Cutting openings in brass?

[Ray Dunakin]

How do you cut openings in sheet brass without bending or distorting it? For instance, to make windows?

[james_coldicott]

Hi Ray,

that would depend somewhat on the thickness of the brass. For thinner sheets I have had good success with a scribing hook- an idea stolen from some notes on working metal by Colin Binnie- link here...

http://home.iae.nl/users/summer/16mmngm/Articles_htms/ColinBinnie/CBWJ.htm

for thicker material I usually end up with a combination of drilling, fine fretsawing between the holes and filing to finish. One day, if I'm lucky, I'll get a pantograph milling machine which would speed things up considerably but that is another story.

No doubt others here with more skills and experience than me will have some suggestions too...

Good luck

James

[gnichols]

Depends on the size of the opening and thickness of the metal.  Drill a hole.  Or drill two holes and cut out the material between them.  Or three holes, etc.  In the non-wise guy department, my favorite tool for this is the jewler's saw, but a dremel with a cut-off disc is often the trick - especially when modifying assembled models.  Finsh with fine files.  Gary

[jacq01]

  James,

  thanks for Colin Binnie  reference, I had lost it.....
  I love these simple methodes.

  Jacq

[Noel Crawford]

For very thin brass sheet (0.15 to 0.25) I sandwich between two thing pieces of wood or strudy card. The fret saw. Works very well.
  For thicker pieces I do the same the cut out on a scroll or jig saw. Beats doing it by hand.
Noel         

[DaKra]

You can also etch them out, if its thin material.   Basically you mask the material you want to keep, and leave the parts you want to disappear exposed.   Then mask the entire back side.  Manually (as opposed to photochemically) masking brass for etching is real easy. You can use paint, scotch tape or even a sharpie marker.    Then place it face down in a glass or plastic container of ferric chloride, check it for progress every 15 minutes or so.  When its done, rinse with water to stop the acid.   Sometimes you'll have a little flash, this can be easily cleaned off with a file.   

Dave

[chester]

Great tip Dave, never thought of that. One could mask both sides of the sheet and dip the whole piece as well I would assume.

[DaKra]

Yes, mask both sides, but put the piece in face down.   Experiment first on scrap to get an idea of how much time the process takes, and how well your masking material is working.     Also clean the brass first, scrub with steel wool should do it.

[marc_reusser]

Ferric-Chloride (PCB etchtant) etches brass?.....how cool....learn someting new every day!.
Maybe I can use this on the rusty boat dio.

Marc

[DaKra]

Yup, and they sell it at Radio Shack, or once upon a time.   It does rust metal, keep your tools away when you are using this stuff. 

[JohnP]

Micro-Mark has ferric chloride also.

Be aware it is a poison, puts out fumes and is bad to get on the skin. Wear heavy rubber gloves. It also stains severely so whatever it gets on (sink, pants, buckets) will have brown stains.

It does work like magic. I have the little Micro-Mark etch kit that has everything you need to make even more elaborate etchings.

RS used to have dry transfer circuit traces that could be used for window muntins etc. But this random link:http://www.riccibitti.com/pcb/pcb.htm shows a neat and cheap way to make a etch resist pattern with a laser printer and magazine paper of all things. You could go straight from a Sketch Up drawing to an etched window in no time.

John

[DaKra]

Cool article, printed it out for testing. Thanks John!

[JohnP]

Let us all know how it works out.

Etching through a thin material with a one sided pattern is not too difficult. The etchant must be kept circulating the entire time. If it is a simple home-made setup, rock the container from start to stop to keep from over etching any area before the rest is complete.

There is another aspect to designing the pattern if precision is needed. They call it the Etch Factor. We can discuss it if anyone wants to hear the tale.

John

[lab-dad]

Doing so much in brass I would love to learn more.
I think I could do a lot of neat stuff if I could learn basic CAD and etching.......
-Marty

[JohnP]

Marty,
Laying out an etch pattern only requires simple 2D software with the ability to fill in areas with hatch. If you are going etch it yourself, solid areas are needed. Most professional etchers use an inkjet type of printing that will print a hatch pattern in very fine (.005") lines.

The etch factor is a compensation you have to add to a pattern to account for the material being etched from the side as well as the top and/or bottom surfaces. It will etch in a bit and you will end up with smaller than expected parts and bigger holes. So add a small amount to dimensions for a perfect fit.

A 3D CAD is needed if you want to virtually fit your design together before sending it out. Of course, messing up a simple home project means you've just wasted time and materials.

I developed and sold a 1/87 brass truss bridge kit for a while. I designed it and then rechecked everything, but didn't get to finishing the virtual assembly until after I placed the order. Crazy thing to do at the time but it all worked out though.

If you have the urge etch brass try it, it is a fun project almost like developing your own photos. Ask questions here or email me-- john <at> jpstructures <dot> com.

John