Building a Carbon Fiber Rack Case, some info/help needed

F

flump

Inspired
So I have had the same rig for a couple of years now, and plan to stick with it for the foreseeable future and also need a fun project. Just a preface, I am a mechanical engineer with CAD, CAM, a CNC machine, and pretty much all the other shop tools I need to have fun already. Also, I don't really care about cost.

The main goal of this (besides a fun project) is keeping this lightweight and with the minimal dimensions needed. I will also be building in spots for removable wheels and handle for easy transport.

I've decided I'm going to make either a 4 or 5 U rack, not real sure on that yet. I also haven't decided how much protection I'm going to build in since this is 99% for local stuff. Right now I'm using a beefy Gator rack (4U); I forget which model but it's cumbersome.

In this rack will be:
Axe-II
Matrix GT1000 1U
Shure PGX-D Wireless
Some sort of power supply

The power supply is why I say 4 or 5 spaces. I actually prefer having a nice surge protector at the back of the rack as opposed to a 1U Furman unit, but I'll have to lay everything out to figure out what I'm going to do.

I will be getting the CF from Dragonplate. I have ordered CF materials from them before and they have been awesome. Probably going to go with some CF with balsa core to save weight. I haven't figured out thickness. I'm going to have to contact them to find out what they recommend.

Here's where I need some help.

Rack parts:
I have searched and Audiopile seems like a good resource? Are there other places I should be looking? I will of course need rails, handles, corner reinforcements, latches, etc. I can always get certain parts from say a McMaster that aren't necessarily rack specific. Especially since I want to keep it light weight.

Rack plans:
Anyone know of any good resources for plans? I'd love to take a look at some stuff. My gator case is all molded plastic and of course the carbon fiber case will be assembled more like a traditional wooden rack case.

Hopefully I can get to designing this on solidworks this Sunday watching some football.

Edit: If someone from fractal would be so kind to send me a 3D model of the Axe-II's outer shell that would sure be nice. Either way it's getting modeled.

Cheers,

Phil
 
Hi,

Like yourself I too run a Cnc machine using cad cam but in a joinery shop, which is great having the access and ability to produce some of my wild baked ideas.
I'm afraid I don't have any suggestions for ya but I'm really interested in how your going to produce it. How have you planned on producing the panels? Are you bonding the CF to a substrate to form them? If so I can't see balsa working best. Maybe a piece of 9 or 12mm mdf with the centre routed out to produce a 50mm all round frame for example with a rail left in the middle to stop any sag from the CF. Any idea how you will form the corners? I've often wondered how I could acheive this without losing space and adding weight, the only way I could see it is by vacuum forming or using some metal fabrication, neither of which I am able to do. Although I have just thought of using something like a 30mm aluminium right angle section and then fixing the panels into it if you get my drift.
I just finished my 7u rack yesterday for my studio. It was just a simple box to the right size and I bought some pre cut rails from ebay so in total it cost me all of 8 quid (about 13 bucks). Nothing fancy but we had some 16mm black mdf in stock so it looks great and is exactly what I needed.
I would recommend you build to the biggest u space that you want. You can always put a fancy blanking panel in that spot but you can't add the space once its made.
I'm trying to design a guitar rack at the moment for my ever expanding collection. I've almost figured it out but could not find any resources on the net or any decent pictures for ideas. Its only for my studio but its amazing how there aint any pre made good quality ones on the market, other than the welded metal tube wrapped in foam style. So would appreciate any suggestions also.
Anyway keep us to date how you get on with pics if you can mate, very interested :)
 
malenko said:
Hi,

Like yourself I too run a Cnc machine using cad cam but in a joinery shop, which is great having the access and ability to produce some of my wild baked ideas.
I'm afraid I don't have any suggestions for ya but I'm really interested in how your going to produce it. How have you planned on producing the panels? Are you bonding the CF to a substrate to form them? If so I can't see balsa working best. Maybe a piece of 9 or 12mm mdf with the centre routed out to produce a 50mm all round frame for example with a rail left in the middle to stop any sag from the CF. Any idea how you will form the corners? I've often wondered how I could acheive this without losing space and adding weight, the only way I could see it is by vacuum forming or using some metal fabrication, neither of which I am able to do. Although I have just thought of using something like a 30mm aluminium right angle section and then fixing the panels into it if you get my drift.
I just finished my 7u rack yesterday for my studio. It was just a simple box to the right size and I bought some pre cut rails from ebay so in total it cost me all of 8 quid (about 13 bucks). Nothing fancy but we had some 16mm black mdf in stock so it looks great and is exactly what I needed.
I would recommend you build to the biggest u space that you want. You can always put a fancy blanking panel in that spot but you can't add the space once its made.
I'm trying to design a guitar rack at the moment for my ever expanding collection. I've almost figured it out but could not find any resources on the net or any decent pictures for ideas. Its only for my studio but its amazing how there aint any pre made good quality ones on the market, other than the welded metal tube wrapped in foam style. So would appreciate any suggestions also.
Anyway keep us to date how you get on with pics if you can mate, very interested :)
Click to expand...

I'm buying the CF sheets prefabbed from here: DragonPlate Carbon Fiber Composite Components - Carbon Fiber Sheet, carbon fiber sheets, Nomex, Square Tubes & Splices, Carbon Fiber Panel, Carbon Fiber Tube & Rod

By prefabbed, I mean already completely laid and bonded. I have also bought cloth from them in the past for my own CF stuff, but in this case I'm looking to buy it in sheet form much like you would MDF, plywood, etc. I'll just be cutting them via a table saw or similar fashion. Anything more complicated and I might use CNC.

Honestly I was thinking of keeping it very simple and just assembling it similar to how the EWI cases are at Audiopile. I'd just like to save some weight and make it EXACTLY how I want it.


Sleestak, thanks for the link. I'll be doing some more searching around on that site you posted as well.
 
The problem with CFRP is: if the reinforcing fibres are not placed in load direction, you need a lot thicker walls as the yield strength of carbon suggest, as CFRP is not isotropic.
So it's hard to say what wall thickness you need. As a rule of thumb though, when using woven carbon based CFRPs (which is used in 99% of cases where the CFRP is visible, simply because it looks better than knitted fabrics), you can go with half the thickness of an ordinary sheet metal chassis.

I'm working as an engineer for a research institute for technical textiles. Unfortunately, I only have experience with industrial CFRP, so I don't really know about the quality of private vendors and can't give you recommendations.


But that rule of thumb I mentioned above should do the trick if you're using bi-directional (woven) fabric CFRPs or multi-directional (0°, 45°, 90°,-45°) knitted sheets.
 
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If I were doing this myself, i'd research some of those shock absorbers that Mesa used in the Sus-4 racks, and incorporate into the design.
 
Zwiebelchen said:
The problem with CFRP is: if the reinforcing fibres are not placed in load direction, you need a lot thicker walls as the yield strength of carbon suggest, as CFRP is not isotropic.
So it's hard to say what wall thickness you need. As a rule of thumb though, when using woven carbon based CFRPs (which is used in 99% of cases where the CFRP is visible, simply because it looks better than knitted fabrics), you can go with half the thickness of an ordinary sheet metal chassis.

I'm working as an engineer for a research institute for technical textiles. Unfortunately, I only have experience with industrial CFRP, so I don't really know about the quality of private vendors and can't give you recommendations.


But that rule of thumb I mentioned above should do the trick if you're using bi-directional (woven) fabric CFRPs or multi-directional (0°, 45°, 90°,-45°) knitted sheets.
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In this case I'm not so worried about the strength of material considering 3/8ths plywood is plenty strong enough for rack manufacturers. They're essentially just going to be screwed/epoxy'd into a box. Also, the balsa(or other wood) core'd CF sheets generally have at least 2 layers on each side that are cross patterned in some way.

dpeterson said:
If I were doing this myself, i'd research some of those shock absorbers that Mesa used in the Sus-4 racks, and incorporate into the design.
Click to expand...

I just looked those up. They seem like a really cool idea to help with shock absorption with minimal weight gain.

Sixstring said:
I looked into doing this a wile ago and gave up as it was going to be way too expensive as a one off.
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This definitely won't be the most cost effective solution in any way. I'm more looking for a fun project with a resulting product that I enjoy using.

After doing some extra research and math on this, the CF certainly won't save me much weight from just standard plywood. Probably 4-5lbs total in a 4-5U rack. One of the reasons I'm going with CF is for the look, as well as the material. Yes I'm aware of "CF look" vinyl decals, and that's just corny.

I have been diving in deeper in other aspects of the rack. For example I will NOT be doing a standard front and back with butterfly latching system. I am going to build the actual rack box slightly longer, and have SOME KIND of flush mounted front and rear. I am also going to attempt to do a slick way of having the front and rear not detachable, and have them slide into the rack somehow instead of coming off completely (or maybe the option of both). I'm thinking some kind of system like a garage door, or maybe some kind of door where it rotates on pins then slides into the rack when parallel to the top/bottom. I'm also going to incorporate some small things (that I could do in the rack I have now) for better/quicker retrieval of the few cables I need to plug in externally (speaker and power)
 
flump said:
I have been diving in deeper in other aspects of the rack. For example I will NOT be doing a standard front and back with butterfly latching system. I am going to build the actual rack box slightly longer, and have SOME KIND of flush mounted front and rear. I am also going to attempt to do a slick way of having the front and rear not detachable, and have them slide into the rack somehow instead of coming off completely (or maybe the option of both). I'm thinking some kind of system like a garage door, or maybe some kind of door where it rotates on pins then slides into the rack when parallel to the top/bottom. I'm also going to incorporate some small things (that I could do in the rack I have now) for better/quicker retrieval of the few cables I need to plug in externally (speaker and power)
Click to expand...

Sounds like it will be fun, I really wanted to do something like this and turn it into some sort of a side business but it's just the wrong time for me. I had a few ideas on a case and other things like guitar stands and such but they would be pretty pricy, good luck on your project and post pic's if you get something mocked up I would like to see it ;).
 
I'm also doing a case project. My 2nd one. Taking longer than expected.

Looking forward to yours!!
 
I agree, you won't save a lot of weight compared to a wood case (depends on the type of wood, though). But you'll save plenty of weight compared to any metal casing (if you don't oversize your walls).

There's some other things you'll need to be careful about:
1) don't tap directly into the CFRP, as Epoxy is brittle. Use inserts for your screw holes.
2) some epoxy resins are not properly UV resistant and are likely to turn yellow when exposed to direct sunlight; check out which type of resin is used for the sheet.
3) remember that carbon has no thermal expansion coefficient; depending on what you put in your rack, leave some room to "breathe" for the units inside or you might not be able to remove them on a hot summer day ;)
 
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