Photoetching

[SDwn]

Can anyone recommend where to get some custom photoetching done?  Thanks  Sean

[Hauk]

Can anyone recommend where to get some custom photoetching done?  Thanks  Sean

I would warmly reccomend several english companies that does etching. Even if you are not living anywhere near the British Isles, I would urge you to try them.

They do a lot of work for modellers, so they understand our needs. The quality is superb.

For smaller projects, I would reccomend a company called PPD: 
http://www.ppdltd.com/

They have sheets as small as A4 (210X297mm). To have a 0,4 mm sheet of brass etched you will have to spend £ 17 (USD$ 27) for the Photo-tool and £ 14 (USD$ 22) pr. sheet. They quote £6 (USD 9,4) for postage, but that will probable be more outside the UK. You have to add your local sales tax to that if you are outside the EU. Inside EU, you will have to add the British sales tax. ( 15% at time of writing)

If you have bigger projects (both in size and quantities) you should check out companies like Chempix and Photoetch Consultants. Their sheets are larger (around A3, 297X420mm),and they oprate to even finer tolerances than PPD. The Photo-tool and setup charges are significantly higher, I think you need to expect around £ 90-100. For the sheets I think they will be just proportionally higher, around  £ 30 for an A3 sheet

http://www.chempix.co.uk/
http://www.photo-etch.co.uk/

Regardless of what company you want to use, you have to prepare digital artwork in a format that the company accepts. They key to success is to study the guidelines for preparing artwork, and not start drawing until you fully understand them.

Good luck!

-Haavard

[finescalerr]

Now that is useful and complete information. Thanks, Haavard. -- Russ

[JohnP]

Sean,
If you're in the US and need something more than just a few small onesies, try http://www.precisionphotofab.com/index.html. I have had work done by them a few years ago. I had chosen them because they had photos of other model stuff on their old website.

Haavard is so correct when he says:

Regardless of what company you want to use, you have to prepare digital artwork in a format that the company accepts. They key to success is to study the guidelines for preparing artwork, and not start drawing until you fully understand them.

The larger places will work with you more readily if your files are at least in the form of top and bottom layer. They will offer services for prepping CAD files for the resist printer, such as adding the sprues and panelization. I did it all myself so I could save the up-front costs. They accepted my files without issues and put them right into the machines.

There are many subtle details to the layout that will get you the utmost accuracy. The chemistry defines most of the results of the etch process; how to draw it to get the accuracy can vary depending on a company's processes.

Post questions in this thread if you want and I can respond with what I know here so others interested can benefit too.

John

[SandiaPaul]

"The larger places will work with you more readily if your files are at least in the form of top and bottom layer"

John,

Could you explain this a bit more fpr us etching newbies?

Thanks,

Paul

[JohnP]

Industrial photoetching processes are designed to etch both sides of a sheet of metal. So the patterns you supply have to include both sides.

Consider the artwork as indicating what areas you want etched, and the remaining metal is what you get for a part. If the pattern shows the same area to etch on the front and the back of the sheet then it will etch all the way through to create an opening. If pattern shows to etch on the front but not on the back then the metal will be etched down to half thickness. And, naturally, if the pattern shows no etch on either side you will end up with full thickness metal.

The half etch is how you get features on the metal surface, such as fold lines, rivets and other raised areas. They will appear as raised areas one half the metal thickness. If you want rivets on a .010" thick brass sheet, you will end up with .005" rivets protruding from the surface of a .005" thick part. The full etch is is how you define the edges of the parts, the sprues or tabs, and the frame. On that .010" thick sheet, those areas will be .010" thick.

The patterns can be overlapped on the screen or using clear Mylar so you can visually see what you are going to get. In CAD you generally just call them different names. If supplying real artwork they are sometimes diferent colors.

Also, some companies prefer three drawings- the full etch areas, the top side half etch and the bottom side half etch.

So that is why you have to find out what they want before you get going too far in creating a pattern.

I'll dig out a file of mine and post it tonight.

John

[Geoff Ringle]

Very useful post, thank you.  I would like to get some stencil sets for some EBT 1:20 stuff.  I think that airbrushing logos would work very well and really help the weathering process.  Geoff

[SDwn]

     Thanks Haavard and John for your help and leads. John, I am sure this depends upon who is doing the etching and material thickness but do you have to add a slight thickness to your artwork to account for the etching eating into it? Also, if half etch the same as double etching? Thanks again for all of your help.  Sean

[JohnP]

Sean, yup you have to account for the etching away of the side of the opening. Many places call it the etch factor. So if you want a .050" dia hole your pattern may need to show it as .047". It of course depends on the thickness, which affects the amount of etch time.

I am not sure what the double etch means in your context. I understood that is a way to get more features on the metal by recoating it with resist and exposing it to a second pattern so it can be etched again. I was told that is complex and expensive. The half etch is most commonly used.

Even with a simple pattern with no half-etch. you still need to coat both sides of the metal. In a commercial process, the back side pattern will match the front side rather than just having the entire back blank. That minimizes the etch factor, so you get only a slight distortion of the edge rather than a larger curve or bevel.

John

[SandiaPaul]

John,

Thanks for the info...its something I want to try someday.

Paul

[DaKra]

There is no substitute for photo etching, but you may be able to get what you need cheaper and faster by laser cutting.   The newer lasers can achieve a very fine resolution of detail, including relief detail. 

For example:



Dave

[JohnP]

Dave, I have all my lacing bar master parts (those little alternating crossing strips) laser cut out of sign plastic. But I still need to emboss the rivets in the ends. Etching would give me the rivet too, but it would be expensive to have a few small part frames done. I wish you could pop a rivet in there somehow in the laser.

John

[DaKra]

John, raised rivets are often best done with photo etch, but there are ways to laser them.   In photo etching, the acid bath strips away a layer of surface leaving the rivet area raised.  I can do this with a laser, too, but it leaves a grainy pattern, unlike the smooth surface of an acid etched part.   Sometimes the pattern is not a problem, as when replicating rough cast iron or cement or wood, but for smooth metal its dodgy.   But there are ways to work around this.  The simplest is to engrave a small recess to accept the rivet, then a separate rivet applique piece.  The recess ensures exact placement.  Obviously, this is not a good method for a piece with hundreds of rivets, or very small rivets!   

[finescalerr]

Dave, do you own your own laser cutter or cutters? Can you provide a little info on what kind of artwork you would need to create typical parts? I've never seen laser work like what you are doing and want to get a better understanding of what can be done and how. -- Russ

[eTraxx]

I was looking at these Dolls House stencils. Available in Brick, Stone etc. The website says that they are made from a "tough plastic/polyester" material. Curious if you can cut them. The ones on the website are 1:12/1:24 .. evidently you use a stencil adhesive spray to hold them to the surface and then glop on the brick/stone compound. Looks kinda neat. Would be cool if we could get something similar in the smaller scales.