Designer Posted February 1, 2004 Report Share Posted February 1, 2004 A couple of weeks ago while visiting Heritage Boatworks, where they are building my sport fisherman, they were planing 8' long scarfs in 1/2" ply in about 2 - 3 minutes using the John Henry scarfing jig. The quality was good and they were well satisfied with it. You would need to do a lot of scarfing to justify the cost though. Quote Link to comment Share on other sites More sharing options...
Greg Luckett Posted February 1, 2004 Report Share Posted February 1, 2004 Seems to me that Charlie is doing without the John Henry and getting the scarfs done in about 20 minutes, so why spend the bucks? Graham teachs scarfing using the non powered hand planes. I have several, but rarely use them anymore. I think I will skip the John Henry tool and start using my planes more. I also would like to attend a class somewhere on boat building. Maybe I can catch one at South Haven this year. What I would really like is to be able to drop by and visit, in person, six pack and coffee in hand, some of you folks on here. What a crew. Too bad we all live so far apart, but thankyou Frank for providing this forum!!! Quote Link to comment Share on other sites More sharing options...
Charlie Jones Posted February 1, 2004 Report Share Posted February 1, 2004 Yes Greg- full four foot panels here. I have a very heavy work table that sits next to my workbench. I screw the panels down on that , staggered the amount that the scarf is going to be. I've stacked 4 sheets with no problems at all. Knock off the most of the wood with the hand power plane (mine's an OLD Craftsman) then finish with SHARP smoothing planes and a LA block plane at the very end. I also have a redwood float like is used in concrete work that I staple a full sheet of sand paper onto- I use that as the very last step to make sure it's all flat- just a quick scrub across the length of the scarf. Wish I could remember what I called the post on scarfing with the step by step pics I posted. CRS I guess Quote Link to comment Share on other sites More sharing options...
Garry Posted February 1, 2004 Author Report Share Posted February 1, 2004 I thought about looking into jigs and such but this may be the only scarf that I ever make. And since I had no desire to finish it bright, I wasn't concerned about getting an exactly straight edge on the scarf. With the bonding strength of epoxy, especially with a little filler, I imagine that the scarf joint is actually stronger than the plywood itself. There will be plenty of fairing and sanding on the tape seams. So the additional fairing and sanding to correct any variations in the scarf joint will not be noticeable. Except for the mistake of using thin plastic that got sucked into the joint, my scarf joints came out great. I made my bevels using a belt sander with four sheets stacked and spaced to get the bevel angle needed. It was easy to use the glue lines as guides to keep the bevel straight. The sanding texture will provide excellent bite for the epoxy. The result was plenty good enough with very little variation in thickness. I don't think that the extra precision of a jig or planer etc. is worth it unless it helps you do a number of joints. Quote Link to comment Share on other sites More sharing options...
capt jake Posted February 1, 2004 Report Share Posted February 1, 2004 Greg, I haven't heard anything good about the West System jig. When I checked on scarfing a while back, nobody had a poositive comment on this jig. I have seen the other router set up before also. Thing is, you would need the smaller laminiate trimmer to minimize the weight tranfer on the end of the jig. A standard router would be cumbersome to use, not to mention the straight cutting bits take a wee bit of practice as they really want to bite in. They are realy designed for finish trimming, not removing a lot of stock. I have seen another jig where the router is place verticle on the jig, thus using the tip of a straight cutting bit. I am having a hard time with the photo file, i will e-mail it to you, maybe you can post it. Quote Link to comment Share on other sites More sharing options...
Tom Lathrop Posted February 1, 2004 Report Share Posted February 1, 2004 Wow, I expect that this amount of interest in scarfing means tha lots of begining builders are just a little apprehensive about the job. this explains all the interest in jigs of all sorts to take the worry out of it. My advice is to forget the jigs (especially the router ones) and just give it a try with a well tuned hand plane. When I first joined Graham's class about 15 years ago in a project to build a 20 foot trimaran for the World 1000 race, he gave me the job of scarfing up 5 sheets of 3mm ply on end to make the wing mast. I'd never done a scarf in plywood before and being ignorant of the possible pitfalls, just forged ahead. After a few hints from Graham, it turned out not to be any big deal even though the multiple sections had to be rolled up because there was not room enough to lay out a 40 foot sheet of ply, even in the school shop. We devised the jig that he wrote about above that, with a few modifications, is still in use today. I think his estimate of 100 scarfs is probably conservative. One neat thing about the screw/plank method of clamping is that it can be done on the boat if needed. I did this recently while finding the limit to which 6mm ply can be twisted in the sharp bow of the little speedboat I'm now building. One side literally exploded while being stressed beyond it's limits. After splicing in a new section, I backed up the plywood with temporary external stringers to prevent stress concentrations and it finally worked out just fine. Main thing is to just do it. Quote Link to comment Share on other sites More sharing options...
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