naive question from a noob

[skypickle]

I'm trying to figure out what a laser is good for and what a cnc machine is best suited to. Both are subtractive . Is there a web page that can go into specifics to answer this question? So often I end up getting in the weeds with details comparing machines. Which should I use if I want to cut pieces out of plastic, acrylic, etc? Which should I use if I want to create something out of aluminum.- like a bass relief design. Of course the laser can do engraving which a cnc machine cannot really reproduce with the same detail.

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[CNCMAN172]

Most affordable laser can old etch metal and cut wood or plastic that is thin. CNc machines can cut all, but there is a huge range of prices and the more expensive machine can handle metal much easier. If you want to cut steel you are looking at much more expensive mills.

$350 to $35,000 how much do you really need?

[skypickle]

well, the thickest thing I'd want to CUT is 1/8" acrylic. But what about sculpting the surface of a 1/4" panel of aluminum? Or suppose I wanted to make a bas relief of a horse and hound on a 12 x 24" piece of oak? or if I wanted to cut precise designs/holes in plastic project boxes which typically have 1/16 to 1/8 " thick walls?

[Jim Dawson]

well, the thickest thing I'd want to CUT is 1/8" acrylic. But what about sculpting the surface of a 1/4" panel of aluminum? Or suppose I wanted to make a bas relief of a horse and hound on a 12 x 24" piece of oak? or if I wanted to cut precise designs/holes in plastic project boxes which typically have 1/16 to 1/8 " thick walls?

A CNC mill will do all of that quite well. The resolution is a function of the tool bit size, quite likely can be smaller than the laser spot. I have used tools as small as 0.005'' for fine work.

Here is an example of bias relief in titanium
https://academy.titansofcnc.com/vide...-titanium-lion

[cornerman]

Tough question to answer
I guess that your knowledge of the software for each would be important!
I started out with a Gravograph IS400 CNC and got real good at making some of the things that you mentioned.
As of this year I ventured onto the laser world
(BOSS HP2440 co2)
I quite often find myself turning back to the trusty CNC
Hope this helps

Sent from my SM-G988U using Tapatalk

[skypickle]

thank you for your words. next step -figuring out which CNC machines to look at. Given the sizes I mentioned -a maximum dimension of 24"- where do I start? is the next parameter precision or speed? I am at the beginning so I would prioritize precision over speed. I won't be machining steel or titanium (that lion was amazing and a 5 axis machine is beyond me) so material choice is also a variable.

[cornerman]

3d printing is an option

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[Jim Dawson]

thank you for your words. next step -figuring out which CNC machines to look at. Given the sizes I mentioned -a maximum dimension of 24"- where do I start? is the next parameter precision or speed? I am at the beginning so I would prioritize precision over speed. I won't be machining steel or titanium (that lion was amazing and a 5 axis machine is beyond me) so material choice is also a variable.

The titanium lion was a bit over the top, but I wanted to illustrate what is possible and show you the fine detail that can be done on a milling machine. Even a 3 axis machine will do that kind of work if you are very clever with your setup.

What you buy depends on your budget and how much space you have available to dedicate to a machine.

Here is one possibility the would meet your work envelope requirement
https://www.ebay.com/itm/16423696754...cAAOSwC1pe3ocw

and a bunch of options
https://www.ebay.com/sch/i.html?_fro...outer&_sacat=0

Or for more robust machines
https://www.ebay.com/sch/i.html?_fro...uter&_osacat=0

[cornerman]

Monoport can work on plexiglass and acrylics
Any luck with polycarbonate materials?
We have Lexan for machine guarding and that stuff does not like to be burned with a laser

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[skypickle]

The titanium lion was a bit over the top, but I wanted to illustrate what is possible and show you the fine detail that can be done on a milling machine. Even a 3 axis machine will do that kind of work if you are very clever with your setup.

What you buy depends on your budget and how much space you have available to dedicate to a machine.

Here is one possibility the would meet your work envelope requirement
https://www.ebay.com/itm/16423696754...cAAOSwC1pe3ocw

and a bunch of options
https://www.ebay.com/sch/i.html?_fro...outer&_sacat=0

Or for more robust machines
https://www.ebay.com/sch/i.html?_fro...uter&_osacat=0

I am afraid of Ebay since I know very little and could easily buy a piece of junk without knowing it. I have some experience around Bridgeports (the old regular mills with just a DRO)and as they age, the tracks get worn in the middle leading to inaccuracies . Although many of the machines are within my budget and I have plenty of space in the shop, I dont want to be overwhelmed. For example I saw this
https://www.ebay.com/itm/32478745949...gAAOSwhZFf226n
but I looked at some videos on utube and getting that thing configured is not a breeze.

My models are made in sketchup and then fusion360. Porting these files to a cnc mill is a gulf I will need to cross.

Also I noticed a distinct separation in mills that do metal vs wood. or is that just my ignorance?

[awerby]

There is a difference between mills that cut metals and routers that cut wood and plastics. While the machines look similar, it takes a much more rigid machine to cut metals with any kind of speed or precision, Also, while routers typically run dry, with a dust collector to keep it from filling the air with particles, mills usually want some kind of wet coolant when cutting metals and produce chips that are heavy enough to stay put for the most part. Mills typically have a spindle that spins much slower, but with more torque than the high-RPM hand routers or 3-phase spindles that mount on CNC routers. So you don't often find them used interchangably, although aluminum is soft enough that it can be cut by the more rigid routers.

[Jim Dawson]

Buying used equipment does require some care, but I have only one machine in my shop that I bought new. The rest were like new mechanically, but required a controls upgrade. Buying used equipment from eBay is some risk, but sellers are generally honest. It is certainly best if you can physically look at a machine before purchase, something I have done in all cases. In most cases a quality CNC mill will be in mechanically pretty good shape even after years of use as long as it has been properly lubricated through its life. An old manual Bridgeport will generally have more wear than the same year CNC machine, just due to the difference in maintenance.

From Fusion 360 to the mill is no problem. Fusion 360 has built in CAM and that is where you develop your tool paths, then it just a matter of post processing to create the G code using the machine/control specific post processor that is included in Fusion. This process is the same for all machines.

All machines will require some setup and there is a learning curve. But it's not that difficult.

Absolutely there is a difference between a machine designed for wood cutting and one designed for metal cutting. In general for a given work envelope the metal working machines are much more riigid and maybe at least 5x the mass of the woodworking machine. Also the woodworking machines have much higher spindle speeds and generally feed faster than the metal working machines. Having said that, metalworking machines will cut wood just fine, they just run a bit slower.

[skypickle]

ok, so I am doing some acrylic work already. BY HAND. It looks awful . I dont do much woodwork. So are there any suggestions? This seems like something that might work for me
https://www.langmuirsystems.com/mr1

[Jim Dawson]

First time I have ever heard of Langmuir machines. If it works as well as shown in the video, then I would say it would work for you. Looks like a light weight machine, but it seem to be inexpensive so that is to be expected.

[dazp1976]

First time I have ever heard of Langmuir machines. If it works as well as shown in the video, then I would say it would work for you. Looks like a light weight machine, but it seem to be inexpensive so that is to be expected.

From reading something on another forum and a bit of scrutiny and math.
Some of the specifications on this Langmuir MR1 are highly questionable.
Spindle power claims are nigh on impossible for a start.
Concerns with company stretching truths into the stratosphere.

http://www.mycncuk.com/threads/15127-Langmuir-MR-1-spindle-servo-8000-rpm?p=128949#post128949

[Jim Dawson]

From reading something on another forum and a bit of scrutiny and math.
Some of the specifications on this Langmuir MR1 are highly questionable.
Spindle power claims are nigh on impossible for a start.
Concerns with company stretching truths into the stratosphere.

BUILD LOG: Langmuir MR-1 spindle servo - 8000 rpm

After reviewing the specs on the Langmuir MR1, they do seem rather optimistic.