Glen-L.com

I have been doing about 8/1 on my 3/8" thick sheets. The joint ended up in a pretty tight curve and has had no signs of trouble.

All of the pieces that I have scarfed and tested have broke outside of the joint. If you have some extra wood you can do some tests to see how comfortable you feel about it.

Will your joint be in a flatter area or in a curve?

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Jeremy

Hope is NOT a plan.

I'm guessing the joint will be in a flatter area between # 2 and # 4 frames on a Zip, about 6 feet forward of the transom.

I'm going to try and scarf the joints using a router and stepping in 3/4" increments. Three passes would be 2 1/4" inches which may be a good compromise. I can lay the sheets on my table saw and use the rip fence as a guide for the router. We'll see how successful I am at controlling the depth and accuracy of my routering.

Roberta

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Roberta
Built Zip "Oliver IV" and Super Spartan "Jimmy 70"

I would think you would be fine at 2 1/4" long.

I don't know if this applies to how you are doing it, but when I did my chines and sheers with a router, going one direction wanted to rip the feather edge while going the other way left it alone. Don't remember which way worked, but it made a difference for me.

Good luck.

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Jeremy

Hope is NOT a plan.

Depends on how the grain of the wood lies and what way the bit is rotating into it. Sharp bits help. I usually stick with carbide tipped bits because they hold their edge better. I have a good rabbiting bit and I will be experimenting and see if this works out. I'm using Joubert Okoume, so the wood should be fairly solid and I hope the bit cuts it smoothly. If not. I'll go the normal scarf or maybe butt joints.

Wish me luck

Roberta

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Roberta
Built Zip "Oliver IV" and Super Spartan "Jimmy 70"

Have a look at this jig... Should be fairly easy to set one up.

http://www.duckworksbbs.com/tools/scarfer/index.htm

S

Thanks, I saw that jig and it appears to be very nice. Just a little pricey for the limited use I would get.

Roberta

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Roberta
Built Zip "Oliver IV" and Super Spartan "Jimmy 70"

We used a router with a wide base and 3/4" face-cutting bit to scarf the 1/4" ply for our Zip. We staggered the sheets and placed blocks at either end of the area to be scarfed, to get the required angle. Any machinists out there would recognize these as sine blocks. Getting the 12:1 ratio was not a problem, but the ply has to be clamped down to an absolutely flat surface to pull this off successfully.

-Mark Shipley

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A boat is just a wooden box with no right angles.

Hi Mark,

I'm assuming you did a flush angle for your scarf. I was thinking of doing a stepped scarf joint and avoid the angle, just plowing out 3/4" wide steps, about one fourth thickness each) and mating the pieces that way. I'm not sure how accurate I can be to get a neat joint or if the wood will tear out too much to get a neat joint, but I will experiment with some scrap and see if it looks doable. I'm hoping using my table saw and a rip fence for a guide will be good enough to accomplish this. I will be limiting my scarfing to 30" wide boards max. I'll let everyone know how it works (or doesn't).

Roberta

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Roberta
Built Zip "Oliver IV" and Super Spartan "Jimmy 70"

We tried several scarfing jigs but found that the radial arm saw produced very nice scarfs in record time.

To scarf 4'x8' panels on the width, we temporarily fastened a sheet of 3/4" plywood to the saw's apron. A guide strip is clamped to the stock to be scarfed. The strip runs along the leading edge of the temporary apron and keeps the stock aligned to the saw's fence.







Click here to see more photos.

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Paul Kane Chelsea, PQ

Building the Glen-L Hot Rod : http://www.boats.chelseacoachworks.com

Sorry for returning late to this thread. Roberta, scarfing plywood via a series of steps will create one or more stress risers in your joint. Maybe this will be a problem, maybe not. The gradual taper will be the superior joint. We did some bending tests using the offcuts from our planking, and they always broke outside the joint. If you decide to make a stepped joint, I would be tempted to back it up with a butt block. Just my two cents.

We had some tearing out of the plywood (Douglas fir) using a 3/4" carbide face-cutting bit. We found that we could minimize this by taking very light cuts (1/16") and moving the router in a circular motion rather than in a series of passes. Having a really sharp bit is a plus and I wouldn't even bother with high-speed steel bits. Even the cheap Chinese carbide bits do an outstanding job.

-Mark Shipley

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A boat is just a wooden box with no right angles.

Definetely stay away from the high speed steel bits. Had one years ago and it dulled in about 3 seconds. Been buying carbide ever since. I haven't done any scarfing yet and plan to do a test piece to see if it works out.

Thanks,

Roberta

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Roberta
Built Zip "Oliver IV" and Super Spartan "Jimmy 70"

The glues used in plywood can be abrasive and dull HSS bits quickly. One final note regarding scarfing with a router: make sure everything--bench top, plywood, sine bars--are "uber-flat" before proceeding.

-Mark Shipley

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A boat is just a wooden box with no right angles.

Another site...
http://www.oneoceankayaks.com/stitchglu ... rfjig2.htm

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THE FRAUD WILL NOT GO AWAY..9-11 WAS AN INSIDE JOB...
http://www.youtube.com/watch?v=hZEvA8BCoBw

http://s147.photobucket.com/albums/r302 ... rd_photos/