The Ship Model Forum

DPR, a question if I may. I don't have a handle AT ALL on 'thousandths' or imperial... just have never worked with them and it makes it really hard to buy sheet metal, mesh, etc, online. I'm learning now as we speak.

Your 0.010 thickness is 0.25mm? A quarter of a mm? [I've looked it up via a online conversion tool] And 0.1" is 2.54mm? I've got it now. 0.020 is half a mil!

I have another query: I need 1 sheet full of a ship-load of fittings. It can only be 1 thickness. I want to do items from funnel cages, inclined ladders, stanchions (and rails?), bridge cabin walls to small boat oars and maybe row-locks and fairleads and 'bottlescrews' and other rigging detail.

What is your advice on sheet-thickness for a general fittings fret for a 1:128 ship?? Is 0.25mm too thin?I have no frame of reference for sheet thickness.

"The metal thickness must be less than the width of the finest detail you are etching - you can't etch 0.005" gaps in 0.010" thick metal"
Do you mean a full cut through of 0.005" etched from one side? Why? Is this because when you have finished, you will have have a 0.010 cut through?

I would think if etching from both side, it is possible? No? Though by the time it is finished, you would have an oversize cut

The general advice I am following is >minimum line width< and <minimum line gap> to be 'sheet thickness x1.2'. That would make the details on my 0.25mm sheet be 0.3mm. I think half mil details would suffice for me... be overkill in fact.

cheers

In my opinion the greatest problem in modeling is getting things too big - or too thick. For example, at the 1:96 scale I am working in, the common (in US Navy WWII ships) material thickness of 3/8" (9.5 mm) scales to 0.004" (0.1 mm) - this is a little over the thickness of a sheet of paper, or just a thin metal foil. Life rails were 0.75" (19 mm) to 1.25" (32 mm) diameter, and these scale to 0.008" (0.2 mm) and 0.13" (0.33 mm). Common 1/4" (6.4 mm) halyards scale to 0.0026" (0.066 mm). While it may be true scale, parts this thin would be very delicate. At much smaller scales it simply isn't possible to achieve true scale thickness of small details.

At 1:128 scale I would do fine detail parts in 0.005" (0.125 mm) sheet, and larger parts in 0.010" (0.25 mm) sheet. Your rule of thumb - minimum part width = 1.2 times the sheet thickness (0.15 mm) should be a good starting point, although with practice you might be able to make parts only 0.125 mm wide in the 0.005" (0.125 mm) material. The trick is to etch quickly (warm etchant) and keep washing the surface to remove the precipitant. This is especially important in areas where a lot of material is being removed, such as with gratings and screens. Also, make a few extra pieces, just in case some don't etch correctly.

These are guides for do-it-yourself etching with hobby level equipment. If you plan to have a professional etching facility do the etching, ask them what rules they use for preparing the artwork. They will be able to achieve much finer details.

Another thing to try is etching from one side only to create small details and folding guides. This is a good way to make name plates with letters standing above the etched background. I recently saw a 1/8 scale locomotive builder's plate etched in 3/32" (2.38 mm) brass, with the letters at least 0.05" (1.25 mm) high. I have seen an N scale steam locomotive firebox side that was triple etched to create three levels of details (overlapping sheets, and rivets).

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A collision at sea will ruin your entire day. Aristotle

Does anyone know of any good references that describe well the process and techniques for creating photo etch? I guess there are really two parts to the problem:

1. creating the accurate drawings; and
2. actually doing the photo etch process?

My Varyag and Kirov class are very demanding with regard to radio antennas, radar antennas, railings etc., so having a crack at photo etch might be a good optrion.
(not too sure about my soldering skills )

Secondly, off topic I know so please forgive, but are there any good references for moulding parts available?

Andrew

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Ex RAN. Anzac, Duchess, Vampire, Yarra, Betano, Bombard, Brisbane, Swan, Melbourne (Carrier), HMS Leander

I have been etching circuit boards for projects for some time now. I wrote up instructions in a PDF on how to do this. I cannot attached the PDF file here, but if you go to this thread on RCGroups you can see what I have done. I'm sure this method can be modified somehow for PE. My thought is to print the top and bottom image on transparency in such a way that if you fold it in half, the top and bottom of the mask line up. Then use my method to adhere the toner mask to the metal to be etched. I would like to see someone try this and see how it goes. Someday I may try it myself.

http://www.rcgroups.com/forums/showthread.php?t=1360740

Thanks Ken,

I will pop over and have a look.

Andrew

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Ex RAN. Anzac, Duchess, Vampire, Yarra, Betano, Bombard, Brisbane, Swan, Melbourne (Carrier), HMS Leander

Ken,

Pretty slick! What is the thinnest trace that you have etched?

One suggestion is that you etch as little metal as possible. Create unconnected "islands" between the details you want to etch. This minimizes the amount of etch precipitate, speeds up the process and extends the life of the etchant solution.

I have etched quite a few circuit boards and photoetch patterns. You need to agitate the board/metal almost continuously and drain the precipitate frequently. If you do this the etching process will take only a few minutes. Think of it this way - as soon as the surface is etched it is covered with precipitant that impedes further etching. The precipitant builds up like mud on the surface and blocks fresh etchant from getting to the underlying metal. You have to displace this precipitant to keep the process going.

For two sided etching you will need two masks, one for each side. The metal to be exposed to light will be sandwitched between the two patterns. Create your patterns so the ink/toner will be on the metal side when you are exposing the pattern (or ironing it on as Ken suggests). For this you will have to print one side as a mirror image. If your printer driver won't reverse the image you will have to do it in your drawing program. Create both sides at the same time, on different layers in the drawing program.

Put "targets" in all four corners of your image outside the etch pattern before reversing one side. These should be outside the metal area on the board/etch metal. The targets can be a simple "+" mark, but make it big with very thin lines. Then, after reversing one side, remove one target from corresponding corners of both sides. This way when you bring the two patterns together, with the metal in between, you can align the patterns accurately, and it is obvious how they should be positioned with respect to each other (think about it).

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A collision at sea will ruin your entire day. Aristotle

I went to Eurocircuits for my PCB



I also had my custom etch manufactured elsewhere as the etching is so fine I don't trust myself to reproduce the etching consistently.

I live in a smaller town west of Portland, Oregon. I have looked in the phone books, and scoured the internet as well, I'm just hoping to find a place somewhere close by that does small runs of photo-etching.

jjasboat,

I'm in Corvallis. I looked up photoetch shops in Oregon and Washington several years back. Unfortunately, I don't have that information any more. But there are several shops in the Portland to Seattle area.

I found some of them in the Oregon Business Directory and others with an online search. If you find a shop that has reasonable prices please post the information here.

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A collision at sea will ruin your entire day. Aristotle

I think the narrowest trace was about .010.

Will eventually try this method.

I don't have a good setup to agitate. I tried a 12v motor on\next to the tray but it did not vibrate very well. Some day maybe I'll fashion a vibrating board. I kept taking the PCB board out and washing it down to remove the residue. Maybe if the tray was more vertical and narrow, the residue would drop to the tray bottom.

With the mirrored images on the film, you can fold it in half lining up the images and targets as you suggest. You could also drill a small hole to use as a alignment point.

DrPR,
I'm in Forest Grove. So far I haven't had much luck with finding a PE shop. My wife works for a circuit board shop locally, but they don't do side projects, especially in very low quantities. I talked to one of the technicians there, he might be able to help me out and point me in the right direction as far as getting very limited runs done. I will post it here if he has a solution.
I looked at your build, very nice work. I like your solution to finding acrylic, I wish we had a place like that here. Finding 1/2 inch thickness here is impossible, unless I want to purchase a 4'x8' sheet.

Jim

To revive this thread... I just received the Micro-Mark PE system and am gearing up to try it. I have a formal, florescent UV bulb I'd like to use as a light source for exposure. Do I need to adjust the exposure time for this or do I simply use the 15 seconds they recommend for noon-day sun?

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dave

Time flies like an arrow. Fruit flies like a banana...
Groucho Marx

Relief etching is done using what we CAD guys call layers. The drawing of the "bottom" layer is done first which includes all the lines, then the relief etched lines are drawn as "the top layer" on top of the bottom layer. You will then have two drawings (files) that you can submit to a photo etcher. Everyone does everything electronically now, so you can email the drawings to the photo etcher which is what I do.

I briefly explain the technique for producing drawing in my "how to" CD called, "Working With Photo Etched Parts". If you're interested in the CD, go to my web site and check it out. http://www.flagshipmodels.com/zencart/

Contact White Ensign Models. They should be able to hook you up with a photo etcher in the UK.

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Rusty White
flagshipmodels.com
Home of the American Civil War warship kits