CNC versus manual

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GummyMonster

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Morning,
So I'm reading the thread on the PM-728V-T Mill, which is the one I'm planning to acquire down the road.
My thoughts right now are to set it up with full DRO's and power feeds. I have troubles with my hands,so I'm trying to minimize the manual turning/moving actions.
Much of the other thread is about setting them up for CNC control. Most of it is waaay over my head right now.
My question would be - what main advantages is there with CNC control over semi manual like the setup I described above. Is the CNC inherently more precise? Or is it more about the time it takes to turn out parts?
I don't need every technical reason, mainly wondering if it's something I need to consider learning, or can I make parts with the same level of precision without CNC?
Thanks for answering my many questions as a newby.
Ken
 
CNC allows you to automate your work. It does not improved the inherent accuracy of the machine. It also allows you to produce more complex geometry than would be easy to do on a manual machine. As a tradeoff, you will lose some manual functionality. You can always add jog wheels, but you'll never have the haptic feedback of "feeling" the cut through the handwheel.

I only have a CNC mill, and while it is super useful, I very much want/need a manual one as most of my work would go faster on a manual.

Get a CNC if:
  • You need to make a lot of the same part
  • Your parts have complex geometry and curves
  • You already work a lot in CAD and enjoy the digital workflow
  • You don't mind the investment and are willing to learn CAD/CAM
  • You don't mind the added time up front to program the machine to make your parts
Stay manual if:
  • Your work is lots of drilled holes and square features easy enough to make on a manual
  • You want to just throw your work in and get cutting
  • You value the "feel" of feeling the machine cut
For me, a manual mill with a DRO would cover 90% of the work I do.

CNC is awesome, but like most things it is a rabbit hole and can get expensive. It is not a must have.
 
I have both. I have to say that Ido manual more often than CNC. The main reason is for simple jobs, it is less work to manually machine the work than to program the CNC. I use my Tormach in a quasi manual mode, using the jog shuttle rather than turning a crank. Kind of a macine by wire approach.

There are times when a CNC is required. Cutting arcs isw difficult on a manual machine unless you have an RT and even then, it can be complicated. If you have curves that cannot be resolved into arcs, the CNC is likely the only practical route. Try cutting an Archimedes spiral on a manual machine.

I bought my CNC because it enabled me to do things that I couldn't otherwise accomplish. My driving project was making custom undercabinet lighting that had a series of elliptical curves. I could not come up with another way to accomplish the task.
 
I have a small CNC mill. I got it to turn out multiples of job related parts and to turn out some tricky shapes. I use the mill in three different ways.

Full CNC for multiples, bolt circles and quick shapes I can use a Gcode wizard to produce. I almost always use CNC to cut out openings in electronic enclosures.

Sort of CNC for drilling arrays of holes for a one or a few parts. I write / edit some GCode to move to the multiple X-Y locations and stop. Then I can drill and go through all the holes, then I can repeat the program for countersinking and tapping using the quill. It results in very quick and accurate positioning.

Manual for simple milling. It would be great to get the hepatic feedback but I've tuned my ears for what sounds and vibration are good and which are bad.

It depends on how you think you will apply your mill.
 
Another option is to get a used CNC mill with manual capability, or to do a CNC conversion of a manual mill in such a way that you preserve the manual capabilities.
 
I like manual because I like to use my hands/eyes/mind while the cutting is occurring. I want to be as physically involved in the process as possible. A front row seat, if you will.

Having said that, I use the DROs and power feeds whenever possible. For my purposes, I am 100% satisfied with manual + DRO. The creations usually take a long time to make, though.
 
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I've found a fully featured, well sized manual lathe with DRO to meet my needs. When it comes to milling machines, I wouldn't give up my CNC mill for a manual machine. There's nothing I can think of doing with a manual mill that I can't do in the conversational programming on my CNC mill. All of the typical around the shop stuff is quite easy and intuitive with a control that has good conversational programming abilities. This means no CAD drawing and no CAM work. When it comes to making parts, I design in CAD and use it for the tool paths. I think what control the CNC machine has is a big factor in this conversation.
 
I built (am building) a small CNC from various parts mostly because I wanted a mill and couldn't justify the up front cost. At this point I could have bought a fairly decent mill for what I have into this one but I wouldn't have had the learning experience.

That said, for your application I think you will be very happy with a manual mill, DRO and power feeds. You can do many operations with a DRO that would only be slightly faster full CNC, maybe slower if you count programming time.

Again, as with everything machine related it depends on your skills, desire to learn, money, and of course what you plan on making.

I do hope to add a 3D printer eventually as well....

John
 
I have both and use them about equally. My Tormach 1100 is CNC, it's running a routine for a repetitive part pretty much every time I head to the shop. I also have a Bridgeport with a circa 1981 Anilam 2-axis CNC. The Anilam CNC keeps the handwheels so I have the best of both worlds on that machine. That being said, since getting the Tormach the BP is 99% of the time used as a manual mill.

Macardoso has the best advice above. It all depends on what you plan on making. If you don't know for sure, plan on buying both. Regardless of which one you start with, and since you've asked the question, you know you want both anyhow!

Bruce
 
+1 on Macardoso's comments.

I have a both a CNC mill and Manual Mill. 95% of the time I use my manual mill. The CNC get used for one off's, that are complex shapes and curves or things that require a lot of repetitive moves, such as "Larger" deep rectangular pockets.

This Old Tony has good video on the basics of cnc using an etch-a-sketch as an example.

 
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