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How to design brass etches?


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Hi everyone. I've made a good start with the laser-cutting design work, but now I need to look at etched brass components.

 

I already have a guide to artwork which states to use black for metal, red for half-etch and white for etch through. I'd like to know what sort of width I need for fold lines and what size half-etch circle to use to form rivets punched through from the read. I'm working in 7mm scale.

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I would suggest that you give your prospective etcher a call, as I believe that each has different criteria and it will also depend on the thickness of the metal, generally the thicker the metal the wider the line. I have a couple of projects on the go, but not got that far yet and I doubt that I will progress uuntil the new year.

 

 

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Hey Martin,

 

This are a little bit old and some a little out of date but the basic concepts are there.

 

White* - etch all the way through

Black* -  solid full etch

Blue/Cyan - Half etch rear

Red - Half etch front

 

* depends on the etcher - best to check

 

The PPD in the UK have some really good guides (attached).

 

I do have a question of my own - do etchers want it still split into layers (i.e. back and a front) or just a single flat image?

 

 

 

Introduction To Metal Etching.pdf Metal Etching Principles and Rules.pdf Etch Drawing Preparation.pdf 2019-Drawing-Dimensions-Tags-1.pdf 2019-ARTWORK-GUIDE-1.pdf 2019-Metal-Thickness-Selection-Guide-V1.pdf

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7 hours ago, Down_Under said:

The PPD in the UK have some really good guides (attached).

 

I do have a question of my own - do etchers want it still split into layers (i.e. back and a front) or just a single flat image?

 

 

I use PPD. They will accept whatever you send them so long as it's in a format they can work with, the more work they have to do the more the set up cost is though.  I send them a completed front and back set of artwork in black and white to keep the set up cost down.

 

 

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8 hours ago, hartleymartin said:

Yes, but I need to put in a half-etch from the rear for fold lines for the corner plates.

 

No you don't. Try putting tabs where the bend in the corner plate is going to be as a guide. Full sized corner plates had a slightly rounded corner due to them being bent up from thickish metal plates.

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Here is the artwork for the wagon as a jpg file. The etches are off to the bottom-right. The bulk of the wagon is to be laser-cut in 1.5mm and 2.5mm plywood. The etches are only for various items of strapping, corner-plates, etc. I still need to draw up the support brackets and the coupling hook plate.

 

1646476553_NSWGRDWagonHighSide5plankGlassonsContract1884.jpg.9251c2831d18f5b80945e1c84f16e78a.jpg

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I would advise paying a little attention to how the tags connecting the parts are to be cut - I put all tags where they can be reached with snips. The tags in the middle will be very difficult to cut without distorting the parts - just leave most of them out, most etches have far too many tags.

If this is just strapping I would suggest half etched leaving the rivets standing out - it's extremely difficult to press out rivets in narrow strips without distortion. You can draw bolt heads and nuts as square or hexagon shape if you want to, for half etch rivets in .015" material I use a radius of about .23mm.

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2 hours ago, chris p bacon said:

Without having a scale I'd wonder that there isn't enough tolerance between parts, Your prefered supplier would be able to tell you.

 

I'm guessing you're going for half etched holes which can be punched out to form rivets 

 

It is an O gauge wagon. For reference, the top of the wagon side is 105mm long.

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