# CNC vs Manual



## Suzuki4evr (Sep 30, 2018)

Hi guys.
I guess this has been discussed before, how do you feel about manual vs CNC mills and lathes. Sure CNC is nice and very accurate and fast,but it is also expensive. So is it practical for us working from home? I lookedat some YouTube mesmerizing videos on cnc work and my conclusion is,very nice to have,but I've seen some fails as well and THAT  my friends looked pretty expensive and time consuming to fix. What are your thoughts?


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## BaronJ (Sep 30, 2018)

Hi Guys,

CNC is great for a production shop where many parts have to be made, all identical in shape.
Totally useless for a hobby shop though.  Unless your hobby happens to be playing around with CNC.


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## BGHansen (Sep 30, 2018)

I don't have a CNC lathe but have a CNC Bridgeport and a manual Jet JVM-830 mill.  My BP is ancient by CNC standards, circa 1984 Anilam 2-axis controller.  I can't upload CAD images to it because of an internal communication problem, so can only program it directly at the control box.  So limited by some standards CNC capable.  

A lot of my hobby projects get done by CNC because it's available to me.  Can't do fancy CNC stuff like others do here, just work within my capabilities.  But it sure makes some projects go so much quicker.  Ever need to bore a hole in a piece of plate to mount something?  Manually I'd do it on the lathe in a 4-jaw, or on the mill with a boring head or on a rotary table.  One the mill the routine would be repetitive passes with the boring head creeping up on the OD.  Or with the rotary table, cut a circle by hand cranking the RT and creep up on the OD by adjusting X or Y after each pass.  In my case, it's CNC on the Bridgeport.  Quick key in of V18 with the hole diameter, V49 for the cutter diameter, then a G76 hole cutting command.  I can quickly change the V18 parameter to creep up on the hole size for a perfect fit.

Sorry for the long post, but frankly if you can afford it, buy it.  Once you have the tool, you'll find more uses for it.  Kinda like cutting wood with an ax or chainsaw at your disposal.  Easy choice there.

Here are pictures of my mills.  I paid $4000 for my BP which is a 1985 2 HP variable speed.  It included a static phase converter, Kurt swivel vise and a clamping kit.  I paid $1200 for the Jet mill with no tooling.  To me, the CNC was well worth it.  Good luck with the search!

Bruce


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## P. Waller (Sep 30, 2018)

Both have a place, I run manual and NC machines daily.

Large manual machines are excellent for large one off parts that would not justify the cost of a large NC machine.
For hobby purposes NC will easily perform operations that would be very time consuming and fussy when done manually, the same sort of ops that hobbyists desire for appearance alone. 

The ability of a NC machine to easily radius every corner and interpolate arcs and angles is the most appealing aspect if the technology for those that make things for fun with appearance being more important then function. 

A well done conversational control machine is very easy to operate, anyone proficient at running a manual lathe will will find running a NC machine simple if the control is well done, this  will be costly however. Companies like Fanuc, Siemens, Mazak and Haas have spent countless hours developing control schemes that are simple and intuitive for the end user, no manual code input required, describe the part geometry, feed rates, doc, speeds and clearances and the machine generates the G code for you.

These are rope pulleys/sheaves that I made several weeks ago for a home project using my employers machine. A 1998 Bridgeport/Romi EZ Path lathe. This is a 20 year old machine that has been rode hard

The programming is very simple.

It would look like so.
This assumes that you have set a Z axis work shift at the end of the stock (-:

MDI
Path 1 (It requires a number, I chose 1)
Rapid Move X 1.25   Z-.100 (beginning of the feature)
Arc Move X .850 Z -.200 R (radius) .200
Arc Move X 1.250 Z -.400 R .200 (end of the feature)
The control will subtract the entered tool width from the overall groove width and modify the tool path accordingly
Path End key
Groove key, this is a canned cycle, it will generate the code.
The conversational control now begins, it will want to know the finish allowance between roughing and finishing, I chose to leave .005 per side
Infeed rate, .010 per revolution, it is POM material so you almost can not cut it to fast
Clearance. This tells it to retract a fixed distance from the part to clear chips if needed.
Step over. This is a percentage of the tool width that it will move over for the next plunge, I chose 80%
All if this data is entered in text boxes much like filling out an online form
Done
3 lines of position data, anyone that can run a manual lathe will be able to run this machine in short order.

Let it rip.
I did not run it at full speed with the door open because this will give you a Delrin chip hat.


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## Suzuki4evr (Sep 30, 2018)

Hey Bruce.
Thank you for your input,I didn't understand half of you mentioned about the cnc lingo,but I can appreciate it. I am sure it makes work a lot easier. I would like to have a DRO though and would realy like variable speed on my A&S mill/drill instead of the pulley system. 

Michael


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## stupoty (Sep 30, 2018)

Suzuki4evr said:


> Hi guys.
> I guess this has been discussed before, how do you feel about manual vs CNC mills and lathes. Sure CNC is nice and very accurate and fast,but it is also expensive. So is it practical for us working from home? I lookedat some YouTube mesmerizing videos on cnc work and my conclusion is,very nice to have,but I've seen some fails as well and THAT  my friends looked pretty expensive and time consuming to fix. What are your thoughts?



some of the small/affordable gantry cnc are very versatile, I have seen some amazing things done with them.

stu


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## Suzuki4evr (Sep 30, 2018)

stupoty said:


> some of the small/affordable gantry cnc are very versatile, I have seen some amazing things done with them.
> 
> stu


Hi Stu.
Do you have pic of these tipe machines for my interest sake?


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## P. Waller (Sep 30, 2018)

Also, way back in 1996 these machines will give you a tool path simulation, I use this to ensure that at some point an OD tool is not inside the chuck (-: This often ends in tears
This is a tapered bore that I programmed this morning for a job on Monday.
It looks like so in simulation


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## magicniner (Sep 30, 2018)

CNC allows you to produce complex 2D shapes that are very difficult with manual machining, if you don't need that perhaps you don't need CNC

CNC allows you to produce complex 3D shapes that are very difficult with manual machining, if you don't need that perhaps you don't need CNC

CNC allows you to produce complex 2D shapes that are impossible with manual machining, if you don't need that then you probably don't need CNC

CNC allows you to produce complex 3D shapes that are impossible with manual machining, if you don't need that then you probably don't need CNC

I used to think some of the "No good for one-offs" and "Not as skilled as manual" BS that is put about by those who cannot grasp what CNC might do for them or what mastering it involves, but as someone who started out Manual Only and transitioned to CNC and who still does a lot of manual work,  I can tell you that a complete modern workshop can and should have both.

At last years Midlands Model Engineering Exhibition I noted a "Badge of Honour" on an exhibit of a partial 1/3 scale Bentley Blower stating that the builder has used no CNC which led me to think three things

1. He's incapable of understanding the advantages of CNC
2. He's incapable of learning to use CNC
3. He's incapable of making the parts 3 times bigger and building a car that's worth having


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## Boswell (Sep 30, 2018)

I pretty much only do one-off hobby work. I had a very small bench top manual mill and I learned a lot on it. I replaced it with a larger Benchtop Mill. PM45-CNC. 75-90% of what I do, I could do on a manual machine but for me, it is easy to do even simple things on the CNC Mill.  For example, the other day, I wanted to counterbore some holes for 1/2-2- cap head screws.  I don't have any counterbore bits but was simple to use the CNC to mill the counterbore with a 1/4" end mill. I also find it is easy to add radiuses to edges that while not functional do add to the appearance. (remember, I am hobby only).  while you can hand code G-Code or buy a system with conversational programing like above, most likely You will need to make a commitment to learning the world of CNC programing, CAD and CAM work to do the more complex work. For some learning computer programs is not a big deal, for others it can be an obstacle.  There is an active CNC section on this forum that you might want to check out.


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## pacifica (Sep 30, 2018)

The big trade off for a hobbiest is the cost of a newer CNC machine. The $10k+ machines arent very big. Tooling is expensive.


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## JimDawson (Sep 30, 2018)

First let me say that although I have never claimed to be a machinist, and can make acceptable parts without all of the newfangled electronics. When I first installed a DRO on a machine, back in the early 80's, I found that the quality of my work improved and my productivity increased. Then many years later when I got a CNC machine, there was another dramatic increase in accuracy and productivity. I really found out I'm a much better programmer than a machinist. 

Having a CNC mill has allowed me to expand the range of parts I can make and even makes me look like a machinist.  About 6 years ago I couldn't even spell CNC. It is possible to make complex shapes on a manual machine, but the setup time and tooling requirement is increased. For instance, it's almost impossible to make round parts on a mill without a rotary table, but with a CNC you just tell it to make a round part and it does.  I haven't taken my rotary table off the shelf in years.

It's completely possible to make this part on a manual machine, but it would have taken several setups to do it.



You can certainly screw up things up in a hurry on a CNC, I have broken my share of endmills by running them into the part or hold down on a rapid move.  But this is why you do an ''air cut'' before running a new program.  I am breaking fewer tools as time goes on as I learn not to do stupid stuff.   Mostly having to do with the tool path of the rapid moves, it takes a little thought, but you can make the tool go where you want it to go to avoid obstacles.

For prototyping and one off parts I like a combination of both CNC and manual, thus my machine is both a CNC and manual machine.  Most of what I do is single parts, rarely more than 5.  This applies to both hobby type work and commercial work.  There is no down side to a CNC/manual machine.  For the type of work I do, it would be impractical to use CNC only, too many steps and time involved in the process for a simple job, like facing off a block of material.  My machine started out life as a 2 axis, Anilam controlled, CNC/manual machine much like the one @BGHansen has. I picked it up for $1000.

I have not converted my Jet lathe to CNC, but have been thinking about doing that.  But if I do, it will retain full manual capability.  If I ever get time I am going to convert my DoALL surface grinder to full CNC and get rid of the hydraulic system, again, I will retain full manual capability.

I do have a CNC lathe and mill in the shop for production work, but they don't get used for the one off stuff.


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## magicniner (Sep 30, 2018)

pacifica said:


> The big trade off for a hobbiest is the cost of a newer CNC machine. The $10k+ machines arent very big. Tooling is expensive.



CNC conversion of a manual mill isn't complex and is within the capability of a half decent hobby engineer, it can cost a few thousand in parts to do it right, the tooling can be the same tooling as for your manual mill, it's a no-brainer if you have the money in the Tool Fund ;-)


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## stupoty (Sep 30, 2018)

Suzuki4evr said:


> Hi Stu.
> Do you have pic of these tipe machines for my interest sake?



Hello, 

I'm thinking about this sort of thing.

http://cncevolution.tooltec.co.uk/cnc-machine-products/cnc-shark-hd-40-tabletop-cnc-machine

They definitely have limits , their more of a 2d sheet material CNC,  but you can get them quite cheaply(relatively)

Stu


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## Janderso (Sep 30, 2018)

I saw a Bridgeport CNC milling machine recently at an auction. I would have no idea what to do with it. It sold for $650. It was in good shape too. 
The whole programming thing is out of my field of reference. (I’m ignorant)


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## P. Waller (Sep 30, 2018)

Janderso said:


> I saw a Bridgeport CNC milling machine recently at an auction. I would have no idea what to do with it. It sold for $650. It was in good shape too.
> The whole programming thing is out of my field of reference. (I’m ignorant)


If you can find a used BP EZTrak that still runs buy it, this is about the easiest machine to use that you will ever come across. They can be operated as a fully manual machine or a 2 axis NC machine, it is likely that the control has failed on a $650.00 machine, it is then a manual BP knee mill with ball screws.


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## MarkDavis (Oct 1, 2018)

I bought a tormach 1100 when I retired, did not know how to make find or save a computer file one year earlier.
It's been a few years since then, and am starting to get the hang of it.
Sometimes I wish there were manual cranks for real simple cuts.
Using the jog controls instead of writing a program has not been good for me.


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