SCARFING JIG FOR USE WITH ROUTER - HELP SOUGHT

Builder's Forum
1

Some years ago - three or four at least - I constructed from plans a S&G Ches 17, then a Shearwater 17, both turning out OK, for a beginner.   Other interests took me away, but I am now back and eager to take on another project, possibly a Shearwater 17 S&G with strip deck.   If well done, a kayak of this kind can be a work of art, and would be a source of much pride and pleasure to complete to - hopefully - a high standard.

 

I recall having seen here, long ago, some plans and/ or instructions for making a sort-of jig to use with a router in the making of scarf joints.   I've made scarfs previously with a hand plane, which wasn't too hard, but they never turned out quite the 100% that the perfectionist in me was seeking: I feel the jig approach may be the way to go.   Unless, of course, there's a better way!

 

I  would also appreciate some guidance as to the type of router bit that is used with the tool to make these scarf joints (a pic would be very helpful as some/ many brands available overseas may not be known here).   Thank you...

 

I have plenty of time to make-up the jig, as I don't plan to start actual craft construction until well after our (southern hemisphere) summer is over, say early second quarter of next year, but that will give me plenty of time to get materials and tools together and so on.   Here in Queensland, eastern Australia, it's simply too hot and too humid to work at this kind of task until then.

 

I'll be building the craft purely as a somewhat time-absorbing and challenging hobby/ recreational activity, with no intention of paddling it myself - I'd hope to be able eventually to sell it at my cost for someone else to enjoy on the water.   At age 74 I'm too old, stiff, and inflexible to be able to get in and out of a cockpit with any ease, and even lifting the craft onto the car top would  be a bit of a chore, but I don't mind in the least.   The construction will give me an interest, and I have plenty of time at my disposal to spend on the project, my main aim being to do an excllent job. 

I'm also looking forward to participating in this most excellent Forum again...

 

Thanks...

 

Lawrence of Suburbia

2

If you google " plywood scarfing jig, you will get lots of info. Also Woodhave tools makes jigs ready to buy with info on which bits to use. Good luck!

3

Thanks, Longboarder.   Woodhaven tools appear excellent - also pretty expensive - their router jigs range from $270 to over $400 - then I've got to get it here (to Oz).

The router bit recommended is about $40 - that's OK.

From memory, the device I saw here originally was similar in operation (a sliding frame that moved the router over the stacked-up ply), but it was made-up of some scrap ply, and by all accounts it worked OK.

But I might consider the Woodhaven item - after all, Santa's on his way, and I do want an excellent finish!

I appreciate your guidance.

 

L of S (formerly known as 'Wordsmith')

4

Here's a simple way to make scarf joints for strip building.

Overlap the ends of two strips by an inch or so and clamp them in-line together with a small spring clamp. Cut them together at any angle you want with a fine-toothed hand saw. Their ends should match perfectly in a scarf joint.

5

Try Guillemot scarfing jig of Scarfing Jig for Router .

6

Thank you both - but keep 'em coming!  

 

The Guillemot item appears very simple but looks effective - I think I'll make up that jig and try it out on some waste pieces I've got.   After all, the simpler the better so long as it works!

 

May need to buy a new router as the one I have is not the best - but the appropriate bit is readily available at a pretty good cost of around $30 for a quality Italian-made item... 

 

I'm also awaiting my new copy of the latest CLC catalogue to see what's available by way of designs, plans, and so on. 

 

L of S

7

West systems also makes an adapter for a circular saw; I have not used it though.

John

8

Hi Lawrence,

I made one of these for pennys. I simply took a 2" batton, cut it to 16" and then again on a diagonal to leave two 8:1 triangles. The one batton at the back about 6" long to join the short siides of the triangles and a longer one on the bottom (opposite hypotenuse) at the pointy end to act as the datum. I then clamped the ply to the edge of the table, a sheet of 12mm ply in my case, and ran the router up and down and moved he jig or slide the whole jig, and then moved the route either side to side or up and down. Either worked. I think if you can build a boat this should be a simple project to start you off? ;-)

I hope this helps.

 

Jan

9

   The ramp and flat bottom router method seems like it ought to work, but the reality is that thin kayak plywood curls quite a bit during the cuts, resulting in distorted or chunky scarfs. Machine scarfs really need to make the cut in one pass to avoid this- circular saw jigs can be effective, but prone to burning and tear out.

I've helped about 10 complete novice non-woodworkers build from plans in my shop, and using my sharp block plane each one has made great joints. It's just not that hard, and it's easy to practice. An entire boat's worth of scarfs will take maybe two hours the first time, one hour the second. Plus twenty minutes to sharpen your plane...

10

I made a scarf joint jig years ago for my hand planes. It was two fir 1x4s on edge parrellel with a 3rd 1x4 "ramp" between them.  One end of the ramp is pivitot mounted with dowel and set nail on one end.  Several dowel holes under the free end of the ramp raises or lowers the ramp to set the scarf joint angle. (I make them all the same)  Clamps hold the material in the jig and the jig to the bench. Moving the plane across the top two parrellel surfaces cuts the scarf angle in the piece(s). You can often cut two narrow pieces at the same time.  I have several hand planes but the red one with the electric cord gets used most. :-)   I would not use a router for a scarf joint myself.  

My last kit, of course, had CNC machine cut puzzle joints.

11

I haven't seen anyone mention my favorite scarfing method; power plane.

Setup the pieces in stair-step fashion at the right distance between steps, clamp together, run the plane down them until there is only a feather edge left, first taking more off and finishing with taking only 1/64" per pass. It is key that the pieces cannot move or flex when doing this. The final step is to eyeball the flat slope you made; it should look like one continuous flat piece.

You can do this with a hand plane, but it is soooo much more work, and very difficult with harder woods such as douglas fir vs pine or spruce. The power plane is equally effective no matter the species.