Author Topic: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?  (Read 11723 times)

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Offline Rose

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I'm going to be using a layered acrylic case for the custom keyboard I'm designing.  Trying to decide on a mounting plate thickness.  Here is what I understand so far.

1.5mm (1/16in) Mounting plate:
This is the thickness that Cherry MX switches snap right into.
Acrylic can be brittle when it's this thin and plates can crack when mounting.
A second layer just below the plate with slightly larger switch holes can reinforce it.
Switches will be easier to remove/replace.
If the sheet used is on the thinner side of it's error tolerance then the switches may be loose.

Thicker Acrylic Plate:
This is sturdier.
The switches are held in place by friction.
If hand wiring, Hot glue is recommended to hold switches in place. (I don't know if this is necessary with a PCB)

Questions:
Will a reinforcement layer on top of the 1.5mm switch plate work?  It might need to accommodate the keycaps, not just the switch holes.

Does the decision affect overall case thickness?  It seems like that extra support layer under the 1.5mm plate will leave less room for wiring and require thicker spacers. (hence the first question)

Is it difficult to get the switches glued to exactly the same height?

I am considering a price difference of <$20 between the two methods to be negligible.  (i.e. hot glue, extra laser time, etc)

The layout for which I am building the case is pretty small so the sturdiness of the 1.5mm acrylic may be less of a factor.
« Last Edit: Wed, 25 March 2015, 13:49:19 by Rose »

Offline neverused

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #1 on: Wed, 18 March 2015, 19:00:24 »
You could have a secondary plate with larger cut outs that goes under the main plate. It would go around the switches and support from below.

With that said, I hope to have a 1.5 mm plate cut from acrylic by next week. I'll try to remember to share my thoughts then.

Offline regack

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #2 on: Wed, 18 March 2015, 19:28:36 »
I'm going to be using a layered acrylic case for the custom keyboard I'm designing.  Trying to decide on a mounting plate thickness.  Here is what I understand so far.

Thicker Acrylic Plate:
This is sturdier.
The switches are held in place by friction.
If hand wiring, Hot glue is recommended to hold switches in place. (I don't know if this is necessary with a PCB)

Questions:
Will a reinforcement layer on top of the 1.5mm switch plate work?  It might need to accommodate the keycaps, not just the switch holes.

Does the decision affect overall case thickness?  It seems like that extra support layer under the 1.5mm plate will leave less room for wiring and require thicker spacers. (hence the first question)

Is it difficult to get the switches glued to exactly the same height?

I am considering a price difference of <$20 between the two methods to be negligible.  (i.e. hot glue, extra laser time, etc)

Here's the layout for which I am building the case.
(Attachment Link)

 
I haven't tried using 1.5mm acrylic, only 3mm Acrlylic.  It flexes enough as it is, I can't imagine 1.5mm holding up very well.  I think your layered approach will ultimately work out ok,  but you'll obviously have to bond the plates together fairly consistently to gain the benefits.

Here's a crappy picture of what 3mm acrlyic looks like from the side:
94515-0
There is about 1.7mm between the bottom of the acrylic and the top of the PCB. 
You have ~3.2mm between the switches - that's a pretty narrow strip of acrylic.
With a key depressed, you have probably ~2mm clearance from the top of the plate, to the bottom of the cap.  I'm not sure if that will be true with all caps.

So, theoretically you could build a 1.5mm plate with an additional 1.5mm layer both above and below that plate for a total 4.5mm thickness.  That would probably be quite nice.

If you're going to try that, I suggest doing a trial run on something simpler (and even smaller) than what you have there.  There is quite a bit of flex in my 59% board using 3mm acrylic.  It's not bad for typing, but when inserting the switches and putting on the caps, I had to brace the PCB underneath with my other hand.

Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #3 on: Wed, 18 March 2015, 19:34:19 »
You could have a secondary plate with larger cut outs that goes under the main plate. It would go around the switches and support from below.

That is what I meant by this:
A second layer just below the plate with slightly larger switch holes can reinforce it.

Offline Oobly

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #4 on: Mon, 23 March 2015, 02:55:47 »
I'd go with a 5mm plate with perhaps slight cutouts for the tabs, but not necessarily. The switches and PCB will hold the assembly together tightly and make for a very solid construction. Also, it's a single piece so less complicated to install. You can even make it a little oversize on the top and bottom and bend it like a GON skinny or Infinity plate so you don't need any other pieces (assuming you're confident in your acrylic bending skills):

Buying more keycaps,
it really hacks my wallet,
but I must have them.

Offline jacobolus

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #5 on: Mon, 23 March 2015, 16:16:38 »
Are you planning to hand wire it? If so, the second plate can be quite thick, and the two-plate method works great.

Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #6 on: Tue, 24 March 2015, 16:04:45 »
Are you planning to hand wire it? If so, the second plate can be quite thick, and the two-plate method works great.

Yes I am going to hand wire it.  I was planning on having the second reinforcement layer only another 1.5mm(1/16in).  This layer will basically be the same as the switch plate but with slightly bigger cutouts so I was thinking thinner => more room for wiring and diodes.

Offline jacobolus

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #7 on: Tue, 24 March 2015, 16:52:05 »
Two 1/16" layers isn’t the best idea IMO. I recommend making the second layer either 3/16" or 1/4" (or even thicker if you want).

Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #8 on: Tue, 24 March 2015, 17:24:34 »
Two 1/16" layers isn’t the best idea IMO. I recommend making the second layer either 3/16" or 1/4" (or even thicker if you want).

Okay.  Why is that?  To squishy feeling?  Too Fragile? 

What do you think about two 1/16 inch support layers? -  One just below the switch plate with slightly larger holes and then another, almost the same as the first but with a few channels cut out for wiring.

I think people have had success on small boards with 1/8 inch acrylic mount plates.  I was planning on gluing the two layers together.

I'll probably cut the plate first and then see how it feels.


Offline jacobolus

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #9 on: Tue, 24 March 2015, 18:12:06 »
Thin acrylic is not very rigid, and is also fairly brittle. If both of your two layers are 1/16" thick, they’re going to easily flex, and if you glue them together, I suspect any fall will either break the adhesive or break one or both layers. 1/4" thick acrylic is *dramatically* sturdier.

Remember, the leads on your switches stick down quite a bit, so even if you use a 1/16" plate backed by a 1/4" plate, you’ll still have room for diodes and wire. There’s basically no downside to using a thicker piece of acrylic, if you’re hand wiring.

In general, I think fewer layers is better. A thick piece of acrylic (or wood or aluminum or whatever) with the holes milled from the bottom and a step for the switches to clip into would be better than a stack of two acrylic pieces, but is much more expensive to manufacture (laser cutting is cheap).

How are you planning to do the sides/bottom of your case?
« Last Edit: Tue, 24 March 2015, 18:14:51 by jacobolus »

Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #10 on: Tue, 24 March 2015, 22:04:03 »
Thin acrylic is not very rigid, and is also fairly brittle. If both of your two layers are 1/16" thick, they’re going to easily flex, and if you glue them together, I suspect any fall will either break the adhesive or break one or both layers. 1/4" thick acrylic is *dramatically* sturdier.

Remember, the leads on your switches stick down quite a bit, so even if you use a 1/16" plate backed by a 1/4" plate, you’ll still have room for diodes and wire. There’s basically no downside to using a thicker piece of acrylic, if you’re hand wiring.

In general, I think fewer layers is better. A thick piece of acrylic (or wood or aluminum or whatever) with the holes milled from the bottom and a step for the switches to clip into would be better than a stack of two acrylic pieces, but is much more expensive to manufacture (laser cutting is cheap).

How are you planning to do the sides/bottom of your case?

Okay.  I'll have to look at going thicker for the reinforcement layer.  I was going to try to cut the entire case out of one 12x24 1/16 sheet and one 12x24 1/8 sheet, creating 4 layers from each.  I am still working on the case files.  Might only be able to fit 3 layers per 12x24 sheet.  The bottom and sides will be layered acrylic too.

Offline metalliqaz

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #11 on: Tue, 24 March 2015, 22:15:29 »
I mafe one of my plates with 1.5mm acrylic and the plate did crack in two places.  I just kept going and in the final product it was impossible to tell that it happened. I use it every single day, no problems.

Offline neverused

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #12 on: Tue, 24 March 2015, 22:51:39 »
1.5 mm acrylic is pretty flexible, I just had a plate cut from 1.5 mm from Ponoko for a project. If you want to use that same amount of layers, you might try moving one of the 1/8" layers up to immediately below your plate. You can keep the same materials, just change the order.

Offline sypl

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #13 on: Wed, 25 March 2015, 12:45:12 »
Why do people use acrylic instead of polycarbonate? PC is much less brittle, which is the great fear when using acrylic. PC bends but doesn't break. A little pricier, but not by much at these sizes. And at 1.5mm it's just about as clear as acrylic, if that's important to you.

Offline sypl

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #14 on: Wed, 25 March 2015, 12:56:13 »
Also, there's a trick I use on my custom keyboard to avoid the flexing caused by too thin a top plate. Ready?

I place switches in top plate and handwire as usual, with column and row wires _very_ close together, as close to switch casing as possible. I then clip the copper pins on the switches so that they're no longer, er, longer than the cherry plunger casing.

Do that with all your switches and you can just plop your keys on top of your bottom plate, which can also be thin. The flat bottom of the switch plunger casing sits right on the bottom plate. In effect if you have n keys you have n columnar supports.

I find 6mm spacers the perfect size to connect the two plates. Because your switch is really sandwiched between two plates with no daylight between them, there's no space for the switches to sink down in to.

I really should write up my build log some day. I did some fun/silly stuff.

Offline metalliqaz

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #15 on: Wed, 25 March 2015, 13:16:18 »
I just use acrylic because it's cheaper and usually available in more options for color/thickness

Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #16 on: Wed, 25 March 2015, 14:00:49 »
I mafe one of my plates with 1.5mm acrylic and the plate did crack in two places.  I just kept going and in the final product it was impossible to tell that it happened. I use it every single day, no problems.
Did you reinforce it with a second layer as described above?

Why do people use acrylic instead of polycarbonate? PC is much less brittle, which is the great fear when using acrylic. PC bends but doesn't break. A little pricier, but not by much at these sizes. And at 1.5mm it's just about as clear as acrylic, if that's important to you.
I am using what is available at my college's makerspace.  They don't allow use of materials that they don't offer onsite.  They have 1/8 black, 1/8 red, and 1/16, 1/8, 1/4 clear acrylic.  I am thinking red or black for my top and bottom layers to hide my first experience wiring.

Also, there's a trick I use on my custom keyboard to avoid the flexing caused by too thin a top plate. Ready?

I place switches in top plate and handwire as usual, with column and row wires _very_ close together, as close to switch casing as possible. I then clip the copper pins on the switches so that they're no longer, er, longer than the cherry plunger casing.

Do that with all your switches and you can just plop your keys on top of your bottom plate, which can also be thin. The flat bottom of the switch plunger casing sits right on the bottom plate. In effect if you have n keys you have n columnar supports.

I find 6mm spacers the perfect size to connect the two plates. Because your switch is really sandwiched between two plates with no daylight between them, there's no space for the switches to sink down in to.

I really should write up my build log some day. I did some fun/silly stuff.
I like this idea.  Keeps it thin and solid.  Are there any downsides?  Harder to solder?


Offline jacobolus

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #17 on: Wed, 25 March 2015, 17:01:36 »
Why do people use acrylic instead of polycarbonate?
The kind of laser cutters people are often using to cut acrylic suck at cutting polycarbonate.

Offline sypl

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #18 on: Wed, 25 March 2015, 21:35:08 »
Also, there's a trick I use on my custom keyboard to avoid the flexing caused by too thin a top plate. Ready?

I place switches in top plate and handwire as usual, with column and row wires _very_ close together, as close to switch casing as possible. I then clip the copper pins on the switches so that they're no longer, er, longer than the cherry plunger casing.

Do that with all your switches and you can just plop your keys on top of your bottom plate, which can also be thin. The flat bottom of the switch plunger casing sits right on the bottom plate. In effect if you have n keys you have n columnar supports.

I find 6mm spacers the perfect size to connect the two plates. Because your switch is really sandwiched between two plates with no daylight between them, there's no space for the switches to sink down in to.

I really should write up my build log some day. I did some fun/silly stuff.
I like this idea.  Keeps it thin and solid.  Are there any downsides?  Harder to solder?
[/quote]

You need some way to keep the wires from touching. Some people use insulated wire and burn it away when they need a connection. I like the naked wire look, so used something else to keep them off each other. I'll reveal this method when the write-up is done.

I wouldn't really say it's any more difficult to solder. You don't have a lot of space for wires to the controller so have to be plan it well, but there's still about enough there.

Offline neverused

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #19 on: Wed, 25 March 2015, 22:33:56 »
Also, there's a trick I use on my custom keyboard to avoid the flexing caused by too thin a top plate. Ready?

I place switches in top plate and handwire as usual, with column and row wires _very_ close together, as close to switch casing as possible. I then clip the copper pins on the switches so that they're no longer, er, longer than the cherry plunger casing.

Do that with all your switches and you can just plop your keys on top of your bottom plate, which can also be thin. The flat bottom of the switch plunger casing sits right on the bottom plate. In effect if you have n keys you have n columnar supports.

I find 6mm spacers the perfect size to connect the two plates. Because your switch is really sandwiched between two plates with no daylight between them, there's no space for the switches to sink down in to.

I really should write up my build log some day. I did some fun/silly stuff.
I like this idea.  Keeps it thin and solid.  Are there any downsides?  Harder to solder?

You need some way to keep the wires from touching. Some people use insulated wire and burn it away when they need a connection. I like the naked wire look, so used something else to keep them off each other. I'll reveal this method when the write-up is done.

I wouldn't really say it's any more difficult to solder. You don't have a lot of space for wires to the controller so have to be plan it well, but there's still about enough there.
[/quote]
It's funny that you mention this, I just started this process last night. I haven't posted this in a build log yet, but here are switches installed in a 1.5 mm plate, with the diodes wired internally. Tonight I will wire up the columns below the switches so that the tallest point is the bottom of the switch.


Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #20 on: Wed, 25 March 2015, 23:19:25 »
Also, there's a trick I use on my custom keyboard to avoid the flexing caused by too thin a top plate. Ready?

I place switches in top plate and handwire as usual, with column and row wires _very_ close together, as close to switch casing as possible. I then clip the copper pins on the switches so that they're no longer, er, longer than the cherry plunger casing.

Do that with all your switches and you can just plop your keys on top of your bottom plate, which can also be thin. The flat bottom of the switch plunger casing sits right on the bottom plate. In effect if you have n keys you have n columnar supports.

I find 6mm spacers the perfect size to connect the two plates. Because your switch is really sandwiched between two plates with no daylight between them, there's no space for the switches to sink down in to.

I really should write up my build log some day. I did some fun/silly stuff.
I like this idea.  Keeps it thin and solid.  Are there any downsides?  Harder to solder?

You need some way to keep the wires from touching. Some people use insulated wire and burn it away when they need a connection. I like the naked wire look, so used something else to keep them off each other. I'll reveal this method when the write-up is done.

I wouldn't really say it's any more difficult to solder. You don't have a lot of space for wires to the controller so have to be plan it well, but there's still about enough there.
It's funny that you mention this, I just started this process last night. I haven't posted this in a build log yet, but here are switches installed in a 1.5 mm plate, with the diodes wired internally. Tonight I will wire up the columns below the switches so that the tallest point is the bottom of the switch.


[/quote]

This looks really nice!  What does it mean to have the diodes wired internally?

Offline neverused

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #21 on: Wed, 25 March 2015, 23:27:51 »
I'll post a pic tonight

Offline jacobolus

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #22 on: Thu, 26 March 2015, 01:31:35 »
You need some way to keep the wires from touching. Some people use insulated wire and burn it away when they need a connection. I like the naked wire look, so used something else to keep them off each other.
I recommend using magnet wire (the kind with a thin polyurethane insulation layer which easily burns off when you solder the wire to something). Most hand wired keyboards I’ve seen on geekhack use wire with thicker insulation and strip it off at the connection points (e.g. the picture a few posts up), but using magnet wire is much easier.

Offline sypl

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #23 on: Thu, 26 March 2015, 06:05:01 »
Yeah, I have that stuff, but it's an orange colour because of the enamel, which I don't like. Silly reason I know. I think I saw some nickel wire on taobao and was gonna order, but don't really need it just yet.

Offline regack

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #24 on: Thu, 26 March 2015, 10:53:34 »
This looks really nice!  What does it mean to have the diodes wired internally?
Yes, I agree, it's really nice and tidy  :thumb:

The switches have the diodes inside of the switch body (like where the LED would go).  There are actually 4 small holes on one edge of a cherry switch, the wider pair can be used with diodes built into the switch body.  The inner pair can be used with LEDs.  As far as I know, you can't do both at the same time.

If you look closely at the photo, you can see there are 4 wires coming out of each switch - one of them is under the black-insulated wires and is soldered to one of the regular pins of the switch. The other is actually soldered to the end of the black-insulated wire.  Those wires lead to the diode.
« Last Edit: Thu, 26 March 2015, 10:55:19 by regack »

Offline megablue

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #25 on: Wed, 01 April 2015, 23:31:45 »
There is a way you can use thicker plate while the switches still clip into the mounting just fine.

You can engrave the areas where the clips touch to make those areas thinner, although I have to say, it is hard to gauge how much you need to engrave to make it a perfect fit though.

Offline jacobolus

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #26 on: Thu, 02 April 2015, 00:30:48 »
You can engrave the areas where the clips touch to make those areas thinner, although I have to say, it is hard to gauge how much you need to engrave to make it a perfect fit though.
Sure, but if you’re using acrylic, you probably want something cheap and easy; laser cutting is much cheaper and easier than milling.

If you are going to take the trouble to mill a plate, you might as well use hardwood, aluminum, a nicer type of plastic, or some other material.

Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #27 on: Mon, 06 April 2015, 13:01:40 »
Also, there's a trick I use on my custom keyboard to avoid the flexing caused by too thin a top plate. Ready?

I place switches in top plate and handwire as usual, with column and row wires _very_ close together, as close to switch casing as possible. I then clip the copper pins on the switches so that they're no longer, er, longer than the cherry plunger casing.

Do that with all your switches and you can just plop your keys on top of your bottom plate, which can also be thin. The flat bottom of the switch plunger casing sits right on the bottom plate. In effect if you have n keys you have n columnar supports.

I find 6mm spacers the perfect size to connect the two plates. Because your switch is really sandwiched between two plates with no daylight between them, there's no space for the switches to sink down in to.

I really should write up my build log some day. I did some fun/silly stuff.

I am probably going to do this.  I have done a test cut and indeed found 1/4 inch of space between he plate and the bottom of the plastic part of an MX Cherry switch.  I was still going to use a reinforcement layer between the plate and the spacer.  Is that even necessary?  Do you have a pic of your setup?

Offline sypl

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #28 on: Mon, 06 April 2015, 23:57:18 »
I don't think it's necessary, personally. I toss my keyboard in to my bag every day and haven't had any problems.

Here's a profile shot of my board. Apologies for photo quality.
96603-0

And a shot from below:
96605-1

I have three layers: a top plate, a bottom plate and a friction layer. Bottom plate is polycarbonate, top plate is acyrlic (because I didn't think of polycarbonate at the time) and the bottom layer is PVC. All nice and transparent.

I think even with another supporting layer it's not going to be very stiff. If you grab two 1.5mm sheets of acrylic, place them on top of each other and bend, you'll find they still flex quite a bit.

It depends on what you're trying to achieve. For me I need it to not flex enough when it's in my bag that it'll crack the plate. It hasn't been as issue so far and if I replace that top plate with polycarbonate one I'm pretty sure that won't ever be an issue (
). Flex whilst typing is solved because the keys are right on top of the bottom plate.

Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #29 on: Tue, 07 April 2015, 01:37:02 »
Nice board!  Thanks for the pics. 

Among your three different layer materials I imagine acrylic to be the most brittle.  It looks like you have plenty of unused space below the plate to fit a 1/8 inch reinforcement layer so I'll probably do that for good measure since I plan to use only acrylic.  I 'm also planning on having at least one, maybe two, outer layers on top of the switch plate.  This will allow me to cut a hole in the plate for my teensy- giving it more room, add stability, possibly protect the keys from getting snagged from underneath, and hide what is sure to be a hideous first soldering experience (I have 1/16 inch acrylic only readily available in clear).

Does that board fit a teensy all soldered up in just the 6mm of space between the plate and the bottom? What is the purpose of a friction layer?  Where is there friction?

Offline sypl

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #30 on: Tue, 07 April 2015, 04:28:29 »
You can fit a teensy in the space between the plates, but only if you have spots with no keys. I only have two spots with no keys, and they're only one unit spaces, not long enough for a teensy, so mine is external.

96611-0

96613-1

That's shrink wrap around the teensy. I thought about fancy cases and the like, but this is simple and holds the wires tightly in place best. And it preserves the 'clear' theme I have going on.

I'm glad you asked about the friction layer. I use my keyboard on top of my laptop keyboard. With plain naked acrylic or polycarbonate it slides around too much. PVC isn't the most grippy material, but it's tacky enough that it doesn't slide too much.

There's a trick to this though too. The more surface area you have in contact with the underlying surface, the more friction you'll have. So, it's important that the bottom layer be _completely_ flat. I think I got the idea from the MiniGuru. So my bottom layer is basically a PVC sheet with holes knocked in it where the screw holes holding the plates together are. The tackiness of the PVC along with a vacuum effect means I don't even have to add adhesive between it and the bottom plate. It's just 'sucked' on.
« Last Edit: Tue, 07 April 2015, 04:36:34 by sypl »

Offline Rose

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #31 on: Wed, 13 May 2015, 14:13:33 »
Also, there's a trick I use on my custom keyboard to avoid the flexing caused by too thin a top plate. Ready?

I place switches in top plate and handwire as usual, with column and row wires _very_ close together, as close to switch casing as possible. I then clip the copper pins on the switches so that they're no longer, er, longer than the cherry plunger casing.

Do that with all your switches and you can just plop your keys on top of your bottom plate, which can also be thin. The flat bottom of the switch plunger casing sits right on the bottom plate. In effect if you have n keys you have n columnar supports.

I find 6mm spacers the perfect size to connect the two plates. Because your switch is really sandwiched between two plates with no daylight between them, there's no space for the switches to sink down in to.

I really should write up my build log some day. I did some fun/silly stuff.

This is the method I ended up using.  It worked very well.  Thanks.

Offline Zukoi

  • Posts: 64
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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #32 on: Thu, 14 May 2015, 23:42:07 »
There's a trick to this though too. The more surface area you have in contact with the underlying surface, the more friction you'll have.

Very nice keyboard build.

Although, there needs to be a correction. http://www.physlink.com/Education/AskExperts/ae140.cfm

More surface area doesn't increase the frictional force because the increase in frictional force is negated by the decrease of pressure across the surface. I suggest adding sticky rubber feet for your grip purposes.

Offline sypl

  • Posts: 114
Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #33 on: Sat, 23 May 2015, 02:54:18 »
There's a trick to this though too. The more surface area you have in contact with the underlying surface, the more friction you'll have.

Very nice keyboard build.

Although, there needs to be a correction. http://www.physlink.com/Education/AskExperts/ae140.cfm

More surface area doesn't increase the frictional force because the increase in frictional force is negated by the decrease of pressure across the surface. I suggest adding sticky rubber feet for your grip purposes.

Rubber feet sink in and activate keys on the laptop keyboard when I increase the force by pressing a key on my own board. I guess I was talking about pressure. I need the pressure to be spread over as large an area as possible to prevent that happening. But thanks for the link.

Offline rsac

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Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #34 on: Sun, 24 May 2015, 11:29:03 »
This is the method I ended up using.  It worked very well.  Thanks.
Acording to your Build log 2 it didn't work so well. You had to glue the switches anyway because the acrylic plate was cracking when pulling them. With glue and the same 1.5mm acrylic plate it didn't crack?

I wonder if this technique would work for plywood, that don't seem to crack as easily as acrylic, but maybe could also be damaged by pulling the keys.

Offline Rose

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  • Location: Raleigh, NC
Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #35 on: Mon, 25 May 2015, 09:37:12 »
This is the method I ended up using.  It worked very well.  Thanks.
Acording to your Build log 2 it didn't work so well. You had to glue the switches anyway because the acrylic plate was cracking when pulling them. With glue and the same 1.5mm acrylic plate it didn't crack?

I wonder if this technique would work for plywood, that don't seem to crack as easily as acrylic, but maybe could also be damaged by pulling the keys.

The method I am referring to as having worked well is allowing the switches to sit flush on base plate.  This eliminates the need for the reinforcer.  I couldn't find a hole size that allowed keycaps to be removed without either the switch coming out or the plate cracking. I used a plate that had larger holes so the switches would pop out if they weren't glued. The glue holds them and the plate doesn't crack.

If you are trying to avoid using glue I would consider a metal plate. Plywood is soft and flexible and might have the same issues I had with acrylic. What switches are you going to use? I might be imagining it but I think I read that clears hold the keycaps tighter than most others.

Offline sypl

  • Posts: 114
Re: Acrylic Plate Mounting: reinforce 1.5mm or glue into thicker plate?
« Reply #36 on: Sat, 30 May 2015, 15:23:24 »
This is the method I ended up using.  It worked very well.  Thanks.
Acording to your Build log 2 it didn't work so well. You had to glue the switches anyway because the acrylic plate was cracking when pulling them. With glue and the same 1.5mm acrylic plate it didn't crack?

I wonder if this technique would work for plywood, that don't seem to crack as easily as acrylic, but maybe could also be damaged by pulling the keys.

My top plate is acrylic as I'd not really thought about polycarb when I began and it has cracked in several places. I don't think I'd use anything other than PC for plates in the future.