" ply about four feet long and 12" wide. Glued & screwed on top of that is another piece of 1/2" ply, same length and about 8" wide. They're arranged so that one long edge of the first piece corresponds to one long edge of the second, giving an stepped board, rather like an elongated L-shape in cross-section.
A stop - about 3/4" x 1" x 8 " - is dadoed, glued and screwed into the 8" ply board at rt angles to its length (accuracy is important here) and a couple of inches from one end or the other (if you lay the board on the bench transverse to you, with the high bit - ie the 8" board - uppermost and toward you, the stop will go at the LH end if you're right-handed and vice-versa).
Place the shooting-board on the floor. Lay the board to be shot on the upper 8" piece, abutting the stop and overhanging the step between the ply boards by about 1/8" or so. Take the longest plane you have (I use a No 7), sharpen it like a razor, set the cap iron as close as you can get it to the edge (1/64 or so), set the depth of cut to as shallow as possible while still taking a shaving, then lay it on its side on the lower step with the cutter toward the board to be shot. Helps a lot if you lube the lower step and the side of the plane with candle-wax or somesuch.
Kneel on the board to be shot to clamp it to the shooting board, then simply plane away at the middle 2/3 or 3/4 of the board, ignoring the ends, until the plane no longer cuts. You've now got a mostly square-edged board which is minutely hollow along its length, so take a couple of shavings all the way through the board until you're getting a full-width shaving the full length of the board. Voila.
Bear in mind that it's not the fact of the plane running along the step of the board that straightens the long edge - it's the truth of the long sole of the plane. The sole of the plane shouldn't actually run along the step, which is why you have that 1/8" overhang. (Unless you are squaring the end of a board, which is a slightly different technique)
As you correctly point out, when you're setting up the plane it does help to set the cutter parallel to the plane sole, and if the sole is at true right angles to the side, so much the better. However it's not crucial, since all you have to do is to shoot one board with its face-side up and it's mating board with the face side down, and any small variation from a right-angle will cancel itself out. This is not true however if you are squaring an end - you need the setup to be accurate for that.
As for blunting one portion of the blade before the rest, I've never found it to be a problem. Most of the hard work's been done already, probably in the vice by going down to the line with a No 5 or so. All your jointer plane is doing is the last final tweak, so it should seldom need sharpening.
It all takes a lot longer to describe that it does to carry out, but it's pretty easy, extremely accurate and a very satisfying job, if a bit sore on my old knees!
HTH
Frank

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Great description. Thanks Frank!
-Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Cool. I've seen rubbed joints mentioned but didn't really know what it meant.
-Chris
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.