FS19 Mold/Stringer Alignment

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maro
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FS19 Mold/Stringer Alignment

Post by maro » Sat Aug 12, 2017 12:45 pm

Hello first time builder here! I'm in the process of building the FS19, I have the molds and stringer ready, setting up i noticed that for molds E and D the stringer sticks out about 3/8" and 1/8" respectively, while at molds F C and B it sits flush. I have measured a couple of time already and I'm pretty sure the cuts are good. Should I proceed with the build or am I doing something wrong? Thanks in advance!



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pee wee
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Re: FS19 Mold/Stringer Alignment

Post by pee wee » Sat Aug 12, 2017 1:43 pm

Is this a kit you're building or are you working from the plans? If you look at page A 314/10 you can see an illustration of how things should look, the stringer and mold edges meet. If you can post a photo of what you've got, it would help show the situation better. At any rate, if they aren't flush you may need to deepen the notch in the molds or shim the stringers up. That's after you've double checked the alignment of your baseline.
Hank

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Re: FS19 Mold/Stringer Alignment

Post by maro » Sat Aug 12, 2017 1:54 pm

From the plans, I'll take some photos when I get to the house, thing is the only way I can see to lower E and D is to lower F and B considerably. My concern is that shimming or deepening the notches may change the stringer's angle and also changing the transom angle

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Re: FS19 Mold/Stringer Alignment

Post by Jeff » Sat Aug 12, 2017 2:04 pm

Mari, please post photo's and wait for a response from Jacques unless another builder can give you specific guidance!! Jeff

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Re: FS19 Mold/Stringer Alignment

Post by Jeff » Sat Aug 12, 2017 2:08 pm

Sorry, I intended to write Maro!!! Jeff

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Re: FS19 Mold/Stringer Alignment

Post by bateau-webmaster » Sat Aug 12, 2017 2:15 pm

Maro,

Pictures are definitely going to be necessary for advice in the matter. It does sound like the notches on one side or the other may be too shallow. That being said it could be an alignment issue with the molds.
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Re: FS19 Mold/Stringer Alignment

Post by Browndog » Sat Aug 12, 2017 4:07 pm

Glad to see another FS 19 being built. I had a similar issue at the beginning of my build. Check out pages 4 & 5 of my build thread in Builder's Power Boats for pictures, a discussion, and my resolution.

Had another issue after flipping the boat hull with a bulkhead from the CNC kit that was too large. Not sure of the cause, but remedied it by trimming the bulkhead to the dimensions on the plans.

Jacques, Tom and others have stressed to me that fairness of the panels and squareness of the jig are most important and finessing the notches may be required to achieve both.

Good luck with your build.

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Re: FS19 Mold/Stringer Alignment

Post by maro » Sun Aug 13, 2017 3:19 pm

Well I'm back! I checked every measurement and I didn't notice that for molds B C D and F I had the length from baseline to jig 1/16 higher, I also lowered the notch at baseline on molds E and D by 1/8", this helped getting stringer at mold D flush, but at mold E it is still 3/16" over the mold. I verified that the jig is square and aligned I don't think it can get any better.This is the measurements i have for each mold.

Mold B Stringer is 1/8 below mold and is flush with the baseline

Mold C , Stringer is 1/4 below mold and flush with baseline

Mold D, Stringer is flush with mold and is flush with baseline

Mold E, Stringer is 3/16"" over mold and is flush with baseline

Mold F, Stringer is flush above and below

I didn't want to add an image of the plans because I don't know if it is permitted, but in the rendering of the jig it seems like the stringer doesn't sit flush at any of the molds but mold F, it looks like the stringer is above the mold at E and below the mold at D C and B, should I use those renderings as a guideline?
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Re: FS19 Mold/Stringer Alignment

Post by pee wee » Sun Aug 13, 2017 3:33 pm

A couple of guesses: your stringers weren't cut out accurately, or your molds weren't cut out exactly right, or your baseline is marked incorrectly (okay, that's three!). Maybe your mold spacing is off . . . (four!).

If it were me it would bug me enough to try and figure it out and correct it. You are very close and it may not matter if things are perfect, as the molds act as a form to encourage the plywood into shape so there is often a gap here and there. You want fairness of the panels, not lumps or dips, so getting it all perfect at this stage may not be critical . . . but it can't hurt and I wouldn't want to be the one to say "don't worry about it". Something is off and we don't understand what it is yet.
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Re: FS19 Mold/Stringer Alignment

Post by Browndog » Sun Aug 13, 2017 6:23 pm

Better to have the stringer a hair low than a hair high as the high point could create a hard spot or lump as PeeWee put it. Hank most likely identified the issue. You are very close.

The mold spacing may be a tad off. If you move mold E a very little bit that may correct the stringer height. I'd check the spacing again or mold height/notch depth. The other differences are slight enough that when you flip the hull, the thickness of the fiberglass cloth, the fillets and fiberglass tape will fill those small gaps.

Fairness of the panels on the mold is I believe the most important issue.

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