Commander Compression Post Discussions

[Commander 147]

John

I would like to offer a few suggestions that might make your job easier.

1.) For the small area you are working in a 6" grinder might be to large. I use a 4" grinder to grind in the bevel around the hole after I have cut it and even that seems a bit large at times.

2.) To cut the hole I often times use a small trim router similar to the one at this link. It allows me to control with a high degree of precision the depth of cut.

http://www.google.com/products/catal...CAcQ8wIwADgA#p

3.) If there is any balsa core intact under the cutout remove it carefully. It was bonded pretty well to the bottom skin which is often times very thin and fragile. Don't try to rush it just get it up slow and easy.

4.) Epoxy resin by itself is very brittle. You need the glass reinforcing to make this area strong. So cut all of your glass fabric pieces before you start putting things back together again.

5.) To keep a lot of resin from running down through the two holes that the mast step bolts through and dripping on your cabin floor you can wet out the top of the bottom deck skin and on a piece of visqueen (plastic) wet out the bottom piece of glass you will be putting in the hole. Then put the glass in the hole and make sure there are no air bubbles under it. Then let that start to kick and set up before you proceed with the rest of the glass. In addition I would use a couple of pieces of tape on the bottom of the holes to make sure nothing drips on the cabin sole.

6.) This repair will really take a small amount of epoxy. So mix small batches of epoxy so you don't waste it and it does not set up on you before you can use it all.

I hope this helps and I wish you the best on your project.

[John]

Rico,

Attached to posts # 5 & 6 are earlier pictures of my compression post. The post cap has worked itself even further into the ceiling. Or if you prefer, the ceiling has dropped even further around the compression post cap. My point is that if I leave that where it is, I effectively will capture the post top by strengthening the area above it. I only asked if someone had been able to raise the ceiling enough that my post would be free to move and or remove. When I open the area above the cap, will the ceiling return to it's orginal form or do I have encourage (read force) the ceiling up to it's original contour.

[Rico]

It sounds like you are on your way!

See what Jerry has done on his commander for reference... Some lovely work there - you should follow his lead. And maybe you'll want to incorporate the mast base in your repair as he did... That is a great idea.
http://www.pearsonariel.org/discussi...1672#post21672

Cut a circle big enough to get to good-solid material... Since you already have a failure I would expect that the area will be the 8" circle (mast base), plus at least 2-3 inches around the perimeter which has suffered deformation. Make that whole area solid... Much less than a gallon!

I would not use pure epoxy. Use a bit of thickener and some glass mat on you repair. Jerry posted a good description of the process a few post above here...

[John]

I have a great mast step made of micarta by a PO. It is approximately 8" in diameter. I am hoping that I am able to cut a 5 in. circle and clean out underneath. If I have to go further, I will, but then will have to be neater in the replacement area. Because of the mast step, I will have to match the curve in deck so I get a good seating.

So the plan is to cut as carefully as I can, clean it out and then stuff it with filled resin......Sounds like I am doing a turkey, doesn't it. How much time to allow for the epoxy cure is a mystery but with some contemplation, I'm sure it will come to me. The other task is insure that the cabin ceiling returns to it's original contours. Easy beans ...ja'think.

[John]

Jerry,

I am not fortunate to have a trim router but I have a regular router. Any reason not to use that and a 1/4" bit to cut the hole? I don't think the top skin is thicker that 3/8's and probably closer to 1/4." I have talked to my friend regarding borrowing his grinder, and he has some 4" blades for it. I think I am in good shape tool wise.

I don't think I understand what you are suggesting to do in the void area. My plan was to fill the entire area with filled epoxy and keep stuffing until I had the void filled and then build the deck area up to match the deck using glass mat. I I have a couple of choices for filler in the void including glass fiber, micre balloons (I don't think it's a good choice) or one of the other solid fillers.

[Commander 147]

John

A normal sized router should do the trick just fine. I like the little one but would certainly use one of my other routers if I did not have the little one. Also you will find that the top skin of the deck is closer to 1/8" thick than it is to 1/4" thick. The balsa core in the center of the deck is 3/8" thick and then you have the bottom skin of the deck that is close to 1/16" thick.

As far as the suggested repair I will draw a picture as soon as I can get some time later today and post it for you. But here are a couple of things I can tell you now. First, the tickened epoxy only goes between the top and bottom skins around the perimeter of the 5" hole you will cut through the top skin. And that assumes that the balsa core is degraded in a larger area than the 5" dia. cutout. While I'm on the subject, you need to know the only way to give the thickened epoxy body so that it will not sag out and run out of the area you are putting it into is to use cabosil (also known as fumed silica). You will want to use micro fibers or 1/4" glass strands to give the epoxy strength after it is cured but you will also need to mix in cabosil to thicken it to a peanut butter consistacy so it will stay where you put it.

Then in the area where you have the 5" cutout you will wet out possibly as many as 8 layers of 1708 biax cloth one at a time to build the core area up to the 3/8" thickness that that original balsa core took up. Then when you are built up to the the point where the glass is filling the core area and even with the bottom of the top skin you will lay down the 8" circle of glass first to get a complete bond with the entire beveled area and the glass you put in the core area. After that you will follow with the 7" circle of glass and then the 6" circle of glass and if the center is still slightly below the surrounding deck area one more layer of glass 5" in dia.

When all of this sets up use the grinder to knock down any high spots and mix up some more epoxy to use as a fairing compound and this time you will need to use cabosil and microballoons. Probably about twice as much microballons as cabosil. The cabosil once again gives the epoxy body and keeps it where you put it and the microballoons will make sanding it later much easier.

Does this help or would you still like the picture? I'm happy to do it but I have some work I need to get done before I can.

[John]

Jerry,

If I understand what you are saying, once I have cleaned out the bad core, I fill the void until I have a 5 in. hole from deck to ceiling. then I proceed to lay in glass matting until I get to the deck level. At that point I start using increasing sizes of mat to rebuild the deck as it was. I can then grind to match the deck, fill if needed and stand back and admire my work. Oh, yes, then I can remove the Gator tape (great stuff by the way) and re-drill the holes to mount my mast step.

I plan on placing a soda straw over my mast light wires and hopefully leave them so they can be removed or fished if needed. This does mean that the glass will have to be layed gently with a slit on one edge to accomodate the wires. Also, if the ceiling does not rebound around the compression post cap, my plan is to cut 2 semi circles of 1/4 plywood and gently jack up the ceiling until it matches the surrounding area an the compression post has a litlle wiggle to it.

[Commander 147]

John

I believe you are following but just to make sure I will post a picture later possibly as late as this evening.

[Commander 147]

John not sure if this picture will do more to explain or confuse but anyway here you go.



If this confuses I will try again.