Friday, November 26, 2010

Seat Back Inside Filleted and Glassed

Today I finished gluing, filleting and glassing the inside of the seat back structure. The panels had to be held together somehow, so I used duct tape along the edges. The tape will probably leave behind some goop or trap some resin, but that should be reasonably easy to sand off later.

I planned to do the filleting and coating the panels with resin and glassing of the joints at the same time. In preparation for this glass strips for the joints were measured and cut. I chose 6 ounce tape for the top triangle and rear joints, and 12 ounce strips joining the front side panels with the rear side panels.

The panels that were previously epoxied were sanded about 1.5 to 2 inches from the edges so the new resin would adhere better. A sanding block was initially used, but with the uneven surface it turned out to be better to use my thumb against the paper.

I mixed two heaping spoonfuls of filler resin and one of hardener in a cup, using a chop stick and one of the spoons. After putting this to one side I then mixed half of a beverage cup of clear resin and hardener.

After laying the seat back on its side I opened up the tape on one edge and unfolded the panels. This exposed the joints. Clear resin was then applied to all edges and the interior surfaces, sealing the wood.

Filler resin was spooned onto the open joints and slightly smoothed. The panels were then folded back into place and the opened edge taped closed.

Since the top was also being glued onto the seat it was easier to continue working on the interior by standing the seat on the top. The fillets of the interior vertices were then filled the rest of the way and smoothed, first with a spoon and then with the squeegee.

The tape was then applied to the edges and wet with additional resin, which was worked into the cloth using the squeegee.

Along the way the duct tape on one of the edges loosened up a bit. It needed some help by applying some pressure against the panel with a heavy iron block.

As there were some small voids here and there between the edges of some of the panels I applied some additional fillet material with the chop stick. Excess material and resin was wiped off with a paper towel.

I originally thought I'd insert the foam bulkhead after the glass and resin were applied. However, the relatively tight fit of the foam and the relative fragility of the seat back prior to the resin setting made me change my mind. I'll do it tomorrow instead - after sanding the exterior and before glassing the outside.

Monday, November 22, 2010


I have not too much to blog this time. A trip to Harbor Freight resulted in the purchase of several packs of sandpaper, a hand sanding block, seven $3.50 adjustable 12" clamps, a bag of sponge brushes and a couple of plastic putty squeegies.

Following this I spent 3.5 hours of quality time sanding the sides of the two stabilizers. The 100 grit paper was pathetically slow at removing material, and wetting it didn't help - particularly since it was not wat-or-dry.

Switching to the 220 grit wet-or-dry actually did better, and certainly kept the dust from becoming airborne. Still, I resorted a couple of times to the belt sander in several areas where the resin ridges were just not wearing down rapidly enough for me.

There are a couple of spots on one stabilizer that were sanded down to wood. Ouch! Those were near the edges, so it is just more incentive to tape the edges as they will be most likely to hit things - and the extra tape will help protect them.

There were a couple of places on the edges where it looked like the resin didn't quite saturate the cloth. We'll see if the next resin and tape application will fill those spots, but it would probably be better to sand them down to the underlying resin - which I did in most of the places.

Still, after going through half of the pack of 220 grit I'm rebelling against the hand sander. An electric random or orbital sander is on my next on my list to purchase.

Monday, November 15, 2010

Tips Taped, Seat Backside Glassed

On Sunday I spent time removing the excess glass and resin from Saturday's wrapping of the stabilizer bottoms and sides. It was definitely too late, but I realized that the cloth didn't need to extend up the side more than a couple of inches. This would have removed any need to trim the excess glass, and would almost certainly have prevented excess resin from dripping down the side and off the top of the overturned stabilizers. The end result would have been a bit lighter, too. Oh, well - next time!

The resin covered interior face of the seat back panel managed to get imprinted with the wrinkled shrink wrap plastic that kept the paint can and the iron block free from sticking. It took a bit of sanding to flatten the pattern, but it was still visible.

Hand sanding the fillet managed to nearly finish off the abrasive coated sanding mesh I was using, but what really started doing it in was hand sanding the bumps and excess glass on the stabilizers. I finally gave up and resorted to the belt sander. That was much faster, perhaps a little too fast in some areas - which will need some re-application of glass and resin - and a bit too slow in others.

Regardless, it looks like there will be a lot of sanding in my future, coupled with applying more resin to smooth out the fabric pattern.

For the seat back I cut a piece of 6 oz glass "boat" cloth, and made sure it covered the side panels and seat back. I then took some 12 oz 45/45 degree knit cloth pieces that I had cut originally to be used to wrap the ends of the stabilizers, but decided were too thick for that purpose, and fit them over the fillet areas. This should help spread the forces from the seat to the rest of the seat back structure.

I removed the cloth, smeared resin on the panels, and applied the 6 oz cloth. It was somewhat of a pain to get it to cover the seat back, the fillet and both sides without there being any air gaps, bubbles or excess cloth at the fillets or on the sides.

Trying to wet out the 12 oz cloth in place was worse. It took a lot of resin and a lot of kneading it into the cloth before the silvery white cloth finally turned translucent. The loose ends tended to fuzz, and generally made a mess. I'm sure glad that this side won't be visible!

With the remaining resin I wet the tips of the stabilizers in preparation for taping.

I took some 6 oz glass tape, cut it into short segments, and applied them to the tips of the stabilizers on top of the resin. The width of the tape would have been nearly a perfect match for the bows, but I decided instead to run the tape vertically. This way the ends would overlap the top and bottom of the tips, where they could be folded over and better cover the plywood.

Again I used my gloved fingertips to work the resin into the cloth, pulling the resin soaked fabric against the panels on both sides simultaneously with thumb and forefingers.

Once the cloth was soaked and in position, some shrink wrap plastic pouches were used to cap the ends. Using some scrap foam rubber to wrap around the tips, and pairs of 1/2" boards and C-clamps, pressure was applied to the tips to provide a poor man's vacuum bag.

It was time to call it a day!

Saturday, November 13, 2010

Glassing Stabilizer, Glueing Seat

Things are going slower than expected, mainly due to family matters and other commitments.

A week ago I was about to update the blog with the relatively minor progress of rounding the edges of the stabilizers and preparation for glassing the outsides. The weight of the two stabilizers are within 1/8 ounce of each other (3 pounds, 13 and 3/8 oz for one and 3 pounds, 13 and 1/2 oz for the other).

To be completely honest I have been procrastinating about putting the seat together. I think I have come up with a workable layup schedule for it that won't require too much in the way of clamp coordination, be fairly pretty and still be strong enough to handle the loads. It will take maybe two days to do it, with the proper partial cure times for the resin, so that the wood will be properly sealed, glassed and bonded and filleted together.

Anyway, I spent an hour one day taking the 38 inch 3.8 oz. cloth and cutting it into 17 inch wide pieces, leaving a 4 inch wide tape that could be used for seams somewhere. The width should be enough to have an inch of fabric drape beyond the sides of the stabilizers when they are glassed. The lengths were enough to extend a couple of inches beyond the ends.

This morning I got out of bed, got dressed, and headed to the garage to start the process. After double checking that the seat back and two side pieces would fit reasonably flush, and setting the stages for the two stabilizers, I mixed the first batch of resin.

Resin was first applied to the back of the seat panel and the insides of the side panels. It was next applied to one side each of the two stabilizers. This left only a little resin in the bottom of the cup, which would cure more slowly than if the resin had not been dribbled onto the stabilizers.

Next, I squeegied the resin over the seat back and side panels, making sure that the edges of the side panels that would glue to the seat back were fully saturated. I then mounted the side panels onto the seat back panel, using plastic wrapped paint cans and plastic wrapped steel blocks for weights to flatten the seat back and to provide vertical alignment for the side panels.

Returning to the stabilizers I squeegied the resin over the side of one stabilizer, then did the same for one side of the stabilizer before running out of resin. Time for another resin batch!

After mixing the second batch I flipped the stabilizers onto their sides and squeegied the remaining sides and tops with resin, trying to keep them from dripping too much.

I took the first piece of pre-cut glass and tried draping it on the stabilizer by myself. This was a bad move, as not only did I not get it centered from side to side but I didn't get it centered from end to end!

After lifting it off and trying several more times I finally managed to get it more or less centered, and spread from end to end, completely gooping my latex gloves in the process.

All was not lost, however. It turned out that the gloves worked quite well in smoothing out the wrinkles, bubbles and folds, working the resin into the fibers and making it lay nicely over the curved edges.

One down, one to go!

I finished applying resin to the second stabilizer, and called to my son to assist me with draping the cloth on it.

After a couple of false applications we managed to get it pretty well centered. I used the squeegie a little, but went back to using the gloves to work the cloth into the resin and saturate the fibers. By this time, however, the resin was starting to thicken and it was taking a bit more work to get the desired results.

The remaining resin in the cup was getting quite thick and couldn't be used, either. Rats!

As it turned out, there were several small puddles on the plastic below the stabilizer where excess resin dripped. This stuff was still quite liquid, and there was just enough to apply to the remaining dry sections of cloth with my glove-covered fingertips. Yay!

I double checked both stabilizers and made sure that there were no obvious bubbles, wrinkles or dry spots. The ends were also checked, but the cloth seemed to be behaving there with no extra clamping needed.

The remaining resin in the cup was now a thick, gooey blob. This was scooped out by hand and spread on the side of the foam seat bulkhead to glue the shim to it.

Later today after things have set it will be time to trim the excess cloth on the stabilizers and apply cloth to the bottoms, and to fillet and glass the seat back.