Carbon fiber electronics enclosure safe?

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#1

Does anyone here know what you need to do to a carbon fiber enclosure to make it safe to house an electronics project?

My understanding is that carbon fiber conducts electricity (at least to some extent) but… I have seen some cf electronics enclosures such as computer cases etc, so I assume there is an acceptable method of insulting a cf box for this purpose?

I want to use a cf box I made as an enclosure for the electronics on my CNC machine build. I just don’t want to cause a meltdown or zap myself.

I am hoping that someone here has some practical advice on this topic…

#2

Just need an insulative layer in between - so carbon for aesthetics perhaps and then insulative inner layers - eg fibreglass and potentially something else depending on how paranoid you are. Also ensure any attachment locations are insulated, eg holes where the case would be attached to a metallic frame with steel screws.

#3

Metal enclosures are the norm for electronics such as CNC control. All PC boards should have the mounting holes isolated from any current carrying traces, so mounting them in a conductive enclosure will not be a problem. Some drives, like the Gecko drives have a metal case that is best mounted on metal so that the heat can be dissipated. I would not worry about the conductive nature of carbon for the enclosure. I have been involved in electronics my whole life and have converted several mill machines to CNC.

#4

So are you saying that a carbon fiber enclosure for a gecko drive is safe but metal is just preferable?

I wanted to use a carbon fiber box because I already have it so it would save me $100 on buying one of those dedicated aluminum enclosures. I have a heat sink for the Gecko and fans for cooling. Do you think it would also need a metal enclosure for adequate heat dissipation?

I could mount the Gecko drive on an aluminum plate inside the cf enclosure. Do you think that would serve the same purpose as a full metal enclosure?

#5

Well, the metal enclosure is not necessarily preferable, I am just saying that it is safe to use with control electronics. I’ve always used steel enclosures, but when I used Gecko drives I mounted them on aluminum heat sink because the aluminum dissipates heat much faster than steel. Regardless of enclosure material, you should probably have venting. I use filtered fans to push air through my control cabinets. Carbon fiber is a poor conductor of heat.

#6

I don’t know if you have all the electronics yet, but Centroid has just released it’s hobby oriented Acorn controller. They are a high end CNC control company who are making a move at the hobby market. I think the controller is priced at $265 which seems really reasonable. I have used Mach 3 before and it is crap. Currently, I run a Centroid on my mill and have no regrets.

#7

I already have a Gecko drive so I use that. I’m not really up for being an early adopter on something like this. I’ll let someone with more CNC experience do the beta testing on new products.

When I researched that topic, people seemed universally happy with the gecko products at the level I intend to use mine at. I’ll keep an eye on it for future builds though. I’ll be better placed to identify my needs after I have some practical experience under my belt.

Right now the only area that I know the Gecko comes up short in is that it only drives four motors which isn’t ideal if you want a fourth axis.

#8

Well, the Acorn is a motion controller, so you would still need to use your Gecko drives. It has been thoroughly beta tested, so I would not hesitate there. What you get is a proven industrial platform in their CNC software that gets you away from the Mach 3 crap (unless you use Linux CNC), and also a motion controller so the computer is not generating the step and direction pulses for the Gecko drives. By the time you purchase a Mach 3 license and a break out board, you could have a far superior Acorn. You also get spindle speed control and plc controlled outputs for your vacuum pump, coolant, or whatever you may want to control. Most CAM packages have post processors for the Centroid, as it is a high end control that has been around for decades.

As for freeing up your A axis for use as your 4th, you should be able to find a board that will slave one axis to 2 Gecko drives. I have never built a slaved axis before, but I will bet there is a board out there to accomplish this. The board just needs to buffer and feed the same step and direction signals to 2 separate Gecko drives.

#9

That is interesting. I haven’t bought a Mach3 license yet so I am certainly not tied to that or any other software yet.

I have a bunch of spare desktop workstation PC’s with parallel cards so there would be no saving there but that’s not important if there is a noticeable benefit to me with the Acorn.

What sort of benefits would you expect to see with an Acorn - Gecko set-up over a PC / Mach 3 - Gecko set-up?

I use Autodesk cad / cam products mainly. Whatever I use has to work with that but that’s my only other limitation. Whatever I use, I am looking for simplicity and a shorter learning curve. I won’t be learning to write code any time soon…

There are solutions to add an extra motor. The Gecko people sell individual drives as well as their 4 motor g540 product. I can just buy one of them. It’s not a huge cost or inconvenience. It’s just disproportionate and it would be better if the G540 could drive 5 or 6 motors out of the box. Plus, I will need an extra free parallel port for the extra drive.

I could also switch to a one-motor x-axis design. Depending who I ask, this is either fine or a recipe for certain doom. My machine uses a moving gantry but it has a narrow work envelope so it’s probably ok.

#10

Reliable and professional level performance. You are buying an integrated system that includes their software and motion controller. Mach 3 is a dinosaur. Mach 4 is not up to par either from what I have heard. Mach 3 was innovative when it came out because it tricked Windows into producing the step/direction pulses in real time via the parallel port. It never worked perfectly and that is the reason why there were several motion controllers marketed for use with Mach 3 over the years. They all had some problems.

Centroid has been producing professional retrofits for decades. No more missed steps, hiccups, etc. It looks like the Acorn is based on their proven software, though it is probably the “light” version of it without as many features. You are not only getting their software, but you are also getting a dedicated motion controller. At the introductory price, it sounds like a no brainer IMHO. If you are close to NNJ, I welcome you to come to my shop and check out my machine.

Look at this video. The guy is a beta tester using G540’s with the Acorn. It looks like his mill is home made. He says he can rapid at 300 IPM which is impressive. I don’t think you can do that with Mach considering it’s 25 Khz kernel speed.

https://www.youtube.com/watch?v=rbCtE1yv4cE

Just to be clear, I am basing my opinion on my experience with Mach 3 and my current Centroid setup. I have used both, and after getting the Centroid, I sold my Mach 3 mill. I have no experience with the Acorn, but base my opinion on using their software and more advanced motion controller/drives, plus the companies history.

#11

That peaks my interest. I thought that problem like missed steps were caused by the motor drives and that people favored the Gecko g540 over other products because it offered a smooth reliable operation. I also thought that the issue could be caused by inputting the wrong settings for job such as cutting too fast or too deep.

If the issue comes from the software then that would mean that any drive paired with Mach 3 would produce poor results.

How is the user interface with the Acorn? I.e. Is it designed in a way that it could be picked up after a little trial and error, or does it require some more complex training / knowledge?

My thought on Mach3 was that I would download the free trial (when I am ready) and see how well it met my needs. I wouldn’t have bought it if it produced poor results anyway but if there is a better option that I can afford then it’s a no-brainer.

#12

Just use the parallel port computer you have and the trial version of Mach 3. You can run up to 1000 lines of code on the trial version. 1000 lines sounds like a lot, but it is really nothing if you are doing anything more than simple contouring. If you struggle with getting the results you want with Mach, you can always upgrade to a better software/controller. The place you may have the most problems is with cranking up the speed on the router. I had little problem cutting at moderate speeds with Mach for the most part. I did have hiccups now and then, which really piss you off when you are in the middle of a part and you ruin it. At least you can prove your design with Mach, then you can decide if you want to go to a more solid controller. LinuxCNC is a very good choice also, but I found it a lot harder to set up, so I never pursued it.

I find the interface on the CNC 11 software simple and intuitive. Mach is not bad either in the interface department. Thousands of people use Mach and are happy with it. I was just pointing out another option that I would choose if I were building a router table.