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DIRTY WELDS ARE NEVER STRONG, CLEAN YOUR METAL BEFORE WELDING
The key to any good weld is clean metal, but what is the best way to clean metal before you start welding? Depending on the tools you have and the overall goal of the project there are a few ways to prep your metal to get a nice clean weld every time.
The best welds come from pure clean metal to metal contact, any foreign materials in the welding area can cause welding imperfections. Even brand new metal must be prepped before it can be welded because there is usually a coating put on new metal so it does not rust or oxidize during the shipping process. This is a factor that is often overlooked and will always result in a weak and ugly weld. Be mindful, once you remove this coating the metal is exposed to the elements, if left out unprotected steel will begin to rust, even indoors.
To start, the type of welding you are doing will determine how you prep the metal. Inherently MIG welding steel does not need the metal to be perfectly clean. On the other extreme, TIG welding aluminum requires contaminant free metal to create a strong clean weld. In all of the examples below you can see the difference the dull color of the "new metal" (left) compared to how it looks after it is properly prepped (right).
Angle Grinder with Flap Disc
Using an angle grinder with a flap disc works great to prep steel for MIG or TIG welding. Mild steel does not require the surface to be super clean to get a good weld. In the picture above you can see the left side is brand new untouched steel, it may look clean but it has a thin coating like stated earlier. Once you remove the coating with the flap disc, all it takes is a quick wipe down with Low VOC PRE or Acetone and you will be able to make clean and effective welds. This method works great for heavy welding on chassis parts, this area is always exposed to the elements which will build up contamination over time. Take the time and clean the metal, you'll thank yourself later.
Be careful a flap disc will remove a lot of material so don't use this on thin sheet metal, it may compromise the metals strength.
Similar to using a grinder this method will work great for MIG and TIG welding steel or stainless, but it can be time consuming and does not always remove all of the coatings. Like using a grinder, you must wipe the metal down with Low VOC PRE or Acetone before welding. In the picture above I used 80 Grit sandpaper, it worked well by removing the coating but also left deep scratches that may not look good.
If the metal you will be welding is very rusty and is not suitable to be sanded or removed with a grinder another option to prep the metal is to blast it. After blasting the metal may look clean but it will still need to be wiped down with Low VOC PRE or acetone to remove and chemical contaminants. The abrasive material can sometimes trap pieces of other metals that can cause the metal you are welding to rust or corrode. Never rely on a blaster to prep aluminum for welding, it is very sensitive to contaminants that can get trapped even after wiping it down.
Cleaning for aluminum TIG Welding
When prepping aluminum there is a slightly different process that you will need to be mindful of. Aluminum is very susceptible to contaminants therefore the cleaning process must be done in reverse to produce clean welds.
First you must wipe down the metal with Low VOC PRE or acetone, this will remove any oils or grease on the surface. The next step is to remove any oxides on the surface of the metal. To do this use stainless steel wool or a stainless wire brush on the area to be welded. Make sure that the Steel wool or wire brush is used exclusively for aluminum to avoid contaminants from other metals. Once these tools come in contact with mild steel they can transfer steel bits into the aluminum which will eventually create rust. Finally wipe down the metal with Low VOC PRE or acetone with a clean cloth or rag, from here you are ready to weld.
It doesn't matter what kind of welding you are doing its always important to take the time to clean your metal before welding. Not only will your welds look amazing they will be a lot stronger which is always an added bonus.
Check out the Eastwood Blog and Tech Archive for more How-To's, Tips and Tricks to help you with all your automotive projects. If you have a recommendation for future articles or have a project you want explained don't hesitate to leave a comment.
- James R/EW
DONT LET BODY WORK GET IN THE WAY OF FINISHING YOUR PROJECT
One of the scariest aspects of vehicle restoration is body work, especially when it comes to filler and sanding. The worst thing to do is avoid it until the end, then be forced to pay someone else to get the work done. With help from Eastwood you'll, learn all the correct steps to basic body work, save money, and feel more accomplished in the end.
Above you'll see the small dent that I'll be repairing, very similar to a door ding you may get in a parking lot.
1. First clean the area you will be repairing, use PRE or acetone to remove any contaminants from the panel.
2. If necessary use a Hammer and Dolley and rough out any dents. Depending on the severity of the dent this may not be required. Filler should not be applied more than 1/4" thick, any more and there is a risk it will crack. With that said, any damage less than 1/4" deep may not need to be hammered out.
3. Sand the area about 5 inches on all sides of the dent with a 80 Grit Sanding Disc on a DA Sander. During this step do not worry about getting the area completely smooth, just remove the paint to expose bare metal around the dent. If you don't have a DA Sander, a 120 Grit Flap Disc on an Angle Grinder can be used. (Be careful, Flap Discs tend to remove a lot of material, very quickly.)
4. Using 80 Grit Sand Paper, hand sand the edges of the paint removed area so there is a smooth transition from clear, to base coat, to primer, then to bare metal. Do not use anything finer than 80 Grit because the sanding scratches allow the filler to mechanically bond to the panel.
5. Mix and apply Contour Body Filler, make sure to use even pressure while applying. This will reduce the need to go back and apply more after you have sanded the first layer. While mixing make sure to follow the correct mixing ratio. If too much hardener is added you will not have enough time to effectively apply the filler evenly. Additionally make sure to use something other than cardboard to mix on. Small cardboard fibers can get into the filler and contaminate the mix. If you don't have Quick Sheets, take a 1'x1' piece of sheet aluminum and bend one side 2" up to 90º. File the edges smooth and now you have a reusable mixing board that wont rust.
6. Use 80 Grit PSA on a Sanding Block for initial shaping, then 120 Grit PSA for finer smoothing. Then use an Blow Gun to remove sanding dust. During this step do not worry about getting the surface perfectly smooth, Glazing Putty is still to be applied.
7. Wipe down the panel with PRE or acetone to remove any contaminants and oils.
8. Mix Contour Glazing Putty making sure to follow the correct mixing ratios like stated above. Glazing Putty should be applied very thin because it's purpose is to level any small imperfections still in the panel after the filling process.
10. Blow the sanding dust off using a Blow Gun, then spray the panel with a heavy coat of PRE. The heavy coat will help you detect imperfections. If the repair looks good wipe it down with a prep rag and you are ready to prime and paint.
Unless you are a pro, sanding blocks are the go to tool when leveling filler. You may see others using a DA Sander but this takes a lot of time and practice.
Check out the Eastwood Blog and Tech Archive for more How-To's, Tips and Tricks to help you with all your automotive projects. If you have a recommendation for future article or have a project you want explained don't hesitate to leave a comment.
- James R/EW
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