DaveH6
First experience with scarfing.
This photo depicts work in progress with multiple sheets of staggered plywood being tapered (scarfed 8:1 ratio) . The desired end result is for the lamination lines to be straight.
I spent about 24 hours scarfing about the same number of plywood edges. I spent too much time trying to achieve a level of unachievable perfection in the fit of the joints. I probably spent 12 hours scarfing stacked plywood to an adequate shape. But, inexperience and compulsive behavior made me take a hand plane to each panel's scarfed edge and fuss with it as I dry fitted and refitted it to the panel which it would be glued to. Another 12 hours of effort. With epoxy's gap filling capability, this was unnecessary and truly nutty behavior on my part. If I did these scarfs today I bet I could complete the job in about 8 hours.
Later, I discovered that some designers don't even require scarfing and instead prescribe butting the plywood together and running fiberglass tape over the seam. Having no experience with this approach, I wonder how a hard spot in the hull is avoided when cold molding the taped plywood panels.
In a Bluejacket hull, the scarfs in the bottom panels are eventually spanned by longitudinal bulkheads. The topside panel scarfs are spanned by cabinets, inwhales, ceilings, etc. so virtually all scarfs are spanned by structures adding substantial reinforcement. I took scrap plywood left over after cutting out a bottom panel and snapped a cosmetically lousy looking scarf over my knee. The scarf held and the wood snapped outside of the glue line. I, like many first time scarfers, let my mind build this task into a degree of difficulty totally out of touch with reality. It is simply not a big deal to create a strong scarf.
I speculate that the most stress my scarfed joints will ever experience was when I was whipping around the topside panels getting them positioned for wiring to the bottom panels.
I started off using a 30 year old Craftsman hand held electric planer to cut the stacked plywood edges to a rough tapered shape. The very nicked blades needed replacement but I choked when Sears wanted $40 for a set of two replacement blades. Off I go to Harbor Freight for an on sale $28 power planer along with two extra blades for $4. This planer worked beautifully on the scarfing, followed by a belt sander and tweaking via hand plane. Snicker if you must, but many HF tools meet my needs as a hobbyist. Besides, what other tool store will give you a free flashlight?
I understand that Chesapeake Light Craft in Annapolis, Md sells plywood panels with puzzle joints cut in the 4’ edges thus no scrafting labor required.
First experience with scarfing.
This photo depicts work in progress with multiple sheets of staggered plywood being tapered (scarfed 8:1 ratio) . The desired end result is for the lamination lines to be straight.
I spent about 24 hours scarfing about the same number of plywood edges. I spent too much time trying to achieve a level of unachievable perfection in the fit of the joints. I probably spent 12 hours scarfing stacked plywood to an adequate shape. But, inexperience and compulsive behavior made me take a hand plane to each panel's scarfed edge and fuss with it as I dry fitted and refitted it to the panel which it would be glued to. Another 12 hours of effort. With epoxy's gap filling capability, this was unnecessary and truly nutty behavior on my part. If I did these scarfs today I bet I could complete the job in about 8 hours.
Later, I discovered that some designers don't even require scarfing and instead prescribe butting the plywood together and running fiberglass tape over the seam. Having no experience with this approach, I wonder how a hard spot in the hull is avoided when cold molding the taped plywood panels.
In a Bluejacket hull, the scarfs in the bottom panels are eventually spanned by longitudinal bulkheads. The topside panel scarfs are spanned by cabinets, inwhales, ceilings, etc. so virtually all scarfs are spanned by structures adding substantial reinforcement. I took scrap plywood left over after cutting out a bottom panel and snapped a cosmetically lousy looking scarf over my knee. The scarf held and the wood snapped outside of the glue line. I, like many first time scarfers, let my mind build this task into a degree of difficulty totally out of touch with reality. It is simply not a big deal to create a strong scarf.
I speculate that the most stress my scarfed joints will ever experience was when I was whipping around the topside panels getting them positioned for wiring to the bottom panels.
I started off using a 30 year old Craftsman hand held electric planer to cut the stacked plywood edges to a rough tapered shape. The very nicked blades needed replacement but I choked when Sears wanted $40 for a set of two replacement blades. Off I go to Harbor Freight for an on sale $28 power planer along with two extra blades for $4. This planer worked beautifully on the scarfing, followed by a belt sander and tweaking via hand plane. Snicker if you must, but many HF tools meet my needs as a hobbyist. Besides, what other tool store will give you a free flashlight?
I understand that Chesapeake Light Craft in Annapolis, Md sells plywood panels with puzzle joints cut in the 4’ edges thus no scrafting labor required.