View Full Version : Scarfing with a router?

Jamaica Mike
01-13-2005, 05:50 PM
I have seen some drawings for a jig for router scarfing. Is there a commercial router scarfing bit and guide that can cut an 8 to 1 scarf in ply?

Prefer to spend my time building boats, not fixtures and tooling.



Dave Gray
01-13-2005, 06:01 PM
I thought half the fun was in building fixtures and tooling. :D

01-13-2005, 08:30 PM
You do not need an expensive router jig,I just mounted a long piece of fir to the bottom of my router.The plywood I was scarfing was 3/8 so I stair stepped it 4 inches apart then set the straight router bit to cut just a hair shallow of 3/8 of an inch, It worked great I will attempt to post pics. http://www.imagestation.com/album/pictures.html?id=2132231580&idx=3

Joe (SoCal)
01-13-2005, 08:36 PM


Bob Smalser
01-13-2005, 09:13 PM
Lotsa serious, expensive, first-time mistakes in boats that shoulda been gotten out of the way making cheapo fixtures, tooling, and shop stuff.

Bill Perkins
01-13-2005, 09:19 PM
That's really interesting .So you stack 4 sheets to cut 2 , the top and bottom ones just serving as guides ? I can see the guides could be just scraps of the ply , or plank planed to match in thickness .

I use a power plane freehand as close as I dare ( way wider blade than a router bit) ,then 60 or 80 grit belt sander ,then a bit of hand planeing .

[ 01-13-2005, 09:32 PM: Message edited by: Bill Perkins ]

01-13-2005, 09:37 PM
Scarfing is not difficult with a power plane and grinder. Go to http://www.boatbuilder.org/godzilliscarfing.htm and check it out.

01-13-2005, 09:39 PM
I use a power plane too, first rough cutting the scarfs, then using a power sander to finish. It is important to add an extra piece of wood to the bottom of the stack so you don't break off the feather edge of the last piece you are scarfing. Years ago a friend asked me how to scarf some wood (plywood?, can't remember), and I suggested a router and jig to guide it. Apparently he did it the way I had suggested and it worked. This was prior to my using a power plane and sander, which works great. And I actually NEVER did go the router route myself. Lowell p. Thomas, Naples, FL

Jamaica Mike
01-13-2005, 10:19 PM
Originally posted by Bob Smalser:
Lotsa serious, expensive, first-time mistakes in boats that shoulda been gotten out of the way making cheapo fixtures, tooling, and shop stuff.Bob:

Didn't say I didn't want to have them, just prefer to buy rather than make them. If I have to make a jig, then I will.

This will not be my first boat, so I have already made some of the dumbest mistakes...


01-13-2005, 11:06 PM
You can spend the money if you want but the router makes these joints flawless I doubt I could have slid a piece of paper between mine.You should take some scrap plywood and try the router.

01-14-2005, 12:34 AM
I bought the John Henry power planer attachment a few years ago and it is great....perfect scarfs every time. Nothing could be simpler...for material up to 3/8"

I must admit this router method is very simple and saves the investment of both a power planer and a scarffing attachment.

the price is not bad if you already own a power planer.


[ 01-14-2005, 12:42 AM: Message edited by: RodB ]

Bob Cleek
01-14-2005, 03:18 AM
Never could figure scarfing plywood. Seems like if you gotta scarf it, your going where God never meant wood to go.

Paul Fitzgerald
01-14-2005, 04:10 AM
Dont forget the West Scarffer. I've had one set up on an skill saw for the last 25 years, works fine every time. I had five 18 inch scarfs cut and glued in quarter inch ply in an hour last month. Just clean the cut with a block plane and perfect scarfs every time.
The only problem is setting the tool up on the saw, so I just leave it on an old one.

paul oman
01-14-2005, 08:14 AM
Cann't you just belt sand the edge of the plywood using the ply layers as guides to thickness and evenness of the 'sanding'?

Also don't you find the scarfed area is less 'bendy' than the surrounding plywood and that shows up in the hull curves/shapes?

paul oman
progressive epoxy polymers

01-14-2005, 11:34 AM
The scarf joints do affect the fairnes of the hull but if you are aware of it is not a problem and can easily be worked around. Whenever I stitch up a boat I check fairness prior to tabbing and first look at all the scarf joints and grind the high areas as needed.

01-14-2005, 12:22 PM
You can cut the scarfs at 12:1, too, which helps.

01-14-2005, 02:27 PM
dthorton, very interesting! and simple! I like it

I saw your boat in slide 1, is it a hunky dory? we want to know!



Paul Scheuer
01-14-2005, 07:37 PM
Any comment on a stepped scarf for plywood. It would seem to provide a neater looking joint, perhaps as strong and flexible as the original panel. The cuts might be a little trickier, but not impossible. I'd use a set of spacer blocks stacked up against the guide.

Note - I put a rectangular foot on my router for my first project, and never took it off.

Paul H
01-15-2005, 08:31 PM
Originally posted by Bob Cleek:
Never could figure scarfing plywood. Seems like if you gotta scarf it, your going where God never meant wood to go.But then we'd be limited to boats 8 feet long. Shorter pieces of wood have been scarged togther for boat work for many, many years.

As to a step scarf, it seems like a good idea to me. The feather edge of the ply sheet has no strength, sand you end up with a shorter, neater scarf.

01-17-2005, 05:00 PM
Stevenj, Thanks for the nice comments about my boat,This is my first boat building project,It is the glen L, Little Hunk.I just got through putting on the fiber glass during christmas.