Laminating Shellback Stem

[timClement]

Hi,

I'm trying to get started on a Shellback dinghy. The plans call for the stem to be laminated from 1/8" mahohany veneer, which I'm having trouble finding. I'm thinking of just getting a 2" thick board and ripping the strips, but the lumber yard nearby can only rip to 1/4". Will this bend well enough to laminate the stem? Would there be any more spring-back with thicker laminations? Any other thoughts/concerns?

Thanks,

Tim

[On Vacation]

You will need to have clear grain lumber for this thickness, if it is coming from the lumberyard. Trying to rip 1/8" inch strips is very difficult. Find a local cabinet shop that will help you on this project. Rip the strips a rough 1/4" and then take them to a cabinet shop. Most better ones will have a drum sander. They will need to run them on top of a board, somewhere around 3/4" the same length as your strips. Sand them to a uniform thickness for this job.

[ 12-23-2002, 10:09 PM: Message edited by: Oyster ]

[Paul Scheuer]

Well, Tim. How much more of an excuse do you need to buy a band saw ? ;)

Actually, you should be able to laminate the stem with 1/4 inch slats, with no problems. Try a piece dry, if it snaps, plan on steam. There are several good threads below that will provide more guidance than you will ever need.

[Bayboat]

Mahogany doesn't steam-bend all that well. A good alternative is to laminate with clear white oak strips and resorcinol. You'll have no trouble with bending 1/4" oak as long as it's clear and without excessive grain runout. Ash would work well, too.

[capt jake]

I spose it all depends on the radius of the bend, but I have been able to laminate 1/4" Mohagany with no problems. Just pull it up slow and even. smile.gif

[EdenRose]

I laminated my curved dory stem out of fir using
my table saw to rip the strips down. If you have access to a decent table saw with a nice blade you should be able to get the strips you need.
1/8" is VERY bendy. 1/4" might work depending on the wood. Pre bend the shape for a day before
laminating and you will have to fight the pieces less once they are glued and slimey and want to move around.

[capt jake]

Aye how true!!, I can cut 1/8" on the table saw, though it is tricky. But I am rather radicle when it comes to that. Zero clearance inserts! Cut them fat and plane or sand them down. I use a planer meself!! smile.gif

[Ross Faneuf]

If you have any kind of table saw you can do this job quite easily. Please don't get frightened of this job, laminations are quite forgiving.

The stock doesn't have to be perfect and clear - just good enough to make sure the pieces you rip don't twist, hook, or ripple, and that the stock is not sub-par on strength. Well-done laminations (i.e. don't stint the epoxy) are better than the individual pieces they are made of.

According to the formula I usually use, somewhere around 3/16" will work fine for this stem (it certainly worked fine for the Pooduck Skiff stem that I made, which is nearly identical). You can probably get away with 1/4, but the clamping forces will begin to get high, and the amount of spring-back may be excessive.

The pieces don't have to be PERFECTLY machined; They shouldn't vary significantly in thickness, (like 1/16"), but .01-.02 is OK. They don't have to be dead smooth. 3/16 is much easier to rip safely than 1/4; using a zero-clearance insert (as mentioned earlier) is a very good idea. If you can't manage ripping a narrow piece against the fence, take it off the outside, so that the waste piece is 3/16", and you move the fence for each successive piece. This will make it harder to get exactly the same thickness on each piece, and the surface may be poorer, but you can try it if you don't like working real close to the fence.

Just make sure you have some extra material - I use pieces 1/2" wider than the finished piece for this kind of lamination. I don't lay the pieces up the way they came of the stock piece - I end for end and flip them (giving 4 different orientations relative to where they were in the stock) so that faults, grain etc don't line up, and thus cancel each other out. And I use LOTS of epoxy to make sure there are no voids - about 100% more than ends up in the finished piece. It's messy, but it all disappears when the piece is cleaned up.

Once the lamination is set, I remove the worst excess expoxy droozle with a Surform. I typically clean up the edges roughly with a power plane, the curved faces with a compass plane. With a roughly flat surface on the edges established, you can get it real nice by running it through your table saw (if you like that sort of daring), a thicknessing sander, flatten on a jointer, or just use a hand plane. That what the 1/2" oversize stock is for - so there's enough waste to clean up well.

[Peter-Built]

Tim
This is slightly off topic but a word of caution. If you purchased a set of plans from the Wooden Boat Store, be cautious with their lines and measurements. For example on the full size template plan, you can pick up the layout of the Transom. Well on the plans I got, it wasn’t even symmetrical. Take tracing paper and trace out half the transom, then flop it over to see if the lines match up exactly. On the plans I purchased the lines were off by at least ¼ inch.

I would be very liberal with the measurements on the planking. Add at least ¼ or even ½” and then shape them to fit and trim to suit after the epoxy is set with each plank. Or make up a set using construction grade first to make sure you don’t end up with planking too narrow. It may have been just a bad set of plans but I found errors all through the plans. Perhaps Mr. White’s original plans were bang on but just check them over thoroughly before proceeding to be sure.

[Joe ( Cold Spring on Hudson )]

Oyster
.
Member # 5154
posted 12-23-2002 10:08 PM *** ** * * * **
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You will need to have clear grain lumber for this thickness, if it is coming from the lumberyard. Trying to rip 1/8" inch strips is very difficult. Find a local cabinet shop that will help you on this project. Rip the strips a rough 1/4" and then take them to a cabinet shop. Most better ones will have a drum sander. They will need to run them on top of a board, somewhere around 3/4" the same length as your strips. Sand them to a uniform thickness for this job.
Who cares :mad: