Easiest, most forgiving body filler to work with?

[hansj3]

I did something stupid, and I bought an ambulance to convert into a road trip/ RV.

The aluminum on the box is kind of rough in areas, so I figure I should do something about the lights while I'm at it.

I'm only going to keep a couple of the area flood lights, and all emergency lights are going to be removed and have the holes patched up.

My plan is to use a spool gun if I can get access to it otherwise epoxy and aluminum plate to the back side of the holes, and then just backfill with the Bondo the thickness of the skin of the ambulance, about 1/8 inch at most.
I had figured the tiger hair style or the fiberglass embedded style is the best solution here but I'm not really well informed when it comes to body work

 

[redbone3]

The tiger hair is a polyester epoxy with strands of fiberglas in it. It is about the strongest filler you can find. It is one of the most difficult to sand down. The easiest to sand down is the Bondo type fillers. The lighter the filler the easier to work. Be sure to really scratch up the back side to promote adhesion.

 

[JC1]

What about getting new metal and using pop rivets to seal up the areas?

I've used bondo hair before with that mesh backing. Got the idea from Chris fix.



My repair turned out pretty good on the civic.

 

[hansj3]

The tiger hair is a polyester epoxy with strands of fiberglas in it. It is about the strongest filler you can find. It is one of the most difficult to sand down. The easiest to sand down is the Bondo type fillers. The lighter the filler the easier to work. Be sure to really scratch up the back side to promote adhesion.

How bad is it to sand?
What I'm working with, is a 4x6" opening for the back of the light. I should be able to use a 12" tape blade to level it pretty well with the surrounding areas. And block it from there. All the lights are apart of large vertical walls that have no contour or anything.

I worry about cracking a little. The chassis and the cab flex a little naturally, so does the box and the chassis. Same story between the cab and the box.

Ambulance boxes are built to a better standard, and really are pretty rigid, but I don't know, maybe some flex would get there?

 

[hansj3]

What about getting new metal and using pop rivets to seal up the areas?

I've used bondo hair before with that mesh backing. Got the idea from Chris fix.



My repair turned out pretty good on the civic.

I'm hoping to minimize holes. Both my wife and I have had bad times with molding rvs in the past, so sealing the back with epoxy or a weld seems more tempting than a pop rivet. Traditionally people just use a bare aluminum plate, and I'd like to make it more aesthetically pleasing if I have to put the work in.

 

[skyactiv]

No need to be too picky about looks. A used hearse or ambulance is viewed as a creepy vehicle by most. I would want to file down body filler before it hardens completely and be careful not to add too much harder.

 

[Trav]

Use this as the primary filler..

Amazon.com: Evercoat Everglass Short Strand Fiberglass Reinforced Filler - Waterproof Filler - 32 Fl Oz : Automotive

Buy Evercoat Everglass Short Strand Fiberglass Reinforced Filler - Waterproof Filler - 32 Fl Oz: Putty - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

If you want to fine finish it use this after sanding the bulk..

Amazon.com: Evercoat Lite Weight Body Filler - Clog-Free Body Filler for Aluminum, Fiberglass & More - 32 Fl Oz : Automotive

Buy Evercoat Lite Weight Body Filler - Clog-Free Body Filler for Aluminum, Fiberglass & More - 32 Fl Oz: Body Paint - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[nthach]

From my recollection of some 14 years ago when I painted my 2nd car, I used Evercoat Rage Gold. It sanded smooth.

3M’s higher end stuff should be fine too, as long as you avoid Bondo. In any case, try to get your metal as straight or true as possible without many high spots. Try to apply the filler matching contours as possible. A Sur-Form tool will be your friend with body filler.

 

[hansj3]

From my recollection of some 14 years ago when I painted my 2nd car, I used Evercoat Rage Gold. It sanded smooth.

3M’s higher end stuff should be fine too, as long as you avoid Bondo. In any case, try to get your metal as straight or true as possible without many high spots. Try to apply the filler matching contours as possible. A Sur-Form tool will be your friend with body filler.

Thanks for the recommendations.

Where I'm working, on my ex ambulance, things are straight, without any sort of contour. The closest thing to any contour is the natural wave the exterior panels have between roll bar hoops.

From the looks of it, drywall skills are going to be more useful than my relatively poor body skills.

 

[hansj3]

Use this as the primary filler..

Amazon.com: Evercoat Everglass Short Strand Fiberglass Reinforced Filler - Waterproof Filler - 32 Fl Oz : Automotive

Buy Evercoat Everglass Short Strand Fiberglass Reinforced Filler - Waterproof Filler - 32 Fl Oz: Putty - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

If you want to fine finish it use this after sanding the bulk..

Amazon.com: Evercoat Lite Weight Body Filler - Clog-Free Body Filler for Aluminum, Fiberglass & More - 32 Fl Oz : Automotive

Buy Evercoat Lite Weight Body Filler - Clog-Free Body Filler for Aluminum, Fiberglass & More - 32 Fl Oz: Body Paint - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

I will have to look into evercoat. Looks like lots of good reviews

 

[dan_erickson]

Evercoat Rage is good stuff

 

[Cujet]

Regardless of which "lightweight" filler you choose, the tools and methods that you use matter most.

It's impossible to deal with "bondo" if one uses poor methods. However, if one spreads it smoothly with wide tools, contours it to the proper general shape with fast cutting tools (think rough cheese grater) before it's completely hard, and only concentrates on the final finish at the end, it's a lot easier to deal with.

Also, using a "fill n sand" primer helps a lot, as the "bondo" does not need to be optically perfect.

By the way, I despise working with fiberglass cloth as a backing for bodywork. In fact, it is easier (and less time consuming) to deal with real metal in most cases. Fiberglass to repair rust is a tough one, as the rust will come right back.

One other hack I really like for old vehicles. Using hard foam (not conventional great stuff). Using low expansion foam (more dense) as a filler for very rusty panels. It can be sanded and painted and will pass inspection. It also works as a backup for bondo. It's not a lifetime fix, but it is good for Northern vehicles where passing inspection is important.

 

[ZTime33]

Regardless of which "lightweight" filler you choose, the tools and methods that you use matter most.

It's impossible to deal with "bondo" if one uses poor methods. However, if one spreads it smoothly with wide tools, contours it to the proper general shape with fast cutting tools (think rough cheese grater) before it's completely hard, and only concentrates on the final finish at the end, it's a lot easier to deal with.

Also, using a "fill n sand" primer helps a lot, as the "bondo" does not need to be optically perfect.

By the way, I despise working with fiberglass cloth as a backing for bodywork. In fact, it is easier (and less time consuming) to deal with real metal in most cases. Fiberglass to repair rust is a tough one, as the rust will come right back.

One other hack I really like for old vehicles. Using hard foam (not conventional great stuff). Using low expansion foam (more dense) as a filler for very rusty panels. It can be sanded and painted and will pass inspection. It also works as a backup for bondo. It's not a lifetime fix, but it is good for Northern vehicles where passing inspection is important.

Cujet, Can you recommend a brand or two of the "hard foam"?

 

[saber1]

I like Evercoat 105 Rage Premium Lightweight Body Filler. It is cheap bought it from amazon after reading some of its good reviews from best body fillers. It fills the grain, easy to sand, doesn't shrink, cures hard, and is easy to find at most big box home stores. It's a tan powder, add water until it is peanut butter consistency and it is ready to sand in 20 minutes.

 

[Trav]

I don't know what you used but it was not Rage, are you sure you didn't use rock putty? Rage 105 is qt size, 106 is gallon, 102 is 3 gallon. There is no mixing with water only hardener.
The 157 is a good filler at half the price, use 416 or 417 glaze for a super fine finish after sanding the filler.

 

[NitroM3]

Cujet, Can you recommend a brand or two of the "hard foam"?

I would be very concerned, foam expansion and contraction rates used on a vehicle after you apply any paint will have bad end results in a short time.
I would suggest if we don’t actually have any experienced auto body members to contact a shop or at least if you do get a name of a foam product call there tech support and ask them about what your intended use of their products is.