Ething brass with PPD.

[wcfn100]

So I've had this project on the drawing board forever, and Ed's thread brought it back to the top of the pile.

I want to etch some louvers for the Kato NW2 and I'm going through PPD.  The biggest issue is planning for undercutting which I knew I'd have to adjust for but I don't want to bother PPD with a bunch of back and forth e-mails.  I know people here have used this service and I'm hoping I can get some answers here.

Here's the file which is drawn the way I want the part to be when finished.



I'm etching in .2 mm brass.  How much material should I add to account for the undercut?  I've read from 1/3 to 1/2 of the material thickness.

Also, I know the techniques for offsetting the rounding of corners.  Is that needed on .2 mm sheet?

Thanks,

Jason

[chessie system fan]

That's a useful part, but would it be better than Archer decals?

Regardless, I'm curious in the answers as I'm working on a few PPD  etching projects.

[wcfn100]

That's a useful part, but would it be better than Archer decals?

I guess we'll see.  I very much enjoyed your dad's thread using the Archer decals, but when it was all painted, I didn't like the relief of the louvers as you can barely see them.  I've wondered if weathering would help them pop out but honestly this is just a project I want to do.  Besides, with the minimum sheet size, I'll probably get 4-5 projects done at one time.

Jason

[Chris333]

With .008" thick brass and a part that small I just don't think it will matter.

You might want to round the top two corners of each louver so they look punched out of metal. The front edge of these are rounded:
https://goo.gl/photos/TnxZ1jtLYqsyUY6s6

[wcfn100]

With .008" thick brass and a part that small I just don't think it will matter.

That's what I thought, but the guy at PPD made a deal about it.  Maybe he missed the thickness as I forgot to put that in the first email I sent that got forwarded to him.

Jason

[Chris333]

Might it be better to etch the whole door with the louvers on it and replace the doors?

[wcfn100]

Might it be better to etch the whole door with the louvers on it and replace the doors?

What about the hinges?

Jason

[Chris333]

Don't have a NW2 shell handy, but I used the BLMA doors on my HH660, they have hinges.
http://www.trainboard.com/highball/index.php?media/erie-hh660-304.45264/
http://www.trainboard.com/highball/index.php?media/erie-hh660-304.45263/

[wcfn100]

Don't have a NW2 shell handy, but I used the BLMA doors on my HH660, they have hinges.
http://www.trainboard.com/highball/index.php?media/erie-hh660-304.45264/
http://www.trainboard.com/highball/index.php?media/erie-hh660-304.45263/

So there's a small relief on the door side of the hinge to create the effect of separate levels?


Jason

[wcfn100]

Chris, do you not like the louvers on that model?  Those are separate right?

Jason

[chessie system fan]

You might be right, Jason.  I say go ahead with the project.  Then I can compare between the two for when I make mine.   

[wcfn100]

With .008" thick brass and a part that small I just don't think it will matter.

You might want to round the top two corners of each louver so they look punched out of metal. The front edge of these are rounded:
https://goo.gl/photos/TnxZ1jtLYqsyUY6s6

I thought about that and it certainly looks great there.  I don't know if it would look as good with stand alone louvers (not etched with the door).

I certainly have the space to include both styles.

Jason

[peteski]

The etching process removes material from all the exposed metal surfaces. Parts etched from both sides will have undercut roughly equal to half of the material thickness (or slightly less).  This doesn't apply to very small areas to be etched (like very small holes. Those small areas etch a bit slower so there will be less undercutting.

I think that undercutting is covered in one of PPD's online instructional documents.

[Chris333]

Hollywood Foundry has a bunch of stuff on drawing etch artwork.

About the BLMA hinges, I think they may have used that triple etch thing.

[bbussey]

At .2mm, you shouldn't have to worry about undercutting.  I never do, on material up to .3mm thick. And yes, it would be ½ the thickness of the metal.