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Author Topic: Etching masks (masking masks, not masquerade masks) . Some random ponderings.  (Read 8164 times)
Dr cornelius quack
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« on: October 06, 2012, 09:43:05 pm »

I want to start etching some designs onto Brass sheet to use as 'Makers plates' for my builds.

The point is, I need to make a number of these all alike and I'm trying to think of a low cost method of getting the image transferred  onto the plate in some form of etch resistant material.

There has been a lot of talk recently on the subject of using laser printed toner transfer, but a lot of it seems to be bemoaning the shortcomings of the method. Poor adhesion to the surface and whatnot.

Now, to my way of thinking, this process is just a form of printing, i.e. generate some image. Replicate it in some resistant medium that can be applied to your workpiece. Print it. Let it dry. Dunk the thing into your etching bath.

So, how about going back to some very simple printing techniques?

Carving a potato?

No good for the sort of numbers I need.

Rubber stamp?

I'm rather drawn to this idea. There are lots of firms out there that can make a stamp from a graphic file very cheaply.

Might work for simple designs without any fine detail.

Screen printing?

Again, kits quite readily available from the crafts suppliers to make your own screens using photo sensitive emulsions to fix the design and a better degree of resolution to the image.

Thoughts please, folks.
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von Corax
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« Reply #1 on: October 07, 2012, 03:39:28 am »

For this sort of job I should think either screen-printing or photoresist with a durable negative. It occurs to me that either technique could be adapted to include serial numbers via some sort of multilayer process.
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alfa1
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« Reply #2 on: October 10, 2012, 11:43:00 am »

I want to start etching some designs onto Brass sheet to use as 'Makers plates' for my builds.



Had the same question about a year ago.
http://brassgoggles.co.uk/forum/index.php/topic,32463.0.html

Never followed it through, but if I had, I would have bought one of those machines second hand (or made one), and paid someone to make such a custom stencil for me.

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Dr cornelius quack
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« Reply #3 on: October 11, 2012, 12:28:21 am »

I've  got the next six days as a holiday, so I'm going to try out a few methods.

I've used photo-resist masks for circuit board making in the past, also drawn directly onto board with etch resist pens.

This time I want a method that can produce a fair number of items with some degree of consistency whilst not costing the Earth in materials.

The etching wand idea seems quite straight forward and looks like a good system for the sort of small size pieces I want to do.

Just a matter of getting the right electrolyte solution.

The power supplies that are sold with the kits don't look like anything more complicated than a d.c. 'wall wart' and I've got dozens of those.

Stay tuned.
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Drew P
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« Reply #4 on: October 15, 2012, 04:27:36 am »

I eagerly await your results and information Smiley.
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« Reply #5 on: October 15, 2012, 10:28:08 pm »

Another option for makers plates is to get a stamp made and punch your deign into the metal. Small stamps aren't an unreasonable price and once you've got it the aren't any additional costs beyond the material you;re stamping and it takes seconds to do.

Some sort of press would give best results, especially with larger designs but small ones should work fine just hitting them with a big hammer. It would also be possible to stamp and cut out the plate form stock sheet in one operation.

One other advantage of a stamp is that you can get quite deep relief without any loss of definition

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Dr cornelius quack
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« Reply #6 on: October 15, 2012, 10:43:05 pm »

Hello.

Here are the results of some experiments I got done today.



In all cases the etchant is Ferric Chloride as purchased from Maplin.

Top to bottom the masking methods are:-

A square of self adhesive vinyl of the sort used to make advertising graphics.

Written directly onto the plate with a 'Sharpie'.

A pre-cut decorative vinyl trim bought from my local 'crafte shoppe'.

Sharpie ink applied with a rubber letter stamp.


The best result is the third one. This took two hours to get the depth of etch using freshly made up solution (cold).

As for the others, they were done with the same etch bath over about an hour. They have much less depth and I rather think that a fresh solution is needed for each new piece.

That being said, the test was really just for the effectiveness of the mask and all performed well in that regard.

The aim of using the vinyl was to see how well it stuck to the Brass throughout the process.
It did very well and gives a very clean edge.

It might mean I buy one of these.

http://www.mdpsupplies.co.uk/silhouette-cameo-packs.asp?gclid=CNWblab7g7MCFSTKtAod-SUA-A

Mr. Narsil,

I'm already thinking about having an embossing seal made to create a mark on any paperwork to go with the finished items.

From what I've seen today, the etching process looks set to allow more versatility in the artwork and I'm going to need a number of sizes.

My local surplus tools supplier has a rather good fly press sitting out in the yard looking all forlorn and unloved.
I'm tempted to go and make him an offer.
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Dr cornelius quack
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« Reply #7 on: October 21, 2012, 12:02:58 am »

Well, this works.



Pre-cut vinyl stickers etched in Ferric Chloride for two hours.

Got an idea for a short cut, more to follow.
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Narsil
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« Reply #8 on: October 31, 2012, 11:47:01 pm »


Another possible avenue to explore is photo-resist masks. In a nutshell you apply a UV sensitive film to the surface to be etched. Print your design, reversed and negative onto a sheet of acetete, lay in position and expose to UV light, the light sets the exposed areas and the unexposed parts can be washed off with a suitable solvent leaving the mask stuck to to the plate.

In a sense you etch the mask and then etch the plate.

It is capable of producing very high resolution and the fact that you can print your designs directly onto acetate gives you al lot of flexibility while still being able to get consistent reproductions.

Kits are available for PCB etching. The biggest investment is the UV light-box but at least you're not committing to a singe design and the cost per unit is relatively reasonable. I think there are also systems which will develop in sunlight.
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Ravenson
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« Reply #9 on: November 01, 2012, 05:50:41 pm »

Ok two thoughts.  First When i was in high school I made a etched glass mirror. I did this in my screen printing/graphics art class.  I made a negative screen and used regular screen printing ink.  It worked great, but for your project you will need to work out how to protect the edges of your plate.   Second I know a jeweler who does a fair amount of etching. He uses one of the stencil cutting machines you can buy at the craft store (Click-It??? something like that) that can cut a thin vinyl contact paper.  His machine has a knife cutter not a stamp style and has the designs on a flash style card.  Usually you have to buy the cards with the designs from the craft store and they are not cheep, but he said that if you get on the inter net there are ways to program your own designs on to your own card.  He said his machine cost him less that $100 ( I think he said $50 but I am not sure).  He was using normal contact paper and seldom has any problems as long as he remembers to burnish the edges well ( I am sure you will need to play with it some)  He was getting very nice sell able results.  I hope this helps and I look forward to seeing your results.

Jeff
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von Corax
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« Reply #10 on: November 07, 2012, 10:02:16 am »


Another possible avenue to explore is photo-resist masks. In a nutshell you apply a UV sensitive film to the surface &c. &c…

Kits are available for PCB etching. The biggest investment is the UV light-box but at least you're not committing to a singe design and the cost per unit is relatively reasonable. I think there are also systems which will develop in sunlight.


Just happened to see this today on Hack A Day: Ikea provides a great UV exposure box
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Dr cornelius quack
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« Reply #11 on: November 08, 2012, 01:43:12 am »

No new results to show at the moment, but I'm getting some kit together to build a self contained etching tank that will follow my usual house style as far as the aesthetic appearance goes.

I picked up a rather dinky little battery charger to use as a power supply but it has a voltage sensor built in that needs a residual emf from the load before it will start to charge. Bugger!!

The next plan is a model railway P.S.U. from before the days of clever electronics.

As for getting the mask onto the sheet. The trials with cut Vinyl have given the best results so far. So I'm going to follow that lead and look at using a self adhesive film laid onto the brass directly and to cut the design with a laser cutter and remove the unwanted mask manually.

This means a trip to FabLab on Saturday to pick their brains about what material would be best for the film. They don't seem to like the idea of putting vinyl into the cutter.
Acetate might be the way  to  go.
Someone has suggested Lettra-tone sheets as a possibility.

An  alternative is to cut out the shape from plastozote foam and use it as a printing block.
« Last Edit: December 09, 2012, 11:37:37 pm by Dr cornelius quack » Logged
von Corax
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« Reply #12 on: November 08, 2012, 06:47:13 am »

They don't seem to like the idea of putting vinyl into the cutter.
I understand the vapour from lasered vinyl mucks up the cutter's optics right quick.
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Dr cornelius quack
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« Reply #13 on: November 09, 2012, 01:06:13 am »

Ahhhh!  Sounds about right.

The choice of material for the mask is just a matter of finding something that is not affected by the chemicals in the electrolyte coupled with an adhesive that is likewise immune to being broken down.

More research needed. Wink
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Dr cornelius quack
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« Reply #14 on: December 07, 2012, 12:20:31 am »

Well, I'm now the proud owner of a Vinyl Cutting plotter. (It arrives tomorrow.)
It hooks up to your computer and turns vector graphic files into cut out shapes in a variety of materials, including self adhesive vinyl.
The vinyl makes for a good masking material when applied to sheet metal such as Brass and the adhesive holds up pretty well against attack by the various nasty etchant solutions I've tried.

The upshot of all this is that I should be able to produce designs in a standard drawing program (all those lovely clip-art fonts and curly bits) and turn them out as etching masks in one operation. Also, the machine will tile a number of copies of the design onto the film at the push of a few buttons, so it fits the bill for making a number of identical plates at once.

Whoop-de-do!!
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jcbanner
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« Reply #15 on: December 07, 2012, 03:45:38 am »

glad to see that Sharpie markers were in your first test. when I worked in the jewelry repair shop, I used sharpie markers for masking two tone jewelry before electroplating. always wondered how well it would work as a mask while etching.

for the photo responsive masking, a UV box would be terribly easy to make, it's basically just a blacklight in a box.
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Dr cornelius quack
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« Reply #16 on: December 09, 2012, 11:33:47 pm »

Sorted!!

Spent the day setting up my shiny new vinyl cutter and figuring out how it works.

Turns out lovely neat cut-outs in self adhesive (Sticky backed, for all you Blue Peter fans out there) plastic from vector graphics files produced on ones PC.

Like this:-



Which transfers onto a brass sheet as an etching mask to protect the metal from the horrors of Ferric Chloride.

Two hours and a bit of Brasso later:-



Dead easy!!

Takes a bit of fiddling with cutting speed and force to get it right, and I'll probably need to go through the same process for the various types of vinyl I'm going to try, but, as a start, I'm most pleased with the outcome.

One good thing about the set up is that the cutter driver allows you to specify the size of the cut out shape regardless of the dimensions of the drawn file, and scales both axes in proportion. Means that you can produce one master design and use it to cut masks in a range of sizes.
« Last Edit: December 09, 2012, 11:38:24 pm by Dr cornelius quack » Logged
Ravenson
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« Reply #17 on: December 10, 2012, 12:33:42 am »

Tell us more about the cutter and how you like it.

Jeff
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Dr cornelius quack
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« Reply #18 on: December 10, 2012, 01:10:01 am »

The next step is to acquire a few samples of vinyl. There are lots of different grades and thickness's, so I'm going to trial a number to find the best stuff for the job.

The cutter seems to be pretty good, so far. It's certainly not built for heavy commercial duties, but then, it didn't cost the sort of wedge you would shell out for a machine that has to run all day long.
Upload the hardware drivers and install a dedicated sign making package (1 year licence) that is included in the deal and the machine is plug and play.

The signage software can open the files directly and the interface is very straight forward.
There are all kinds of clever options that let you tile multiple copies of the image onto the sheet material and optimise the layout for best economy. Not looked at any of those yet, I've just been playing with the speed and force settings to get a clean edged cut that doesn't go right through the backing paper.

One thing to note is that the choice of fonts used is quite critical. not so much from the machines ability to cut, but from my ability to remove the waste bits without trashing the narrow strokes of the letters. I did get better after a few attempts.

The temperature in the workshop was at a level that distresses Brass Monkeys today and the thicker material was a bit less flexible than it should be, so I'm going to run the machine in a warmer room next time to see if that makes a difference.

Stay tuned.
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Drew P
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« Reply #19 on: December 10, 2012, 03:57:49 am »

Damn that's a very nice and clean etch! I shall need that recipe Wink.
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« Reply #20 on: December 10, 2012, 10:31:37 am »

Couple of thoughts: Ferric Chloride works better if agitated, perhaps a cheap aquarium pump to get it moving, and, possibly, an enameled metal bowl and a heat source to warm the FeCl3..?

(I, too, shall be investigating this route, thanks!)

Smiley
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Dr cornelius quack
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« Reply #21 on: December 10, 2012, 08:47:01 pm »

Couple of thoughts: Ferric Chloride works better if agitated, perhaps a cheap aquarium pump to get it moving, and, possibly, an enameled metal bowl and a heat source to warm the FeCl3..?

(I, too, shall be investigating this route, thanks!)

Smiley

Yup! Soon as I get the mask making down to a routine operation, (right sort of vinyl, practice at weeding the cut of unwanted segments and what not) I intend to build a suitably steamy looking etch tank. Some of those old school aquarium pumps with the central disc rotor and two pistons would fit the bill rather well.

I'm still going to head in the direction of electro-chemical etching. Ferric Chloride granules are a bit pricey and are a one shot option, having to be disposed of after they have etched a few plates and replenished.
The notion of an electrolyte solution of Copper Sulphate that just passes current rather than reacting chemically with the base metal seems much more ecologically sound to me.

Also means that I can have a huge humming power supply and some curly wire and a big knife switch and some meters and pulsating filament bulbs and a lightning conductor......and stuff.
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« Reply #22 on: December 10, 2012, 11:29:55 pm »

Get your set-up up and working before investing too much in its look... You will find that both ferric and copper sulfate will get all over your work space and especially around the etch tank. I have moved my power supply up to a shelf to stay away from the splashy bubbles...
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jcbanner
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« Reply #23 on: December 11, 2012, 12:32:57 am »

Couple of thoughts: Ferric Chloride works better if agitated, perhaps a cheap aquarium pump to get it moving, and, possibly, an enameled metal bowl and a heat source to warm the FeCl3..?

(I, too, shall be investigating this route, thanks!)

Smiley

Yup! Soon as I get the mask making down to a routine operation, (right sort of vinyl, practice at weeding the cut of unwanted segments and what not) I intend to build a suitably steamy looking etch tank. Some of those old school aquarium pumps with the central disc rotor and two pistons would fit the bill rather well.

I'm still going to head in the direction of electro-chemical etching. Ferric Chloride granules are a bit pricey and are a one shot option, having to be disposed of after they have etched a few plates and replenished.
The notion of an electrolyte solution of Copper Sulphate that just passes current rather than reacting chemically with the base metal seems much more ecologically sound to me.

Also means that I can have a huge humming power supply and some curly wire and a big knife switch and some meters and pulsating filament bulbs and a lightning conductor......and stuff.

I've seen very good results with Copper sulfate.  if you put an agitator in your solution, be sure it does not produce bubbles. those will act as a mask and blemish your results.
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Dr cornelius quack
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« Reply #24 on: December 29, 2012, 06:53:44 pm »

Now, that's what I'm talking about!!




Set up a decent sized etch tank in a small aquarium from a local bargain store.
Power from a CB radio type regulated supply.
Cathode is a Copper mesh soldered into a sheet Brass frame with a copper tube attached to feed the power and hook up to the air pump to agitate the mix.
Electolyte is Sulphuric acid/water mix which appears to be producing some Copper Sulphate as it goes along.
Masks are vinyl cuts produced on the cutter.



Process time of two hours gives a bite of about 0.5mm.
Real crisp edge to the etch.

I is a happy Quacky!!
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