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geekhack Projects => Making Stuff Together! => Topic started by: agodinhost on Tue, 26 February 2013, 12:13:05

Title: building aluminium plates using photoresist dry film
Post by: agodinhost on Tue, 26 February 2013, 12:13:05

Hi, anyone already tried to build aluminium plates using photoresist dry film (http://"http://www.ebay.com/itm/1pcs-Dry-Camera-Film-developer-Board-PCB-Photoresist-Sheets-for-DIY-PCB-6-x-8-q-/390353956978?pt=Vintage_Electronics_R2&hash=item5ae2e8b072")?

Some time ago, when I got my first "blue contact" on ebay, I saw this article (http://"http://www.instructables.com/id/Killer-PCBs/?ALLSTEPS"). Read the "Step 11: Solder Paste Stencil"

I'm wondering IF this same process could be applied to a thicker aluminum sheet to build plates for the GH60 and others.

Title: Re: building aluminium plates using photoresist dry film
Post by: alaricljs on Tue, 26 February 2013, 12:17:40

Erm, no.  The costs of getting rid of that much acid would be ridiculous.  On top of that, there's no way to get a clean perpendicular hole through aluminum using that sort of chemical process.

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Tue, 26 February 2013, 12:23:07

Hmmm, even using Ferric Chloride (http://"http://www.ebay.com/itm/250g-Ferric-Chloride-FeCl3-For-Etching-Copper-PCBs-etc-/360585165366?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item53f48cfa36") ? It's cheap ...

To get perpendicular holes the Ferric Chloride could be applied above the sheet - so the gravity will do his thing (something like a shower filed with FeCl3).

Not counting hand made there is any cheap alternative out there for the plates?

Title: Re: building aluminium plates using photoresist dry film
Post by: alaricljs on Tue, 26 February 2013, 12:25:13

Define cheap, the plate GBs and one-offs that have been done lately have been really quite reasonable at under $30 for a TKL size plate.

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Tue, 26 February 2013, 13:43:11

IMHO $30 is already expensive so anything lower would be cool.
I know, taking in consideration all components it's cheap but, let's say:

qty	item	value
62	MX Switch	$60,00
1	PCB	$50,00	BatchPCB
1	Plate	$30,00
1	Plastic case	$20,00
*	small components	$30,00	atmega, resistors, diodes, caps, crystal, cable, usb connector
	Total	$190,00

I think that any homebrew alternative would help to lower these values.
That's why I'm still thinking about how to make it at home and if it's possible to get a decent precision on it.

The case could be made using Kydex, cheaper than acrylic and easily folded with one hot air pistol.
I was wrong: acrylic is way cheaper.

The PCB could be divided in two boards: one to hold the switches/diodes/leds and a second board to hold the uC, caps, crystal and usb connector. The switch board would be simpler - possibly a single sided PCB (with jumps, sure). I'm wondering about this approach, a single sided PCB would be easier to be done at home!

There is no much to do with the other parts - unless some crazy guy start to produce some good quality switches at home ...

Title: Re: building aluminium plates using photoresist dry film
Post by: alaricljs on Tue, 26 February 2013, 13:49:29

Well, samwisekoi has done a PCB-free KB with a teensy most recently (as others have in the past), so you could choose to scratch the PCB.  That also covers the daughterboard controller approach at <$20 for a teensy.

The key to lower pricing on the expensive parts is getting others interested in your design and getting quantity orders in.

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Tue, 26 February 2013, 16:39:51

I think that the PCB version is best suitable for 60% keyboards without plate. You can use both, sure, but the final result will be heavier and more expensive.

By what I saw in some Poker pictures it doesn't have a plate, I'm wrong?

A PCB-free design would require a plate to hold our switches, however, this plate would be more expensive than a homebrew single sided PCB. Anyway the plate can't be made at home!

I asked samwisekoi about his keyboard, I couldn't find it in the forum yet ...

Title: Re: building aluminium plates using photoresist dry film
Post by: alaricljs on Tue, 26 February 2013, 20:04:54

Typical poker has no plate, but there have been several aftermarket plates sold (separately and with case).  Many happy customers praise the results of "solid"

While it's possible to homebrew a workable KB PCB, the drill accuracy of a fab'd board can be noticed.

Here's a thread (http://geekhack.org/index.php?topic=40567.0) about no-PCB building, and it references (with link) the keyboard I had already mentioned.

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Tue, 26 February 2013, 22:43:42

True, even using a magnifying glass and on slow motion would be hard to keep the good aim - there are too many holes to drill. Not impossible though.

Do you think that would make any diference using SMD components? The smd switch requires 2 holes instead of 4 (the 2 plastic reference pins).

Another option would be to create some kind of standard for the plates, this would help to reduce the prices because everybody would be using the same plates instead of being constantly reinventing the wheel.

I saw lots and lots of plate designs in the forum and I think that we could use the initial GH60++ idea as an initial standard:

Quote from: samwisekoi on Thu, 03 January 2013, 13:57:14

... What I envision for the GH60++ is a variety of sizes with a common core.
GH60++ 60%  5x15
GH60++ 65%  5x16
GH60++ 70%  6x15
GH60++ 75%  6x16

(http://geekhack.org/index.php?action=dlattach;topic=38847.0;attach=11211;image)
GH60++ 75% PCB with break lines for 60, 65 and 70% sizes.

Assuming this idea we would have two options for the plate designs:
1) the obvious individual design, 4 plates - one for each kind of layout (60, 65, 70 and 75%)
2) one design with weak lines to fold and cut the plate (more or less like what samwisekoi did with the PCB)

So, standard plates, standard PCB and, sure, standard cases ...

So someone by any reason want to build one slightly variation (a winless kb), it would require some kind of cover at the win hole switch ...

Title: Re: building aluminium plates using photoresist dry film
Post by: alaricljs on Tue, 26 February 2013, 22:49:50

What SMD switch?  The Cherry MX plate mount switch is the same exact thing as the PCB mount switch, just without those 2 plastic pins.  Using them requires that you use a plate to get proper position registration.

As for the 'one true plate', never gonna happen.  People like choice.  1.5x mods, 1.25x mods, ISO, ANSI, .....

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Tue, 26 February 2013, 22:53:04

Hmmm, ISO, ANSI, can't we just reposition the keycaps?

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Tue, 26 February 2013, 22:56:49

My mistake, I got the MX datasheet and I thought it had a different footprint.

I wasn't thinking in "one true plate". I was more in the "give then a cool kit with a good set of possibilities" ...

Title: Re: building aluminium plates using photoresist dry film
Post by: The_Beast on Tue, 26 February 2013, 22:59:07

Phantom. Supports many layouts, only thing you need to change is the plate for said different layouts

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Tue, 26 February 2013, 23:19:47

I saw the Phantom project one month ago and the group buy were already closed at that time.
I do remember that I saw only one PCB for the phantom and I'm wondering how it would support different layouts ...

I've looked at "http://deskthority.net/wiki/Phantom_Instruction", it's there?
I saw 5 different plates there:
- PHANSI125: 87 switches
- PHANSI150: 86 switches
- PHISO125: 88 switches
- PHISO150: 87 switches
- PH7BIT: 101 switches
BUT only one PCB. I'm still wondering how different plates could be used with the same PCB ...

Anyway the phantom is way bigger (don't know the name you use for this size), I'm fond to the 60%
8-)

Title: Re: building aluminium plates using photoresist dry film
Post by: The_Beast on Tue, 26 February 2013, 23:24:03

There are more layouts than that IIRC


The GH60 should be supporting even more than that, I think it was like 18 layouts

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Wed, 27 February 2013, 20:26:54

I found one thread talking about homemade PCBs: Topic: Homemade keyboards - PCB crafting - Teensy tinkering (http://geekhack.org/index.php?topic=15542.0).

As far as I can tell it's good enough for me!

(http://i53.tinypic.com/2rdjjty.jpg)

(http://i54.tinypic.com/35i9h91.jpg)

Camon, it's doable!

Title: Re: building aluminium plates using photoresist dry film
Post by: alaricljs on Wed, 27 February 2013, 20:52:04

Never said it wasn't doable, but that first example has obviously misaligned switches and that would kill me.

As for different layouts on 1 PCB, PCB pic (http://deskthority.net/wiki/File:PhantomPCBFront.jpg) you should be able to see the pads that are tightly packed on the bottom row.  That provides support for slightly different positioning of each switch.  This allows for 1.5/1/1.5 or 1.25/1.25/1.25 for the left hand mod cluster.  There are a number of different sections of the PCB where different switch positions are possible.

Title: Re: building aluminium plates using photoresist dry film
Post by: agodinhost on Thu, 28 February 2013, 07:05:02

I'm not sure but I think he could used a ruler to align the switches - can we force a bit the soldered switches to align then? I do still need to order some switches, as soon as I sell my kidney I'll have the money to get a hundred then I'll be able to test it.

Regarding the different layouts on 1 PCB, now I got it, thanks!
I thought it were some kind of mistake at the PCB design.

Title: Re: building aluminium plates using photoresist dry film
Post by: alaricljs on Thu, 28 February 2013, 08:42:41

One of the switch leads is a rather sturdy chunk, the other is a leaf.  Even so, there's little leeway once a switch is soldered.  If you can manage to jig it up with a ruler held to the PCB to align the switches while you solder all the more power to you.