Mist Miss - Desert Build

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JimmY
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Re: Mist Miss - Desert Build

Post by JimmY »

Starting to make some good progress.

I agree with the comments above. Encapsulate the frames now with at least two coats of epoxy (except edges), and sand the final coat so that its is ready for a final encapsulation coat after the flip. I also put one coat of encapsulation epoxy on the inside of the plywood skins prior to installing them as well. This will save a lot of time crawling around the interior of the hull. I used System 3 Silver Tip epoxy for encapsulation since it is a "non-blush" epoxy and you can re-coat without sanding within 24 hours. Any holes in the frames will get filled with the encapsulation epoxy.

I ran all of my gussets through the router table with a round over bit, but sanding them is fine too. Also, consider filling the space between the gussets with scrap frame material. Otherwise the space is a good place for dirt and water to collect.

On the nails, I pre-drilled smaller holes and used a carriage bolt ground down a bit as a nail set. This prevented getting hammer marks (my shop teacher called them "elephant tracks") in the gussets and set the nail heads even with the surface of the plywood.

I used Poxygrip for all my structural bonding. I transferred it from the cans to "ketchup" squeeze bottles (dollar store) and had a small rack that held them upside down so they were always ready to dispense epoxy. I used small graduated cups (like Nyquil shot glass) or a scale for measuring.
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

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acflynn
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Re: Mist Miss - Desert Build

Post by acflynn »

Thanks, Carl, Neel and Jim;

Carl - Interesting on the "priming" with Poxy-Shield. I didn't recall that from the several times I've read the book. I'll have to re-read that section. And a big D'OH! on the plywood countersinking. I KNEW that wasn't the right approach, but I must have forgotten in my blind lust to test my new countersinking bits!

I agree the layout board is key, as seen below (note the finger smudges from the 4x8 sheet of carbon paper). It was difficult driving that first set of screws into my MDO top layer to align to the carbon lines from the plans. You can see a bit in the final photo from the above post - lines for frames 6, 5, 4 and 3 are visible. And the wax paper allows for visibility as well. I think that photo was taken after I had lifted the frame after letting it cure overnight, so it may have just been laying there when I took the photo.
Image
On the sanding, no wonder everyone whole-heartedly recommended the bench belt/disc/spindle sanders! Yikes!

Neel - thanks for the encapsulation advice. I'm not sure I'll go to the lengths to countersink the nail heads, but definitely pre-drill and I'll be sure to encapsulate the heads. Your frames look so nice and tidy, I think mine look grotesque by comparison!

Jim - when you say "on the inside of the plywood skins", which are you talking about? The ply gussets and 3/4" floor member? Or are you talking about the hull plywood? I wasn't certain.

Also, "space between gussets with scrap frame material" - that's essentially the Gusseted Frame with Filler Block as described in the book, correct? I was considering that and keeping that area clean is a point in favor of that approach.

And lastly, the carriage bolt as a nailset approach - I'm assuming using the curved bolt head in contact with the nail head, to make the nail head concave? Or did I misinterpret that?

So to summarize: Looks like I made two mistakes on assembling my first frames:
1. countersinking in plywood (recoverable, and a slap on the wrist)
2. Not measuring where my cut-outs were going to be (battens, keel, chine, sheer), as I'll likely lose (at least) one nail per side when I make those cut-outs on this frame (for the chine), but since I have yet to do the backside, I can reinforce there.

Based on the above advice, I'll encapsulate once I cut the notches for the sheers, chines, and battens. And some dispenser bottles, mixing cups, cheap-o brushes, and more gloves are on order!

Thanks!
- Andrew
Slowly building a Mist Miss in the Arizona desert

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mrintense
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Re: Mist Miss - Desert Build

Post by mrintense »

Filling the gap between the gussets with hardwood will keep junk out of the gap later and make it easier to dress them up if you want.
I glued the filler to the frames separately from adding the gussets, but you could probably do them at the same time.

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Carl

Crafting a classically styled Vera Cruise

Clipper Boating

TomB
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Re: Mist Miss - Desert Build

Post by TomB »

mrintense wrote:
Thu Jan 16, 2020 11:41 am
Filling the gap between the gussets with hardwood will keep junk out of the gap later and make it easier to dress them up if you want.
Plus one to that. I didn't want to waste time doing it. So I spent 50 time that sucking the stuff out of the gaps. :oops: Tom
In the home stretch on a Tahoe 23

JimmY
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Re: Mist Miss - Desert Build

Post by JimmY »

Hi,

I meant the plywood skins when you start planking the hull frame. It is easier to ensure a good encapsulation on the inside of the skins before installing them.

For the nail set, I ground the threaded end end flat and reduced the diameter to match the side of the nail heads. This set the nails flat and even with the plywood surface.

I think Carl clarified the "fill the gap between the gussets comments.
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

Tony Hain
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Re: Mist Miss - Desert Build

Post by Tony Hain »

In hindsight I wish I had filled in the gussets. Do it now!
Tony Hain
"Never under-estimate the bounds of human stupidity" (Robert Heinlein)
and on a more optimistic note "nor the capacity for human brilliance"

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Re: Mist Miss - Desert Build

Post by footer »

I filled mine in after I as done with the hull and painted them brown. But I’m not done with my interior side walls and still plan to cover them with some stained mahogany.
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acflynn
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Re: Mist Miss - Desert Build

Post by acflynn »

Thanks Carl, Jim, Tom, Tony and Footer - I filled in, though next frame I will do it BEFORE the first gussets go on.

But it was a rough go of it. My Frame 2 experience was rather humbling, as I do a "post-project assessment" on that. I counted at least five separate areas where I can improve, some of which were mentioned above. I think I'm still in decent shape structurally, so I shouldn't have to re-do Frame 2, but it'll likely nag on me for awhile. Like in Top Gun: "You need to be doing it better and cleaner than the other guy!" So this week I'm going to regroup and tackle it fresh this weekend on Frame 1 (which also has a solid floor timber - baby steps).

I did some additional research, and had some questions on epoxying:

1. When/why would I need to use fillers (such as microspheres or silica) to "thicken" the epoxy? I'm guessing this might be for encapsulation on vertical surfaces or for fillets, but I'm not seeing the application at this point with just (already thick) Poxy-Grip on frames and gussets, or am I missing something?

2. What are the tolerances (as in, how out of whack can it get) of my 1:1 Poxy-Grip ratio? Thus far I have measured by weight (in grams), but there may be differences between resin and hardener (and I'm talking 51/49 or 52/48). I noticed there is now a bit less hardener remaining than resin (though that could just be because of the thicker hardener still trickling down). Keep in mind I'm shooting for 50/50, but will an accidental 52/48 ruin the batch?

Thanks again as always for the advice!

- Andrew
Slowly building a Mist Miss in the Arizona desert

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Bill Edmundson
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Re: Mist Miss - Desert Build

Post by Bill Edmundson »

With poxy-grip you should not need to thicken. Poxy-shield yes.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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mrintense
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Re: Mist Miss - Desert Build

Post by mrintense »

As Bill mentioned, Poxy Shield would need to be thickened but only if you are planning on using it as a structural adhesive. For encapsulation it remains in its un-thinned state. Keep in mind when encapsulating that Poxy Shield "blushes" as it cures and this will need to be cleaned off with warm soapy water before applying the second coat (assuming that the first coat has fully cured.) I believe if the second coat is applied in the cure window (approximately 16 hours I think), then you can get away without removing the blush. But definitely test this out first. I've been using non blushing epoxy for encapsulation so this has not been an issue.

Back to the thickening, Poxy Shield can be used as a structural adhesive if it's thickened. Poxy Grip is only used as a structural adhesive because it's already thick. Hope this makes sense. I believe it says in the Boatbuilding With Plywood book that you can use thickened Poxy Shield in lieu of Poxy Grip to save having to buy both. This is what I've been doing from the start. I can't say how strong it will be when I finally start using the boat, but everything seems plenty strong right now.

As far as mixing ratios, every epoxy has different ratios and these can vary by weight and by volume. For example, the SilverTip epoxy I use for encapsulation is (1:2) by volume but but (44%:100%) by weight. It should state in the instructions on the bottles. It's best to get these close especially when mixing smaller quantities. Always hang onto the mixed epoxy after you've used it to make sure it's cured.
Carl

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Jimbob
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Re: Mist Miss - Desert Build

Post by Jimbob »

I used poxygrip for structural stuff and silver tip epoxy for everything else.
poxygrip is ready to go with a 1:1 ratio. I always mixed by volume with no problems. Don't trust the pumps for the silver tip epoxy. Squirt into measuring cups individually. I used disposable bathroom cups for measuring. Put the epoxy in one cup and the hardner in another cup. The cups have ridges, so it's easy to get the same amount in each cup. Mix together in something else.
Jim
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Re: Mist Miss - Desert Build

Post by footer »

I used silver tip system 3. I mixed in graduated mixing cups. I found if I left the mix in the cup while I was try to use it, it would start hardening before I was done.
I found if after mixing it, I poured it into a roller pan, it gave me a lot longer working time.
I never thickened or thinned my epoxy. System 3 was great and didn’t fog over.

JimmY
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Re: Mist Miss - Desert Build

Post by JimmY »

I used a combination of weight and graduated cups and syringes to measure poxy-grip, and never had a bad batch. I am a bit anal on this stuff and had worked with epoxy before on other hobbies and projects. I think the weight is probably the easiest, and had a small postal scale for this and kept a calculator handy to figure the ratios. I always worried about doing the two cup thing, since the two parts are different viscosities and could leave different amounts in the measuring cups. To get around this I used two large syringes and with the plunger pulled out would fill them to the marks, and then use the plungers to make sure all the epoxy was squeezed out.

For the Silver tip, I used the pumps and again never had a bad batch. When using the pumps, always start with pump of part A and then a pump of part B, and then back to part A. This will prevent you from forgetting how many pumps you put in (was that 3 or 4 pumps of part A? :? ).

I think a lot also depends on how well you mix it. Mix it, and then mix some more, and scrap the sides and bottom a lot.

+1 on the System 3 Silver Tip. It is no blush so you can re-coat within 24 hours with no sanding or cleaning. This makes building up your encapsulation layers much easier.
-Jim
Nothing says poor craftsmanship like wrinkles in your duct tape!

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acflynn
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Re: Mist Miss - Desert Build

Post by acflynn »

Neel - just wanted to thank you (back on page 3) for the forstner bit advice on "countersinking" the nail heads. I just tried a few (1/4" matches the SB ring shank nail heads) - nice and flat. Really makes it more finished and refined. I'm going to be using that approach going forward.

And Jim - I used an actual 1/4" nail set (part of a cheap set, it was the largest) and that helped as well. No elephant tracks!

Tonight I was able to do some of the above touch-ups and also used famowood to fill in two areas: 1. the holes from screwing the beams down to the layout table (in mahogany famowood) and 2. filling in the not-to-be-countersunk-again screw heads on the plywood floor gussets (in a maple-colored famowood, which matches the Doug Fir marine ply gussets).

At this point I feel like I'm in a good place and am looking forward to employing the lessons from Frame 2 this weekend on Frame 1. Onward!
Slowly building a Mist Miss in the Arizona desert

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acflynn
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Re: Mist Miss - Desert Build

Post by acflynn »

Success! I took the lessons learned from Frame 2 (with multiple mistakes mentioned above) and worked on Frame 1 all day today. I may not be the fastest, but was much more comfortable with the process. I did spend about half the time sanding and fitting. I guess there is such as thing as being "too proud" on my cuts - lots of sanding to deal with that.

This was also the first trial of the new plastic pump bottles - really thick stuff, but it eventually trickled out (which may be good, as I don't need hardener spraying all over the place). It was much better than pouring and I was able to get an exact (as I can tell) 50/50 mix. I may look to warm up the epoxy more prior to using next time. Even though it's kept in the house (at about 72 degrees) it was still a bit sluggish. When I did my transfer to the pump bottles I set them in the kitchen sink filled with hot water for a while. I may try that approach next time. Overall today I was much calmer, less rushed and more in control. I used a completed batch for 3 sections, then mixed a new batch for the remaining two sections. I had time to slather the epoxy down, set the gusset on, and then pre-drill the nail holes (including forstner-bit drilling for the nail heads).

So Frame 1 is one-side complete, with floor timber gusset (3/4" ply) and 4 gussets on the corners, and tomorrow I'll flip and do the other side. Hopefully I can get a frame done in 2 days. Next challenge will be either the transom (which is multiple assemblies, with some timbers stacked to double-thickness), or Frame 3, which will be my first two-piece floor timber, joined with the floor timber gusset.

As Josh Burks said multiple times in each of his videos, "Making good progress!"
Slowly building a Mist Miss in the Arizona desert

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