ArVeeNiner

ArVeeNiner

Well Known Member
I am a novice when it comes to fiberglass. The only fiberglassing I've even done was plugging up the HS and elevator a couple of years ago.

So, I cut out the oil door opening of my SJ cowl (see pictures below). I think the Van's supplies you with a seperate oil door for their cowls but not on the SJ. The piece you cut out IS the oil door. Anyway, I used a hack saw blade and a coping saw blade as per the directions. I haven't cleaned up the cuts much at all since my rough cuts last night.

So, I want to obviously round out the corners and make the cuts straight. Of course, that would make the gaps between the door and the cutout unacceptably large.

My question is how do I build edges back up so that I can make a nice fit? Is thickened epoxy enough to build up the edges? I'm thinking for instance in the corners, place tape on the outside of the cowl then place a glob of thickened epoxy inside. After curing I could sand it all to my liking. Will this work or am I asking for the edges to break off someday?

Thanks

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You *could* try to salvage that thing, but it'd probably be more work than just laying up a whole new thing on top of it...

What I did (too late for you) was to lay up a section on top of that area, before cutting the opening.. (oversize the layup).. then cut it out.. and make a whole new door out of this layup I did before the cutting.

You could probably still do something like that.. I'd say.. Cover the opening with tape (so the f'glass doesn't sag) and lay up a whole new part.. I'd do 4-5 layers.. (I did more and it's simply not necessary and makes the part too thick)...
 
First you need to build a flange. Tape your door cutout back in place with slick tape on the inslde and wax the tape. Lay up three or four plies medium to heavy fabric on the inslde of the cowl, which gives you a plate matching the cowl contour. Remove it and the tape when cured.

Before going further, carefully finish the edges of the door hole. Make them perfectly straight with an equal radius at each corner. Remove as little as you can.

Now hold the new plate up to the back of the hole and mark around the edge. Cut a square hole in the plate 1/2" inside the line all sides, and trim the outside dimension 1/2" larger. Clean, sand, position inside the cowl and drill 4-6 holes to clamp it in place with clecos (the holes are no big deal, you can fill them later during cowl finishing with micro or flox). Bond the flange into place. Smooth in a nice filet of micro/epoxy around the joggle with your fingertip. When cured remove the clecos and sand the micro filet nice and neat.

Now drop the door into the flanged recess. Chances are you'll find it doesn't look so bad with a little edge cleanup so it matches the pretty cowl opening. Probably no need to add anything to its edge; even an 1/8" space between the edge and the flanged opening will look fine if it matches the opening. That space will get smaller with paint anyway.
 
ArVeeNiner said:
I am a novice when it comes to fiberglass.(snip)

My question is how do I build edges back up so that I can make a nice fit?(snip)
Click to expand...

There are a million ways to do this, but here is one that is "fast and dirty but should give you good results:

1) carefully shape the door exactly like you want it. I would use something like a dime to define the corner radius with a fine line sharpie and sand to it. Glue some 80 grit to a straightedge (scrap angle works great) and get the edges perfectly straight. Once you're happy with the shape, carefully wrap the edges in clear packing tape. Take care around the corners to make it lie flat--this will require multiple radial "relaxing incisions." The inside and edges are most important. Cover the entire backside (underneath ) with tape

2) Sand the inside of the cowl with coarse (30 to 80 grit) paper back a couple of inches from the edge of the hole.

3) Mount the door in the hole, making sure the edges are level. There are a lot of ways to do this, but you can bridge the gap in several places with popsicle sticks with a blob of bondo on each end, or use little scraps of aluminum with a #40 hole in each part for a cleco. Just make sure it is level and reasonably stable. if you use clecos, put them far enough from the edged that they won't be in your way.

4) now would be a good time to mount your hinge, or at least plan for it so you don't have to redo any work later.

5) turn the cowl upside down, and tape a one-gallon ziploc bag over the door. Very carefully draw a line on the bag with a sharpie about 3/4" outside the door. You can draw on the cowl first and trace it onto the bag if you want. this will define the outside of your flange. carefully mark on the bag any areas (like the hinge) where you don't want fiberglass.

6) Cut three(or four) pieces of fiberglass cloth a little bigger than your marked lines, and stack them inside the bag so that they extend beyond the sharpie lines. Make sure you turn each layer 45 degrees so the weaves don't line up.

7) put on gloves and mix a little epoxy. Two shots of resin and hardener each from the West system pumps would be about right for something this size. Mix very thoroughly, the pour the mixed epoxy into the ziploc bag on top of the cloth, squeeze out the air, and seal the bag.

8) Using one of those yellow plastic bondo squeeges, or maybe your EAA membership card, work the epoxy into the cloth, right through the ziploc bag. Any flat surface, like your workbench works well. You can tell when the cloth is saturated properly, because it turns translucent. push any air bubbles out beyond your sharpie marks.

9) As soon as your cloth is saturated, cut the excess away with scissors, right through the bag on your premarked lines. Do this over a trash can, because epoxy drips are a pain to clean. This should leave you with a little square of saturated glass, with plastic on both sides. Peel the plastic off the side which will go on the cowl.

10) Carefully position the saturated cloth on the presanded inside of the cowl and door. Flatten it out thoroughly with your squeegee, then leave it while you go clean the epoxy of your wife's scissors. Let it cure overnight. The plastic will come off now or later, leaving a shiny finish.

11) The next day, pop the door off, and mark, cut, and sand the hole in the middle, leaving a flange for the door. Use a round file to make a nice inside radius.
 
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part two, unnecessarily long :)

Once you have the door and the flange like you want them, retape the door with a couple layers of thicker tape (like duct tape) to define the gap. Be especially careful on the corners

scuff sand the cowl around the opening, and remount the door. This is easiest and best if you already have your hardware mounted. Otherwise do the popsicle stick and bondo trick from the back.

With the door in place and taped, squeegee on some dry micro (a couple squirts each of the west system, thoroughly mixed, then keep adding micro balloons and stirring until it stands up like peanut butter) onto the presanded cowl and into any gaps between the door and the cowl.

After the epoxy is thoroughly cured, remove the door and take all of the tape off. Then replace the door, and carefully sand with a long, hard flat sanding block to level the area around the door and the door itself. If you do this right, you will have a perfectly level door, and a gap equal to whatever thickness of tape you used.
 
Radomir said:
You *could* try to salvage that thing,
Click to expand...

I guess I didn't think I was near salvage mode at this point. I thought my rough cut wasn't excessively rough. Oh well, that shows you how little I know about this process.

Making an entirely new door is exactly what another SJ customer had done and posted on his web site. He said don't even bother with the piece you cut out. That is surely an option.

Dan and James, thanks for painting a vivid picture of the flange etc. I guess I was thinking that I'd just lay strips for the flange but like you suggested, why not just make a square and cut out the middle? Of course!

James, I think I understand part two of your post. You fill the epoxy in the gap between the door and the edge of the cowl hole. When it cures, it's sitting on the flange so there is no chance for it to break off.

Thanks everybody!!
 
ArVeeNiner said:
I guess I didn't think I was near salvage mode at this point. I thought my rough cut wasn't excessively rough. Oh well, that shows you how little I know about this process.

(snip)
Click to expand...

A general rule of fiberglass: There is no possible way to screw up so badly it can't be fixed.

It may be true that it's easier and quicker to start over, but it can always be fixed ;)
 
You might want to.........

Invest in a Dremel tool, cut off wheels and a 3/8" sanding drum. These tools work fiberglass to perfection. I made my door where it opens to the inside using a home depot european cabinet hinge. Cost about 6 bucks. You make the door where it fits flush, fiberglass a couple of layers on the back of the door where it has a small lip around the door to position it just right. You don't need to use quarter turns to hold door, hinge pressures it all the time. Worked out very clean. You see nothing but a small crack around the door.

If you decide to do the above, be sure to hinge the door where it is hinged on the bottom side of the oil door opening. This way it will miss mount and gives direct access to the oil stick.

Worked out good for me.
 
DanH said:
First you need to build a flange. Tape your door cutout back in place with slick tape on the inslde and wax the tape.
Click to expand...

Dan is right. But even before you do that you need to finish the door to the final thickness that it will be because what you have there will be way to flexible and not hold up well. Cut a thin slab of foam using a band saw. Make it about 3/32 to 1/8" thick. Size it to be about1/2 inside the perimeter edges of teh door and then bond it on with some contact cement. Scarf the edges of the foam so that it tapers down to the surface of the door. Add another 1 to 2 layers of glass on the entire interior of the door (tape the door in place on the cowl so that you do not end up with a stiff but twisted door).
Now lay up a flange as described by Dan. After the flange is finished you can install the door to the cowl with the hing but keep it removable (clecos).
Now finish the door to its final shape with the rounded corners you want.
Add plastic packing tape around the perimeter of the door (wax as before) and cleco the door in place. Squeegee a flox mixture around the perimeter of the door to fill any mismatch between the shapes of the door and the opening. Do not use micro balloons for this. It is not hard enough and it will not hold up well when forming/defining an edge such as this.
After it is cured, pop out the door and remove the tape. Sand the perimeter of the door to reduce its size about 1/16" all around and you have a door that matches the perimeter opening. Because of the thickness of the tape you now finish sand around the perimeter of the door opening to make the cowl exactly flush to the surface of the door.

The second half of this process can be used by any builders using a cowl with an already molded opening if they are interested in having a very nice fit of there door
 
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Thanks guys. I spent the day riveting, bonding, and fiberglassing in the upper cowl hinges and doing plumbing (the house kind, not the airplane kind) while pondering the oil door. I think you guys gave me some good ideas of how to proceed.

CNEJR, yea, I have the super duper deluxe Dremmel kit that I've used for years. I have no doubt that I can clean up both the door and the opening using various tools including the Dremmel. But, Sam James' idea of using the cut out door AS THE ACTUAL DOOR is not feasable without either adding flox as was suggested or making a new door, also suggested. The initial cut would have to be absolute perfection. A hacksaw blade and a coping saw blade (with Vice Grips attached) doesn't lend themselves to perfection.

So, starting on Wednesday (my EAA chapter is meeting tomorrow night) I'll:

-Clean up the door and the opening to something that looks presentable.

-Beef up the door as was suggested. I had planned to do that anyway. I picked up some cloth on Saturday from Tap Plastics near my house to stiffen up the door. I can't remember the name of the cloth but you sandwich it between fiberglass layers. They have a demo there at the store using two layers of carbon fiber both with, and without this fabric. The difference is amazing. This will make my door thicker which will affect the flange.

-Then I'll make the flange with the door in place so that I get the lip right.

-Somewhere in here I'll attach the hinge as suggested.

-Finally, I'll fill in the perimeter of the door to make a nice fit.

-If all else fails, I can make a new door like Radomir says.

I'll post my results here when I'm done.

I'm actually looking forward to working with this stuff. It's magic in the right hands. Dan H. is a fiberglass magician!!!

Thanks again.

KJ
 
<<Dan H. is a fiberglass magician!!!>>

I need to make a comment here.

That's not fair.

You had several very good responses from several good builders.

That aside, let's go a bit deeper. The key to this stuff is thinking all the way through the task to the desired result before you ever go to the shop. You roll it around in there, trying this and that in your head until you develop a good way to accomplish the whole task. It's a fundamental of fabricating anything.

KJ, you were more or less focusing on one little part (the edge of the door) after you had cut it. When Radomir did the same job he thought the job through before starting and made a plate layup he could later trim into a nice door. My first reaction was "what about the rest of the job?". And look at the post from James, very detailed and covering every tiny step. It's his training; James is an eye surgeon. He doesn't cut into somebody's eyeball before thinking through the whole job in exquisite detail, over and over again. It carries over into his airplane work. We need to train ourselves to do the same.

Sam Buchanan wrote an excellent piece on the subject and hosts it on his website. I highly recommend it:

http://home.hiwaay.net/~sbuc/journal/smart.html
 
I like to think working with fiberglass is like working with drywall. If you bugger it up, put some more filler in there and sand it to match.

In your case, this is not structural.

If I were you, I would add the lip on the inside of the cowl that will hold the door flush with the top of the cowl surface. Once you have that in place, you can fill the gap between the edge of your door and the top of the cowl with some microballoons and epoxy. This will make your door look like a perfect fit. (BTW, you can rivet aluminum to the inside of the cowling to provide the lip to close the oil door against. IMHO, it is easier to fiberglass for this.)

Thus if you sand the door down a little bit, not a big deal as your microballoons will fill in the gap, as I said.

In my case, I used a hidden hinge and Hartwell Fasteners, which worked great.
 
N941WR said:
I like to think working with fiberglass is like working with drywall. If you bugger it up, put some more filler in there and sand it to match.
Click to expand...

That was my thought exactly. I figure that however ugly things get, I can grow back fiberglass.

I'm still not too worried about the door. My mistake was following the Sam James instructions! I still don't see how the expectation was to use the piece you cut out as the door. If I just decided to toss the door and make a new one, I would have drilled four holes in each corner to make sure each have the same radius. In fact, I almost accidentally did that!! I marked the holes and picked out the drill bit. I then double checked everything and realized that would screw up the door that I was to make from the scrap piece. Oh well.

Believe me, I know all about planning out a job beforehand. I do it as my job! I also work with procedures and I believe them. THAT is my downfall here!! :(

Thanks for all the great suggestions. I have a plan now.

So, I went to Tap Plastics today looking for flox. The guy never heard of it. They had Cab-O-Sil (which I already have and am familier with), microspheres, milled glass fibers, and chopped fiber glass. I bought a can of the milled glass fibers. Would microspheres be better?

Who knew that my dirty landry would make the front page of VAF!! Thanks DR. :( I expect that my good looking door will make it to the front page as well, right? That's assuming that I CAN make my door good looking. :)
 
fiberglass fillers

as far as fillers go. cabosil is a thickener. micro balloons add volume to your mix , and milled fiber adds strength. I like to do a combination of the three. so if you have say a dixie cup of resin( a few ounces) I put in a pinch of milled fiber for stength a pinch of cabosil so your mix will hang in place and finish thickening it up with balloons. if you just use cabosil you will get a hard heavy syntactic(glue) also it can get hot when it kicks off if you have a big mass of it. I posted some pics the other day of my oil door if you like to see look for the oil door hidden latch post.
happy building
-E-
 
Thanks for the info. Yea, I saw your door. If mine ends up half as nice as yours I'll be happy.

I'm finally going to be able to continue working the door this weekend.
 
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