Bruce McCrory
22-Jan-2004, 19:09
I am looking to Deardorff to be my first LF camera. Since it is wood and obviously second-hand, I tried to research as much as I could of repairs and maintenance. A few things struck discord in my experiences with wood. Caveat; this is not experience with cameras but the same principles apply.
Design/Construction.
The table is of scarfed end-grain glue joints (X-configuration). The idea is probably to balance wood longitudinal expansion in all directions of the horizontal plane. I notice that wood Canhams use the same configuration. Seasonal movement is the greatest in this direction. This concept is fine, if the grain is straight, from the same source piece, abutting, and matched faces.
Unfortunately, the weakest glue joint is end-grain butt joints. The scarf is better but still a butt joint. A better configuration would be lapped face and quarter grain attachment; finger joints, tongue-and-groove being two examples. I understand the tables can start to separate at the joints. I will be very critical of my camera's table.
From Ken Hough's web site, I find that all Deardorffs were built from mahogany (Swietenia, "new-world" presumed). For nothing more than by name, this wood is difficult to distinguish from its "copies", Luan (Philippine), and African Mahogany, neither of which have the desirable characteristics of spanish (new-world) mahogany. What makes it good wood? Stability, low differential of grain movement, and durability. It is highly regarded for boat building. Of Western Hemisphere woods, mahogany, cherry, and black walnut (Juglans) have low differential of expansion. That is, swelling and contraction are fairly evenly distributed throughout the grain structure. That is why these species are common materials in wood cameras.
From my jaunts through the web, I found discussion of repair times for Deardorffs. It is a noble thought, but seasoned wood is pretty close to its ultimate stability and won't change direction in such small pieces as you find on cameras by sitting on the same shelf for months. It needs to find a different climate in order to get ugly. Wood pieces ripped from large blocks, and strippings, may spring and twist if from reaction wood and from spiral grain. As pretty as it is, I don't want environmentally grain-figured wood (as opposed to cut-figure) on my machine. Fresh cut and un-seasoned, or poorly seasoned wood pose major warp concerns at this scale. I've never seen "green" mahogany in a lumber store.
Glue joints will cure between the shop and my house while in the careful hands of the delivery people, thankyou.
Finish. Of the three common construction species, only cherry would give me concern when not protected. The others make good fence posts when heartwood is used. They all should be protected, and on all surfaces. No paint is better than half painted. Wood is a moisture sponge. It expands when wetted, by humidity or other, and you know the rest.... A finish seals the surface.
Wisner has the right idea regarding finish material. "Look to the sea for your answer, oh seeker." Spar varnish is designed for wood boats. It is flexible yet tough and resists moisture penetration. Eventually, weather and sun break down this shell, but I don't plan to park my camera in the yard. Maybe, trip and send it into a river, but that is not a plan either. I'll just take precautions.
Maintenance. While in college I had a great opportunity to work on the summer estate of a college benefactor. Wife had the prettiest little mahogany Century ski boat. The town's ancient boat-builder refurbished it after several years of improper maintenance. Every day, I wiped all exposed surfaces with oil. Could have been Pledge furniture finish, I've forgotten. (hbm)
Design/Construction.
The table is of scarfed end-grain glue joints (X-configuration). The idea is probably to balance wood longitudinal expansion in all directions of the horizontal plane. I notice that wood Canhams use the same configuration. Seasonal movement is the greatest in this direction. This concept is fine, if the grain is straight, from the same source piece, abutting, and matched faces.
Unfortunately, the weakest glue joint is end-grain butt joints. The scarf is better but still a butt joint. A better configuration would be lapped face and quarter grain attachment; finger joints, tongue-and-groove being two examples. I understand the tables can start to separate at the joints. I will be very critical of my camera's table.
From Ken Hough's web site, I find that all Deardorffs were built from mahogany (Swietenia, "new-world" presumed). For nothing more than by name, this wood is difficult to distinguish from its "copies", Luan (Philippine), and African Mahogany, neither of which have the desirable characteristics of spanish (new-world) mahogany. What makes it good wood? Stability, low differential of grain movement, and durability. It is highly regarded for boat building. Of Western Hemisphere woods, mahogany, cherry, and black walnut (Juglans) have low differential of expansion. That is, swelling and contraction are fairly evenly distributed throughout the grain structure. That is why these species are common materials in wood cameras.
From my jaunts through the web, I found discussion of repair times for Deardorffs. It is a noble thought, but seasoned wood is pretty close to its ultimate stability and won't change direction in such small pieces as you find on cameras by sitting on the same shelf for months. It needs to find a different climate in order to get ugly. Wood pieces ripped from large blocks, and strippings, may spring and twist if from reaction wood and from spiral grain. As pretty as it is, I don't want environmentally grain-figured wood (as opposed to cut-figure) on my machine. Fresh cut and un-seasoned, or poorly seasoned wood pose major warp concerns at this scale. I've never seen "green" mahogany in a lumber store.
Glue joints will cure between the shop and my house while in the careful hands of the delivery people, thankyou.
Finish. Of the three common construction species, only cherry would give me concern when not protected. The others make good fence posts when heartwood is used. They all should be protected, and on all surfaces. No paint is better than half painted. Wood is a moisture sponge. It expands when wetted, by humidity or other, and you know the rest.... A finish seals the surface.
Wisner has the right idea regarding finish material. "Look to the sea for your answer, oh seeker." Spar varnish is designed for wood boats. It is flexible yet tough and resists moisture penetration. Eventually, weather and sun break down this shell, but I don't plan to park my camera in the yard. Maybe, trip and send it into a river, but that is not a plan either. I'll just take precautions.
Maintenance. While in college I had a great opportunity to work on the summer estate of a college benefactor. Wife had the prettiest little mahogany Century ski boat. The town's ancient boat-builder refurbished it after several years of improper maintenance. Every day, I wiped all exposed surfaces with oil. Could have been Pledge furniture finish, I've forgotten. (hbm)