BadReligion
SILVER Star
Other than rattle can painting an occasional wheel or set of sliders, or pushing out massive quarter panel dents on my 80 series, I have never actually done any proper body work that involves filling holes, sanding, priming, painting, etc.
I recently picked up a pretty nice 40 series ( Bought my first 40! 36k mi 1974 FST. ), and while it is in overall great condition, there were a few previous owner modifications that I am reversing. One of those was an addition by the PO of custom running boards. While the original 5 holes from the stock running boards were used, they also drilled a total of 4 extra per side into the lower rockers. Three of these are small (0.30") but the 4th is larger (0.45"). My plan is to weld those up, repaint the repair, and then mount a new set of OEM running boards that I just purchased.
Knowing that there are going to be several projects like this on the 40, I did buy a welder (Miller Multimatic 220) and have spent a few hours learning how to weld as I plan on doing all of the repairs myself. After "filling" plenty of various size practice holes in 16ga metal, I am ready to weld on the 40 but just wanted to make sure my proposed plan is mostly correct. I know there are probably a few ways to do it so any advise or input would be helpful.
When filling the practice holes, I used one of those magnetic copper spoons as a backing. The small 0.30" holes were pretty easy to evenly and completely fill in a single pass, while not putting too much heat into the metal. However, the 0.45" holes were definitely more challenging. While they could be done in a single pass and filled in thoroughly, this produced a lot of heat and caused the metal to warp. Several passes a few minutes apart seemed to prevent warping but required a bit more clean up, which also puts heat back into the metal. I did experiment drilling out the holes to 0.5" and welding in 1/2" 16ga metal discs/blanks. That seemed to work well so I may use that method for the larger holes but single pass method on the smaller ones. I was using Hobart ER70S-6 0.030 wire, but may go down to a 0.024 wire. With the Multimatic, I would simply select 16ga metal on the parameter screen but slightly dial down the voltage by 0.2 or so and slightly decrease wire feed speed. Using a 75% argon, 25% CO2mix at 18 CFM.
The paint on the 40 is probably a 6/10 (no rust but obvious cheap single stage respray) so my paint job doesn't have to be perfect. I don't plan on repainting an entire section of body, but instead just respraying the rocker and trying to blend the new paint slightly into the old. From what I have read, once the welding is done and cleaned up, the bare metal needs to be primed. It seems like most people in this section like epoxy primers, especially if you plan on painting next to existing paint. If I understand correctly, self etching primers can eat away at the old paint if there is any overspray. However, with an epoxy primer, you need to paint over that in a several day period, otherwise the epoxy completely dries and the final paint will not adhere.
So if using an epoxy primer on metal, the order would be;
1. clean metal with acetone, spay on epoxy primer
2. apply high build primer (high build 2k) and block sand to get level
3. wet sand with some 600 grit, clean again and then apply final paint
4. wet sand with 800 or 1000 grit if needed to clean up, then go through various cutting/polishing compounds with orbital polisher
Did I get this right? Also, when welding on the truck, obviously I want to get the ground clamp as close as possible to my work, but should I also disconnect the battery and possibly fuse panel?
Here is a shot one of the rocker panels:
I recently picked up a pretty nice 40 series ( Bought my first 40! 36k mi 1974 FST. ), and while it is in overall great condition, there were a few previous owner modifications that I am reversing. One of those was an addition by the PO of custom running boards. While the original 5 holes from the stock running boards were used, they also drilled a total of 4 extra per side into the lower rockers. Three of these are small (0.30") but the 4th is larger (0.45"). My plan is to weld those up, repaint the repair, and then mount a new set of OEM running boards that I just purchased.
Knowing that there are going to be several projects like this on the 40, I did buy a welder (Miller Multimatic 220) and have spent a few hours learning how to weld as I plan on doing all of the repairs myself. After "filling" plenty of various size practice holes in 16ga metal, I am ready to weld on the 40 but just wanted to make sure my proposed plan is mostly correct. I know there are probably a few ways to do it so any advise or input would be helpful.
When filling the practice holes, I used one of those magnetic copper spoons as a backing. The small 0.30" holes were pretty easy to evenly and completely fill in a single pass, while not putting too much heat into the metal. However, the 0.45" holes were definitely more challenging. While they could be done in a single pass and filled in thoroughly, this produced a lot of heat and caused the metal to warp. Several passes a few minutes apart seemed to prevent warping but required a bit more clean up, which also puts heat back into the metal. I did experiment drilling out the holes to 0.5" and welding in 1/2" 16ga metal discs/blanks. That seemed to work well so I may use that method for the larger holes but single pass method on the smaller ones. I was using Hobart ER70S-6 0.030 wire, but may go down to a 0.024 wire. With the Multimatic, I would simply select 16ga metal on the parameter screen but slightly dial down the voltage by 0.2 or so and slightly decrease wire feed speed. Using a 75% argon, 25% CO2mix at 18 CFM.
The paint on the 40 is probably a 6/10 (no rust but obvious cheap single stage respray) so my paint job doesn't have to be perfect. I don't plan on repainting an entire section of body, but instead just respraying the rocker and trying to blend the new paint slightly into the old. From what I have read, once the welding is done and cleaned up, the bare metal needs to be primed. It seems like most people in this section like epoxy primers, especially if you plan on painting next to existing paint. If I understand correctly, self etching primers can eat away at the old paint if there is any overspray. However, with an epoxy primer, you need to paint over that in a several day period, otherwise the epoxy completely dries and the final paint will not adhere.
So if using an epoxy primer on metal, the order would be;
1. clean metal with acetone, spay on epoxy primer
2. apply high build primer (high build 2k) and block sand to get level
3. wet sand with some 600 grit, clean again and then apply final paint
4. wet sand with 800 or 1000 grit if needed to clean up, then go through various cutting/polishing compounds with orbital polisher
Did I get this right? Also, when welding on the truck, obviously I want to get the ground clamp as close as possible to my work, but should I also disconnect the battery and possibly fuse panel?
Here is a shot one of the rocker panels:
Last edited: