Welcome to part 4 of this adventure of making a large sheet metal HVAC duct. In Part 3 we saved the bodies, converting them into sheet metal parts and exported as DXF/DWG. In this final part I’m going to show you how to modify the exported parts in DraftSight to get a laser/plasma friendly part that gets the best yield out of the material.
I will start out by opening up the inlet and saving it as a different name. I used the same name as the SOLIDWORKS initial part. Next I’m opening up all the parts in order from the inlet and then copying and pasting into my main duct DXF. So in doing this I should have my 7 parts.
Editing these parts can be challenging but believe me, your boss will thank you. From the screen shot below, you can see the current parts together and note that this is the size of sheet metal you’ll need.
I’m going to modify 3 parts (every other- parts 2, 4 & 6) to fit nicely inside the other parts. I take part 2 and cut it in half, keeping both halves and then join them together on the opposite side. Take a look at the screen shot of the progression on this part.
I first start by drawing a vertical line, starting in the bottom middle to the top middle. My line didn’t snap stop at the top, so I drew past and trimmed afterwards. I then made a horizontal line on the new vertical lines mid-point. I then copied this and used the “Split” command on both sections, deleted the end lines and merged the opposite sides together. I then made this into a block and started fitting it into the inlet
Common shortcuts for commands: “L” for line, “SC” for scale, “TR” for trim, “MID” for mid-point, “Ctrl + X + V” to paste as a block and the typical windows shortcuts work here, too.
Doing this to the 3 parts, making them blocks, fitting them inside one another and now comparing the lengths before and after- you can see the difference is just over 39″ in length or over 41 square feet. That’s a big difference to the sheet metal yield. The cutting time can be reduced if the edges are shared when cutting.
This concludes this series. Please subscribe for more advanced tips and tricks on developing this duct work in the near future.