Transferring lines between station molds?

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Grumple
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Location: Halifax, Nova Scotia

Transferring lines between station molds?

Post by Grumple »

Hey Guys,

I just had my first experience tracing station molds. I am trying to do it the way CanoeCraft suggests, using a batten, finish nails, carbon paper, etc.

After some discouraging initial batten tests (all snapped at turn of bilge for station 0), I switched to using a strip of plexiglass, which is working much better. However, the tracing process is beating up the plans a bit, and I'd really like to avoid tracing a mirror copy of each station mold.

As suggested in CanoeCraft, I'm thinking of tracing one copy of each mold, then cutting them out on a band saw with a second sheet of MDF pinned to the bottom such that I end up with an identical copy. Then as others have suggested I'll sand them while still pinned together to ensure each pair is the same.

Having said all that, does anyone have any clever suggestions for transferring the DWL, centerline, etc from the mold I originally traced onto the copy that was cut out with it? The best I can think of so far is to use the band saw to mark the start of the lines along mold edges while pinned together, then just draw lines connecting the marks on the second mold after the pair is sanded and taken apart. (ie the same method CanoeCraft suggested in order to transfer the lines on a given mold to it's back-side).

Does this make sense? Will the lines drawn from the saw cuts be accurate enough to avoid trouble? Any better ideas?

Based on my experience so far I think next time I will follow what some others seem to have done, and make a copy of the plans for each mold, glue them directly to the wood, then cut them out. I did make a backup copy of my plans before I started hacking apart/tracing the original, but I've noticed the fidelity in the copy isn't 100%, so I'm hesitant to use it.
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Jim Dodd
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Re: Transferring lines between station molds?

Post by Jim Dodd »

Hi Grumple

I used a set of French curves when I lofted plans. I believe it worked at least as good as if I would've tried battens of some sort. Battens can vary quite a bit depending on their flexibility.

The old adage of "there's more than one way to skin a cat", comes to play here.

I always drew my plans out on poster board. It seemed easier to trace, than the thin paper the plans usually are drawn on.

Good luck !

Jim
Keep your paddle wet and your seat dry!
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Cruiser
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Re: Transferring lines between station molds?

Post by Cruiser »

I pretty much followed CC for tracing the molds on my first project.

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This is a pic of the back side of the plans, and the carbon paper I used.

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And a pic of the flexible rulers I used in place of a batten. The carbon tracing is too light (my opinion), so I would use the flex ruler to get the exact shape and then make a darker line.

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This is just a close up of the darker lines and the short flex ruler, more or less shaped to make the line. Not sure if this is of much use to you, but I found it a lot easier to use those flex rulers for that part of the task.


Brian
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Grumple
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Location: Halifax, Nova Scotia

Re: Transferring lines between station molds?

Post by Grumple »

Thanks for the suggestions, guys. I can definitely see the advantage now in using thicker material! I'm probably tracing too hard, but finding that I'm cutting the through plans in the lines that get repeatedly traced for each mold.

Brian, my setup looks nearly identical to what you are doing except using a plexi-glass batten that I bend along its thickness instead of width. I do find I need to use pins/brads to hold the batten securly in place while I trace. The combination of retracing lines and poking holes with nails is quickly making for a rough looking sheet of paper plans...

I'm going to carry on for now, tracing one copy of each mold, and see how the band-saw trick work to create mirror copies.

Thanks!
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WMegl
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Re: Transferring lines between station molds?

Post by WMegl »

I also followed the CC instructions with no problems. I did use a CAD program to plot my points and then using 3 points at a time the computer found a best fit curve, but I did not use that curve. I only used if for reference. I used a batten and the points in the lofting tables for my final curve. My drawings were printed off a plotter onto mylar which is tough. I did experiment with battens making sure the grain structure was pretty smooth and uniform and I experimented with several thicknesses, the thinner the better, until I found one that worked well.

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