Just saw the classified ad in Wooden Boat on a Puzzle Jig for scarfing plywood sheets together. Has anyone used this jig? I'm curious as to how well does it works. The company is www.fishbonesupply.com
Just saw the classified ad in Wooden Boat on a Puzzle Jig for scarfing plywood sheets together. Has anyone used this jig? I'm curious as to how well does it works. The company is www.fishbonesupply.com
A puzzle-joint scarf only exists because the the mechanics of cutting CNC plywood kits. It has no inherent advantage over a normal scarf joint. In fact, I'd argue that it's inferior. In most circumstances, I'd choose a Payson Butt or or Butt Block over a puzzle joint. I see no reason to do them in your home shop.
"It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (The Compleat Cruiser)
Ditto what David G said. That is an industrial convenience joint for mass-production and kits. A butt block or a Payson butt is even simpler and quicker to make if all you need is a low-end utility joint, but a proper scarph is better yet. With the router jig you're trading the satisfaction and pleasure of using a plane to make that structurally superior scarph joint in exchange for the dangerous commotion of whirling carbide and a second-rate shortcut. There's no joy in it, nor much craft.
I agree with what's been said and I'm really disappointed in the kit folks for adopting such a lousy way to join panels. At least one of them was doing some passable step scarfs a few years back. That struck me as barely acceptable compromise. I guess they're saving a few minutes of router time.
A well made scarf joint doesn't show too much if the grain lines sorta line up. A puzzle joint really calls attention to itself. Lots of ways to make the 8:1 slopes, I use a belt sander - no setup required.
I hate routers.
Perhaps someone could come up with a better design, like intertwining mermaids or something, but puzzle joints, at least of the CLC design are ugly, that is reason enough not to have them on your boat.
Absolutely agree with the responses. Puzzle joints make a boat scream "I was built from a kit!" and are weaker to boot. And now scratch builders want to imitate this cheap look???
While I'm no fan of visible puzzle joints under a bright finish, many such joints are obscured by paint, rendering aesthetics a moot point in many discussions. That leaves ease and economy of executing the joint as well as joint strength as relevant factors when deciding how to answer the scarf question.
To a scarf newbie, contemplating the process to plane or belt sand desired, uniform slopes presents some question as to speed and quality. Those who have employed these methods have the benefit of the experience to inform them as to efficiency and effectiveness. The scarf virgin, however, the aforementioned questions dancing in his head, might quickly gravitate to a puzzle joint jig because the speed and quality of operation would seem easier to imagine.
The nut of the foregoing is that to someone like me who faces scarfing for a SCAMP and two Kaholo stand-up paddle boards, I am tempted to go the puzzle joint jig route because I can better envision the process and the results. Furthermore, I am inclined to think, at least with wider joints, that a jig would enable quicker scarfing.
At this point, I am less concerned with enjoying the pleasures wielding a hand plane delivers or discovering that the process is easier and more effective than imagined. I'm looking to economize my scarfing time, so perhaps there is a unicorn out there who has both scarfed with a puzzle joint jig and without and could thus offer comparison observations.
As to joint strength, if glue surface area is what dictates strength of joint, I have to think there is negligible difference between an 8:1 joint and the Vickery puzzle joint jig. This is just a guess as I've not calculated the surface area achieved by the serpentine line cut by the jig.
I'm 50-50 on which way to proceed and would probably do well to stack up off cuts of some non-Okoume stuff and discover what I don't know. I still think there are some time efficiencies to be had going the jig route and would appreciate input.
Hi, my experience with scarphing joints is mostly with very thin 3mm ply. As has been stated already making the scarfs is simple and easy.
However, gluing the joint and aligning it properly is not always so easy. This is especially true when dealing with pieces that are no longer square; for example if you have cut the scarph and the outline of your panels prior to joining them.
it seems to me a puzzle joint could eliminate many of the problems I have had in the past.
They use proper scarph joints.
Puzzle joints in plywood are attempting to solve a problem that does not exist. They are used by CNC kit makers because a 3 axis CNC machine cannot cut a true scarf and the machine is able to cut puzzles easily. Rick's thoughts are typical of beginners but are wrong on most all counts. A puzzle joint is not as strong as a scarf and the glue area has nothing to do with it. A CNC step scarf is far better than the puzzle joint and is very close to a well made scarf in strength. The step scarf makes a nearly invisible joint and also provides its own registration which some novices have problems with. Its only disadvantage is that the edge is a bit fragile for handling and shipping but a little care solves that.
Like most such tasks, making a scarf joint requires that the builder must first quit worrying about the supposed difficulty and just get to work and make a couple to find that they are no big deal.
As Tom points out, most CNC machines are three axis machines. A fourth "C" axis would allow for the rotation of the cutting head and cutting of the bevel and hidden "puzzle" features to allow for self-aligning non-slip joints. They would, unfortunately still have the fragile edges.
Has anyone tacked that problem in terms of packaging the scarf ends? James? How do you folks package those?
"The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails."
-William A. Ward
I have great respect for those salts that have seen, done and then graciously guide the next man forward. This is not a rejection of the tried and true nor an unwillingness to forge ahead down the well-worn path. Our current state has presented us this new oddball joint and we would do well to understand if we can add it, if not to our personal joiner's pallets, than to the collective.
Expressions to the contrary, notwithstanding, my layman's brain has yet to intuit how a puzzle joint with nominally equal glue surface area to an 8:1 scarf is weaker. Does testing data exist?
The growing preponderance of kit boats will ensure that home built small craft containing puzzle joints will achieve parity if not eventually outnumber boats built with traditional scarfs. I can't imagine purveyors of kit boats are enterprising without some test lab numbers which show the puzzle joint is strong enough.
Is it too early, then, to agree that the puzzle joint appears to be strong enough? Furthermore, across a variety of joint widths, would it be wrong to say a puzzle joint jig offers a time efficiency over an 8:1 scarf achieved with a plane or belt sander?
Last edited by Thorviking; 08-27-2013 at 11:53 AM. Reason: Spelling
I agree that a puzzle joint is plenty strong enough for almost all joints need in building a small boat in plywood. The thing that sets it apart from a scarf is that the stress is not gradually transitioned across the joint. A scarf makes that gradual transition so that no hard point is introduced. A puzzle or any similar joint cannot do that. Maybe a person needs some knowledge of static stress to see that but its true nonetheless.
The point most here are trying to make is that it is not only ugly, it is a dead giveaway that the builder is afraid of doing a scarf. If that is the message a builder wants to send, all right, have at it. Some have said and it is absolutely true that if kit makers had not introduced the puzzle joint as a way to make joints that the machine could easily do, it would have never appeared. Making puzzle joints with saws or routers takes more time and involves more exacting work than making a scarf. If I need a quick and dirty plywood joint I use the Payson butt joint, especially if there is not enough material for other types.
You can lead a horse to water but he may not be thirsty.
Let's consider a hypothetical: A newbie to scarfing but not to using both hand and power tools is asked to scarf the ends of two sheets of 6mm marine ply to create one long sheet in the neighborhood of 16'. He is presented a sharp hand plane, a belt sander with a fresh belt of appropriate grit and all the tools and incidentals necessary to lay out, clamp, align, glue up, etc. an 8:1 scarf. He is also presented a router with appropriate bit and the Vickery puzzle joint jig recently advertised in the latest issue of Wooden Boat magazine as well as the necessities listed above (and, no, I have no financial or other interest in this or any other puzzle joint jig). He is shown what the joints look like and sent off on his own devices.
Would we fault this man if he chose to employ the router and jig? I wouldn't. If he's like me, he sees a more straight forward path in completing the task and gets right at it, taking care to align the jig so as to cut a puzzle joint yielding straight lines.
We then ask him to take an additional two sheets of ply and effect a traditional 8:1 scarf using a hand plane, and we have him repeat this using the belt sander. Would we be surprised if he takes a moment to sit in his thinking chair and stroke his chin to plot a course of action? Of course not. Even if he is then shown a pictorial sequence on effecting the joint, he is probably still thinking of the ways he can spoil accuracy.
Glue up also seems to be more straight forward for the jig method. In the case of flat sheets, it is only a matter of keeping the two sheets from separating laterally. For the 8:1 scarf, alignment concerns lie in all three planes, with joint surfaces perhaps still a niggling thought. Weights, cauls, clamps, jigs, in whatever combination--to keep the joint aligned and held together during glue curing--also must be brought to bear. More mental and physical/mechanical detritus to manage.
At the end of this man's scarf-fest, we ask him to share observations. We would expect him to say that cutting scarfs with a hand plane and a belt sander, as many in this forum can report, ended up being easier than he envisioned, but he had to cut these joints to be able to say that.
With the mystery of the unknown removed and fluency in all three approaches gained, would we think the man not right in the head if he reached for the puzzle joint jig for his next scarf?
In this day and age of emerging technology--knowledge sharing forums like this one, included--as well as increasing desire to spend time in satisfying ways, it should come as no surprise that our conversations often center around old versus new. "Just build the damn boat, already!" often gets said, I'm sure, in ones's mind when reading various threads, but let us stop and consider that the first time boat builder has more options to choose from, and thus more decisions to make. Furthermore, a guy who has been around the block a few times and rightly can vouch for what has worked for him might resist a new way to skin the cat because he doesn't need to. And so we parse and split hairs because we can and because there can be fun even in these endeavors. Perhaps we can also acknowledge that new traditions get their start every day and that the puzzle joint, like stitch and glue and epoxy before, has to clear the hurdles posed by natural bias before it is more widely embraced.
We all seek sufficiency, efficiency and rewards in what we set out to do. Maybe, as Bobby reports, a hand planed scarf is mighty efficient, but I don't think anyone is offering a side-by-side comparison so we don't yet know which way is faster.
Whatever advocacy I might be offering on behalf of the puzzle joint, it does not extend to defending it on aesthetics. As I wrote earlier, a coat of paint is enough to hide the sin. Furthermore, it is not a matter of being afraid to cut a scarf as it is well documented and understood that the joint is easy to effect.
I'm finding ways to like the jig and the joint for the reasons I offer in my previous posts, reasons that have existed only since I spied the Vickery jig advertised in the last edition of WB I received just last week.
Any project requires a plan and it strikes me that the universal questions surrounding the scarf joint (cutting, alignment, glue up) are answered for the first timer when he considers the jig approach, no small thing.
It's not obstinate to present the puzzle joint jig as a viable approach. I recognize the benefits of a hand cut scarf. I also now consider that the puzzle joint is strong enough for the conditions we find in building small craft (your point about stresses noted and appreciated). Yes, it is ugly and yes you can paint it away. If it doesn't offer time savings in cutting the joint, I would argue the puzzle joint makes alignment and glue up easier and faster. Concerns over accuracy are all but eliminated and, as I've shared, the novice can detour around the thinking involved and devote his attention elsewhere.
Rick, you are wildly overthinking this. Scarph joints are as easy to shape, (actually much faster when stack scarphing), align and glue as a puzzle joint. Scarphs are as strong as the wood itself. Take a short board and a long board and join them with a scarph joint then bend the panel at both ends. The board will break in the middle, not at the joint. This is because scarph joints are gluing long grain to long grain. Boards joined by puzzle joint will break at the joint. This is because a lot of the joint is short grain glued to short grain. Doesn't work so well. And this is also why all kit builders spec an extra layer of FG front and back on the joint, because they know that the joint is inherently weak. I now realize that the puzzle joint is aptly named because I'm puzzled as to why anyone would pick it over a scarph.
Just curious. Anyone know how much they want for their jig? I have yet to make my first scarf joint. I have only used a simple butt block joint which is not only ugly, but adds an extra piece which can get in the way of installing other parts. The video does make the process look easy but I'm guessing for the same cost you could probably buy a pretty nice and quiet hand plane which would find many other uses besides joining plywood together. If I had the jig, I personally wouldn't hesitate to use it but I'd also be tempted to build or buy a scarfing jig for a router or circular saw if I was going to buy one. Eventually I will grab a couple pieces of scrap plywood and just try doing the scarf joint myself. I'll bet with a small amount of practice I will get it good enough especially with thinner plywood. I'm sure it is one of those skills that looks harder to do than it actually is.
If you really want the puzzle joint jig, I say buy it and give it a try. It probably works good enough. One tip if you do get one. Let the router come to a stop or make sure you are away from the jig before you take it away. I ruined a dovetail jig by hitting it with a still spinning router bit.
Sea Dreams A.K.A. Brian
Trent in post #9 would seem to understand where I'm coming from. I'll attempt to clear up your puzzlement.
While I might be over-thinking this, let me throw out there that you might be under-thinking this, at least not considering a different perspective. You are considering the notion of scarfs from the perspective of one who has experience cutting them, giving little thought, perhaps, to what a newbie faces. I'm guessing a puzzle joint jig didn't exist when you cut your first scarf. The ease and effectiveness you've found in cutting scarfs by hand isn't directly known by those who have yet to cut a scarf.
As I describe in previous posts, the prospect of utilizing a puzzle joint jig clears up the questions I entertain when I consider the steps necessary for cutting and glue up. While a traditionally cut scarf is easy to effect, the newbie only knows this because he is told this. When he cuts the joint is when he knows this for himself. Until then, can he not appreciate the imagined ease and efficiency a jig can provide? The newbie isn't constrained by anything; the veteran might be constrained by what he knows, however effective it may be, and it may prohibit him from seeing the advantages a new pair of eyes see.
It's not that I'm seeking to avoid cutting scarfs in a traditional way. I started my avocational woodworking career building a dog sled when I was 15, effecting mortise and tenon joinery, steam bending and rawhide tied joints, pretty heady stuff for someone who had yet to build anything more advanced than a dog house. I can appreciate tradition and hand skills, but just like I switched from rawhide to nylon twine to build my next sled, I recognize that the march of technology can present new solutions that might prove advantageous.
We don't need to achieve bomb-proof scarfs for what we do in small craft, so there is a point where the added strength of one approach is of value only to those who care. A puzzle joint is plenty strong, as Tom says. I've already laid out my thoughts on aesthetics and other observations on speed, accuracy and convenience.
Us newbies aren't trying to ignore the tried and true. We see the utility of a hand cut scarf joint, just as we see that a new way to cut the joint offers advantages, too.
Try this with 2 scraps of 1/4" plywood. Pick the edges you want to scarf together and draw pencil lines 2" back, this will layout 8:1 scarfs. Line up one piece with the edge of the bench. If you are picky about the bench put a sacrificial scrap under piece #1. Line up piece #2 on the pencil line of piece #1. Clamp them both to the bench with whatever method work, one easy way is a couple of small finish nails. Take your plane and start working on the edge, the angle of the step will keep it lined up right. Your goal is a flat plane from the pencil line on the top piece to the edge of the bottom piece. The laminations of the plywood will guide you as you go.
The beauty of this is that if you get a 7.5:1 angle or a 9:1 angle it won't matter. Both pieces will be the same and they will match when you glue them together. If you try it once, you will see no need to invest in a guide which produces weaker joints.
Last edited by hokiefan; 08-27-2013 at 09:22 PM. Reason: correct measurement for pencil line
The Vickery jig will set you back $75 plus shipping.
I was inclined to consider the cost a worthy investment until Dusty's comment about the need to reinforce a puzzle joint with a layer of FG. I still think there are some advantages to be had, especially in the alignment and glue up phases, but now I'm reconsidering.
THIS SITE, an 8 to 1 scarf in 1/4" plywood is only 2" back.
I just tried a quick test scarf in 1/4" scrap plywood. I only went about an inch or so back but this was just a quick test anyway. I did it pretty much exactly how you instructed. I nailed the two pieces together on the edge on a bench. Then I ran a somewhat dull hand plane across the parts. I ripped a piece out of one piece but glued it up anyway. It looked better than I expected and wasn't nearly as hard as I imagined. With a little more care and perhaps a sander or even sanding block to finish it off, I think I could make a usable scarf joint pretty quick. Of course this was a short piece but it did give me a better idea of how to make a scarf joint. Thanks for the inspiration to finally give it a shot. If you have a couple scraps of 1/4" plywood, give it a try. Even if it doesn't work quite right, at least you will have gotten the experience and should have a better idea of what is involved with this simple process.
Sea Dreams A.K.A. Brian
There are two kinds of boaters: those who have run aground, and those who lie about it.
Last edited by Dusty Yevsky; 08-27-2013 at 09:27 PM.
Also I find that the one time I scarfed 1/4" material alignment and clamping is not difficult. I've only done a handful of scarfs with 3mm but so far I have always had imperfect alignment despite my best efforts.
I can get the joint square enough but there is either a small ridge or a small hollow at the edges of the joint - if that makes any sense.
Thicker material seems to be no problem, practice on some scrap is a good idea for beginners.
$75 seems steep, If you have a drill press and some patience, you could make your own puzzle joint jig.
I remember my first scarf joints. I was given the task of scarfing full 4x8 sheets of 3mm plywood which were eventually formed into a 40 foot sheet for a wing mast. The completed material had to be rolled into a hoop in order to join the next pieces since it would not fit in the shop. A much trickier task for a raw beginner than thicker and narrower material. I wasn't asked if I could do it, just asked to start work on it. If I ever decided to get a scarfing jig it would probably be a John Henry for a power planer or the Gougeon type for a Skil saw.
Last edited by Tom Lathrop; 08-27-2013 at 10:13 PM.
Where do you get the idea I'm resistant to cut scarfs?? I come to boat building ignorant of scarfing, but I know what a sharp plane is. I've spent perhaps 70 hours in two different workshops learning hand plane skills and hand cut dovetails from Rob Cosman. I built three dog sleds before I was 16. I've laid out and cut with hand tools one bent in a timber frame in a weeklong workshop. I've made traditional Northwest Coast Indian steam bent cedar boxes, just to touch on the high points of my history with sharp planes and hand tools. I'm certainly not resistant to cut a scarf.
I am resistant, however, to steering clear of a joint just because someone says its ugly or lacks sufficient strength or because it demonstrates what some might take as squeamishness in boat building. While I don't think anyone meant ill, a bit of condescension toward the puzzle joint and anyone who considers it seemed to be expressed by a handful, and I thought it in the interest of full vetting of the subject as well as my edification to parse these things.
In addition to having Tom declare the puzzle joint is plenty strong for its application, he helped me to see more fully the stress issues that go beyond glue surface area, so cheers to him.
And cheers to you for informing me that kit providers advise a layer of FG to reinforce the puzzle joint, something that would have escaped me as a plans builder for SCAMP and two Kaholo SUPs. If you read back you can see my potential enthusiasm for the home made puzzle joint begin to wane when I learned the perceived speed of joint execution would be slowed by this step.
And double cheers to Bobby, who in addition to providing a recipe to cut a scarf, one I am already familiar with yet grateful to receive again from a generous thread participant, helped clinch my rejection of the home made puzzle joint. Bobby pointed out the "hard spots" an FG reinforced puzzle joint creates which inhibits achieving fair curves.
Perhaps we can all thank Bobby for providing what I think is probably the only rational reason to avoid home made puzzle joints--because they inhibit fair curves.
After reading Tom's last post, #32, I can see I could use to continue beating back misperceptions. In essence, I was challenging the claims the puzzle joint was insufficiently strong, it is ugly and only weak-in-the-knees boat builders would resort to using it.
Again, it is strong enough, as Tom admits and countless kit makers imply.
The joint is ugly. Yes, it is, but what's your point? It can be painted. I would not resort to a puzzle joint for bright work.
I wasn't exhibiting resistance to cutting a scarf by plane or belt sander, I was, as a 50 year old with plenty of non-boat building woodworking experience, challenging the apparent orthodoxy. I was making what I think was a compelling argument in the interest of speed and convenience to effect longer pieces of plywood, and instead of having my assertions challenged I am declared incorrigible and resistant to adopting "best practices."
There is no skill involved in cutting a scarf, as is admitted in so many words by everyone who invites the newbie to try, so this idea that anyone who picks up a puzzle joint jig is to be shamed for doing so is rubbish.
Again, Bobby deserves a round of cheers for providing the imminently rational reason to avoid the home made puzzle joint--it creates unfair curves. We might do well to tell the next newbie considering the purchase of a puzzle joint jig this rather than convey arguably specious claims, eye-of-the-beholder aesthetic sensibilities and what translates as personal insult.