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I have a couple dented pieces of ductwork nordfab. Trying to come up with the best idea to put it back round again. Looking to the brain trust for ideas too. Is there a simple way i am not thinking about? Nordfab fas a rolled outer edge ill need to preserve too. Thanks for any ideas.
Body shop technique... Drill a hole in the middle of the dent. Insert a sheet metal screw. Pull the dent out. Remove the screw. Bondo over, or just aluminum duct tape. Repeat in as many locations as necessary. I've seen a specialized slide hammer with a screw tip intended for exactly this purpose.
How much dented, crushed, slightly creased? Do you want it to look pretty or just be the right cross section area? Maybe some photos.Quote:
Originally Posted by Mike Heidrick
The nordfab has a clamp that spans the rolled edges on each piece so its function more than pretty as you want it to be air tight.
Metal fabricators sometimes drive steel balls (sized just under a pipe's inside diameter) through a bent or dented section. In effect, hammer the dent from inside. That works on jobs like fluid line and exhaust pipe.
In your application, I would lathe turn a truncated cone with the major diameter about 1/16-1/8" smaller than duct ID, and the minor diameter small enough to nudge under your worst crush zone. Bore a hole in the center of the cone for a stout rope. Pull the cone through the duct; the cone will self-align. Straight duct: no sweat. Sweeps: shorten the cone. Ys and vari-angles: use a disk of 3/4" ply and hope it doesn't turn sideways (no harm, but no dent removal).
BobV
I use galvanized pipe nipples as anvils. Spend some time sanding the pipe smooth so it leaves a nice finish on your work piece. The pipe doesn't need to match the diameter of your ductwork, but the closer the better. Some judicious hammer tapping will get you round. Again, a smooth surface on your hammer face nets a better surface on the work piece.
The metal at the bottom of a crease will be shrunk, and the surrounding metal will be stretched. Some time tapping along the bottom of the crease with a blunted center punch against your anvil will stretch that crease and relieve the surrounding metal.
If you're worried about your dent-removal skills, grab a section of vent from Home Depot or the trash or whatever, bash it with a hammer, and practice on that before you work on your important stuff.
Great ideas. The pieces with out of round edges are 6" and 4" I believe. I may make a few circles on the cnc, glue them up, and taper them on the shaper.
A Cherne plug might do the job.
Bill D.
That is what I would do make a swedge and be done with itQuote:
Originally Posted by Mike Heidrick