Friday, November 22, 2013

The 125-38SBP (Brute) Dissected, also "There's Grinding and then there's Grinding

I'm in the midst of completing a group of "Brute" shooting planes. I use the magnetic chuck of my surface grinder to hold parts during assembly. The chuck supplies the other two hands I generally need during this task. During the process I thought it might be interesting to snap a picture of a cross section of this plane.

This tool is bedded at a low angle of 38 degrees. It's a bevel down design so 38 degrees is the effective cutting angle. This configuration puts the bevel of the iron almost in a line with the cutting action of the plane. With a primary grind of 25 degrees and then a secondary bevel of 27 to 28 degrees it still has around 10 degrees of clearance angle. Plenty, but it does need to be maintained.

The threaded holes serving as assembly points will have taper pins interspersed between those locations when all the parts are in place. This creates a very accurate and rigid structure, for all practical purposes a metal torsion box. The taper pins go into reamed holes and fit zero clearance. When the pins are set with a hammer it creates what we used to call in the fabrication industry, "End of the World Stuff".

If I've performed my work correctly it goes together marvelously well and makes a well fitted assembly. For this to happen quite close tolerances have to be maintained on every part that makes up the assembly.

All the grinding of the interior surfaces has to be completed prior to assembly and then protected during subsequent operations.  Clean vises and not trapping chips between vise cauls and the interior of the plane body is something that requires close attention. Other wise it is possible to damage areas that are no longer accessible for further work. When the threaded assembly pins are in place, peined and the taper pins are installed, it's then time to refine the exterior surfaces. Of course one of the most important functional surfaces on any plane is the sole.

The components of this plane are made from so-called precision ground stock. It is supposedly flat to .001 over a distance of 12 inches. I find that it is rarely this accurate. What comes in as precision ground and what leaves my shop as precision ground are two entirely different versions.

While grinding a designated amount of material is removed per pass. This differs depending on the material being work. Most are surprised to know that harden material like plane irons are actually easier to grind than the annealed material that makes up the body of the plane.

 As you proceed with this work the material warms slightly and expands.  In a process that starts with material being removed by 5 tenths to 6 tenths of one thousandth per pass, the final passes will be in the 2 to 3 tenths range. The entire body of the plane is allowed to completely cool again to the ambient temperature of the shop prior to making the final passe. On the first of the two final passes material will almost always be removed at the toe and the heel and not in the center of the sole which has cooled and contracted. Only after these final passes do you achieve a sole that is in fact quite extremely flat. Not allowing the plane body to cool prior to the last passes will leave a slightly low area just before and aft of the mouth opening.

In function this would not allow you to achieve as fine a setting of the iron and would not hold the fibers as tightly for shearing at the front of the mouth. Note the tightly wound shavings, of end grain no less, in the above picture. A very sharp iron and the other mentioned factors come into play to create this result as well as a polished surface on the end of the 45 degree cut of the sample board.


Leon Redbone was performing in Savannah, Ga. and was accompanied by a gentleman playing the tuba. During a break between songs the tuba player turns to Leon and says "Leon the Invisible man is here", Leon replied, "tell him I can't see him right now!" 

Thursday, November 7, 2013

Desert Iron Wood

For some time now I've been interested in obtaining some Desert Iron Wood to use as totes and knobs and infills for my planes. My first attempts at purchasing this material didn't go well and I ended up with pieces with such obvious defects that I just didn't think they would be acceptable.

A couple of months ago I received an email from a supplier of this material advertising defect free bowl blanks. They were pricey but I knew the opportunity to obtain pieces this size defect free might be few and far between so I made a purchase.

When I received the blanks I was most pleased to find that one measured single digits in moisture content. A couple of weeks in my finishing kiln and it was ready to use. There was just one problem.

I've never turned a knob or shaped a tote from this material and the plane for which they were destined had to be ready for the recent Lie-Nielsen event at Woodcraft Atlanta.

Working unfamiliar materials with short time is not something that I approach lightly. Honestly I was excited to work this material and scared to death at the same time. If I invested a lot of time and then experienced a problem I wouldn't have sufficient time to recover. I finally decided nothing ventured, nothing gained and set about the work.

I began work on the rear tote early in the morning and finally applied the first coat of finish that night at 11:30. This material has a specific gravity of 1.20. I first thought that was a typo and it was more like Macassar Ebony which is 1.02. Nope, it's 1.20. I milled the blank with a fly cutter on the mill equipped with carbide inserts. The shavings coming off this material were shaped more like metal shavings than wood shavings. This stuff may well be harder than brass.

I do a certain amount of material excavation on a tote with power tools and I was thinking router tooling was going to be a problem, ironically the surfaces left behind by that tool were glassy smooth. When starting the hand tool removal of wood with a chisel I had envisioned having to pull up a new edge on my 1/2 chisel quite often. Once again this material surprised me. It actually got out of the way of a chisel fairly easily. However when I attempted to make the tight inside corner at the top the tote nice and sharp by cutting into the corner with the chisel I noticed this material kept fracturing right in the corner. I eventually had to resort to abrasives wrapped around the tight corner of a piece of brass to remedy this issue.

After all the fixing points were established and the final shape was attained with a varied selection of hand tools all the surfaces were final sanded up thru 1000 grit. When I flowed on the oil finish that night at 11:30 I was rewarded for my efforts. I've been to this point with a lot of different materials but the experience with this wood was something different and particularly special.

The  turning of the knob the next morning went quite well and in the end I actually had the plane completed with a day to spare.


Monday, November 4, 2013

Lie-Nielsen Hand Tool Event at WoodCraft Atlanta

Besides being a very well stocked woodworking store and having a well appointed shop adjacent to a state of the art teaching facility, WoodCraft Atlanta is a very friendly, welcoming place to visit. You can tell the customers that frequent this store are comfortable there. I don't know about you but I'm always going to migrate to the place where I feel comfortable and this weekend during the 2 days I spent in this store it was apparent the people that frequent this store feel the same.

I know when I walk thru the door Steve Quehl, Robert and the rest of the staff are going to welcome my presence and if it's your first time there they'll do the same for you.

I've participated in several events at this store and this weekend there was lots of activity.

Curtis and Tim were on hand from Lie-Nielsen demonstrating tools and answering questions. These guys are knowledgeable and charismatic about hand tool work. If you talk to Tim you may well learn a bit about lobster fishing as well.

The local SAPFM chapter members were there performing all kinds of interesting work. These members basically just bring in pieces or parts of pieces they have in process so people can observe them performing these task. It's pretty amazing and it's a learning experience as well. The tool chest below was made by a gentleman named Ken Kline and it is an amazing piece of work. He's brought this piece along to other events and I always discover something different about it every time I have the pleasure to see it.

The chair below is the work of Marion Smith. The details in both of these pieces is remarkable.

Several local turners were on hand during both days turning all kinds of different objects. With the holidays approaching Christmas tree ornaments seemed to be a popular item.

Bob Zajicek of Czeck Edge Tools was there with a full array of his offerings and Jon Fiant a local Work Bench Builder from Marietta was on hand talking to folks about workbench construction. The bench in front of them was made by Steve Quehl at the French Oak Roubo Project this summer. Bob and Jon were standing next to a piece of history.

There was also a bandsaw tune up clinic and a Saw Stop demonstration, and I was there as well showing some planes that I had just completed, but I was the one taking the pictures so you'll have to take my word for it.