Wooden Boat People

By McKenzieDriftBoat.com

Trimming the hull to shape

Anyone have any good techniques for trimming the bottom to fit while keeping the side angle. Anyone ever build a jig to use a router? I have my hull curing in a vacuum bag as we speak. It is trimmed big so I can cut to final shape. There is a ton of Kevlar, biax, etc in it and it is not gonna trim easy. Hand sawing is out, plus I need to be really careful because the outside panels have no glass and I don't wanna gouge them up. I saw dorfs technique with the metal ski scraper and a fine tool. That looks good but I think with the Kevlar in the hull the fine tool might be underpowered. I don't have one either so that presents a problem. I like the idea of the high blade speed of the router. Just trying to figure out how I could use it and keep the side angle. Also since the boat is in the frame and ready to rock, I'd like to glue the hull down first and trim excess instead of precut ring where I could screw up and leave excess material air cut too much away. I love using a bearing bit and tracing to size. Anyone ever been successful doing this,

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Permalink Reply by chris towles on September 20, 2013 at 2:59pm

Guess I should also specify that this is a stitch and glue boat and will eventually get a radiused chine. Although all and any trimming techniques are welcome. Sometimes u need to improvise. Hoping to glue the bottom up to the sides which are on the frame now and use the router to trace to hull shape and cut thru all that glass high speed.

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Permalink Reply by Phillip Westendorf on September 20, 2013 at 4:50pm

Chris,

I get your concerns, so look into this as a possible solution.

If you have access to a router which handles 1/ 2 inch shanks consider buying a 1/2 dia shank tapered end mill. You can get them in HSS (High Speed Steel) or solid Carbide (bigger bucks). They are available in standard tapers from 1 degree to 45 degrees. The working end is 3/4 to 1" Long. Check this out.

http://www.use-enco.com/CGI/INPDFF?PMPAGE=161&PMITEM=327-1715

Another possibility is to purchase a router trimmer bit with a bearing on upper end. Amana Tool makes a 3 1/4 inch long with 1/2" dia shank, 3/8 working dia x 1" lg. working end. You'll need to make a tapered bushing to mount to the bottom surface of the router base with an angle to match the angle between the DB's bottom and sides.

I'am guessing that will be somewhere about 110-115 degrees. So the Bushings Inside Dia (ID) will have to be a few thousands of an inch greater than the bits bearing OD (a 1/2" drilled hole will do). You'll need to make the length of the bushing long enough to obtain the desired angle. Mount it on the base of the router and give it a go. I tried to make a sketch of the bushing. "C" is the centerline of the router base where the bit is exposed. Connect points "A-A" and then "B=B" to complete the drawing (well sketch). "D" is where the bearing would be mostly exposed with the working end fully exposed below "D".

A_______________ C __________________B

l l

A___l l____B

If you need a better explaination let me know and I can make a "Measured Drawing" (That's what Master Wood Worker Norm Abrams calls a detailed drawing).

Hope this helps you get closer to where you want to be. G'Luck

Dorf

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Permalink Reply by tungsten on September 21, 2013 at 8:19am

Won't Cutting glass and Kevlar with a high speed tool/blade will dull it right quickly.Even slowing it down will dull the bit I think.

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Permalink Reply by tungsten on September 21, 2013 at 8:37am

Never tried cutting Kevlar in epoxy but a jig saw can be beveled to match, and blades are cheap.You'll need a thin metal edge wrapped around your sides so the blade can follow.Go slow with a steady hand it should work.

I was wondering what was going on with your build,there's just not enough time in the summer for boat building eh?

good luck.

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Permalink Reply by chris towles on September 21, 2013 at 10:04am

Yeah . Fishing season is tough. I've prob taken over 50 trips out in the last 2 months. Plus I'm playing music pretty regularly.add to that a list of projects..Custom drybox and running boards for the bosses raft, fixing up the old trailer, and finishing pa speaker boxes with bedliner and tons of hardware , the garden, etc and there isn't much time left over for building. I also got to a point where the boat shape was not quite right and I needed to fix it, but I lost momentum and needed to step away. Got back to it last week with models first, then lofted the boat and seems like I got it right this time. I had cut the floor beginning of the summer but I waited to glass it to see if I needed to tweak the shape. Turns out I cut width with the final shape so I was good to go.

Got after the floor 2 days ago by myself. was a little too much work for 1 persons with all that glass. Was 4 hrs or so before I got it in the bag, then had a leaky bag and put a big hole trying to adjust the thru bag connector I did some emergency repair and got the bag to hold pressure but the pump pretty much ran constantly. I'm gonna go pull it out shortly, but when I went under the boat and looked up at the laminate I was evacuating some resin, probably not as much as if I had gotten the bag on quicker but oh well.

As to cutting..I've cut Kevlar boats a number of times usually with a grinder and cut off wheel, circular saw, or jigsaw. Most of thse were 6/7 glass/poly layups with kevlar as the innermost layer. i was cutting these boats at the seam line thru an additional 8 layers of 6 oz tape. thats 15 layers of glass poly and kevlar! Cuts easily with any of those but I am sure it dulls tools. Ill sacrifice a cheap router bit if it will give me a clean tight cut. My jigsaw cuts are always slightly wavy. I'm sure I could get really close to matching the profile of the sides on the frame, but I'm sure it would be slightly off. Really want to trace the sides exactly. I have a variety of bearing bits, most have shorts shafts tho. Angling the base which is what ill likely have to do will leave the bit too high up to cut. I have some roundover bits that might trim it close but honestly all I am worried about on the cut is that I cut thru all that glass and have a tight seam where the glass meets the top of the side panels. The core is easily sand able and shapable otherwise