Cutting Gains - How to Do It?

[AndrewT]

Well, I thought I was being really clever last weekend. I jury-rigged a fancy router jig to cut the 1-3/8" x 30" long gains on my lapstrake build. Worked like a charm for the garboard planks - which had a straight edge to work from.

Moving on the next pair of planks, my system worked okay for the gains at the aft ends of the plank, which had a fairly straight edge to work from. But the forward ends are another matter entirely. The curve at the forward ends of the planks prevents my fancy jig from working.

What I did was to clamp the plank upright, on edge. Then I clamped a straight piece of 2x material to the plank, flush with the top edge of the plank, just to give me a wider base to work from. Next, I clamped a piece of 1/4" cold-rolled steel to the (now 2-1/4" wide) top surface. I aligned the edge of the steel with the start (flush with the outside face of the plank) and end (flush with the inside edge of the plank) marks and clamped it into place.

Next it was a relatively simple process of running a bearing-guided straight bit along the edge of the steel to cut the sloping rabbets. As I said, this setup worked fine as long as the plank edge was straight (or nearly so).

All of this was necessary because I do not have a rabbet plane. Which brings me to the actual point of this rambling post: How do you people cut gains? Has anyone built the "gain-o-matic" jig and could share some photos? I think since it works by routing from the face of the plank, the curved edge wouldn't be a problem, but I can't find any decent photos of the thing and I don't have a copy of the book.

Any other clever ideas would be welcomed. I tried using a regular plane, but I'm going to tear up the plank, the plane, or something else out of sheer frustration if I continue down that road.

[Thad]

I've always used a rabbet plane, usually with lines drawn and a batten held to the inside line. Blocking the plank end up allows cutting gain to the end.

[AndrewT]

As mentioned, I do not own a rabbet plane. Unless the sell them at Hone Depot, I need another solution.

[Mrleft8]

Make a 30"+ long shingle looking ramp dealie that your router can ride on to give you your disappearing rabbet (gain). Screw or otherwise attach two rounded guide "buttons" to your router fence so that the far edge of your straight bit is 1 3/8" from the theoretical edge of your plank.... This may take some fussing if you're going for piano finish quality work. 1 3/8" is a pretty wide lap though..... How big is this boat?

[SMARTINSEN]

Make a 30"+ long shingle looking ramp dealie that your router can ride on to give you your disappearing rabbet (gain). Screw or otherwise attach two rounded guide "buttons" to your router fence so that the far edge of your straight bit is 1 3/8" from the theoretical edge of your plank.... This may take some fussing if you're going for piano finish quality work. 1 3/8" is a pretty wide lap though..... How big is this boat?

A variation of this method, more or less, is described in issue 186 of WB Magazine by Ellis Rowe, building the Simmons Sea Skiff. Page 37. He used a bearing guided cutter rather than a fence. You could always go for the digital download.

Where are you located? If you are within an easy drive of Easton, I would let you borrow a rabbet plane.

[TerryLL]

I've always used the low tech method. Mark the gain with a pencil, scribe the line with an Xacto knife, cut the gain with rabbet plane and chisel. Works well as long as your tools are wicked sharp.

[jalmberg]

As mentioned, I do not own a rabbet plane. Unless the sell them at Hone Depot, I need another solution.

I wrote a blog post about question when I reached the same point in my first build:

http://www.unlikelyboatbuilder.com/2.../symmetry.html

Bottom line: expend a little time to find a used rabbet plane. Believe it or not, they are as common as, well, rabbits!

[JimConlin]

I've only used a rabbet plane guided by a batten for cutting gains.


The main reason I've not even thought of getting fancier is that it would be a disaster to bugger up a plank that's already on the boat.
Another is that I'm not smart enough to figure out how to make a jig that rolls the right way.
The rabbet plane might be slow, but it's controllable.

[TerryLL]

I've only used a rabbet plane guided by a batten for cutting gains.


The main reason I've not even thought of getting fancier is that it would be a disaster to bugger up a plank that's already on the boat.
Another is that I'm not smart enough to figure out how to make a jig that rolls the right way.
The rabbet plane might be slow, but it's controllable.

That's the same rabbet plane I've got. But I lost that fancy box eons ago.

[Gib Etheridge]

Rabbet plane city...
http://www.ebay.com/sch/i.html?_from...All-Categories

[JimConlin]

That's the same rabbet plane I've got. But I lost that fancy box eons ago.

I don't have the box, either.
I lifted the pic from here: http://www.supertool.com/StanleyBG/stan11.htm

[Eric Hvalsoe]

Duplex rabbet plain with post and fence. Actually two of them, so I don't have to change fences from side to side working either end of the boat. A little pricey if you are a one off home builder. But geez, 1 3/8, as someone else asked, what size boat is this?

Routers are great, if I can do it with a router, I'll do it. A gain the size you're talking about
would get me thinking.

[AndrewT]

Sorry I've disappeared....been out in the workshop swearing a lot. But I finally got the gains cut. The "little shingle deal" was the answer. Took a bit of futzing, but since I only had two planks remaining - a total of four gains to cut - I was able to knock them all out yesterday. Cutting the curved ends took some doing, but I found that clamping the shingle ramp on one end and then pivoting it with the other while routing worked out okay.

The boat is a 15' flat-bottom skiff. First boat I've ever built. Plans were quite specific about the size of the gains, but from what I've gathered while looking for the solution, most folks cut smaller gains on both planks where they meet - one front, one back. My plans call for a single gain on one plank only, which maybe explains the difference? Plus, the planks are 11-1/4" wide - which probably explains more of the difference.

[Mrleft8]

Ah.... Yes. I would expect that a 3/4" lap would be plenty on a boat that size if both planks were lapped. Also makes for a stronger lap. The feather edge on a single lap joint can become very fragile.

[Eric Hvalsoe]

The very wide planks maybe sort of explains it, but that is still a mighty wide lap.
The small lapstrake boats I sometimes build, usually traditional cedar plank, utilize a 3/4" lap - I cut all the gain on one plank. It is not problem at all. I used to cut matching shiplaps, that is tiresome, and I think more likely to split. I always thought matching bevels were an interesting way to go with the gains as well.