Scarf Cutting Jig Part 3 Testing

Today was the day... the jig was built and equipped with a laminate trimmer. It was ready to go.

I did a test cut and made a minor error that resulted in a tear-out right at the end of the piece I was cutting. The minor error was setting the router bit too deep. I made the adjustment and cut another piece. It turned out pretty well. Cutting the second piece went smoother than the first two (what's that about practice?).

I matched the two cut surfaces and, without glue, they looked pretty good. Time for the true test - gluing the joint together. A couple of C-clamps and two pieces of lumber worked to hold the glued joint in place while the glue set. One problem I've read about is that the pieces being glued can slip out of alignment. I decided if I sandwiched the pieces being glued between two other pieces and clamped everything together I could minimize that slip.

Here is the end result:



It isn't perfect but for the first attempt I think it is very good. The camera seems to hide the small imperfections. All in all, I am very pleased with the results. I am now confident I can create the lengths of wood needed to make the gunwales, gunwale caps, inwales, and skids.

The Scarf Cutting Jig - Part 2

Yesterday the jig was pretty much cut, assembled and ready to be put to work. There was just one thing missing - the cutting tool!

The jig I patterned mine after was designed for a full size router. I don't have one of those but I have been looking at them at Home Depot and Lowe's. Next to the routers I've seen laminate trimmers - essentially light duty routers. After a bit of research I decided a laminate trimmer would be effective for making the scarf cuts in the western red cedar I am using for the gunwales and inwales on the boat.

Today when I was out running errands I went past Harbor Freight and decided to stop there to see what they offer for routers or laminate trimmers. I was pleasantly surprised to find a decent looking laminate trimmer on sale for $21. Yes, this is Harbor Freight and, yes, they are notorious for cheap tools that do not last forever. But, I thought, $21 is a lot less than the $80 (minimum) for a similar tool at the big box stores. So, living on the edge, I bought the trimmer.

Here is the Scarf Cutting Jig complete with the laminate trimmer.



I will make the first test cuts tomorrow after work (It is Sunday late afternoon and I'd rather not disturb the neighbors' quiet weekend). I suspect I will have to make some adjustments to get the jig tuned to make accurate cuts for good straight joints.

The Scarf Cutting Jig

My variation of the scarf cutting jig is pretty much done! A little bit of cutting here, a little bit of gluing there, and after a few nights I have a completed tool ready (almost) to go to work!



and from another perspective:



My variation is narrower than the jig that inspired this effort. See Projects List

The piece of wood to be cut is clamped into the jig,



A router or laminate trimmer, fitted with a 3/4" straight bit, will sit on the carriage (the piece sitting on top of the base). The router will be pushed across the piece being cut, the carriage is moved (about 3/4") down the base, and another cut is made. These steps are repeated until the full scarf is cut. The slope of the base is 8:1, so to cut a scarf in a 3/4" thick piece of wood, 8 cuts will have to be made. (This is much easier for me to see in my mind's eye than to describe in writing!)

It occurs to me as I write this I still haven't clearly described a scarf joint. So let me try...

If you need a longer piece of wood than what is available it is possible to glue two (or more) pieced together to obtain the needed length. Gluing two pieces of 2 x 4 end to end might work, but it would be a very weak joint - if it held at all. One way to improve the strength of a glued joint is to increase the mating surfaces being glued. Another way is to reduce the angle at which the mating surfaces come together. A scarf joint is one way to achieve larger surface area and reduce the angle. Here is what a finished scarf joint should look like:



That is what I am trying to achieve with the jig, and as soon as I purchase a router or laminate trimmer (watching a couple on eBay now) I will begin testing the jig. I suspect I will have to tweak it a bit to improve the accuracy of the cuts - the more accurate the cuts the better the joints will be.

Another Two Weeks? How did that happen?

I knew time has been slipping by and that I have not been keeping the blog up to date. On the other hand I did not think I had done much worth reporting. I mean, how many times can I report on sanding the rudder or shaping the centerboard? These are tasks that are necessary but take time and are not glamorous. So, this morning when I decided I wanted to report on what I've been up to, I was surprised to see I have been pretty busy after all.

Stanley #5 Jack Plane: Two weeks ago I took the plane apart and, as reported, it was a mess! I bought mineral spirits, steel wool, and a big-enough plastic bin. I soaked the parts in the mineral spirits and scrubbed everything with the steel wool. Remarkably, the dirt and grime washed away and I was left with collection of rusted parts. The Dremel tool fitted with an "abrasive finishing buffer" (think Scotch-brite like material) removed much of the rust from plane body. I was left with a reasonably clean plane in need of paint. But I am not interested in refurbishing the tool to "like-new" condition, so I am satisfied with its appearance for now.

The sole of the plane was rusted and in dire need of flattening. I purchased some 1/2" ply, a piece of acrylic (glass would be better but I haven't found what I need just yet), and some bits and pieces (i.e., a 2 x 2, some glue, duct tape) to fabricate a platform to insert into the WorkMate to sand the sole of the plane.

Once the rust was removed I squiggled a reference line on the sole with a permanent marker. As I continued to sand the sole, the reference line would be sanded away - but whatever part of the reference line remained would indicate low spots. Once the line disappeared the sole would be flat. I was surprised how quickly the sole cleaned up.

Honing and sharpening the iron (blade) looked like it would be more work than it was worth. The back of the iron was pitted and the cutting edge did not look very good. I was seriously considering buying a new iron but decided to ask for opinions before spending the money. The advice was, "If you feel like spending $35 on a new iron, go ahead but the pitting is common on old irons and the edge just needs to be worked a bit." So, I flattened the back of the iron (sanded it smooth) and decided to purchase a honing guide to hold the iron at a constant angle (important and necessary).



I am happy to report the jack plane has been cleaned, sharpened, reassembled and put to work! And it works beautifully!

Centerboard: The centerboard blank was laminated (reported on two weeks ago). The lessons learned from the rudder project helped smooth out and speed up the laminating process for the centerboard blank. Once the epoxy set up, I removed the clamps and began shaping the centerboard. That work continues but I must say the jack plane is making quicker work of it than the block plane. I am glad I have both tools (and according to a good friend, I need at least one more plane - a #4 smoothing plane).

Here is the centerboard cut to its profile shape (the emerging foil shape is not apparent in this picture).


Scarfing Jig: A previous report describes the need for a number of "scarfed" joints, and a relatively simple jig for cutting the pieces to be scarfed together. I have begun building the jig. A 2' x 2' piece of 3/4" plywood and some 3/4" square stock have been cut up and glued together to form the sides. 3/4" plywood will be cut for the cross pieces and ought to be glued up later today. I will pick up the materials (masoninte and some 3/4" stock) for the carriage later today, too. The Japaneese saw (see earlier reports) worked very well in making straight square cuts - better I think than I could have done with a powered jig saw. I am happy with that tool, too!

New Tools: I ordered a metric tape measure, some foam brushes, and some spring clamps last weekend. The tape and brushes were delivered on Thursday and I expect the clamps to arrive early next week.

While I understand that the metric system is more logical and should be easier to use than the imperial system, it is going to take some getting used to metrics. However, a simple calculation (multiple 5/8" by 6) using imperial measures turned out to be even easier in metrics (16mm x 6). I still think (and visualize) in terms of inches, so I need to work on that.

The 1" foam brushes are for working with epoxy and they are disposable. The best price I've found for them in a store is 40 cents apiece, but I paid 27 cents each (including shipping) for these.

The spring clamps will be useful for clamping the chine logs to the hull panels, framing to the bulkheads, and the gunwales, inwales, and inwale spacers (when the time comes!). Actually, I am planning to purchase the plywood for the hull panels and bulkheads soon. I can build the bulkheads here in the apartment.