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Fishman38

fishman38 OK20

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I used some fencing wire i had in the barn.  I drove an angle iron stake in one end of the barn, drilled a hole thru the wall and ran the wire to a come along  chained to a tree.  Worked pretty good.

Enjoy your build.

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Strongback is done. Thought I would make the legs long enough so that with 2 1/2 sheets of maybe CDX ply on top I've got a long clean work surface at a comfortable height for gluing up the stem, keel and whatever else needs doing before starting to assemble the frames.  At that time I'll cut about 2 feet off the legs to put the bottom within reach.post-2179-0-61149600-1363800519_thumb.jpgpost-2179-0-77284600-1363800547_thumb.jpg

 

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post-2179-0-87340900-1364529921_thumb.jpg

 

The CNC frame kit.  Just about ready to get started.

 

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Oops.  Not quite.

 

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This is obviously after a hard day of cleaning and rearranging.......................

 

post-2179-0-53183100-1364530007_thumb.jpg

 

Just getting a feel for where to start.

 

 

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Picture of the drwg of the jig I plan to use to laminate the 3 sheets of 3/16 for the transom.  Very similar to that used by Miyot, building the OC 24.  I am a few clamps short so thought I'd try this. :(

 

 

I am puzzled about:

1) when the transom should be installed; I'm thinking after all the frames have gone in and before the stringers. Or maybe it doesn't matter?

 

2) how exactly it should be fastened to ensure adequate strength to support a 400 lb motor, especially while trailering. Any comments/pics would be appreciated. The pictures posted by NZ Lance are very helpful; however any additional info would be very welcome!

 

After another long look at the plan, it's apparent that the weight of the motor is supported primarily by the bonding of the transom to all four bottom stringers, the keel, the bulkheads of the well in addition to the sides and bottom. I assume these bonds include some type of permanent metal fasteners (bronze?  Stainless Steel? screws) as well as the epoxy, fillets and battens (I hope I'm using that last word correctly--not sure, I'm talking about say 3/4 x 1 1/2 inch solid stock used in the corners where two plywood panels meet at right (or other) angles.

 

 

 

 

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post-2179-0-69660700-1365906027_thumb.jpgpost-2179-0-59987700-1365906166_thumb.jpgpost-2179-0-51894300-1365906195_thumb.jpgFinally getting started gluing up the keel, stem and bottom stringers.  Once this is completed will clear the table, cut the legs off and turn it back into a strongback.  Afraid I may have goofed on one of the bottom stringers.  Looks like the finger joint may have moved and didn't realize it till after the epoxy had kicked off.  I think it left the stringer mis-aligned, and if so will cut out a section at the joint and learn to scarf.  The jugs of epoxy were used for weights.

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Results of todays 2 1/2 hours..........................Question: does the size of the epoxy batch affect the flash time?  I mixed a batch of two pump strokes which was easily workable for 2 plus hours and hard set in 6 1/2 hours.  This was with the "slow" hardener.  The next day I mixed a batch of three pump strokes that kicked off in a little over an hour.  The temperature was a few degrees, guessing 3 or 4, higher on for the second batch.  Just wondering what I did wrong.  I followed the recommended procedure of one stroke resin, one stroke hardener etc.  Might I have not let the resin pump fully reset on one or maybe two strokes?

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Temp definitely affects pot life as well as thin film working time.  The amount in your container affects pot life as well.  The more in your container the faster it kicks or heats up.  When using straight epoxy(without additives like microfibers) pour your resin into a larger shallow container right after mixing.  This will help dissipate the heat caused by the resin beginning to harden.  This will give you a little more time.  When mixing fillers such as microfibers, spread them thin onto a trash piece of ply wood.  This will give you some more working time as well.  Better read up on epoxy use.  You don't want to get caught gluing an important large part and have it set up on you.  Hope this helps.  Google Gougeon Brothers epoxy use.  This should help.  Get their user manual.  I would read it before going forward.

                                                                                                                                                 Dave

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 I use different epoxy than what you are using.

 

I  have different size containers  for each quantity  that I mix. If the temperature is warm in the shop I like to use wide containers. I use paper bowls from the grocery store.  If you mix a large quantity  in a tall cup it will tend to kick faster.  I use a small block heater in the winter to heat my pump and in the summer I will put the unused epoxy in my fridge to slow down the reaction. If you are on a concrete floor you can place the container on the cool floor and it will also slow it down.  Your results may vary.

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I checked out your keel and stringers in your pics.  I didn't see any squeeze out of your resin on your keel lay up.  I hope you are using some kind of filler in your epoxy during glue up,such as microfibers or cabo sil, etc. You can't use straight epoxy to glue things like this up.  The epoxy needs a filler to help fill small gaps.  Straight epoxy will continue to soak in after you join the parts resulting in a dry joint.  No strength.  The procedure is to wet out the parts like you did on you stringers, then mix up a batch of resin with microfibers, put that on and then join the parts.  Perhaps you had already cleaned up the squeeze  out.  

                                                                                                                                                                                                                                                                                             Dave

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Dave, I did use the thickener that Graham provided.  The question is did I use enough.  I tried to mix it according to the West System User Manual.  I used a roller to spread it and it was thick enough that it was a little difficult to spread with the roller; might should have used the notched spreader , but there was quite a bit of squeeze out; a few places I would have liked to have seen more.  I had cleaned most of it off before taking the pics.  Also I had wet it all down then mixed a couple of batches with the microfibers.  Hopefully it'll be ok.

 

I have the Gougeon book.  Haven't read it cover to cover yet but am trying to read the relevant parts as I go.  Also have the West System User Manual and ditto on it.

 

The only problem so far has been with the one stringer that I mentioned in my previous post.  It was as if there was air trapped in the joint and the pressure kept pushing the two pieces apart.  Because of the setup, I decided to let it be and if necessary cut that section out and redo it.  The other three turned out fine.

 

Thanks so much for your input.  Please continue to point out any errors you see.

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Tarbaby thanks also for your input.  I thought maybe what I experienced was the result of slower heat dissipation due to the larger volume. Also I'm sure that the concrete floor issue was part of the problem.  The first batch was mixed with resin and hardener that had been sitting on or near the concrete floor for several days.  That night I left the components sitting on a table and turned the up a few degrees in the shop a few degrees.  I'll pay close attention to those factors in the future.

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Glad to hear you did use a filler.  I worried a little on that one.  A notched spreader is the way to go.  I mix my filler a little at a time until it is a little thicker than ketchup.  Or even a like a thin peanut butter for some applications like on vertical surfaces.  How much to add will come with experience.   As soon as I have the right consistency I spread it thin on a trash piece of ply wood so it will not cure to quickly.  Then I use a small plastic mix stick to apply it.  When gluing up panels like the transom or planks, I use it about like ketchup.  As soon as I have the right consistency I immediately pour it on the wet out panel  and spread it with the notched spreader.  You have to move and have everything ready, especially on large panels like a full sized planks on the bottom.  The only time I use a roller is for wetting out large panels and planks, etc.  As the weather warms I will be switching to a slow hardener  I have already put off glue ups because of the temps.  Sounds like you are right on track. 

 

One more thing, I use a few screws during my glue ups to keep things from sliding all around.  You have probably found trying to glue boards together is like holding onto an eel.  They want to slip all around.  A few screws pre drilled before lay up stops that.  I figured you already knew that but just in case.

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A few screws pre drilled before lay up stops that.

 

 

Actually I wasn't sure whether this was a commonly used technique in gluing the solid woods.  I think "pre-drilled" is the operative word in your comment.  Another might be "with a sharp  bit".  In edge gluing the stem components I was having trouble with the eel-like sliding around of the parts while clamping after the glue had been applied.  I believe these parts are cut from Southern pine.  I try to keep my drill bits fairly sharp but when I tried to drill a pilot hole the bit hit a hard grain and decided to go around it.  Offset the two pieces by about 3/32 even with a clamp in place.  BTW is it necessary to fill the hole after removing the screws and if so with what, or do you leave them in place?  If so what type of screw do you use for this?

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I use metal lath screws.  You can get them at Lowes.  I use these for all my glue lay ups.  I have not broken one yet.  I did not fill the holes after removing the screws, but they will be eventually, one way or another.

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I have a motto that I live by in my shop...... "Dryfit everything!"

 

If you make two parts and glue them together  they will go everywhere but where you want them.  You must with every part of the boat; screw them together,  unscrew and then re-screw them back together with glue.  The screw holes will line up where you want the parts to be.

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It isn't just to prove it fits before gluing, though that is reason enough.   But to practice fitting it in place so you will know what you are up against before you slobber it all up with epoxy.

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