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Everything Else » 3D Printers and CNC milling??

October 24, 2012
by Ralphxyz
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So how is everyone coming along with their 3D printing and CNC milling projects??

I know a few people have mentioned 3D printing or CNC milling in their threads.

sask55 (Darryl) had described a very involved CNC project.

I am on a pre-order beta list for a 3D printer/Milling machine that for the price I could never make from scratch.

Of course so far they have only made a prototype and are not ready for production.

They started out making the 3D printer extruder and have built from there. Apparently they have a full machine shop so they are able to make all of the pieces themselves.

Anybody got any thing to say? I'd love to hear what you are doing, where you are at!

Ralph

October 27, 2012
by sask55
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Ralph

Since you asked I will give an update on my very long term project.

The prototype board for my CNC mill project is in a box under my bench right now. I don’t have much time in the summer to do anything with the actual hardware, so I put things away until fall. Last spring I had the prototype board set up and working to control one of the three stepper motors as well as reading all four of the digital callipers back to the PC. I will be getting hardware out one of these days.

Last spring I was having some issues handling the data flow thru my master MCU in a timely manner. Also the excel based VBA on the PC was incapable of keeping up with all the calculation to display the calliper position info while deliver a steady stream of control code bytes to the motor controllers fast enough. Each full step of the stepper motor results in a table movement of .0005 inch. That increment is ideal and matches up very well with the resolution of the digital callipers I am using, while exceeding the practical limits of the mill itself. In order to move the mill table at a reasonably fast rate the electronics and software in the control system must be capable of delivering a constant stream of changing control codes to the stepper motor control chips.

Thanks to Noter I have an excellent solution to the data congestion that may occur on the master MCU. By using uart rx interrupts and a uart buffer I believe I will be able to get much better efficiency dealing with the data flow to and from the three slaves and the uart, without risking the loss of data that is arriving while the MCU is doing something else. I believe that by setting up the PC GUI using a compiled language and losing all the overhead involved with the VBA in Excel I will be able to have the PC monitor the movements of the mill table and spindle in real time. By reading the movement with the digital calliper the PC could take appropriate action if things are not moving in accordance with the control code instructions.

I am redrawing the semantics for my layout using Eagle. I was having no luck trying to get all the required electronic components laid out on one printed circuit board. I even considered three and four layer boards with very little success. Over the summer it occurred to me that putting all this on one board is very impractical. It would be very difficult to trouble shout as well as set up. My current idea is to have a mother board with the master, uart connections, relays and supporting hardware. I will also have three daughter boards with the slave MCUs, motor controller chips, calliper connections and supporting components. This approach seams much more manageable. All that is required is four data connections and four power connections between the masters and each of the daughter boards. Three SPI data bus connections one SS connection. A 24V 15 amp motor power supply, Two independent 5 Volt power supplies. Each of these Power supplies are required to be controlled by the MCU to enable a sequenced start up to the slave MCU/ motor controllers chips as suggested in the Toshiba data sheets. And of course a ground connection, maybe two if I decide to not use a common ground between the motor power and the control logic power sources.

Anyway to make this long story a little shorter, I have a long way to go but feel I am making considerable headway. I feel I may have reasonable solutions to all my known issues at this point. Over the summer I have done very little on this very long term project. Soon I should have more time to get back at it. Between all the various aspects involved, form learning to use eagle and C# as well as my very limited experience with C it is taking time.

I have all the major hardware components. I will require a considerable number of various types of connectors or plugs to make all the connections between the boards, the power supplies, the callipers, the limit switches and so on. I am considering options and looking thru supplier sites. I have to mount the three steppers on the mill, set up the other two motor controller chips, fly back diodes and other supporting hardware on my prototype. It is apparent looking at my prototype board where the term “Rats Nest” may have originated from in the eagle board layout software. There are a lot of connections I have just about given up on trying to keep it looking neat. My long term hope is to get my prototype working well. Then develop the software to read Gerber files that can be produced by the eagle board layout. Then use the mill to drill and cut the printed circuit boards for this project. Then I could move the entire thing from the prototype to the PC boards for my CNC system. As you can see that is a long ways off.

I have said before I am not in a hurry. I just really enjoy doing this stuff even if I sometime don’t know exactly what I am doing. I usually get the results I am looking for if I persist. I expect there will be a number of other issues come up as I progress. I am reasonably confident I will get this working someday.

The idea of purchasing a system something like the one in the link you posted has certainly occurred to me as well. It would be much more practical and possibly a better end result, depending on what I am attempting to do with it. But for me the interest is in getting there as much as the destination. Honestly other then cutting and drilling the odd PC board and I don’t require a setup anywhere near this heavy to do that, I do not have any reel plans what I may do with my CNC mill if I had it working 100%. I am sure it would be used for a number of things I have in mind but for now I am content just working towards the CNC mill.

The last word that comes to mind when I think of this project is practical. Who knows if I will ever get it working well enough to accomplish some of the ideas I have in mind. And as my wife may ask why do I want to do thus things anyway.

Darryl

October 27, 2012
by Ralphxyz
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Thanks for the update Darryl, anybody else?

I know myself too well to get to involved in a project like this. Well I get involved in them but they eventually overwhelm me.

"The wife" is always something you have to watch out for. Mind is exceptionally tolerant.

She actually encourages me when I get depressed over trying to get something to work.

Ralph

November 13, 2012
by bluestang
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It's coming along Ralph sorry slowly but shurly I will get a working video soon.... Currently wrapping up final designs and flaws found as the build process goes along.

November 14, 2012
by Ralphxyz
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Hey bluestang, thanks for the update. Maybe you and Darryl (and others?) could post some pictures of the construction. Videos of things moving would be cool also, they would not have to be functioning as a 3D printer or Mill I'd just like to see them move. I would love to see Darryl's calipers at work (of course maybe he also would love to see that :-).

Of course I'd also like to know what software you all are planning on running. What 3D CAD, what CAM programs are you thinking of using?

Ralph

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