The Poet Creek Express - Foamie Hybrid

[KCStudly]

Atomic, would you have any concern with me just laying the cloth down and squeegeeing straight thru? If delamination with the foam/spackle is that big of a concern (not building an airplane, really not) I suppose I could bore a series of “post holes” thru the foam down to the top of the ceiling/hatch inner skins and fill those with thickened epoxy before laying out the cloth, but even that sounds “mental extreme” to me.

Karl says they would use mat for the outer ply (usually over gel coat in a mold) because the random fibers hide better than the woven cloth on final finish. Woven cloth was only used on the inside/back of the molded parts he made while working for Callaway. I think I would rather fill weave with thickened epoxy and maybe have a little weave texture showing than have all of that extra weight and epoxy.

Wagondude/Bill, .

Tonight I made a couple of spacer blocks out of scrap pine to turn the plunge router into a flush cutting end mill. Just used the small Surform rasp and hand block to knock the corners off of the blocks so they wouldn’t dig into the foam. Double back taped them to the foot of the router making sure to leave enough space to span the guard blocking.


Simple to set the cutter flush using a straight edge (scrap block).


A few passes sliding back and forth, a little brush with the small sanding block, and everything is nice and flush.


In the meantime I started making up a couple of test blanks to help me decide which way to go on covering. On one edge I sanded a 3/4 radius to simulate the roof edge, and on the other I glued on a 1x2 piece of cedar. The cedar will get an 1/8 inch round over to simulate the door openings and hatch seal areas. I will also distress them some, apply some spackle and sand it fair to simulate my typical construction. Shown here with packing tape holding the cedar edges glued up with TB2 because it was easiest (hope it holds okay, should get plenty of air to cure in this configuration).


I’ll probably cut these in half and do at least four variations:
(A) Two plies 6 oz BID. I’m thinking 45 deg bias strips on the edges to aid wrapping, but no bias on the flat because in full scale I’d rather just roll out cloth along the trailer axis, rather than cut a bunch of overlapping bias pieces.
(B) Canvas applied over epoxy, wetted with same, no bias. May try laying part dry and wetting with squeegee.
(C) Canvas applied with TB2, wetted with epoxy, no bias.
(D) Canvas applied with TB2, wetted with latex paint, no bias.

I have a bunch of FG tape left over from another project, but it is not bias, so I’m not sure about using it, but it may be useful.

[OP827]

KC, YMMV, I found that one 6oz FG cloth layer over the foam seems to be enough for me. Suppose to fill the FG weave a few hours after squeegeeing of first layer of epoxy started to harden with second and third coat of epoxy, as in boats lamination technique. White exterior paint (reduces surface sun heating) and holes/cuts/wood inserts/glue lines filled with epoxy do help to prevent delamination on large flat surfaces like in trailers. Sorry for jumping in, just sharing my personal, non-expert experience and what I have learned from my own research.

[Atomic77]

So KC are you wetting your surface first? Do you wet your cloth prior to lay up? Then squeegee the excess through?

[KCStudly]

So KC are you wetting your surface first? Do you wet your cloth prior to lay up? Then squeegee the excess through?

That's what I'm hoping to determine once I lay out the tests.

I have very little glassing experience. From what I've read (and can remember... it was a while ago) about West Marine, they suggest laying larger (dry) pieces of weave down on the dry surface first, then squeegeeing the epoxy thru from the top. The reasoning being that it is easier to position the cloth more accurately while dry (although when applying a second ply it would obviously have to go over wet, so maybe not such a good argument).

What would you do (... please don't say Filon )? Any suggestions for a schedule?

[OP827]

I also had very little experience with epoxy FG and look at me still doing it on the trailer, more than 6 epoxy gallons are down, it is all good. With your skills KC and attention to detail, you'll be fine if you choose this path or any other. Cheers!

[KCStudly]

Thanks for the vote of confidence, OP.

Funny how there are so many ways to build these little things, and no one correct way. And yet, most every one turns out.

[Atomic77]

I can tell you how we do lay-ups at the race shop...keep in mind we are building something that goes over 200mph and has to keep a driver alive when they go airborne. I set up a lay-up table covered in plastic. Then I cut all my pieces to fit. I would rather have to mix more epoxy than cut more material so have it all dry fit first. I use the pre-measured pumps at the shop or you can use graduated cups...it's too expensive to screw up. I wet out the area with a chip brush first, without going overboard. I have my pieces laid out on the table and i pour the West over each piece then squeegee it through. I stand the spreader, (i use a plastic body filler spreader) almost straight up and squeegee as much of the epoxy out as possible. Use the corner of the spreader to get under the piece and carefully pull it up without stretching it. Now when I lay it in my pre-wetted area I know with an incredibly high amount of certainty the piece is thoroughly saturated. I'll repeat this until I have multiple layers. Usually 3 to 4, depends on the situation. In the end I will do whatever I can to squeegee out as much epoxy as possible. I will stand the spreader up 90 degrees and using a fine chopping motion I will work the bubbles to the top. I've done it so much I can almost get a wet lay-up to survive as successfully as a bagged lay-up. At the speeds we go and the severe punishment the hull takes pounding the water, we have to be on our game with construction and that's how we do it.

(But I would just use Filon.)

[KCStudly]

Thanks!

[OP827]

West pumps are working good with West system epoxy. When I switched to East system (same 1:5 ratio as West) as it is significantly cheaper (and slightly thinner than West, good for lamination in cooler temps) here in Canada, I decided to switch to digital scales. The ratio by weight method gave me the most confidence in the mix correct ratio. Hardener pump was often misshooting shoots (with slightly thinner East system hardener). Did mixing by weight ratio since then and never had an issue. Did some bigger amounts to do work quicker. With bigger mix I would mix it for 60 to 120 sec and never keep it in the cup longer than two, max three minutes. I would pour the mix out on the piece and start spreading with a spreader. That way I can still mix a lot of epoxy making a lot of surface quicker, but avoid exotherm reaction in the cup. I did almost full red plastic bear cup (12oz+) sometimes when I had to do the roof large surface and I knew it'll use a lot of epoxy. I never had an exotherm incident...yet. In my build so far I laminated in close to horizontal position. I did two large cloth panels initially over a wet surface on the large roof and had some difficulties positioning large sheet of cloth and eliminate wrinkles, then I switched to dry method on horizontal large surfaces and it went good. Just my amateur experience, working alone with no special equipment or tools. When on vertical, I will be using a brush and small amounts of mix to wet and laminate slower to keep it under control. Keep in mind that you want to have epoxy finish type FG cloth. There are other FG cloth types (like f.e. for polyester resin only) that would NOT saturate properly with epoxy.
EDIT: If I was doing glassing on wet, I would precut to fit all the cloth pieces and roll them clean and nice on/in a tube so that when rolled out on the wet surface they lay nicely and flat with no need to move it much around to adjust, just a thought. I wonder how Atomic usually does the large, close to flat surface layup like it is on a trailer with wet on wet method.. ?

[Atomic77]

Wet on wet. Two guys handling the cloth.

[KCStudly]

I've been borrowing Karl's small digital scale and weighing. Even still, I think I should print up a chart for quick reference. 'X' number of oz's resin plus 'Y' oz's hardener equals 'Z' final batch weight; that way I don't have to do any math in my head (...even tho I'd like to think I am fairly good at math, mistakes do happen...) and all I would have to do is pour to a known target.

Have also been saving my large DD ice coffee cups for over a year, so I should have plenty of mixing cups; couple of stacks about 18 inches high.

I probably won't get to the layup stage on the test pieces tonight because I still need to round over the cedar edges and simulate some spackle "repairs".

I was not aware that there were different qualifications for polyester vs. epoxy cloth. I got the cloth I used for the front radius reinforcement at Defender (Waterford, CT); I suppose they may have asked me what resin I intended to use, schmaybe. It seemed to work fine and the remnant is what I plan to use for the test samples. The tape I have was originally for pipe lagging (I think); very fine weave.

[OP827]

Thanks Mike for your expertize and information here.
KC, I ended up using a calculator in my shop to get how much hardener to add after I dispensed the epoxy in the cup. To make it simple here is what works for me. First I fill the cup with epoxy as much as I think I need for the batch and then get the reading on the scale. I know how much empty cup is so I substract the cup weight from the calc. Then I determine the weight of hardener to be added which is 0.18 multiplier by weight for East system epoxy, your epoxy can be different, look into product datasheet. So I reset the scale to zero with epoxy cup on it and slowly add exact claculated amount of hardener, slowly, by using the pump until it is precisely what is needed. It does not have to be exact a few drops more don't matter, it will still work perfectly. I just find this method easier and less stressfull for me as I can take as much time as I want until I added hardener. I also have a clock to check that I stir the mix for a right amount of time. Cheers.

[KCStudly]

The West containers say 5 resin to 1 hardener, but I think the information I read online gives a narrow range with an ideal value listed with a decimal point (I don't recall what it is at the moment).

I recently hung an extra watch I had (NRA membership perk with sweep second hand) in the loft, so that will come in handy.

Spent some time tonight pricing out glass supplies, figuring quantities and looking for bias tape.

Quick update (with pics to follow in a later episode), I rounded over the cedar on the test samples, distressed the surfaces (one clamp dent, one ding with torn edge, and a shallow sanded depression with some intentional tear out at one end... all to one side of each sample), and filled with spackle. Not an exact representation (no "mix" on the cedar and no guide coat of primer), but should at least give me an idea of what I'm dealing with and has already given me more experience laying out and cutting cloth and bias strips.

While discussing options and techniques with Karl, he grabbed one of my test sheet plies and hung it over the roof edge dry. It did just fine at 90 deg over the 3/4 radius. Then he laid it on one of the test samples to see about the 1/8 inch radius... before I could remind him that the panels had wet spackle on them. Oops. No big deal to cut another piece of cloth, and the spackle didn't get messed up to badly.

Aircraft Spruce has peel ply tape in various widths. I might use that to leave a prepared edge if I jamb out the door frames in a preliminary step. I'm not sure how I would go about doing the header; maybe bed the strips in micro slurry to get them to stick upside down (slightly tilted back). Maybe just run the cloth up to the door opening and paint the jamb out with epoxy with no glass. So many things to consider. Considering glass/epoxy more closely seems to add complication, but then the result seems like it should be worthy.

[Atomic77]

Don't fret about the pumps. I only use them in the race shop out of pure convenience. The only time we use scales is when we use Hysol because it's much more unforgiving than epoxy. At home and for all the epoxy I've mixed for my build, I use the graduated cups with 5:1 markings. After you get it mixed, pour the epoxy into a throwaway cup. Then turn your graduated cup upside down on a piece of paper. All the epoxy will run to the paper. And the next day you can peel the epoxy cleanly out of your graduated cup and start fresh all over again. I'm from the fiberglass club and I believe it's well worth it.

[KCStudly]

Just for the record, from West System:
"Dispensing without Mini Pumps (Weight/volume measure) - To measure 105 Resin and 205 or 206 Hardener by weight or volume, combine five parts resin with one part hardener. To measure 105 Resin and 207 or 209 Hardener by volume, combine three parts resin with one part hardener (by weight, 3.5 parts resin-1 part hardener).