Thanks, that's definitely an option.  At one time I remember people still filling their case inside with expanding foam.  Do people still do that?  Does it work?

...
Are carbon fiber shards harmful?

Hi, guys, I'm always looking for anything I can do to lighten my load when I'm out and about.  I have this quasi-bipolar taste of leather/canvas and carbon fiber/brush metal.  Don't know what to do with that sometimes.

Anyway, many years ago I built a carbon fiber shell for my Macbook that you can read about here.  Man, that was a long time ago.  I've been thinking that it would be cool to have a carbon-fiber base (not shell on an existing base, mind you) for my Poker.  It will also have a titanium plate (thanks mkawa and The_Beast), so that goes along with the "light but awesome" theme.

My question for you guys is this:  would a plate make up for the crappy feeling that often accompanies plastic/lightweight bases?  Would I be shooting myself in the foot by going through all this trouble (and working with CF is a LOT of trouble) just to end up with a keyboard that sucks?  Could I do something like a foam fill or a silicone insert that would counteract that feeling?

What say you, geekhackers?

hmmmm....  why don't you start with a fiberglass phenolic G10 or G11 base and see what it feels like? otoh the pcb will probably already be G10/FR4, but it's going to be very thin compared to the 1/8"+ you could make yourself (and YES, wear a respirator WHENEVER you're cutting glass or carbon fiber composites!!! the particles are exactly the worst size for lung cilia (the cell formations that pull oxygen out of the air). they're too small to eject via the bronchial tubes, but too large to pass into the blood stream. the result is damage to lung cilia, and lung cilia, like corneal cells, are very fast growers. what that means is that when you damage them, they duplicate and grow back very quickly. it also means that when you damage the RNA carriage mechanisms or base dna they're carrying and they become malignant cancer, they grow _fast_. late stage lunch cancer is almost always terminal.

_always_ be careful around materials with small hard fibrous formations. lung cancer and emphysema is NO JOKE. whatever the work is, it's not worth your life.

wait, sorry, i was talking about g10 bases.

yah, why not pick up some GPO3 or G10 or G11 for a nice thick, but lightweight bottom plate.

UHMW and delrin/acetal GF20 or GF30 are also really good materials that are lightweight but very strong and abrasion resistant.

the titanium is actually going to be a little more springy than stainless (400 series anyway) at the same thickness, so the main benefit is lightweight, and all the materials above keep the weight down while maintaining about the same tensile and young's modulus.

the terrible feeling mostly comes with very weak plastics like ABS formulations. you don't _have_ to have woven carbon to get a strong light composite. in fact, glass fibered thermoplastics tend to be stronger than anything but very high end carbon fiber because they maintain about the same isometric tensile, while a single layer carbon weave will only have high tensile along the grain of the weave.

I love the idea of a cf case.  But if you are going light weight plate mount an aluminium plate would actually be lighter than titanium and depending on the alloy could be stiffer.  That is if I remember my material properties right.

Quote from: heedpantsnow on Mon, 17 February 2014, 10:47:37

Quote from: Melvang on Sun, 16 February 2014, 12:14:51

I love the idea of a cf case.  But if you are going light weight plate mount an aluminium plate would actually be lighter than titanium and depending on the alloy could be stiffer.  That is if I remember my material properties right.

I'm not totally convinced of that.  Anyhow, an aluminum plate wouldn't protect the side of the PCB so that's a no go.

One issue I'll have to deal with is that CF is electrically conductive. What other issues can you guys think of?

I was speaking for the mounting plate.  Not for the case.  But titanium is heavier than aluminum in this case since the part dimensions are not going to be altered here like they are in other industries.  Aluminum is about 168 pounds per cubic foot depending on alloy, and titanium is about 235 pounds per cubic foot.

http://mobilitymgmt.com/Articles/2010/03/01/Aluminum-vs-Titanium.aspx?Page=2

Also here is  web page relating to wheelchairs comparing aluminum to titanium.  A lot of tubing tech in wheel chairs comes from the trickle down concept from the bicycle industry.  In that industry aluminum, titanium, and carbon fiber have been used for a number of years.  To get the same stiffness in a titanum frame that you would get with an aluminum frame you have to make the tubing a lot larger and go with a thinner wall to increase the surface area enough to get to the same stiffness.  A number of years ago I was lusting after a specific MTB frame from a company named Ibis.  The frame was the Bow Ti.  It was a unified rear triangle setup with a simple air shock for rear suspension damping only.  To actually hold the weight of the rider it had a pair of tubes on either side of the frame that went from the headset to the rear dropouts uninterrupted that acted as two leaf springs. 

Plus, I have experience in bending aluminum, and a bit with titanium.  This comes from working as an Aviation Structural Mechanic in the Navy, working on H-60 Seahawks.  These are the Navy's version of the Blackhawk.  The only major differences being the addition of a rescue hoist and a lot of avionics packages available.

One other nice advantage of aluminum is price.  Check mcmastercarr.com and compare some raw material prices.

Not a problem man.  I don't have an issue with either material.  But titanium is a massive pain in the ass to work with unless you have good high quality tooling.  But stronger isn't really the word that I would use here.  Depending on the shape and if you can reengineer the part for the physical properties, neither really is stronger.  But given the same shape and dimensions aluminum is generally stiffer.  I wouldn't hesitate to make a case out of CF if you have to tooling and the experience with the stuff.  But in the op you mentioned that you wanted to make it as light as possible and was thinking of going with titanium for the plate.  I just wanted to correct you on some very wide spread misconceptions.

I have a plan, and I'm planning on it being awesome.  I won't be able to work on it until June, though.  Will probably go with a mdf mold with channels for interior ribs, kevlar first (inside of case and electrically inert), then short-cut fiberglass (to absorb a lot of resin and give it some rigidity, then 2-3 layers of CF.  I'll post here when I start on it.

Thats almost as sexy as machining porn.

Quote from: Badwrench on Tue, 15 July 2014, 14:07:41

Nice work.  I love using kevlar, but totally agree on how hard it is to cut. 

Curious, how are you going to finish the top edge of the case? 

My first choice is to fold over and clamp the last layer of carbon, using superglue to hold it before the epoxy.  It's a rather light 5.7 oz 3k tow 2x2 twill.  The tiny bend radius can work to my advantage by making a little rounded edge, as long as it doesn't splinter.  What do you think?

If that doesn't work, I can either round the edges off with a dremel or last resort use some tiny c-channel molding from McMaster:  http://www.mcmaster.com/#rubber-molding/=sun8vb (I would prefer to avoid that as it won't be as clean).

I'd love any feedback or opinion, I'm totally not an expert at this but enjoy learning.

Quote from: Badwrench on Tue, 15 July 2014, 14:46:51

Quote from: heedpantsnow on Tue, 15 July 2014, 14:32:58

Quote from: Badwrench on Tue, 15 July 2014, 14:07:41

Nice work.  I love using kevlar, but totally agree on how hard it is to cut. 

Curious, how are you going to finish the top edge of the case? 

My first choice is to fold over and clamp the last layer of carbon, using superglue to hold it before the epoxy.  It's a rather light 5.7 oz 3k tow 2x2 twill.  The tiny bend radius can work to my advantage by making a little rounded edge, as long as it doesn't splinter.  What do you think?

If that doesn't work, I can either round the edges off with a dremel or last resort use some tiny c-channel molding from McMaster:  http://www.mcmaster.com/#rubber-molding/=sun8vb (I would prefer to avoid that as it won't be as clean).

I'd love any feedback or opinion, I'm totally not an expert at this but enjoy learning.

If the weave is small enough, definitely try to wrap the finishing layer over the edge to get a nice rounded edge. 

Thanks. Any concerns over the superglue (dried) interacting with the epoxy resin?