Tuesday, April 27, 2010

Recore Marathon

So I took this week off work with the intent of getting as much done on the recore project as possible.  Not too hot, not too cold, and it's too early for black flies and mosquitoes.  Well, the temps have been good; black flies are getting worse each day.  I think the little bastards know that they can attack as soon as I mix up a batch of epoxy; knowing full well that I can't swat them or I will end up covered in stickiness.

Anyway, I was really happy with my first foray into the recore last week when I laminated up 6 small areas on the cabintop to get used to the process.  However, based on a discussion I had on Plastic Classic forum, I decided not to attempt to layup the core and cloth at the same time.  Tim Lackey reasoned that it was more important to ensure a good bond with the bottom skin than to worry about saving a few hours time.  He also noted that as your layup size gets bigger, so does the difficulty.  Boy was he right.

Late last week I decided it was time to tackle the main cabintop with a large section of core.  First I wet out the inner skin, edges, and each of the pieces of core that I cut and fitted earlier in the week.  Next I mixed up a thickened batch (Aerosil) and troweled it in the gaps between the inner skin and outer skin along the edges.  Time for another batch, this time slathering it onto the inner skin with a notched trowel.  At this point I set each of  the core pieces onto the inner skin and squished it down until the thickened epoxy squeezed out the edges.... Phew...

By now I was sweating like a pig and worried that everything would kick before I got it in place.  Once I got the final piece all set, I mixed up another thickened batch and slathered it over the top of  the core making sure to fill any gaps and kerf lines in the core.  I also partially filled the core-less areas where deck fittings are to be placed later on (so not too much heat builds up; I filled these after first batch kicked).  I finished up by putting bags of sand over the core to keep it everything in place while it cured.

Everything went well, but it was a bit stressful.  First, I was worried some of the bigger batches would kick before I spread them.  Second, I was doing all the mixing myself, so I had a lot of trips up and down the ladder and staging.  I don't think I would have been comfortable adding the cloth step at the same time.  I would have had to fill all the core-less areas immediately, risking too much heat buildup; but mostly, it would have just been way too much at once... I'll leave that to the pros and slow things down a bit.  It's not like I am launching this year anyway.

Saturday,  I tackled the foredecks.  First I spent more time than I'd like taping up thru-deck holes and shoring up the decks from the inside.  This is probably a good time to mention how bad I am at estimating time for projects like this.  I have a bad tendency to only focus on the actual work of doing the recore, I forget to calculate the time spent doing things like taping up holes, shoring up the decks, grinding tapers, cleaning up.  All this adds up to more time than the actual recore work itself.  To  make a long story short, I actually thought that I could cut the foredecks out, grind tapers, sand and prep inner skin, and install the core on all on Saturday.  HAAAAA.


I did manage to get all the foredeck cut out and remove all the balsa.  It was clear even before cutting the skin that the core was in bad shape throughout the entire foredeck area, but when I cut off the top skin, I found that while there were localized areas of rotten core (around stanchions and poorly mounted cleats), there was a lot of good core that had de-bonded from the top skin.  Unfortunately for me, these areas clung tenaciously to the bottom skin. I spent about 2.5 hours using a myriad of power and non-powered tools to get it off.  I knocked off at about 3:30 on Saturday and because of a previous commitment, I couldn't do anything Sunday, so I started back up again this morning and used my mad time estimation skilz to confidently tell my wife that I would be finished with the foredeck core today so we could take the kids to the Museum of Science tomorrow... Oops.  I spent the entire day grinding tapers, sanding and prepping the cabintop where I installed the core last week and cleaning up the foreskin (ha).


I finished by fitting all the balsa that I'll need for tomorrow when I actually install the foredeck core.   By far the majority of time spent today was on the tapers.  This is not a skill that I think I will need that much in the future, but I am getting very good at putting a beveled taper with a 4 inch angle grinder and 24 grit discs.
A few notes on tools used over the past few days:
1.  RIDGID ZRR2611 6" variable speed random orbit sander -  This is the first time I have had the chance to really use it and I am really
 
impressed.  It is quite heavy so it is well suited for gravity assisted applications like this one but I wouldn't want to use it on a wall or overhead.  In addition to variable speed, it has a orbit oscillation adjustment that you can switch from 1/8 to 1/4 inch oscillations.  It also has a real dust port and full cowl around the sanding pad, so when hooked to the vac, it is really dustless.
2.  I have been using my 5" DeWalt 18v cordless circular saw to cut the decks but even though I have 3 batteries, I can only cut so much before I down time waiting for charging.  I got sick of waiting around for this, so I broke out my corded Bosch CS20 7-1/4" circular saw and what a difference (duh, of course)...


I'll still need the DeWalt for tight areas, and the Dremel Multimax for even tighter areas (works great for cutting out stanchion areas), but for long runs, I will be using the big Bosch in the future.


2 comments:

  1. just found your blog and love your furniture re-dos. I'm hoping I will find a post on the homemade wall cabinet as I love it!

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  2. Wow, I can't imagine myself working on such a huge DIY home improvement project let alone do it on a boat!

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