Considering CNC Mill... what should I look for?

[JimDawson]

How easy and cheap? If it's a matter of pull out the old system and plug in an new one, I can probably handle that. But I don't know about wiring at a pin level. I guess if you're replacing everything, it's pretty much all together and all you are doing is connecting it to the servos. That wouldn't be too hard. I guess what I'm saying is plug and play with components is about my speed. If it's wiring soldering etc, not so much.

Modern retrofit CNC controls are pretty easy install, well documented. Of course there is some wiring, but not overwhelming, and no soldering needed. Look at it as a skill building experience. I have a very low tolerance for 30 year old controls technology, so IMHO upgrading is the only way to go. Costs could run from a couple hundred dollars on the extreme low end to as much as you want to spend. Like anything else, you get what you pay for. My CNC mill originally had an Anilam control and I ran it until if finally failed, right in the middle of a production job. I did the retrofit and was back up and running in 12 hours, didn't even take the job off of the table. I was planning on the retrofit when that job was done so had all of the parts on the shelf.

Under no condition would I convert a manual machine to a CNC without having a well equipped machine shop available. Too many bits & pieces need to be made to make everything fit.

I find that using a pendant control is very uncomfortable for me, you can't feel what the machine is doing. I want my hands on the handwheels, but I have over 50 years of running manual machines.

I do have to admit that getting a CNC machine actually made me look like a machinist, my part quality went way up and allowed me to easily do things that would take hours or be next to impossible to do with a manual only machine.

 

[Chipper5783]

I have been going back and forth with this. Part of me says yes, I want to use it as a manual machine. But that may be just because I have been thinking about manual machines and making things in those terms. That's also why I lean towards a Bridgeport VMC type machine, rather than a fully enclosed unit. Part of me says "Plugging in a piece of metal, and pressing start isn't really making it yourself." But the part of me is focused more on the part , and doesn't want to be doing all of the repetitive steps needed to make it says, "just let the machine do that." Also, some of the things I want to make would require 4th axis control with simultaneous movement, which I couldn't do manually anyhow.

I've read that a pendant can provide full manual control that is even better than hand dials. What do you think about that?

I've done a lot of manual machining. I have 2 good manual mills.

Recently, I got a 20 year old Bridgeport VMC - it is fully enclosed (I did not know you could get a VMC any other way). Fully enclosed is awesome - I certainly would not want it without the full enclosure. After ~ a year of messing around with it, I'm pretty comfortable with G-coding direct at the machine. I still have not found the feature of "plugging in a piece of metal and pressing start". That would be a very handy feature!

The CNC mill is great, because you can make parts that would be very difficult to make on a manual machine. My learning is that the CNC is very much like a manual machine, except you send a line of code instead of cranking a handle. The machine is dumb, it only does what you tell it to do. It is 100% up to you to tell it what to do. If you tell it to do something wrong, it will try to do that too. Machining with a CNC machine is still machining.

You could get someone else to program the part program (often a company will have one or two setup guys, then a bunch of operators) - then you just plug in the piece of metal and press the start button. I agree that isn't really making it yourself.

Get a CNC mill, learn to run it. The learning curve is steep - even if you are really comfortable with machining. It opens up some fantastic capabilities.

 

[ArmyDoc]

Modern retrofit CNC controls are pretty easy install, well documented. Of course there is some wiring, but not overwhelming, and no soldering needed. Look at it as a skill building experience. I have a very low tolerance for 30 year old controls technology, so IMHO upgrading is the only way to go. Costs could run from a couple hundred dollars on the extreme low end to as much as you want to spend. Like anything else, you get what you pay for. My CNC mill originally had an Anilam control and I ran it until if finally failed, right in the middle of a production job. I did the retrofit and was back up and running in 12 hours, didn't even take the job off of the table. I was planning on the retrofit when that job was done so had all of the parts on the shelf.

That's reassuring - the documentation portion in particular. It's not like I haven't repaired wiring. If is as simple as "this connects to that" I can do it. I just need to be told what goes where. It's always a matter of not knowing what I don't know that makes me nervous.

 

[Chipper5783]

Doing a manual to CNC conversion? Back to the question above whether you want a project (which is fine) or you want to do projects?

The purpose built machines have so many good features, which are possible to implement on a home built conversion unit - but I suggest it will be much cheaper and better to purchase that capability up front. What features? - full enclosure, tool changer, flood coolant, 4th axis, protected slides and systems, wide speed range, chip conveyor, . . . . It is all possible on a home built conversion, and my hat is off in admiration for anyone who does that. I suggest it is much cheaper to purchase what you want / need.

If you buy a machine, don't think that means you can't buy another one. Go ahead and buy yourself a manual mill, play with it. In a couple years, get a CNC mill, then you'll have a better idea of what you want/need.

 

[ArmyDoc]

You could get someone else to program the part program (often a company will have one or two setup guys, then a bunch of operators) - then you just plug in the piece of metal and press the start button. I agree that isn't really making it yourself.

Get a CNC mill, learn to run it. The learning curve is steep - even if you are really comfortable with machining. It opens up some fantastic capabilities.

The only time I worked in a machine shop was one summer in college. They had guys who did that. I tried talking to the guy who running a cnc machine, but he was more of a machine operator than a machinist.
I have a very small amount of experience running a bridgeport CNC mill. It was not easy!

One thing I do have going for me is I know a guy in California that programs G code for a living. Hadnt thought about that till now... feelin' more confident. Thanks!

 

[bakrch]

One "hidden" feature in some CNC mills is Custom Macro B language. With FANUC it is usually a free feature. You can essentially write your own canned cycle to do the more mundane tasks. For instance ... bolt circle, grid drilling, pocketing, slotting. You essentially use the control as an elaborate calculator with variables, formulas, conditional loops, branching, etc ...

If the machine control does not have the feature activated or is behind a ridiculous paywall (looking at you HAAS. $2800), there is a nice piece of software called NCPlot that you can write macros with and then convert it to regular g-code. Last I checked, NCPlot was about $300 and supports up to 4 axes. The back and forth can be a little annoying, but it's far faster than drawing something new on CAD. Just change a few numbers, drop a file into a folder, click a button and load the g-code. Mach 4 industrial also has the macro feature for less than half of what HAAS charges.

I have our mills at work loaded with a bunch of macro programs that the machinists use regularly. None of them know how to code, but they can walk up to a gcode mill and make parts with very little training. Handy feature for repetitive tasks. This is essentially what many conversational controls are, but the macro is working behind the scenes hidden behind a proprietary GUI.

 

[bakrch]

One "hidden" feature in some CNC mills is Custom Macro B language. With FANUC it is usually a free feature. You can essentially write your own canned cycle to do the more mundane tasks. For instance ... bolt circle, grid drilling, pocketing, slotting. You essentially use the control as an elaborate calculator with variables, formulas, conditional loops, branching, etc ...

If the machine control does not have the feature activated or is behind a ridiculous paywall (looking at you HAAS. $2800), there is a nice piece of software called NCPlot that you can write macros with and then convert it to regular g-code. Last I checked, NCPlot was about $300 and supports up to 4 axes. The back and forth can be a little annoying, but it's far faster than drawing something new on CAD. Just change a few numbers, drop a file into a folder, click a button and load the g-code. Mach 4 industrial also has the macro feature for less than half of what HAAS charges.

I have our mills at work loaded with a bunch of macro programs that the machinists use regularly. None of them know how to code, but they can walk up to a gcode mill and make parts with very little training. Handy feature for repetitive tasks. This is essentially what many conversational controls are, but the macro is working behind the scenes hidden behind a proprietary GUI.

Here is an example. This macro is actually included with NCPlot, but I modified it slightly to be in our HAAS mill at all times. All the machinist needs to do is change the numbers (to the right of the equals sign) inside of the yellow box, and all of the calculations happen in real-time as the program runs.

 

[Boswell]

My CNC mill can be run manually but I find even for simple cuts, I use the CNC capabilities.

The other day, I need to clean up one side of a piece of bar stock. and it was easier to type G1 X10 than to turn the X handle 100 revolutions.

 

[Aaron_W]

You might give some thought to finding a small CNC mill, like a Tormach, or CNC mini mill. Sherline offers CNC ready and complete CNC packages, and there are ready made kits to convert some of the popular mini and small mills to CNC. Then use that to see if CNC is really something you want to dive into. Maybe even think about a 3D printer or CNC router which use a lot of the same programs. Cheaper to buy, easier to move and easier to sell if CNC isn't your thing.

 

[ArmyDoc]

You might give some thought to finding a small CNC mill, like a Tormach, or CNC mini mill. Sherline offers CNC ready and complete CNC packages, and there are ready made kits to convert some of the popular mini and small mills to CNC. Then use that to see if CNC is really something you want to dive into. Maybe even think about a 3D printer or CNC router which use a lot of the same programs. Cheaper to buy, easier to move and easier to sell if CNC isn't your thing.

I appreciate the advice, and caution I hear in your post. I do have a 3D printer that I bought last year. I've only done one project from start to finish yet, but it was a lot of fun. It's a 3D puzzle, octogon in cross section, that twists on it's central axis. There are 4 oval tracks of marbles that when you twist 45 degrees become a spiral. Mix up the marbles, then try to figure out how to get them back to start. I got the idea from a hexagon one that I saw on line and printed. Here's a link to the one on line that I printed.

Here is mine in each of the 4 orientations before returning to the original, but 180 degrees from start:


As you can tell, while I was able to make it, I haven't solved it yet!