Considering CNC - What's Your Opinion

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TomS

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I've been machining for many years both as a profession and hobby. My understanding of manual machining is high but I know little about CNC other than a software program tells the electric motors which direction and speed to turn. That's an over-simplification of what I think I know but that's why I want to learn more. So I've been thinking about getting into CNC machining (milling mostly) but don't know enough yet to pull the trigger. My budget is limited so buying a new machine with the size capabilities I'm looking for probably won't work out. I have an 2 HP Enco mill/drill that's a couple of years old but because I'm electrically and electronically "challenged" going down the retrofit road is not a good idea, at least for me. I'd like to find a "package" that I don't have to piece together with software that is relatively simple to learn. Used machines are a consideration but I don't want to buy something that's worn out or inherit someone else's problems.

I found an Ebay listing for Model Shop CNC that looks interesting. Other than losing some Z axis capacity what do you think about going this route? It appears to be complete, except for the computer and monitor. Anything else I'm missing or should consider.

Sorry for the jibber-jabber just trying to give everyone a feel for where I'm coming from.

Thanks in advance for your opinions.

Tom S.

http://www.ebay.com/itm/CNC-XY-Mill...371?pt=US_Heavy_Equipment&hash=item19de2fbad3
 
Seems like with that package you only get a 2 axis system (you will be cranking the Z axis yourself). I did this on my mill before I completed the quill feed, but it gets a little old, and you will not be able to do 3d contours (maybe that's not a feature you need).

You may want to check out the "Basic CNC" thread in this forum. We were able to condense a lot of info there.

Whatever your budget is, make sure you consider the software side in it too. What size machine are you looking for?
 
DMS said:
Seems like with that package you only get a 2 axis system (you will be cranking the Z axis yourself). I did this on my mill before I completed the quill feed, but it gets a little old, and you will not be able to do 3d contours (maybe that's not a feature you need).

You may want to check out the "Basic CNC" thread in this forum. We were able to condense a lot of info there.

Whatever your budget is, make sure you consider the software side in it too. What size machine are you looking for?
Click to expand...

First let me say thanks for your comments. This particular package does come with a Z axis motor but not a mounting bracket or coupling. I can handle making the bracket. I can only assume at this point that it's a simple matter to activate the motor.

I'm looking for an X axis travel of about 10" to 14" and X axis travel of 6" to 8". Wish this package had more X travel but at 10.5" it should handle most of what I anticipate needing.

I've heard and read of Bobcad and Mach 3 software. Don't know the intricacies of using them but my understanding is they are good programs.

- - - Updated - - -

Ray C said:
Welcome Tom to the summer semester of CNC for newbys... I'm in the same boat. Please feel free to jump in on this thread: http://www.hobby-machinist.com/show...Lining-up-the-ducks-Asking-software-questions


Ray
Click to expand...

Thanks for the info and invite. I'll check out the link tonight. Yard duty calls.
 
Sorry, I missed the bit about the Z axis motor.

Mach3 and BobCAD/CAM fill 2 requirements you need to really use a CNC machine. Mach3 is a "controller"; you feed the controller the GCODE program that you either wrote by hand, or that your CAM package generated, and it tells your machine to do based on that. BobCAD/CAM lets you draw your parts, and then generate code to feed into the controller. Mach3 is very common (the most common PC based controller). BobCAD/CAM seems to be a love it or hate it sort of thing. For both of these packages, I believe you can download a trial version to see if you like them.
 
DMS said:
Sorry, I missed the bit about the Z axis motor.

Mach3 and BobCAD/CAM fill 2 requirements you need to really use a CNC machine. Mach3 is a "controller"; you feed the controller the GCODE program that you either wrote by hand, or that your CAM package generated, and it tells your machine to do based on that. BobCAD/CAM lets you draw your parts, and then generate code to feed into the controller. Mach3 is very common (the most common PC based controller). BobCAD/CAM seems to be a love it or hate it sort of thing. For both of these packages, I believe you can download a trial version to see if you like them.
Click to expand...

I'll check out the trial versions and see what questions come up. Reading elsewhere I understand that a translator program is needed to transmit data from the CAD program to the controller program so G code can be generated. Any suggestions and what can I expect to pay?
 
The "Translator" program you describe is called a CAM (Computer Aided Manufacturing) package. I think BobCAD may have that integrated into it, but it may be an option (I don't use BobCAD personally).

Prices range widely, and I have seen prices from a couple hundred, to 10s of thousands of dollars for the high end CAM packages. I currently use AlibreCAD and AlibreCAM. Total cost was under 3k, but I didn't get the "basic" versions.

One low cost package I have seen mentioned is "CamBam", but I didn't spend much time trying it out personally. I'm sure others will pipe up with there experience as the evening progresses.
 
First you should define what you plan to do with the CNC. This will determine the type of machine you need. With access to a machine shop and your knowledge you could build your own machine from scratch to fit your needs. I built a 27x48x5" gantry machine capable of high precision work on wood, plastics, and aluminum. The machine was built for less than the eBay machine is selling for. BTW, if you are doing much engraving or 3D carving, you will find the Z axis is by far the busiest axis. So make sure you pay close attention to this axis.
 
Tom, setting up the electrical bits on a CNC conversion isn't all that difficult. Quite a few of us on this forum have ordered stepper motors, power supplies, boards and ballscrews on-line. Control hardware is mostly plug-and-play, with some settings to enter into the controller software. You have the skills to machine ballscrews and make the brackets.

You'll find lots of help in this group. Budget can be a big issue that's hard to overcome in a ready-to-use machine, unless you happen to find something advertised that isn't 400 pounds of nightmare. You could even think of that as a kit - all of the parts are there, just have to be put together properly.

As much as I like the hands-on feel of machining, there's something about watching your CNC mill cutting out something you designed and told it to make, with the occasional "Oh nooo!" moment thrown in.
 
I would definitely get in touch with Steve (Jumps4) and talk to him about what you want to add CNC to. He has done his own and a couple of others with other members already so he has a pretty good system figured out and it seems to be working glitch free pretty much straight out of the box. I know steve did his RF clone and so did Mac (7HC) as well as another fellow he is also helping build an enclosure for too. Matt at Precision Mathews also has some CNC kits he installs on his machines that should simplify the install quite nicelt also. There is nothing to be scared of doing it for yourself. The learning curve is steep but gentle and tha hardware is very forgiving and quite robust so you can install those parts easily in an afternoon. I believe if you have been a machinist for very long you definitely have the skill set you would beed to install it and make it work very easily. So I have faith in ya and I am sure you can do it with just a little bit of help if you get stuck along the way. So don't give up before you even get started because it is actually easier than you think to add all of the parts, and building G-code is very logical so you will learn that very fast too.....

Bob
 
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