How do you cut openings in sheet brass without bending or distorting it? For instance, to make windows?
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 (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
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
James,
thanks for Colin Binnie reference, I had lost it.....
I love these simple methodes. ;D ;D ;D
Jacq
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
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
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.
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.
Ferric-Chloride (PCB etchtant) etches brass????.....how cool....learn someting new every day!.
Maybe I can use this on the rusty boat dio.
Marc
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.
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 (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
Cool article, printed it out for testing. Thanks John!
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
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
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
Thanks John!
This is something I will try! someday...
-Marty
Hey John
Do the etchers use the laser jet to print onto clear film for exposing the resist, or do they print directly onto the brass using the ink as a resist?
Curious if/how high tech has made its way into commercial etching or if they are still doing things the old fashioned way. Any info you have would be interesting to me!
Dave
Anyone tried the photo etch setup from MicroMark?
Tom
Dave, the hatch pattern I had to make for my source was on the areas to be etched away. I believe they used the printer to create a clear overlay of my pattern that was then sandwiched onto the resist-coated metal sheet. The sandwich was then exposed to UV light. The open spaces representing the shapes hardened on the resist to protect the metal from etching leaving the rest to rinse away. Then into the etchant spray tanks it went and out came etched parts. A bit old fashioned but accurate and repeatable.
Tom, I have the lil' etch kit. They provide the resist, developer, etchant, a laminator for applying the resist to the metal, etc. It works well in theory. There is lots of room for operator error though. The most difficult thing is to maintain alignment if you are trying a double sided etch. I bought it to make a fixture for drilling small holes precisely .030" apart for a rivet embossing fixture. It is better at etching very thin (.005") metal due to the problems in circulating the etchant. Even with the included bubbler it can still be uneven without rocking the container. Give it a try; you will have fun with it.
The images below of are the pattern for a small section of the part sheet on my previous post. One is the bottom, the other the top. One problem I had was in applying the hatch on my drawing areas that had rivets. My TurboCAD cheap version has a feature that applies a hatch around enclosed spaces, but it choked attempting to avoid the gazillion rivets. It may have been my weak computer. So I had to select each rivet and "cut" each hatch line with in the rivet. I was literally clicking for days in my spare time. If I did it again I would get a liquid cooled computer with the neon lights inside just to make sure it was big and tough enough.
John
Hi All,
just a comment on photo-etching here in the UK which (looking at John's artwork) I assume uses a different system to that employed in the USA- maybe I'm wrong and I may be teaching y'all to suck eggs but I haven't seen this described in any of the US modelling magazines- maybe I just don't read enough of them...may still be of interest for those not familiar with the process...
Etching artwork here uses a three colour system-
Black etches all the way through
Red etches half the depth on the Face
Blue etches half the depth on the reverse- all colours drawn solid
In the olden days you'd hand draw your artwork which was photographed twice- once with a blue filter- only picking up the red and black areas, then with a red filter so picking up the blue and black. One negative for each side of the metal sheet. The transparency was then used to fix a photo resist layer on the metal.
This way you can put fold lines/ rivet punching centres etc. (or etch the surface and leave rivets full depth) on either side of the metal which was etched just long enough to eat half of the material- the black areas of the drawing being exposed to etchant on both sides meet in the middle.
Now that digital artwork is the norm the drawing is still produced in the same way with three colours and two transparencies printed up- though my etcher will still work from hand drawn artwork and photograph it in the old fashioned way (or would last time I looked!).
James
Considering the immense talent represented on this site it is interesting that none of us seems to be expert in photo etching. Remember that airplane modeler Havard found a link to who photo etched hundreds of exquisite brass parts? And that lousy, sociopathic crook from Backwoods Miniatures made extensive use of etched brass parts before turning more of his attention to castings.
Those of us with CAD might consider drawing out the parts and sending them to a water jet outfit. Presumably that would obviate the need for etching.
Russ
For those a little gun shy about photo chemical etching using something as dangerous as ferric chloride, here's the old fashioned way of electrolytic etching. I found this site completely fascinating.
http://steampunkworkshop.com/electroetch.shtml
Hey James-
The method my etcher used eliminates the need for the black layer. If I put the hatch lines in the same area on both sides then of course it etches through. The rivets on the one sample drawing are white round circles. The bottom side sample drawing shows the same area as all white. So there is where the half etch occurs for the protruding rivets. I used lots of half etch bend lines on the model too. Using a separate layer for through etch and half etch probably would make it simple to design and analyze the pattern. Believe me I wished all they needed was a solid area, those hatch lines were difficult to handle in large amounts.
Chester-
I'll check out that site, thanks. I recall another guy who posted information about an actual pumped spray etch system he made in his garage. I'll have to find it.
Russ-
My question is, on what side of the fence do you need the photo etch expert? Doing the actual photo etch work to the standards we all are familiar with requires big expensive machines that are full of harsh chemicals and moving parts. That can be left to the experts who do it on a commercial basis and are familiar with the EPA and OSHA requirements. But the design of a sheet of parts to cut, bend and assemble into an outhouse or rickshaw is within the capabilities of anyone who has shown their work on this site. My project started as only a *dream* and ended up with boxes of etched brass sheets that could be assembled into an HO truss bridge even though I do not consider myself any kind of expert. I had no clue how it worked nor how to do it. I just wanted to get it done. But several years later I sold out two runs. The cash outlay for a big project like that was extensive but I took the chance.
To make a few copies of something for your own models would probably require using the Micro-Mark kit. The commercial places charge for set-up, then for the run. Once they are running your job the cost per sheet goes way down as the quantity goes up. So if Marc wanted an etched brass model of one of his bikes he should do it himself, but if we all wanted a few a vendor could do it.
If there is someone here who wants to know more and/or who wants to know of a commercial place that works with model makers on a regular basis let me know via message or right here. I am working through the resin casting process right now but would not mind if my experience with etched brass does not go to waste... or get flushed by likes of this beautiful Brooklyner-Schneider Hopfen-Weisse I am currently enjoying.
Thanks, John
A few more parts pics are attached, a little low on resolution but that's all I have saved that I can find
John,
so do I understand correctly that you have to produce two drawings- one for each side of the metal sheet being etched? The UK system is one drawing that produces two (different) negatives so making referencing much easier when it comes to making the drawing and after reading your comment on producing hatched lines saves an AWFUL lot of time. Or have I got it wrong? :-\
James
James,
There is only one CAD drawing but it has two layers. As far as the computer is concerned there is only one file. But that file has pattern or image for both sides of the sheet. The etcher software will sort that out when they run it on their system.
I you can print out each side on paper and check the alignment of the patterns. I put the top sheet on the bottom and looked at them on a light box the old-fashioned way. Just for my own reassurance. But the computer is far more accurate and easy to see.
On the CAD drawing you probably know the user can assign colors to each layer. It is easy to see the alignment while looking at the drawing on the screen with both layers turned on.
The hatch lines were a pain because of the size of my drawings and the many, many features on them. I needed a bigger computer (speed and memory) to do it easily. I personally did not need to draw them, the hatch feature did it for me.
My laser cutter provider has a system where the machine recognizes red for through cuts and blue for scribing cuts. In the same way, I make a CAD drawing with two layers in the different colors, but can view both to see what the result will be.
I hope I answered your questions. :)
John
Wowsers! That is some beautiful photo etched stuff, John! The little folded up piece looks much better than a casting. Most impressive. -- Russ
Ah, I've got it- thanks John. It all makes sense now- baby induced sleep deprivation must have been numbing my brain for a while! ;)
Just trying to get a handle on the (very different) systems used on each side of the pond.
I still thing the UK system has advantages over the US one- I imagine all the hatching makes interpreting the alignment- even on a cad drawing a bit of a pain- that's where the single layered, three colour CAD that UK etchers use is so much easier.
Finally, ditto Russ' comments above- the bridge is GREAT.
Thanks for taking the time to explain how you got the parts etched. A fantastic result
James
Happiness is a big photo etched part with rivets all over it. ;D And it looks like everything fits perfectly, very nice work there, John.
That cross-hatching seems slightly insane. I wonder why it was necessary, does some sort of oddball machine interpret that as a solid area, and how?
Gee, thanks fellas *blushes*.
I have this thing for bridges and rivets and always wanted to model them accurately. My lil' business through which I sold the brass bridge is an outlet for my experimentation, and an attempt to supply real bridges to modelers who care. The brass bridge looks great and assembled accurately but the .010"/.005" brass was a tricky material for modelers to handle in such an extensive way. Also, I had first thought of layering the etchings so the lacing strips attached on the surface of the beam flange angles but costs prohibited that. The overall look of the thin sections and lots of accurately placed rivets was a success though.
The crosshatching is spaced as I recall .005" apart because their artwork printer prints lines .006" wide. That will make the etch area solid. Why it is I do not know. The insanity rests with me for making my own actual etch files- most customers make a regular CAD drawing and they translate it into the artwork. I save a good amount of set-up cost that way.
A few years ago I decided to continue my riveting quest using resin in rubber molds. Again I stumbled into it blindly, which is the best way- no limitations. My concept and design of the D&RGW truss model is very sound, but I have found that even the best RTV is not dimensionally stable. I am learning to compensate for it so the parts are all within tolerance. My masters are all thin section with decent rivets so even with the resin casting I am avoiding the heavy metal look. Even the rare imported scale bridges seems to use heavy lost wax castings for the lacing strips. I am hoping the Print-a-Part technique will help with mastering the tough parts while maintaining a good cross section.
Thanks!
John
I kitbashed a double-track version for a customer (below). Lookit them rivets!
The bridge is jewelry. It would surprise me if the cast resin parts are as "perfect". -- Russ
That is GORGEOUS! I think I just wet my pants!
-Marty
Superb bridge model, you have achieved about as near to perfection as one can hope to get in that scale. I've also found the problem with commercial production is you have to balance perfection with ease of assembly. The compromises can be painful.
Sounds like the etching company uses a plotter to print the lines. I guess they print directly on film, the plotting lays down enough ink to be light proof, as opposed to toner. Just guessing though.
Since this has turned into a photo etching thread, I'm hoping we'll hear from Dan Pickard. He posted a couple of photos of an etching work station he built, wondering how that's going now.
Dave
For those who are just looking for a simple tool, don't forget nibblers. They usually require about a 1/2" hole, then you can nibble out whatever you want.
John
Thanks for getting us back on topic, Nephew John!
Let's start a separate photo etching thread if anybody has more to contribute. The results, as we have seen, can be stunning. One thing we should discuss on that thread is when photo etching is the best solution and when other, possibly more accessible methods (e.g., laser cutting), can work as well or better. Great subject. I want to learn more.
Russ
Russ, I was thinking today when I get home I would apologize for the thread hijack. I got excited. Well, you know what I mean.
I have a manual nibbler and use it every so often, but I am glad it is still in the toolbox. It is cheap and handy tool that works on brass, aluminum and even light steel. It may wrinkle .005" thin stuff but works up to about .020". It requires a starter hole for blind areas but then can quickly open up straight lines with right angle corners so little clean up is needed. It's even a handy way to cut sheet stock down to size without using a saw.
So back to Ray--(still there?)-- what size opening and what thickness metal are you thinking of?
John
Oh, I was just thinking it might be a better way to make window frames for my buildings... brass would be more durable.
I too would like to learn more on photo etching. My only experience was when I was a factory pro racing R/C cars, I etched my own circuit boards and they were oh so crude.
John
Gee Dave, thanks for dobbing me in...
Yes, have done a few home etch pieces, and after having a quick read through the thread, seems the technique I have been using (and what local professional etching guy has told me) is a bit different. When it comes to the artwork side of things, CAD unfortunately does my head in, frustrates me too quickly trying to get simple things done, it does think like I think! I ended up just using a free program called Inkscape, to essentially do a B&W positive/negative drawing of my items to etch. I was able to use that program like I think, just drawing in the solid blocks of black to form the shapes or patterns I needed. A few years ago there was an article in one of the Finescale Annuals about building an On3 Heisler which showed a page of the B&W artwork for etching it.
Once my artwork is drawn (in my method, solid black is the resist layer and is what the brass piece will look like, white areas will be etched away by the ferric chloride), I have used a toner transfer paper put out by Pulsar ProFX. I had read on different websites about using photo paper, or magazine paper as a transfer medium, which is not always successful due to the paper not realeasing the toner onto the brass. The Pulsar Pro FX gear is designed to (and works well too) hold the toner image, use heat to transfer the image onto the brass sheet, and then once transfered to the brass, drop the brass straight into a water bath. The toner transfer paper peels off very easily after about 30 sec. Should note that the toner is "not set" on the transfer paper, and requires heat to fuse it to the brass. Heat needs to be about 170 degrees celcius to fuse, so a cheap laminator doesn't get hot enough (only get to about 110 degrees), but there are laminators that have a variable heat setting (mine goes to 210 degrees, so works well. I have found the toner transfer paper to work well beacause its a two part layering process, first the toner is transfered to the brass, then the toner is "sealed" with a foils layer. The image transfer has seemed better than another method of a "Press and Peel" resist layer, because the toner and then foil are two thin layers (holds detail better), where as the P'n'P film is much the same principle, just both layers at once (ok for large solid etch shapes, but not as fine for say small lines of rivets etc).
More later...
Dan
I should add that my commercial etching guy uses photoetching, which is about a 14-15 step process, which explains why etched material can be so expensive. Artwork is first converted to the file he needs, then printed as a film (bromide maybe?), which can stay in storage as the master. Brass is first well cleaned and then treated with light sensitive coating, then the film artwork used as mask as such when the brass is exposed under UV light, creating the resist layer, and then the brass needs to go into a developer to actually create the visible resist layer. Eventually the brass sheet goes through a ferric chloride spray etch machine, and then cleaned of the resist layer at the end. Not really a quick and easy process by any means...
I'll do some pics of my average home efforts in the near uture to show some of the results. The issues I have at the minute are still with artwork alignment. I can get away with that for one off pieces or test etches, but isn't reliable enough for long repetitive runs.
Dan
Ray, if you can use even a simple CAD program you might want to investigate using a laser cutter person to cut plastic windows for you. I have a laser cutter guy who cuts my bridge master parts and mold plates for me. He can cut different thicknesses of a special, non-melting plastic used for indoor/outdoor signage. Google (sorry Russ) SketchUp could be used to draw the lines. I find the sign plastic to be very durable. It bonds using AC super glues.
John