Monday, July 23, 2012

Quarter panel filler work

I continued to use my forward momentum to blow through the next step of the quarter skin repair, completing in a week what I used to drag out for months (literally, sometimes).

The first step over a new weld is fiberglass filler.  I also ran tape along the very top of the body line, so when filler squished over the top I could rip it off when I pulled the tape off.  The tape will keep the filler even on the top lip of the quarter.  I also skimmed the B pillar/sail panel with polyester filler as it was extremely wavy.

This is my helper, Junebug, our 7 mo. old Golden Retriever.

After fiberglass, I ran two skim coats of polyester filler (Marson Platinum), with each single skim running the entire length of the panel.  The skim extends down far enough that I can feather it in to the rest of the panel to create a smooth transition.  This was the second attempt at skimming this; my first attempt resulted in one of my skims not having enough hardener and I could scratch it off with my finger.  I was on to this by the rough edges; they should be very smooth and feathered.  So I took it all off and skimmed again.  As it was, it worked out much better for me because my redo skim coats were perfect and near flawless...much better than the initial first two.  It was hot; about 90 degrees when I was skimming, and the filler was kicking quick.  I was using slightly less hardener than I normally do to try and keep ahead of it, but we all know how that turned out...

I also had to do quite a bit of building work on this quarter end cap.  I had to build the top side up about an 1/8", and build the side out about 1/8" as well as it had collision damage and did not set flush with the quarter extension when bolted on.  I use fiberglass filler for situations where I'm asking the filler to work hard, then skimming it with polyester.

Finally, as the last step before shooting Slick Sand, I shoot one coat of epoxy to sandwich the filler between epoxy.

Sunday, July 15, 2012

Botched quarter panel skin repair

I made good work of everything detailed in this entry, completing it all in three days after manning up and taking the heat in the shop for long days.  In an earlier entry I wrote about replacing a quarter skin.  The repair went well except for major warpage I encountered along the weld, and it was due to a new method I was trying.  Countless (or so it seemed) hours of on-dolly hammering to stretch was to no avail but with the warpage as pronounced as it was, there was absolutely no way it would be able to stay in this form if I wanted a straight side.

The Problem
The problem was due to how I made the welds.  I would make single spaced out tacks and let it cool naturally.  However, for the next round of tacks, I then placed the next tack directly next to the old one rather than splitting the difference between two old tacks (this latter method is how I've done all my welds up to this time).  This new method is pictured in the original entry I linked above.  It made a nice pretty weld but really affected the way the metal was pulled with each new tack. 

The Fix
By cutting the weld back open, I should be able to relax the metal and do some additional stretching.  Then reweld back shut, but splitting the difference in distance between tacks rather than laying the new tack next to the old as I did before.  Second, constantly stretching the weld area after each round of tacks should help me keep ahead of any extreme shrinkage and distortion.

I first experimented with making a ~6 inch opening of the old weld.  I found it works best to open longer sections at a time because weird stuff happens at each end of the cut.

Putting the welds back in show the best way to tack it back shut, splitting the distance between welds, as opposed to spacing tack welds out initially, then putting all new tacks next to the original tacks instead of between them.

The fix was a great success and the horrible warpage I had before is now gone.  The difference between the side of the panel is night and day.  It's puckered in giving me room to fill.  This will be a nice panel to work now.

While I was at it, I had this original corner bracket in the rear.  It was bugging me because it was all chewed up and didn't look good.  I had an extra new one so I decided to just replace it.

So I cut the old one out, carefully removing the spot welds...

And got the new one welded in place.

After grinding down the welds and cleaning it up, this is the final repair.

I prepped the panel and shot it with SPI epoxy.  I prefer to do my filler work over epoxy for maximum corrosion protection.  Filler work will begin the next day...

Saturday, July 7, 2012

Slick Sand: Sprayable polyester surfacer/primer

Today I'm going to start detailing the beginnings of my final blocking, for which I enlisted the help of Evercoat Slick Sand.  But first, everything begins with finishing up the hood scoop from where I most recently left off...

I decided I did not want the turn signal indicators in the hood scoop so...

I roughed up the edges of the fiberglass with 180

Then laid down fiberglass cloth with fiberglass resin, using a simple Bondo fiberglass patch kit that can be had anywhere (even Wal*Mart) for $20.  It's cheaper than buying the components on their own and having a lot of material left over in the end.

This is with the cured cloth/resin.

I then skimmed the opening with Evercoat fiberglass filler.

And skimmed that with Evercoat EZ Sand 2k glazing putty for a smooth finish.

The next step was to spray with Epoxy, then Slick Sand.  I bought this gun from TCP Global for about $45...with a 2.5 mm tip it's nothing short of a cannon.  It is fantastic quality and shoots the Slick Sand unreduced perfectly.

After the fiberglass had UV cured by sitting outside for 5 days, I shot it with Epoxy.

And there is no trace of a hole ever being present in the turn signal openings.  Any tiny imperfections will get covered up by the Slick Sand.

I then shot the scoop with 2-3 coats of Ever Coat Slick Sand, an extremely high build primer/surfacer.  It's actually sprayable polyester filler.  The hoodscoop was very wavy since it is a fiberglass part, and I wanted to do an experiment to see if I could completely block out the waves using only Slick Sand and no skim coat of filler.  Truth be told, I didn't think it would happen.

Tape along the center ridge line and block up to this; it will keep the center ridge straight and sharp, and prevent reshaping of the ridge line.  The Slick Sand dries quite hard and is difficult to initially block.  In the end I have found that starting with 120 works great to cut, then 220 to remove the 120 scratches.  To my surprise, after blocking the scoop down, and then shooting with another 2 coats, the entire scoop blocked completely flat without the use of any skim coating filler.
Along with the hood scoop, I also shot the roof, driver's side door, and top of the trunk with several coats of Slick Sand, usually shooting 2 at a time, blocking, then shooting more.  Here are some tips I have either read or learned on my own:

  1.  Buy a cheap gun to shoot Slick Sand.  That way if it sets up in your gun, you're not out your good gun.
  2. Buy a gun with a large enough tip.  It seems somewhat defeating the point if you buy a high build product, only to be thinned out so it doesn't build as well.   I think Ever Coat recommends at least a 2.0 mm tip.  My 2.5 mm tip was plenty sufficient.
  3. Do not leave the Slick Sand in your gun for more than 30 minutes or it risks setting up.  I did not mix more than I could shoot in 30 minutes.  At the moment I added the hardener, I started the timer, which would include mixing, spraying, and flash times.
  4. Do not use an in-gun strainer, or even filter the product as it pours into the gun.  The gun I bought had an internal strainer and the Slick Sand basically spit and sprayed poorly.  I removed that and was back in business.  I eventually even stopped filtering it as I poured it into the gun because it would take so long to drain through my filter.  Even unfiltered I had no hitches when spraying.
  5. Start cutting with 120, then move to 180 or 220 for final blocking.  Once the initial layer is off, it sands very nicely.  It will spray on with lots of peel so the initial blocking seems to bounce right over the top.
  6. A lot does not go a very long way.  I mix up half a quart at a time.  I pour out 16 ounces, and then add half a tube of hardener (11 ml, to be exact) to the 16 ounces.  The tube of hardener has graduations on the side so you can see how much to add.  One gallon comes with four tubes of hardener; one tube per quart.  Mix well (it greatly thickens upon adding the hardener) then spray, allowing for adequate flash.  Half a quart basically allowed me to shoot one coat on my hood scoop, door, roof, and trunk lid before it was all gone.  I then poured some lacquer thinner in the cup, swished around, and sprayed the lacquer thinner out to get everything out of the gun's system, then mixed up  more and sprayed a second round.  In  doing this I never end up wasting any and I don't risk it setting around too long and setting up in my gun.
  7. Spray when it's cool outside to keep it from setting up too fast.  I sprayed early on when it was 60's and 70's out.  It's been over 100 consistently for the last week or two (108F yesterday) and I'm glad I got most of it out of the way.
  8. Mask off anything you don't want overspray on WELL.  This is definitely overspray you don't want to have to remove.  Additionally, it makes the floor sticky so I laid a blue tarp on the floor and painted over this.  I had read about this ahead of time so did not have to end up with a sticky garage floor.
All in all, I have used 3/4 gallon between the roof, trunk, one quarter, one door, hood, and hood scoop.  The hood is final blocked, as is the door, roof, and trunk.  The quarter is close but will probably require another coat or two.  The moral of the story is it will probably require 2 gallons to do an entire car.  I still have another quarter to do.  I may have to end up getting another quart.

Final thoughs on Slick Sand:  Amazing build and sands great once you've cut off the top layer.  You can keep blocking and blocking and blocking before you see signs of breaking through.  The advantage of this is you can keep blocking until the last of that guide coat is gone and still have room to shoot another layer of guide coat and block it again.  It did amazing things with my quarter that definitely had a few spots my hand could feel after my metal working (and filler work), which was probably sub par at best, I admit.  I was counting on the Slick Sand to be my crutch and it really was.