Designing 90° Sheet Metal HVAC Duct – Advanced Tip 2

In part 4 of my making a Sheet Metal Duct guide, I showed how to get the best material yield. Today I’m going to show you how to add etch marks so that all parts can be rolled together as one, zip cut, reordered and then welded together.

Sheet Metal Parts in DraftSight

With the parts already placed together, copy it and move it beside the original making sure they are aligned.

Create a duplicate in DraftSight

Next, draw a vertical line upwards, but have it aligned with the bottom. Draw this according to your manufacturing standards, I am using 4 inches and then drawing a horizontal line across both group of parts.

This next segment makes the drawing very busy, but I promise it’s for a good reason. Use the “Copy” command to copy the two lines we just created and make the attachment point the bottom of the vertical line. Don’t use the Ctrl+C as this is a different command to the “Copy” one. What I did was “Copy” a few segments, stopped, then copy all the entities I just created to make this go faster. A good example is the picture below.

Lines added in DraftSight

With all the lines added we can now trim each group. Use the “Trim” command and select all the horizontal lines we created. Next, we are going to select every other section. On the other group you are going to trim the opposite lines to remove, just like the picture below.

Trimmed lines

On the pattern to the right I added a horizontal line on the outside top right corner (dimension doesn’t matter here),  then deleted the outside box. In the layers area I created a layer called “Etch” and switched the color to magenta. I placed the right group of lines in the new created “etch” layer and colour.

Etch layer added

There are a couple steps remaining. Use the “Move” command and the selection point to choose the inside point on the new horizontal line and attach it to the other group. This should line both groups up perfectly. The last step is to delete this line, center the view and save your work.

Move etch lines into place

This will make your laser machine etch the magenta lines and cut the white lines with proper set up in the nesting program. This also enables all parts to be rolled at the same time, which will save manufacturing time and provide uniform rolling.