More etching / the smallest rivet I can etch?

[peteski]

This is actually made from two etched parts layered over each other: the bottom layer is the vertical grille lines, and the top layer is the doors/hinges.  The metal is 0.010" phosphor bronze and the raised grille lines are the full metal thickness.  (note, both top & bottom parts were etched with an overlapping border frame, to help align them.)

I'm confused by "raised grille lines are the full metal thickness". To me it looks like the bottommost piece is a rectangle with the vertical grille lines half-etched.  If they were "full metal thickness" or 0.010", wouldn't the plastic loco shell be visible through the slots in the grille (etched all the way through the 0.010" metal)?  Or did you mean that the width of each vertical grille line is 0.010"?

[bbussey]

Thank you. A couple of us are working on a locomotive and there about 4 versions of the tender. In the final revision we plan to include all variations on the fret but I would like to nail down what size of rivets look the best otherwise I'll have to include two or three versions of each set of sides to allow for various rivet size choices. This is why I was planning to do a test.

I thought of including my side that I have done, also some other various sizes of rivets, a few panel lines and finally some folds so I can test how wide fold lines need to be, and how best to account for how they affect the length of a piece once folded.

Unless this information is available somewhere.

I did adjust my drawing as you suggested. I changed the .005" rivets to .008", and the .006" rivets to .009".

You may have to bump the larger rivets to .010, or shrink the smaller rivets to .007 to see the difference on the model.

Also, for 90-degree bends and less, make sure your fold lines are on the inside face. For 180-degree bends, the fold lines should be on the outside face.

[craigolio1]

Awesome tips. Thanks.

[ednadolski]

This is actually made from two etched parts layered over each other: the bottom layer is the vertical grille lines, and the top layer is the doors/hinges.  The metal is 0.010" phosphor bronze and the raised grille lines are the full metal thickness.  (note, both top & bottom parts were etched with an overlapping border frame, to help align them.)

I'm confused by "raised grille lines are the full metal thickness". To me it looks like the bottommost piece is a rectangle with the vertical grille lines half-etched.  If they were "full metal thickness" or 0.010", wouldn't the plastic loco shell be visible through the slots in the grille (etched all the way through the 0.010" metal)?  Or did you mean that the width of each vertical grille line is 0.010"?

The vertical grille lines themselves are not etched, so they are the full thickness of the metal.  The rest of the part is a front-side half-etch, including the space between the grille lines.  The end result is that the grille lines stand 0.005" above the half-etch surface. (There are no holes in the part that go completely thru the metal.)  When trying the different sizes,  I varied both the width of the grill line and the spacing between them.

The part with the doors is also mostly a front-side half etch.  The holes over the grilles go completely thru, and the hinges/latches are the full thickness.  Note how the etching process tends to 'round over' all the edges -- if you look under magnification, it has a bit of a 'melted' appearance which is a result of the etchant.

The plastic shell under the grille/door area was completely removed, so that the parts could be properly flush with the rest of the shell surface.

Ed

[peteski]

Thanks for the explanation Ed - as soon as I started reading your latest post I realized what my brain did .    I was thinking in terms of "negative space", as in the etched slots between the grille bars, not the bars themselves.  I get it now.

[ednadolski]

Thanks for the explanation Ed - as soon as I started reading your latest post I realized what my brain did .    I was thinking in terms of "negative space", as in the etched slots between the grille bars, not the bars themselves.  I get it now.

NP    I went with that direction because, while I heard that multiple depth etchings are possible, I've never done them and it just seemed simpler in this case just to put two layers together.  I'd expect multiple layers would add significantly to the cost, if it required multiple phototools, maskings, and passes thru the etchant.  For me it would not save much except for a few square inches of space and some assembly time.

Ed