tag:blogger.com,1999:blog-1321553715454450871.post1146385638997396628..comments2024-03-27T12:51:12.930-07:00Comments on Woodworking in a Tiny Shop: Making a Sharpening Block for a Scrub Plane IronTiny Shop Woodworkshttp://www.blogger.com/profile/10375332433853904113noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-1321553715454450871.post-46269539162420210062016-08-05T08:38:51.452-07:002016-08-05T08:38:51.452-07:00You are absolutely right, Sylvain. I hadn't t...You are absolutely right, Sylvain. I hadn't thought about the elliptical shape - so I guess I sharpened my iron not round, but elliptical. Like you said, in the local 1 1/2" of my iron, the curvature of the ellipse is probably not too different from that of a circle. Great stuff!Tiny Shop Woodworkshttps://www.blogger.com/profile/10375332433853904113noreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-62795443860958554252016-08-05T02:22:57.702-07:002016-08-05T02:22:57.702-07:00If your jig honing surface is cylindrical, your bl...If your jig honing surface is cylindrical, your blade edge should be elliptical. As the section of a cylinder by a (geometric) plane is an ellipse.<br />Long axis: 2a, small axis: 2b.<br /><br />The crown of the blade would be at the end of the long radius.<br />Wiki gives the curvature k. (please look because I can't tape it here because of the exponents)<br />For x=a and y=0 it gives<br />k=a/b² the local radius being 1/k or b²/a=8" in your case<br /><br />Although the curvature of the ellipse is not constant, let's suppose taking into account the width of the blade and the crown radius that the variation is negligible across the blade width.<br />For a geometric plane cutting a cylinder at 30°, the ratio between a and b is <br />b=a sin30°. b being the radius of the cylinder.<br /><br />8= b²/a= a²sin²30/a= a sin²30 or <br />a=8/sin²30 or <br />b=8 sin30/sin²30= 8"/sin 30° =16"<br />as you found.<br /><br />Sylvain<br /><br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-32757937224599394212016-04-29T08:24:32.780-07:002016-04-29T08:24:32.780-07:00Hi Stefan. I think a block plane iron would be pe...Hi Stefan. I think a block plane iron would be perfect for this. Just have to plan for it in the width of the plane. For my plane, I bought a length of 1/8" thick, 1 1/2" wide O-1 steel and shaped it with hacksaw and files. That was last year and might have been my first try at hardening and tempering metal. I was very nervous about it - I had never used a torch before. But I used a propane torch, some concrete cinder blocks for safety (to contain the flame - probably didn't need this), and some vegetable oil for quenching. I tempered the iron in the oven for an hour at 350°F. I had read a lot about it before starting. It was fairly easy, but I have no way of knowing whether the blade was properly hardened and tempered. But it seems to be working OK. I think with more experience I'll be able to feel whether an iron is hardened and tempered properly.Tiny Shop Woodworkshttps://www.blogger.com/profile/10375332433853904113noreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-55390983605740696342016-04-28T23:54:47.276-07:002016-04-28T23:54:47.276-07:00Hm, I'm fearing a bit more the blade hardening...Hm, I'm fearing a bit more the blade hardening part.<br />I will need one for one of the next projects. Actually I'm thinking about reshaping a block plane blade. Don't know if that will work.<br />Have you made the iron by yourself?Anonymoushttps://www.blogger.com/profile/17569365598390231433noreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-16396812884196718752016-04-28T11:50:31.227-07:002016-04-28T11:50:31.227-07:00Yes Stefan, that is the Sellers compass plane. I ...Yes Stefan, that is the Sellers compass plane. I made it last year (from maple) before making the seat for the shop stool. It works pretty well. The tricky part was getting things lined up properly during glue-up.Tiny Shop Woodworkshttps://www.blogger.com/profile/10375332433853904113noreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-24376680416105602142016-04-28T10:53:29.314-07:002016-04-28T10:53:29.314-07:00Hi Matt,
I like your little compass plane. Is it t...Hi Matt,<br />I like your little compass plane. Is it the Paul Sellers model? Have you done it by yourself?<br />Cheers,<br />StefanAnonymoushttps://www.blogger.com/profile/17569365598390231433noreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-39443033342614600702016-04-24T22:00:36.792-07:002016-04-24T22:00:36.792-07:00Thanks for that, Bob. I guess I have a "chic...Thanks for that, Bob. I guess I have a "chicken or the egg" situation. If I had a blade with a true 8" radius, then I could use that to create the sharpening block. And if I had a block with the right concave curve, I could use that to shape the iron. I don't have any kind of grinder, so I have to shape the iron very roughly with mill files and sandpaper. So if I can make a block at least close to the right shape, that will help me sharpen the iron to the proper curvature.Tiny Shop Woodworkshttps://www.blogger.com/profile/10375332433853904113noreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-32001840516289774832016-04-24T09:06:20.613-07:002016-04-24T09:06:20.613-07:00And as you discovered the hard way, the profile va...And as you discovered the hard way, the profile varied with small changes in angles.<br />That's why traditionally, carvers used the actual tool (gouges etc) to cut a piece of wood with the required profile as a honing or stropping block.<br />If you do if free hand, the trick would be to replicate that angle for a best fit. If you use a jig, record the required setting. Or simply with the iron still on the plane, gently rub it backward.<br />Easy, don't want to create a back bevel, just kiss the blade to keep the edge fresh by removing the inevitable small fractures at the edge. Not sure if I wrote that clearly but you get the gist?<br /><br />Bob, the old carver Valley Woodworkerhttps://www.blogger.com/profile/07322487171914484954noreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-72455280819059946772016-04-23T18:08:29.816-07:002016-04-23T18:08:29.816-07:00If I had the proper radius on the scrub iron, then...If I had the proper radius on the scrub iron, then that would have been the way to go to make the hollow. But my blade had too tight a radius. But still, that would have been a good way to start making the hollow - not sure why I didn't think of that - maybe the iron was too dull.Tiny Shop Woodworkshttps://www.blogger.com/profile/10375332433853904113noreply@blogger.comtag:blogger.com,1999:blog-1321553715454450871.post-69048369744374367942016-04-23T02:42:31.383-07:002016-04-23T02:42:31.383-07:00Interesting post. This is something I want to do a...Interesting post. This is something I want to do also as I hate the figure 8 pattern of hand sharpening. Why not use the plane to 'plane' the hollow needed? I would do it in a jig like your 'ready to use pic'. I did good in geometry but not good enough to figure out this angle.Ralph Boumenothttps://www.blogger.com/profile/10606484453109932074noreply@blogger.com