Boxcab For Chris

[sparky]

Chris- there are alternatives to ferric chloride for etching.  I've done some experimenting with a hydrogen peroxide/muriatic acid mix, and it seems to work just as well as the FeCl.  Plus, it's cheap to make and replenishable by adding more peroxide.  You can google it and find a lot of information.  Here's one link:

http://www.starshipmodeler.com/tech/fh_pe.htm

[TrainCat2]

You can, however, do multiple etchings for certain effects, but it's a lot of work and with DIY it's all kind of hit-or-miss.)

This image is an example of the effects from multiple passes through the etcher.
http://traincat2.com/images/models/1200301B.jpg

The lattice work was produced with two passes yielding 0%, 25%, 50%, 75% and 100% etched. Since there are two pieces sandwiched together back-to-back, the effects is equaled only in casting IMHO. As stated, it is not easy and requires precision.

[sparky]

Bob- your bridges (and other stuff for that matter) are awesome.  A couple of questions for curiousities sake:

How long does it take to assemble a bridge like you show in the last post?

What type of machine do you use to produce your etchings?

[TrainCat2]

Depends on the bridge. The Pratt (single or double) is around thirty hours.

I use a used resist sprayer/dryer and a converted PC board etching machine. I have to send out the artwork to be gerber photoplotted and made into tooling. I don't have that processes in house YET. The biggest problem is DERM. They are very nasty about the chemicals and waste.

[Chris333]

David has it right about the rivets and other items. They are only "half etched" Half way through.

On this door:
[img width= height=]http://lh6.google.com/ErieChris333/R5ZQvLCDA_I/AAAAAAAADLQ/xQOTiR2jEes/s800/IMG_5178.jpg[/img]

The lower panel was only etched from one side. The window was etched from both sides.

I think it was Bob who posted this link:
http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/

But I haven't tried it yet. I haven't etched anything for a while lately.

[sparky]

Chris-

I had posted that link in my earlier post, but then changed it to the "starshipmodeler" one because I couldn't get the "instructables" link to work.  The one you re-posted doesn't work either.  I'll try again:

http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/

[Chris333]

It sounds like the way to go and soon as I run out of FeCl3 I will try it.

[RDG_Rich]

The lower panel was only etched from one side. The window was etched from both sides.

Wouldn't that work in reverse then for rivets?

[Chris333]

Rich,

For rivets that bulged out (like real ones) You have to half etch the whole piece leaving only the rivets un-etched. Those passenger car sides I made have rivets that are dimples. So only the rivet is half etched. If I put the rivet on both sides of the artwork in would become a hole instead of an indent.

The problem with half etching whole pieces at home is that I don't have a pressurized tank to keep the acid eating evenly. Plus I don't have jets spraying the etch to the sheets. I'm just dipping the sheet in a tub and agitating it a bit. So I get what you saw in the boxcab piece.

You can look at Bob's bridges and see that rivet detail is possible, but he has much more sophisticated equipment. Here is one brass MFG's etching equipment:


If you want "real" rivets I would get with a professional etcher and try doing the artwork yourself. If you can live with dimples then you can do that at home.

[bsoplinger]

Since this has somewhat mutated into a general etching thread, how does one get square corners?

Obviously if you just draw a square opening, when it is etched the corner will actually get eaten so that its not a right angle. I'd guess that it wouldn't be that complicated of a shape and would be based on at least the thickness of the material if not also the material type. It would also be different for an inside vs an outside corner.