CNC vs Hand turning/milling

[rickharris]

I am fortunate to have access to a CNC Mill and Lathe as well as Routers and a laser cutter at School.

BUT apart from the ability to produce many identical items from the CNC system - The speed of the laser cutter to cut wood/plastics I generally find that for one off items it is faster and easier to do the task on the old hand lather/mill than it is to draw out/plan and run it on the CNC.

This begs the question then - For the hobby machinist is CNC worth the bother. For the cost in general you can buy a bigger/better manual lathe or Mill and with a little care and perhaps a few jigs/special tools you can produce just as good and accurate result.

Or maybe some of you with CNC equipment will correct my thinking and persuade me that CNC is really useful for the hobby machinist.

 

[Powder keg]

It's a hobby. Is it worth the bother to you? That is the question. for me, I'm trying to round up stuff to build a CNC router right now. To me it's worth it)

Wes

 

[BobWarfield]

It really depends on the part. A simple bushing can be very fast on a manual lathe. Something even modestly complex might be much faster on a CNC.

Consider this fixture and bearing block for the team build:

With a CNC, there'd be no point in making up the fancy fixture plate or fooling with a rotary table to do the little curved top. Let's say I wanted to make 2 of these little bearing plates, one for each side of the crankshaft. I'd take a plate slightly thicker than the desired part and slightly larger, and clamp it down to the table. Push your button and you surface the top, cut the profile most of the way through (full thickness for the part, but not the plate), and drill and ream holes appropriately. Now flip over and face until the parts drop out.

That's a lot faster than I can do those manual steps. As for the drawing and CAM (generating the g-code), it would take me no time at all, and as you can see, I'm more comfortable with drawings for something like this so I draw them up anyway.

A CNC lathe might be slightly less useful for a hobbyist, but any ball turning or taper turning is dead easy with the CNC and you've no need of a ball turner or taper attachment. In fact, I suspect you could save enough from all the various add-ons to do a CNC conversion. Think of all the stuff you wouldn't need to buy or build such as DRO's, ball turners, taper attachments, rotary tables, and the like.

OTOH, you have to decide what you like to do. Some of the fellas here run CNC all day at work and have no desire to do more at home. They want the manual machining aspect. I have to admit, I couldn't recommend going straight into CNC without a feel for what it's like to do things manually.

Cheers,

BW

 

[Alphawolf45]

I am hobbiest setup with both manual and cnc machines....very handy to have the choice of a variety of machines to work with..Sometimes cnc mill really justifies itself , while most of the time its my preference to use a manual mill for the jobs I invariably work on..

 

[Twinsquirrel]

Forgive my ignorance and being slightly off topic, but is it possible to run a CNC mill/lathe manually also?

David

 

[Loose nut]

For some people setting up and running a cnc program is the hobby, the end result has less value than the trip to get there.

I'm the opposite I like to make things the old fashioned "manual" way that would be easy to do by cnc, the trip is still the fun and when you get done you can say " I did this" not a machine.

Different strokes, but there is no right or wrong way.

 

[rake60]

I operate and do some programing on a CNC for a living.
I love my job!

At home my machines are all manual.
I find the finshed product more rewarding being made 100% manual.
On the other hand I admire the home CNC guys!
I know what it takes to write an NC program.
My machine at work is conversational programing.
I can not program the NC that many of the home machines require.

Rick

 

[mklotz]

I sat in front of a computer writing simulations of weapon systems for a good part of my working life.

While it's fun now to use the computer to learn and interact with the modelmaking community, when I want to have some fun, I want to turn handles, devise jigs and fixtures and make tools.

 

[Powder keg]

I used to have Loose nuts point of view. Sure, Once you have the program all you have to do is place the part in the machine and push the green button. But, It isn't that easy. I've been doing CNC for over a year now. I took 2 night classes on programing and running CNC's. I run a CNC mill all day long every day. I still feel like I'm in physical therapy for the mentally challenged.

With CNC, I can make nicer stuff in way less time than it would take to do it on a manual machine. I'll have some examples in the near future. My time is limited. I don't have enough of it. So anything I can do to fix that, I'm game.

later, Wes

 

[rake60]

I do have to say I learn a lot from the CNC programs I run at work!

Last week I was making a very large pin socket that called for a 2" square hole
in the back side for a 2" air hammer drive to engage.

The program was to drill 4) 3/8" holes in the corners of the square for relief areas.
Then it drilled a 2" hole in the center of the square, and finally called up a high speed
1/2" end mill that made the final passes to finish the 4 flat sides.

I thought, I can do that on a smaller scale at manual speeds!!!

Rick

 

[Mcgyver]

This begs the question then - For the hobby machinist is CNC worth the bother. For the cost in general you can buy a bigger/better manual lathe or Mill and with a little care and perhaps a few jigs/special tools you can produce just as good and accurate result.

On a practical level I mostly agree with that, but, for many, myself included, its just another hobby. I've gone the route of making my own controller and break out boards - what a great excuse to learn a bit of electronics and acquire even more tools!

There are some real challenge cnc'ing a lathe, well at least if its to cut threads, but a mill is easily within the realm of diy....so like engines i make that i don't really need, I'm making a cnc i don't really need ....but it interests me. If I was more serious about it, I’d buy an old excello or bport with a shot controller, but that seems like a lot of work and expense as in low low quantities manual is usually more direct/efficient.

It will do some interesting things that would be a great challenge manually, like routing a circuit board for example.

 

[Cedge]

I'm definitely not anti CNC and I will admit to a healthy curiosity about it. I just really enjoy the "feel" of the metal and the instant feedback you get while running manual machines. The challenges of getting a manual machine to do a complex, tricky or intricate cut are mentally rewarding and produce a feeling that I've found darned near addictive.

I can certainly see where getting the code right to perform the same chore on CNC would be rewarding. I'm just not sure the novelty of sitting and watching the machines do the work that I so much enjoy would last long enough to justify the costs I'd incur by converting my little mini mill to CNC. If I was going to be doing multiples or production on a regular basis.... then yes I'd be looking to do it with a bit of automation.

In the mean time I'm quite content with my manual efforts, even as I admire the work the CNC guys are able to produce.

Steve

 

[John S]

Read this for another point of view as regards time.

http://www.arceurotrade.co.uk/projects/Why_CNC/whycnc.html

.

 

[Alphawolf45]

If a man continues with metalsworking hobby for many years he will naturally acquire as many machines as will fit into his workshop...Judging by observing my own friends- Most folks will eventually have multiple lathes and multiple milling machines.. And since both manual and cncs have their strong points it is then desireable to have examples of each....I presently have 4 vertical milling machines , 2 are manual and 2 are cncs, each is 2500lbs and heavier..now I want little tabletop cnc mill just for engraving.....I want one of everything, dont you?
.
I just now got my very first steam engine running (Yeayyy!!) but not entirely finished, I am thinking how to make the last couple parts.Design in my head and then will draw it in autocad and later this morning will mill it with the cnc mill. It is the quickest way to make one part that has a lot of curves in it.

 

[Dick L.]

I've been doing G code programming for 12 yrs. now and I always find new ways to do things. At home I only have the 2 axis Lagun and it is an older conversational Proto-Trak but as the CNC machines become more affordable I will surely add to the fleet. Learning the trade in the late sixties and apprenticing under guys with 35 yrs. at it taught a lot of fixtures and approaches, but most importantly patience. CNC machines and process have their own problems to solve and fixtures to design. The challenge is still there ! Nothing can build your scrap pile like a CNC machine. ;D There is an old saying goes something like garbage in garbage out.....
Many ways to get there, the important part is to enjoy what your doing I think.
Dick

 

[Loose nut]

Read this for another point of view as regards time.

http://www.arceurotrade.co.uk/projects/Why_CNC/whycnc.html

.

The guy writing this article missed out on one very important point, in the time frame he was talking about most jobs were 10 hrs. or more a day 6 days a week at a minimum, they didn't have any more time available for hobbies than we did and probably less. On top of that the equipment most of them had to work with was minimal and probably of lower quality, a small clapped out lathe and hand tools would be common. The still turned out some fine work.

 

[Tin Falcon]

some interesting points here
this is a hobby in America so we can all set up our shops ,spend our time and hobby funds as we see fit large or small , domestic or import manual or cnc.
I have been wanting to convert my seig 2 to cnc and keep the manual capability's. I have the plans have some money set aside for a controller I guess the need for qc tooling is holding me up some can not quite see putting out the $600 for a tormach tooling set.

Learning something new is appealing. I ran a cnc lathe for a year and have had rudimentary training exposure to CNC milling. g code is just another computer language based on the Cartesian plane I have had enough math that it does not scare me.

I will say that it very rewarding to be at a show and have folks look at your work and ask did you use a CNC and they look very startled and surprised when you tell them the work was done on manual machines.
Dave
to answer your question

is it possible to run a CNC mill/lathe manually also?

Yes there are two ways of doing this
1) keep your cranks hooked up to the feed screws. when you want to use manual mode turn off the electronics and crank away.
2) remove the hand cranks and install stepper or servo motors install electronic dials that allow fro manual input.
IMHO you need to be more cautious with method two you lose the feel that you have in manual mode and are more prone to crashing a tool against a part.
on the other hand it can give jogging a bit more control . a matter of preference of course method 1 is also cheaper.
Tin

 

[rickharris]

Thanks for the replies gentlemen, Interesting issues raised, If only I had the space (and the hard cash) for one of everything!

I guess it is very must dependent on where you see your focus - Personally I like to machine by hand, On a good day I even like wielding a file.

I don't imagine she who must be obeyed will go for the CNC hobby route she stands aghast when I explain exactly how much raw materials cost these days (and all I do is make swarf out of it!)