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Trial By CNC

Kevin Price

Trial By CNC

Postby Rogue Sub » Wed Feb 15, 2012 10:57 pm

I have always enjoyed playing with machinery and hardware and had dreamed of one day owning a CNC to do my bidding. The biggest obstacle in my way had always been cost though. THe machines are just not very cheap and most of us hobbiest cant afford to throw down that kind of cash just for a machine. As I had resided to having this as a mere fanciful dream something wonderful happened. A friend of my surprised me by bringing one of these machines within my grasp. I am extremely grateful to him for this. I would finally be able to produce parts of the highest quality with the ease that advanced machinery brings to our lives. I mean, it is so easy that it is taking away from the true skill of creating things by hand. Right?

It is this question (or statement) that has brung me to write this little blog if you will. What is involved in this process? How much skill is involved? What is the learning curve?

These are all questions which I am hoping to explore and share with all of you as I take on the task of learning an entirely new process. I will let it be know that I have absolutely no experience in this. I had a college corse in basic 2d CAD over 10 yrs ago( of which I remember nothing). My experience with computer controlled machines is exactly zero. Even in the Navy everything I did was manually or mechanically operate. Remember I was a mechanic not on of those wire biters.

Now lets get up to date of where we are at this point.

I was fortunate enough to have been in the process of building myself a nice little soldering station in my work shop. Why is that fortunate? This darn thing needs lots of dedicated and stable space. It has a bed measuring 4' x 2'. This is a great size for me and my 1/96 obsession. Bassically I will be able to make a 1/96 nautilus in top and bottom halves without the need of joining piece together after cutting!!!

The unit I am using was made by a company called Moose Creek. It is not top of the line like a K2 unit but it will definitely get the job done for what we have in mind. Im not planning on building parts for a satellite. We can put that on the future project bench. Included with the recieved package was the bed, rails, stepper motors and motor controller. These may not be the official terms for these items but this will be corrected after some books come and the knowledge base is increased. It also came with to router mounts. One for a dremel motor and one for a rotozip.

Image

The first big lesson: Hardware

At first I thought this was going to be a quick and easy thing to get going (much like many other people would probably assume). This was not to be the case. I still need quite a few things to make this a productive tool. First would be a router. I looked at the dremel and then the rotozip and it was very obvios that the rotozip would be the better option for this tool. It has more power and better construction then the dremels do. I have also burned out quite a few dremels in normal use let alone continuos hours of operation. This is obviously not the a big concern as the rotozip with the variable drive sells for around 150 dollars.

The next hurdle I discovered was that the controller box required a parallel printer port. None of the computers in my house had one of these. A quick email to family members for their old laptops and in the next week I had two equally powerful used laptops at my door. Things were starting to look promising. That is until the next hurdle.

The software I decided to get me interfacing with the motor controllers is called MACH II. You can get this older version of the software from the manufacturer for free or pay around 150 for the newer MACH III. I of course went with the pocket saving MACH II to get me started. Unfortunately to my surprise I found out after the fact that neither are recommended for use with a laptop. Well why the heck not!?!?!? I was a bit set back. SO, I hit the forums to find out. It turns out that since most laptops are designed to save as much power as possible, most are designed to go into a processor power saving mode. This action can cause an interrupt in the pulse or data stream to the CNC causing errors or "crashing". Other with more knowledge can feel free to correct or agree on this. Can you imagine being at the end of a 12+ hours cut just to have the machine mess it all up due to a hiccup in the cpu. Yuck! At this moment I can decide to try the laptops and hope for the best or I can attempt to resurrect my old desktop (thank god I kept it for some reason) and add a port to it. I decided for resurrection! Better to be safe then sorry. Why take the easy path and cross your fingers when the hard path will yield pre determined results? I am still working on the desktop and am waiting on the new port to show.

Lesson 2: Its not just hardware

Its all about software. It seems to be nearly a 50/50 shot to the wallet when it comes to these things (depending on the parts and such of course). The software for this can add up fast. I have chosen (under recommendation from various friends) to use 3 programs.

Rhino- a cad program that is used to create what ever item you wish to create. This runs around 1000 for a licensed program
Visual Mill- This program crates G code or the tool path. Essentially it takes the drawing from Rhino and converts it into pathway for the cnc to follow to create your item. This was recommended because it is fairly easy to use and very easy to make hold tabs, little pieces that arent removed to hold the part in place. This I believe is around 700. Im not sure because it is one of those "call for price" which is never a good sign.
MACH III- This program takes the G code and uses it to directly control the CNC machine to create your item. As stated before you can go for free or choose the 150 dollar option.

In all after adding the computer, monitor, software, tools (including cutting bits), macine you are in it for a pretty penny. I dont have all the of the items yet but am working to get the machine at least up and running which I wll continue to share with all of you. I am also still exploring forums trying to find "second hand " software or used software at a discount price.

Thats it for now. More to come as I learn it and do it .
Kevin
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Re: Trial By CNC

Postby Bigdave » Thu Feb 16, 2012 9:33 am

This should make interesting reading my friend. :D
I actually feel your pain. :roll:
That is brain pain from the strain! :shock:
Good luck and have fun.
I will be watching. :lol: BD.
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Re: Trial By CNC

Postby Sub culture » Thu Feb 16, 2012 10:44 am

There is EMC2- linux based and free. Can't you switch the low power modes off on the laptop?
'Why are you staring at an empty pond?'

Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Re: Trial By CNC

Postby Rogue Sub » Thu Feb 16, 2012 7:36 pm

I have looked into the switching the power modes and it does not seem to be as simple as going into power options in windows. Some have had success going into bios and editing there power features. So far the one I was hoping to use either does not have the problem or does not have that option in bios. The question is do I want to risk it to find out?
Last edited by Rogue Sub on Thu Feb 16, 2012 10:06 pm, edited 1 time in total.
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Re: Trial By CNC

Postby Thor » Thu Feb 16, 2012 9:57 pm

You do not! You may end up spending a ton of $$$ to replace parts damaged in a hard datum crash.


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Re: Trial By CNC

Postby Pirate » Fri Feb 17, 2012 1:07 am

"Hard datum crash" —Ouch. Sounds painful.
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Re: Trial By CNC

Postby Bigdave » Fri Feb 17, 2012 9:47 am

It can be for the cutting tool! :shock: :lol:
Not to mention the parts connected. :mrgreen: BD.
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Re: Trial By CNC

Postby Rogue Sub » Wed Feb 29, 2012 8:02 pm

Having never done this before there were going to be obvious things that I would not know. I knew I had to get caught up with terminology first or nothing else I would read was going to make much sense without even more internet searches. To get there I could do a few things. Scour the web to gather the various bits of info I needed or get a book that wasnt to in-depth yet had everything all put together. You may have guessed I went with the book. I like books because they dont have batteries that die, are still portable, take nicely to post it notes, and are put together in a cohesive manner (most the time). Dont put all your trust in the internet!

For my book I decided to get
"The CNC Cookbook" by E. Hess

It cost me about $25 dollars on Amazon and is about 200 pgs

I found the book brought me up to date very quickly. There was tons of info left out of course but I now have the basics learned. I think it was worth the investment as a quick reference. As a side bonus the book also covered various method for building your own cnc router and converting existing mills and lathes to CNC. Specifically it covered the Proxxon and Sheerline Mills.

Now for a bit of honesty

I did not get the book or read much prior to getting everything all set up. The parallel port I ordered for my computer showed up a few days before the book so in a lack of patients I decided to get things running. I went through the process of getting my old quad core running and hooking it up. I then cleaned off every bit of unnecessary software and loaded my free version of mach 2. Next I plugged the CNC controller box into the computer and turned everything on. The stepper motors made their little chatter and everything seemed to be good. Went to the mach 2 program and attempted to move the table in manual mode and nothing happened. Several reboots and wire checks later and nothing!

Here is where I think the failure happened. Plug N Play! Yup I was assuming that since I plugged it in and the controller software was loaded that I would be able to plug it in and everything would fire up. Not the case and this is where the book became handy. Most of these "homemade" units are just that, made by hand. This also means that when they are making the controller box and wiring the motor controllers to the parallel port break out board, they can wire it to jsut about any pin that will meet the purpose. What this breaks down to is, I never told the program which pins of the box did what. End result, nothing works.

I also learned that there are many variables about your table that need to get entered into the controller programs to make it work. Some of these essential things are derived from and include screw pitch, motor steps pre revolution, lead, speed, etc

Basically how can the program control the board properly if it doesnt know what its controlling?

This is where we leave off for the moment. Next step will be to go back and properly set up the machine through the controlling software. I have also yet to find a router that will fit the provided mounts. In anticipation of a failure at this I have purchase some angle and flat steel stock to weld up and make my own mount. I really dont want to do that though.
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