Mulberry Goblet

Mulberry Goblet

Long ago I acquired several tall round blanks that were sold for the purpose of making lidded boxes and that was my original intention for the wood. However, I found that the process, despite having a book about how to do it and having one in person lesson with my Dad, was more difficult than I had imagined. I put aside the idea of making lidded boxes for a while but still wanted to do something with the wood on hand, so I decided to experiment with a new shape. I have not been displeased with the result.2014-09-16 14.22.03

Lidded Boxes

Lidded boxes are popular turned item with both wood turners as well as those who admire turned objects. However, unlike pens and simple bowls, making a lidded box requires a fair amount of skill and practice due to the precise tool control required to a lid that fits tightly. My Dad took a multi-day course on making them from a professional wood turner in New England, so that gives you a sense of what is involved skill-wise. I have read a book on the process but I learned better with hands-on practice and a visual reference, especially for anything involving three dimensions.2014-09-16 14.22.28

Mulberry Basics and More

The common name Mulberry refers to trees of the Morus genus, within which there are 10-12 recognized name species, depending on which authority you consult. There is also hybridization occurring, especially between Red Mulberry, native to eastern North America, with a United States range from Maine to south Florida and west to southern South Dakota and White Mulberry, imported from China as an ornamental and as a food source for the, now failed, United States silkworm industry.  I obtained my Red Mulberry from a sawmill in Missouri. It was plainly identified as Red Mulberry. Mulberry is not a wood used for lumber purposes, although small quantities are used by wood turners for smaller objects. Because it is not typically harvested commercially, it can be more expensive than many other native North American woods. Most samples come from ornamental trees that have been removed for some reason. The fruitless varieties are popular shade trees although they do also grow wild in their native region.

2014-09-16 16.00.27Mulberry heartwood tends to be yellow-orange in appearance while the sapwood is white. The pores are small and tight and the grain may display a whirling figure or pattern, in part due to the relatively rapid growth of the tree. I grew up with three mulberry trees in the backyard but I do not know if they were of the red, white, or some other variety. Surprisingly, while mulberry grows quickly, the wood is quite hard in comparison to other woods. The Janka Hardness of mulberry is 7,470 Newtons (N). The Janka scale is a standardized scale of wood hardness and any given measure means relatively little except in comparison. Mulberry is harder than red oak, which measures in at 5,430 N and harder than white oak which measures 5,990 N. Mulberry is even harder than hard maple which measure 6,450 N, making Mulberry one of the hardest native North American woods. Certainly it is not the hardest wood commonly used by wood turners. That honor most likely lies with Lignum Vitae which measure a whopping 19,510 N! If details of this type interest you, the Wood Database has detailed information like it available for hundreds of species both common and rare. Mulberry is certainly hard enough to relatively quickly blunt turning tools, so resharpening will be frequently required, or the use of tools with replaceable carbide bits, such as the Easy Wood Tool line, is a faster and easier alternative.

Deformation During Drying

My piece of mulberry had been cut round while green and then coated in wax to slow drying. Instead of turning it green, I allowed it to dry over several years. Different woods will shrink and deform at different rates and to different degrees, and in the case of Mulberry, shrink is lower than in some other woods, but it did still change shape over time. 2014-09-16 15.54.54I tried to capture this with a photograph but it is hard to see. If one looks closely, you can see that the degree of wood loss necessary to round the portion of the piece that is horizontal to the grain is less than that lost on the portion of the wood across the grain. As the moisture moved faster out of the cross-grain areas, pressure was applied by the shrinking fibers which pulled the horizontal sections towards each other, resulting in a flattening effect on the round. My experience has been that this is always the case with slowly dried woods, especially notable in those turned round green and then slowly dried. The same effect would occur if the wood was turned green and not waxed, or left unwaxed originally, but the effect would likely be much more pronounced if dried quickly.

Turning Between Centers to Start

I often have a hard time placing my faceplate exactly center on a blank, especially a deformed blank. The threaded opening for my lathe is 1.25 – 8 so the opening in the face plate is relatively large making it hard to hold exactly center when attaching it. My first attempt, when placed on the lathe, was obviously off center and I didn’t want to lose as much wood as rounding in that position would require, so I tried a new approach. I placed the blanks between centers, which made it easy to position each end exactly on the marked center point. While it was still out of round, the required loss was greatly reduced and I intend to use this method in the future. I also easily found that the ends were no longer flat, so I shaved them down ever so slightly to achieve a flat surface. Because of the space required for the center bit, a nib of wood was left remaining that was about 1 inch or so, and when I went to attach the face plate again, I found that this served as an excellent means of holding the face plate very center while drilling it into the blank.

Additional Cuts

Once the divot was cut and the blank remounted, I was able to hollow out the goblet form using an Easy Wood Tool hollowing tool, after cutting out some of the wood with a Forstner bit. Cutting with the bit makes the process much easier, especially when going into end grain material on a hard wood. 2014-09-16 17.29.25Once the goblet was cut to about half of the overall length, I proceeded to mark measurements on the outside of the blank so be sure that I wouldn’t accidentally cut into the goblet hollow form and to be sure that adequate material was left for the foot. I then used the Easy Wood Tool Detailer as a parting tool to cut deep grooves on the marks as well as for removing some material to make the stem section. Then, the rounded nose of the Easy Wood Tool Finisher made the rest of the stem cutting very quick and easy.2014-09-16 17.31.02

End Grain Tearout Reduction

I had seen a video on reducing end grain tear out which emphasized that all cuts must be made in the direction of the grain of the wood. In this case, the cuts moved from bottom to top on the outside and from top to bottom on the inside. I was skeptical that this could make a difference at first, but it proved to be helpful. And, the closed pore nature and close grain of the mulberry, coupled with its hardness, made it quite easy to achieve a very nice clean cut finish even before sanding. I still followed my usual sanding routine but it was much quicker than it would be with a more open pored wood such as cherry or walnut.2014-09-16 18.36.29

Finish Application

After sanding I applied a coat of Odie’s Wax, let it set up for about an hour or so, and then buffed it out on the lathe with a cotton rag. The wax didn’t markedly change the color of the wood, but it did leave a nice smooth finish. I was nervous about remounting the piece in the Cole Jaws for finishing the bottom since I wasn’t confident in the compression strength of the hollowed goblet, but there were no complications or issues and the bottom finished nicely.

The Results

This piece represents several experiments with new materials and new techniques. I had never worked with mulberry wood before and I was curious about it. I don’t have a lot of the wood, but I do have a sizable slab from one of the trees from my childhood home that I have yet to work with. I now have a better sense of what to expect from it. I had also never attempted anything even remotely goblet shaped and I was pleased that I was able to figure out how to make the form and manage to produce it. I had also never tried exclusively cutting with the grain of the wood in an attempt to reduce end grain tear out, and I was pleased to discover that it seemed to make a noticeable difference. Finally, while I have used Odie’s Wax once before, it is still relatively new to me and I continue to be impressed with its performance on hard, closed pore, wood. While I wouldn’t drink or eat out of this goblet since I didn’t use a food safe wax finish, overall, I think the experiment was an excellent learning opportunity and a success in the end!