Puzzle Joint Jig

[[email protected]]

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

[David G]

Re: Puzzle Joint Jig

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.

[James McMullen]

Re: Puzzle Joint Jig

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.

[JimConlin]

Re: Puzzle Joint Jig

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.

[mcdenny]

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.

[SMARTINSEN]

Re: Puzzle Joint Jig

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.

[Dusty Yevsky]

Re: Puzzle Joint Jig

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???

[Thorviking]

Re: Puzzle Joint Jig

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.

Thanks,

Rick

[trent hink]

Re: Puzzle Joint Jig

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.

[Robert Meyer]

Re: Puzzle Joint Jig

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'm curious what type scarf joints your Emerald Marine Candlefish 16 outboard boat kits use?

[James McMullen]

Re: Puzzle Joint Jig

They use proper scarph joints.

[Tom Lathrop]

Re: Puzzle Joint Jig

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.

[Canoez]

Re: Puzzle Joint Jig

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?

[Thorviking]

Re: Puzzle Joint Jig

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.

Tom, while you speak a truth that there is nothing so effective in the quest of building a boat as getting out in the shop and building a boat, this is not merely a case of trepidation paralysis. I tell myself that for my next boat project I'll take my time, explore processes and widen my joiner's pallet. The three that lie in front of me, however, cry out just to be done, at least those operations, principally scarfing, that squat in my brain demanding attention and resolution.

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?

Rick

[hokiefan]

Re: Puzzle Joint Jig

Tom, while you speak a truth that there is nothing so effective in the quest of building a boat as getting out in the shop and building a boat, this is not merely a case of trepidation paralysis. I tell myself that for my next boat project I'll take my time, explore processes and widen my joiner's pallet. The three that lie in front of me, however, cry out just to be done, at least those operations, principally scarfing, that squat in my brain demanding attention and resolution.

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?

Rick

I can layout and cut a scarf in the time it takes you to set up the puzzle jig.

Find some scraps, sharpen your plane, and try it. It really is very easy.

Cheers,

Bobby