55 Wagon Progress

[MP&C]

Thanks for following the thread! The day job kept me travelling much of last year, so the posts were few and far between. I'm trying to catch up a bit now..


I've got a couple threads I did on the donut dolly, one on 18 ga cold rolled steel using my fake donut dolly, and another on a flat of sorts aluminum door, that seemed to respond much better. I think the factory 19 ga steel would respond much better than the 18. But anyhow, here we go...

Donut on steel:

One of the guys over on the metal shaping web sites has a neat tool he sells called a donut dolly. It works more proficiently in off-dolly shrinking a crowned panel because it supports the bottom side in more than one spot (around the perimeter) as the panel is bumped from the top in the center of the donut dolly. This would seem to be useful in body repair, especially to address high spots found after blocking primer where heat would not be as feasible.

A few days ago, someone on another forum asked for advice in removing an outward roof dent. I suggested a low-buck alternative to the donut dolly, simply using a PVC pipe fitting. Where it may not work as aggressively as the donut dolly which has more mass, sometimes slower is better, especially when trying something new. I just today got around to trying this process in the shop, and rather than use the roof of something sitting here, we will use a piece of 18 ga CRS to simulate a roof.

Grid layout for the Wheeling Machine, and completed "sample" roof...








The first order of business should be to make some profile templates. In the case of an actual dented roof, use the opposite, undamaged side. This will allow you to check your progress as you go, and easily find the remaining high spots.








Using a crowned body hammer, a "dent" will be added from the back side, crossing both of our template areas.





With the dent added:











I chose to use a PVC elbow, it had two different sized ends for two tools in one. As with any body tool, they should be free of any burrs that may mar the metal surface. I also added a slight radius to the edges...








Holding the dolly against the bottom of the panel, you can see that due to the dents it only touches the panel at the red arrows. Based on off-dolly principle, the shrink would occur more prominently in the direction of the red arrows.





Here are the tools we will use today:





After some off-dolly bumping:





Check with the templates








Progress....these are light taps only with the hammer. We just want to bring down the high spots, not create craters.










Here's where I finished up...










I have a little over an hour in making the panel, denting, and removing the dent. Where I still could have gone a bit more, it was about to a point where high build primer should have masked any remaining imperfections. This dent removal could also have been accomplished with heat shrinking using an O/A torch, etc, but for those times where you may not wish to use heat and want another option, this seems to work well. I think with using the donut dolly and it's heftier mass, one could shave some additional time off the repair

[MP&C]

Donut on Aluminum:

I had a left over door from a bus repair earlier this year, and as it was damaged the least, we thought to keep it as a starting point. New ones in primer go for just under 1K, so I think we can save some money here....

The last time I used the "donut dolly" was with the low crown body hammer (the flat one) but when I tried it on this flat panel, progress seemed to be rather slow. I think the low crown hammer was better matched to a crowned panel, and with this panel being flat, I may have better luck with a crowned face body hammer. So as we're starting with bent metal anyhow, what's a little trial and error going to hurt? I'll just keep my fingers crossed that the hammering force would not be great enough to pound dents in the other direction. (we're looking for consistency and moderation )





Here's our dented sample today, an aluminum door skin with a nice crease that travels just about the full length of the door.













As the donut dolly is very closely matched in size to the hammer diameter, accuracy in locating the devices opposite each other is crucial. Depending on the panel you are repairing, this may be a challenge in itself. To keep the tools properly aligned and thus provide a more efficient shrink, I suggest a grid on either side, matched to identical starting points.








I numbered every fifth one just to keep better track of where I was. Some days you need all the help you can get. Also shown is the damage before starting, located at grid 5, 10, and 15, just for reference of our progress.











As I am working with a flat panel, I am able to use a straight edge to monitor the progress and see where additional shrinking may be needed. If you are using this process on a crowned panel, I would suggest making a profile template matched to the undamaged side of the car. Also, seldom does the crown on a panel remain consistent from one end of the panel to another, so it is very possible you may need different profile templates to accurately guage different sections along the panel.

After about 30 minutes of work, here are the results, again located at grid 5, 10, and 15.











And the light reflection shows considerable improvement over the first pictures....








This is now at a point we could strip the paint off the door, and any remaining defects would be taken care of with high build primer.

It was difficult to hold a hammer, donut dolly, and camera all at once, so what you don't see is that the hammer is used on the inside of the door, or "high" side of the dent, and the dolly was used on the outside, or "low" side of the dent. So that shows the theory of the donut dolly, basically using off-dolly principle but by spanning a dent/ding, the off dolly benefit is realized on both sides of the dent for more effective bumping.

[MP&C]

This picture shows the actual donut dolly instead of the PVC fake. As you can see, a bit more mass...

[MP&C]

Started the prep for shaving fender number two.....

















Then the top of the seam was trimmed....











When trimming along through the center, I noticed a weak spot on the back side....








This is where some dirt had been trapped behind the bolting plate on top of the flange, and looks like it wouldn't have been long in coming through paint. To be able to trim the pitted area out, the lower section was trimmed with about 3/16 extra... see the scribe mark...



Planished flat..





Clamped over fender and scribed....





Trimmed for tight fit. Note that butt weld clamps are used to hold for fitment only, joint will be butted tight when welding...




until next time....