CS17 #375

[Tgabe]

Here is the new workshop for the build.

Plywood arrived and the first lines have been drawn. I am sure I will have questions along the way. Building the boat with my 16yr old son. He is pretty excited, as am I.

framing

slab poured, partial siding

finished.

[Dnjost]

I am very jealous of your building space 

[Tgabe]

I already have a question about the plans. There are two measurements on the side, aft (p.2) that indicate stringer location. one is 9 1/8 along the aft bulkhead and the other 8 7/8 at the stern. Are these measurements taken perpendicular to the straight edge or are they taken along the angled line of the bulkhead and back edge

?

[Designer]

The dimensions are perpendicular.

[Howard]

tgabe:

 

One of the easiest and accurate ways I've found to mark out these dimensions is by using a set of trammel points on a yardstick. The yardstick I use is an older Lufkin model that is no longer made, but it is equally as accurate as my tape measure. Any good stiff yardstick or strip of wood could be used. I have seen 3/4" square yardsticks in antique stores that would probably work very well. Generally, the yardstick is used to get the trammel points set approximately right, and I then fine tune them on an accurate, flat measurement of some type. Trammel points simply allow you to build what is essentially a large beam compass.

 

With the end point centered on a known reference starting point, you then simply swing an arc on your line. With a fine lead pencil, this is accurate, and in the case of bulkheads, etc. if you swing both sides at the same time, both sides are symmetrical, which is tough to do if you are trying to measure each side by itself with a tape. By swinging one side, then the other, the intersecting arcs form the points indicated on the plans. I then set a small brad nail at that point to reference my straight edge against. I can then draw an accurate line and my straight edge doesn't slide around or move on me and I with it pushed firmly against the brad nail, I no longer have to fiddle around making sure both ends are lined up where they should be.

 

Not sure if this is the best way to go about it (CNC cutter comes to mind), but lacking that, this is the best way I've come up with.

[Tgabe]

Howard,  thanks for the tip. I will order some trammel points. It makes sense.
  Side and bottom panels have been cut out except for straight edge which will be cut after joining. Bulkheads and transom will be next.

 

Having trouble attaching pictures but I will keep trying. 

[LennieG]

Howard-

I know this is a gem but I am not getting it yet. Will read it 10 times in next week. If we all get together at something like this years mess -about would love to see it live...

thanks

[Tgabe]

Here are a few pictures of the side and bottom panels stacked. Weighted down just to keep them flat.  Ping pong table makes a nice flat surface.

 

 

[LennieG]

Gentlemen, start your engines.....

looking like traction.....good luck

[Tgabe]

As a rookie, I have been nervous about using the epoxy for the first time.   I have read as much as I can about using epoxy and decided to do a practice butt join with some scrap plywood.  I  made the "sandwich" of board, plastic, glass tape, epoxy etc.

Used pure epoxy on the wood and glass tape, and filled the joint with a little thickened epoxy.  All in all it came out pretty good.  The seam is solid as rock.  I`m glad I did the practice run.  I learned that I use too much epoxy - it was pretty thick on there after hardening.  And, I need to do a better job of smoothing out the plastic film.  There were quite a few wrinkles in the solidified epoxy.  I also think I didn`t use enough pressure on the seam.  Instead of clamping, I used some weights (20lbs.) to hold it all down, but there were some voids or divits in the final epoxy - also could be due to using to much of the stuff.

 

So, I think I need less epoxy, and more pressure.  Any guidance here would be helpful.

[Miyot]

Just enough pressure to mate and hold the two parts together.  To much pressure can squeeze out most of the epoxy causing a weak joint.  Always use some kind of thickener, such as microfibers, when laminating or joining two parts where some gap filling is necessary.  Clean up good right after making your joint.  It is far easier to clean up before the epoxy hardens than after.  I'm sure some others will chime in with many good ideas on epoxy work.

[LennieG]

I think Miyot said it well. You need to see " squeeze out" coming out of all edges to know you had enough goo, but not more pressure than that..... The thickener also helps from keeping the goo from running too much....adds viscosity. Good luck.

[LennieG]

When you are filling the weave of the cloth you don't need to thicken the goo.

[PAR]

You'll use much less resin if you do thicken the weave filling coat(s). There are a few different types of fillers, some thicken (bulking agent) the goo, but it can still sag. Other materials offer strength (carbon, cotton flock, etc.) or some other feature (fire resistance, etc.) and silica is used to control viscosity. In most every thickened mixture, you'll use a little of a few different materials. For example, to fill a weave, I'll use balloons (for bulk), talc (to make it smooth and easier to sand) and silica (for viscosity control), so it stays where I put it. The amount of each is dependent on the task, with vertical and over head work requiring much more silica, than flat, hand down work.

[LennieG]

Paul-

when you say talc are you speaking of Walgreen's/CVS type talc powder?

 

Paul-

when you say talc are you speaking of Walgreen's/CVS type talc powder?

 

[PAR]

Well baby powder does have a few extra things in it, so you'll smell nice, but yep, that's the stuff.

[LennieG]

Excellent. My CB smells like coffee from the ground walnuts, and now my seats 

Like diapers. Perfect.

[PAR]

Thanks for filling my head with that visual reference . . .

[Tgabe]

Am I doing something wrong?  I have glued up two butt joints using 3" glass tape. I put plastic over the wet seam and used a roller to smooth out the excess.  They finished joints have ripples and pockets in the dried epoxy.  Is this normal? I want to end up with a smooth hull, will these places get filled with epoxy when I coat the hull (or  glass the hull)?  How much do I sand off at this point?  See pictures.

 

"Help me Obi-Wan Kenobe, you`re my only hope."

 

 

 

[Howard]

Gabe:

 

That is not unusual. Solution is to sand the edges outside the margin of your tape down flush to the edge of the tape, including the selved edges. You don't want to sand through the tape.

 

Ostensibly, stacking multiple layers and doing them in bulk is a time saving method, but in my experience, it goes faster for me to do each joint one at a time and not as several layers. So I put down the plastic, butt the two plywood sheets together, then put in finish nails about a foot or so back from the edge to hold them in place and to keep them square to each other. One nail on each corner, or four nails total. I'll then wet out the joint, plus the margin of the tape. Give it a few minutes for the epoxy to soak in, then lay the dry tape on the wet epoxy to wet it out. Then smooth it out as you normally would any glass job to fully wet out the tape, but not leave any extra such that your tape floats up. That gives gives me a cleaner, neater tape job that one floating on epoxy. Once the epoxy starts to kick, I'll use a razor or sharp knife to sip off the selved edges, leaving me a clean edge and almost no sanding or fairing to do later on. Once it kicks to dry and the joint is strong enough to survive a turn, I'll flip the two plywood panels over and do the backside.

 

For me, that goes faster and cleaner than fairing up the bumps. The only additional time involved is waiting for the epoxy to kick.