JEM Watercraft

An amazing amount of advice in just a few post, all from one simple question! I LOVE how this works!

The "cut close but not quite" and finish with a belt sander and plane method sounds like the best way to go. Good for a single panel or a stack of panels.

I do have, or I had the router bit Mick suggested, but I'd need another one to try that method. I used that bit to trim the bottom to size when I built the Pirogue. Seems I tried to trim the whole thing, all the way around in one pass and did, only I got impatient and went a little too fast.

That was the day the garage suddenly filled with smoke.

I "cooked" the router bit, the smoke came from the last foot or so of the bottom panel, just as I finished. No real damage was done, but it was kind of scary for a minute or two.

Well, I know better, now.

I'm not sure if I'll get any cutting out done today or not. Since I have the ply (and then some,) and two sets of plans, I'll probably go ahead and loft up both the Freedom and Southwind. Once I get started drawing the pieces out, I'll likely keep going and get them both drawn and ready to cut, at the same time.

I won't be doing a "two boat build," but I think doing the drawing for both at the same time and maybe the cut-out for both makes sense to me. When I'm ready for the second build, I'll have a bit of a head start, just like I'd bought a kit.

Thanks for all this help! (Some of this should be copied over into the "Tips & Tricks section.)

Mike S.
Spring Hill, FL

Whilst still on the subject of measuring and cutting, I have an oblique question. Does anyone else use a metric measuring tape instead of one with English measure? I have one tape that has both systems, and find the metric is just a bit tighter on tolerances.

Thoughts?

WHATS METRIC
Ron
Is that sort of like metamusale

Kayak Jack wrote:Whilst still on the subject of measuring and cutting, I have an oblique question. Does anyone else use a metric measuring tape instead of one with English measure? I have one tape that has both systems, and find the metric is just a bit tighter on tolerances.

Thoughts?

A lot of builders prefer metric especially if they want to make some simple modifications.

JEM plans are precise to the 1/16" and 1mm. Now you are not expected to be able to draw and cut that tight for everything to fit together properly. But the precision is there so a builder can get as precise as they like to.

Kayak Jack wrote:
Whilst still on the subject of measuring and cutting, I have an oblique question. Does anyone else use a metric measuring tape instead of one with English measure? I have one tape that has both systems, and find the metric is just a bit tighter on tolerances

Most of the cheaper home hardware type tapes out here have both imperial (or standard) and metric on them. After ll these years using metric, I still hve to convert back to feet and inches to work out how big something is.

Having said that, as a check before I cut from Matt's plans, I measure and mark in standard, then check against the metric equivalent before I cut.

jem wrote:
JEM plans are precise to the 1/16" and 1mm. Now you are not expected to be able to draw and cut that tight for everything to fit together properly. But the precision is there so a builder can get as precise as they like to.

Thew have worked for me when I paid attention to the measurements. The only time they did not work was when I mis measured one panel and cut it. Not the plans fault , mine and mine alone since I realized the mistake and redid them everything fit like a hand in a glove.

You just have to do like the plans tell you and then recheck it a couple of times before cutting.

Chuck.

Mick,

Just a quick question about your router bit...... Is there any particular reason for using the bit with the bearing on top? or can a flush trim bit with the bearing on the bottom be used?
Obviously the 'Master' panel would need to be on the bottom of the stack...instead of it being on top with the bit your using.


Andrew

lark2004 wrote:Is there any particular reason for using the bit with the bearing on top? or can a flush trim bit with the bearing on the bottom be used?

With the bit with the bearing at the top of the cutter, it allows you to see what you are doing in relation to the template that you are trimming to. The template would be on the top of the stack. A bit with the bearing at the bottom of the cutter can be used, but you are cutting away material blind to where you are in relation to the template. The template would be at the bottom of the stack. You would just have to be MUCH more careful, but you could use one.

DM

Although I didn't ask that question, I sure do appreciate the answer! Thanks to Andrew for asking and DM for the answer.

Mike S.
Spring Hill, FL

G'day Andrew,

I agree with what Mouse has said.

Early in my experiments with these bits, i tried the one with the bearing on the bottom. It can be done but is much harder to do.

The bit with the bearing on top, properly called a Pattern Bit, is much easier. even so, you need to be very careful to keep the base of the router sitting squarely on the surface of your ply. Particularly so with the thinner ply for a pattern. Tilt the machine one way or the other and the bearing will miss the edge of the pattern and the bit chews into your panels very quickly. Having said that, it is not difficult to use. i would recommend some practise cuts on scrap before attacking the real thing. You will quickly see what I mean.

The extra time spent in panel alignment and set up is well worth it in time and effort savings. Once set up, it takes about 5 minutes to trim all matching panels to exactly the same shape and size. In the Laker hull panels, that means doing 4 panels at once.