Hi all,


I have had a few questions on the etched plates I did for the 'boat anchor' Waldown drill press so I figure I'll post and describe as best I can. This might go over a few posts. Hopefully it is of help to someone out there. Note, there are other ways to go about it, this is just what I did.

Waldown thread is here: https://metalworkforums.com/f65/t205...wn-drill-press

First things first - this isn't an exact industrial-like repeatable process. Well, it wasn't for me anyways. It'll take some patience. There are a lot of variables that mean you will need to experiment for yourself. Things like how hot your iron goes, or the strength of the acid you can buy, or how the ambient temperature affects the 'aggressiveness' of the etching, or even the type of laser printer toner. etc etc.

A good thing is, it can be done at home - though not in an apartment. Acid gives of fumes when etching and you do not want to breathe that. At all. So, open air and don't stand anywhere near it when etching. And keep people, dogs, etc away as well.

** Stuff you need:

* laser printer. I have a cheapie, but it does need to be laser, not inkjet
* clothes iron
* hydrochloric acid - get this at bunnings or a pool shop. 5 litres was like $15 or something. You wont need all that.
* hydrogen peroxide. Yes, the hair bleach stuff. Chemists sell it, so do supermarkets (in the hair section).
* 1mm aluminium sheet
* a glossy magazine, or blue 'Press n Peel' printed circuit board etching paper

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** The basic process

The process is as follows:

* create the image of the etching in your favourite image editing software
* print that image in reverse (like a mirror image) onto glossy paper or the PnP blue
* transfer the printer toner from that printed image onto a prepped aluminium plate using an iron
* etch the aluminium plate in acid/peroxide mixture
* paint it
* remove paint from raised parts

I'll go through each step below and outline what I did and what I learned. It may be different for you, but this is what I did.

** Image editing

My starting point was photographs of the plates kindly supplied by forum members. I used 'the gimp' imaging edting software to clean them up, straighten them, make edges less 'fuzzy', remake some parts and so on. The gimp is 'raster' image editing software - it edits photos and such. Others may prefer 'Inkscape' which is 'vector' image editing. Vector images are lines and curves. Vector is really the ideal as line edges are not 'fuzzy'. Vector images scale up and down in size perfectly whereas the fuzzy edges of lines and edges in a vector image become more pronounced as you make an image larger. Personal choice I guess. I wasn't familiar with either package. I started with gimp because my starting point was iages. Watch some videos.

The goal of editing the image to create a black-upon-white (or black-upon-transparent) image where the black part is the stuff you want raised after etching - or inversely, the white part is the stuff you want etched away.

Like, here is an initial image I started with (apols if sidewards - it ain't on my machine):

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Turn it into this:

Screenshot 2020-09-20 124622.png

Then print it like this:

Screenshot 2020-09-20 124529.png

But, worth printing test images and offering them up to the machine to make sure you get the size correct:

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** Print the image onto a 'transfer medium'

Once you're happy with your image you need to get that image printed (in reverse) by a laser printer onto some medium that will permit the printer toner to be melted off of it on to aluminium. We can't print onto aluminium directly, so we print onto something else, then transfer that image onto the aluminium. The key here is 'transfer'. The laser printer prints (melts) the toner onto the medium, and then we remelt it off again onto the aluminium.

If you're a cheapskate like I was initially, you can try a vacuous glossy magazine as a print medium. Maybe the more vacuous the better as they tend to increase in glossiness - I went for 'Vogue'. But, it is the glossiness that gives the ability to remelt the toner off. Like, the printed toner is actually on some waxy coating on the paper, not on the paper itself. So it can be melted off again.

Alternatively, you can use some printed circuit board (PCB) transfer paper - something like 'Press n Peel blue'. I got some from jaycar electronics. It isn't cheap (at all), but gave me far more reliable results than the glossy magazine.

I think the glossy magazine thing is likely okay for PCBs where the actual depth of etching is very small. But with etching machine plates, we're going for quite some etch depth and the glossy paper method just didn't seem to last as long in the acid as did the Press n Peel.

I think the reason is, when using glossy paper, the toner is the only thing on the aluminium to resist the acid - whereas with the PnP blue it is the toner PLUS its own blue magic layer so there is more stuff to resist the acid.

I ended up using Press n Peel for its greater consistency but some photos in this thread might show magazine paper. I did a fair bit of experimenting.

In either case, you want to get the printer to print as much toner as it can - we want as much resistance to the acid as we can muster. I went through print settings and went for highest quality, adjusted darkness levels etc to try to maximise the amount of toner printed.

here is the process I used:

* print the image onto some standard paper - we'll use this to help with positioning our actual medium.
* tape a section of your chosen medium over the top of that above printed image
* insert that paper back into the printer
* print again

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** Transfer the printed image onto aluminium plate

The idea here is we're going to remelt the printed toner onto aluminium using a clothes iron.

Cut yourself some aluminium plate - somewhat larger than the actual plate you're making. You need room for the print medium and some also some extra room to tape that medium to the aluminium.

I tried both 1.2mm and 1mm plate. The 1mm plate is easier to deal with.

You need to prepare the aluminium plate. I wet sanded the plates with 1000 grit wet and dry under running water, then after drying, cleaned thing with acetone. The sanded surface gives the toner something to hang on to.

Tape your 'transfer medium' printout to the aluminium with the toner towards the aluminium - now you see why it is in reverse!

IMPORTANT: you really have to make sure you don't get dust or stuff on the print or aluminium or wherever. About 50% of my failures were dog hair coming out of the universe from nowhere. Really.

IMG_20200701_193713.jpgIMG_20200701_194348.jpgIMG_20200905_084533.jpg

Okay, not all clothes irons are the same. Some hotter, some not. You'll need to experiment if things don't go well up front. For example, I found that my iron is hottest after it goes through its power-on heat up and its heating light goes off. After that, it is never as hot by like 50c or something. So, every time I did a transfer I turned the iron off. Then on again for the next ironing and let it go through that 'bootstrap' heating cycle again.

The process:

* put some package cardboard from an old box or something down
* place your aluminium plate on the cardboard with the taped-on paper side up.
* place a sheet of paper over it - this will stop melted tape glue getting onto your iron
* when the iron is up to temperature, place onto aluminium plate and press down fairly firmly and don't move it - I did this 2 minutes. We're heating stuff up and doing some toner melting.
* then, move iron around about over the plate - using the edge of the iron (with iron on slight angle) make sure you go over all the image-to-be-printed and apply pressure. This 'targeted' pressure really helps the transfer. Go to all the edges, the middle etc, but, get pressure onto all parts of the image. I did this for 2 minutes.
* after the 4 minutes of ironing, if you're using glossy paper, get it into a sink / bucket of water and let soak until the paper wants to come off. If using PnP blue paper, run it under water to cool it then lift the PnP. BTW, the aluminium will be BLOODY HOT, so be careful.

Repeat until you get a transfer you're happy with. If a transfer didn't work very well I just used acetone to get it off the aluminium and have another go. ALL errors show up in the final etching - so, no point after that.

IMG_20200701_200139.jpgIMG_20200701_201230.jpg

Some examples - not all successful!

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note the excess blue on the power switch print above: probably means iron for too long - but .. a cue-tip (cotton bud) with some acetone will clear that up. At least thin it out. It won't last long in acid.

** Etching

Here we do the business and let science dazzle us. And we be very careful. This is nasty nasty stuff folks. The etching gives off vapours - only some of which you can see as steam. Treat the process with respect. I wore gloves, had a bucket of water handy, and stayed well away while it was all going on. Took a deep breath, went to inspect stuff, went away, took a breath. No breathing around the etching.

There is a lot of variability in this part of the process. Like, how strong is the acid? What concentration is the hydrogen peroxide? What is the temperature? (etching is much slower on a cold day than a warm day). I read online that the etching mixture was 1 part acid to 2 part peroxide. I just stuck with that even though maybe there was a more ideal mixture. Dunno.

prep the plate:

* trim off any excess aluminium from around the plate. I snipped of what I could with some tin snips and left a small border for filing.
* tape up the back of the plate. We're only interested in etching one side not both!

IMG_20200628_125818.jpg

process:

* in a small acid plastic container add the 2 parts peroxide, then add the 1 part acid. "Add acid to water, like you oughta". Don't add the acid first, add it last - this is to reduce chance of injury from acid splashes as you add something to it.
* have a small container of water nearby. We'll use this to dunk the plate in so we can check the etch depth
* put the blank in the acid mixture. If it starts 'boiling' quickly then it is way too fast and you'll need to make a more dilute mixture. For me, on a cold day, it could take like 10 to 15 minutes before it seems it was really doing something.
* when it is underway, occasionally, get the plate out to have a look, maybe even dunk it in water so you can then feel the etch depth with your (gloved) finger more safely. When I got it out of the acid for a check, I'd dunk it in water, then walk away with it for inspection to get away from the vapours.
* when you're happy, rinse the part under running water and remove the tape from the back under that water also - the tape can trap acid in pockets.

How deep should you etch? As deep as you can get away with - maybe 0.5mm or so, but you can get by with less. It has to be deep enough for paint to live in and when we're removing paint from the unetched bits, you don't stuff up that paint in the etched parts.

Keep in mind that the etching is not only eating its way 'down', it's also eating 'sidewards', which means it is trying to eat its way underneath the 'resist'. Not so much an issue with a shallow etch, but as you get deeper, the acid tends to try an attack the sides of stuff so lines or small text get eaten away sidewards and lose definition.

IMG_20200628_154239.jpgIMG_20200628_132025.jpgIMG_20200902_173151.jpgIMG_20200719_165753.jpg

** Painting

This part you can likely figure out - paint it, then using whatever means you have, remove the paint from the raised parts. Mostly, I used 1000 grit wet and dry flat on the mill table and gently sanded until paint came of those raised parts and exposed some aluminium.

Depending on the depth of the etch this can be a little hit and miss - a 'miss' being you end up marking the paint in the etched sections.

I used a rustoleum rattle can paint because it's what I had and we're in COVID stage 4 lockdown. That was probably a bit thick and made the sanding process more 'miss' than hit. A thinner spray paint would have been a lot better. For the power switch, which was not a very deep etch, I ended up spraying some paint into a cup, adding some thinners to it, and then dabbing that into the etched areas with a small artists brush. I then scraped the excess paint from the raised area with an exacto knife and then give it a very light sanding to remove some small exacto knife scratch marks.

I guess, whatever works for you.

I then sandwiched the plate in between two cardboard pieces, put it in the vice gently, and draw-filed away excess aluminium to get the final shape.

I did try to apply some clear, but, the only clear I have did not like the rustoleum, or vice versa.


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All comments and thoughts welcome, hopefully that helps someone out there with an old machine what wants some lovin.

oh, some of those that served:

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Good luck!
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