Laser cutting

[glwoodturning]

I know nothing about CNC other than what the initials stand for. I have a 2000 version of Autocad, I don't suppose that it is as easy as drawing a pattern and the cutter will follow it!!!!
I enjoy scroll saw work to raise funds for charities but with deteriorating eyesight I am looking at alternatives.
Gordon

 

[akirk]

mmm
you have posted the thread as laser cutting and then you talk about CNC and ask about replacements to scroll saw work...

Lasers
Lasers are a varied bunch from the cheaper end (Diodes) to more expensive CO2 lasers etc. but roughly speaking they do two things:
- engrave (patterns / lettering / etc.)
- cut
they do this by your adjusting the speed the laser moves at / the % of the laser's power / the number of times you go over the same line - you vary this for each wood / thickness you choose to cut
you also choose the actual laser head from eg. 5w / 10w / 20w / 40w for diode and 60w+ for CO2 - this varies the range of power available
Lasers are generally 2D (x-axis and y-axis) - flat work - though you can buy rotary systems to engrave on 3D objects, but they effectively turn to make the 3D object the equivalent of a 2D plane

CNC
CNC is basically a router running around a framework - you can change the bits on it and it cuts the wood according to what you have put on. You still have choices such as how many times to run smaller cuts v. bigger cuts - the difference being whether you snap the bit or not!
A CNC is not fully 3D (unless you get into 5-axis jobs) - but it does bring in a z-axis which the laser generally doesn't - this allows more of a 2.5D approach in that you can get 3D cuts / shapes - you just can't attack the whole item all around (e.g. making a perfect sphere) as it has to sit on a surface...

CNC is generally more expensive to buy and trickier to use - needs more specialist software and a better understanding of 3D objects - lasers are much simpler - as long as you can use a basic programme such as Lightburn (pretty much industry standard) then it is much more point and go... There are some companies starting to build much better systems which needs less involvement (glowforge in the USA is a good example) but we are still 1 or 2 generations away from making it very simple - and that is laser, not CNC.

The downside of CNC is the burning of the wood edges, so a degree of sanding might be needed afterwards - but it is deeply satisfying watching it cut complex curves etc.

all of this is a generalisation of course!

here are some examples of jigsaws I have been cutting on the laser - I use scroll saw patterns and then with almost no adaptation, cut them on the laser...

what do you want to make?!

 

[ChaiLatte]

you have posted the thread as laser cutting and then you talk about CNC

At this stage of the discussion, he is asking about AutoCAD and 'drawing a pattern'. Hence, I think that the detailed distinction you make between the two processes is somewhat irrelevant at this point.

AutoCAD will do very well for making 2D profiles for _any_ computer-controlled machine to follow. That is the CAD part of CAD/CAM.

The CNC machine that does something with the output of the CAM program could be a pen plotter, a vinyl cutter, a laser cutter, a waterjet, a plasma cutter, a milling machine, a huge John Deere combine harvester.

You would save the profile as a dxf, which acts as a common input to all these machines.

It is after the dxf, in the CAM part of CAD/CAM, that the specific machine you use influences what you do with that profile. In a simple pen plotter the 'cutter' (a pen) will, as he says, follow the pattern (with the immediate added complication of needing to lift up off the paper where you do not want a line).

A milling/routing cutter that has a non-zero kerf will generally follow the pattern but on one side or the other of the line (just like sawing a piece of wood).

The point is that unless you are doing 3D profiling, a simple 2D dxf outline produced in AutoCAD is an excellent place to start.

 

[akirk]

Thank you for your analysis of my post

I think that if the OP is looking to move to something automated to replace scroll saws then understanding the main options as laser / CNC (both of which were mentioned) is really rather relevant, not so sure that he will be making a 'huge John Deere combine harvester'!

Yes AutoCAD will produce 2D images to be followed - however it is not the simplest solution if not needing to run a CNC - lightburn or any basic vector program / even websites which convert bitmap to vector such as vectormagic will all provide suitable files for a laser and at much simpler learning curves

hence my question about what he wants to make as that should drive the solution - I do a lot of 'scroll saw' stuff on the laser, but for some stuff a CNC would be better...

and while you are correct that any computer controlled machine is technically a CNC - that is not modern parlance - a laser cutter is not the same as the machine which is sold as a CNC, uses a router and a solid bit - two very different machines...

 

[glwoodturning]

Thank you both for taking the trouble to reply in so much detail. I am attaching a few photos of my bits and pieces that I have made over the years. I have seen laser cutters priced as low as £300, would these cut 9mm ply and if so would the burnt edges have to be cleaned up? The black edges can be quite attractive on thin wood. How does a laser cutter follow a pattern? Does it scan it? If it is put onto the wood I would expect it to burn. What thickness are the jigsaws that you have photographed please? I use 1/16" or 1/32" ply for the tractor and butterfly and similar projects.
Sorry to have so many questions, but apart from seeing the odd sales video I have very little idea of how these work. Thanks again
Gordon

 

[akirk]

price of a laser is roughly based on the power
power is roughly a metric of how thick a piece of wood it can cut
to cut wood you don't want lower than 10w and ideally 20w+ unlikely to be in the £300 range
lower priced lasers engrave they don't tend to cut...

I have a 5w NEJE - doesn't cut, great at engraving
I also have a 20w XTool D1 Pro - does both and will happily cut through 10-12mm of oak
The jigsaws above are 5.5mm walnut / cherry
I have no issue cutting 12mm+ of ply - but it can be a bit erratic as glue is often not evenly applied when made...
The laser either follows a vector (mathematical curves) - and you really need that for cutting... or it can burn a bitmap (photo image) which it tends to do for engraving... burning happens where the laser is in one place for too long - so cutting can make that happen as it is concentrated and has to go through the wood, so the fringe casualty is burning - engraving should not burn and there are options usually to use a pump to blow fresh air onto the nozzle to reduce burning, but it doesn't eradicate it...

There is a lot of good material on youtube, perhaps worth watching?

This is an example of 10mm quarter sawn oak I cut on the laser to make a doll's cradle - not insubstantial! As you can see - I sanded down the edges afterwards

 

[glwoodturning]

price of a laser is roughly based on the power
power is roughly a metric of how thick a piece of wood it can cut
to cut wood you don't want lower than 10w and ideally 20w+ unlikely to be in the £300 range
lower priced lasers engrave they don't tend to cut...

I have a 5w NEJE - doesn't cut, great at engraving
I also have a 20w XTool D1 Pro - does both and will happily cut through 10-12mm of oak
The jigsaws above are 5.5mm walnut / cherry
I have no issue cutting 12mm+ of ply - but it can be a bit erratic as glue is often not evenly applied when made...
The laser either follows a vector (mathematical curves) - and you really need that for cutting... or it can burn a bitmap (photo image) which it tends to do for engraving... burning happens where the laser is in one place for too long - so cutting can make that happen as it is concentrated and has to go through the wood, so the fringe casualty is burning - engraving should not burn and there are options usually to use a pump to blow fresh air onto the nozzle to reduce burning, but it doesn't eradicate it...

There is a lot of good material on youtube, perhaps worth watching?

This is an example of 10mm quarter sawn oak I cut on the laser to make a doll's cradle - not insubstantial! As you can see - I sanded down the edges afterwards

View attachment 177185
View attachment 177186

View attachment 177187

 

[glwoodturning]

Thanks again, I think that price will; be a factor for me. As I am getting older - 88 next month I need to think what benefit I will get and how easy it is to get started - brian doesn't like too many new tasks. I will have a look at YouTube
G

 

[JoeNinety]

price of a laser is roughly based on the power
power is roughly a metric of how thick a piece of wood it can cut
to cut wood you don't want lower than 10w and ideally 20w+ unlikely to be in the £300 range
lower priced lasers engrave they don't tend to cut...

I have a 5w NEJE - doesn't cut, great at engraving
I also have a 20w XTool D1 Pro - does both and will happily cut through 10-12mm of oak
The jigsaws above are 5.5mm walnut / cherry
I have no issue cutting 12mm+ of ply - but it can be a bit erratic as glue is often not evenly applied when made...
The laser either follows a vector (mathematical curves) - and you really need that for cutting... or it can burn a bitmap (photo image) which it tends to do for engraving... burning happens where the laser is in one place for too long - so cutting can make that happen as it is concentrated and has to go through the wood, so the fringe casualty is burning - engraving should not burn and there are options usually to use a pump to blow fresh air onto the nozzle to reduce burning, but it doesn't eradicate it...

There is a lot of good material on youtube, perhaps worth watching?

This is an example of 10mm quarter sawn oak I cut on the laser to make a doll's cradle - not insubstantial! As you can see - I sanded down the edges afterwards

View attachment 177185
View attachment 177186

View attachment 177187

Just out of curiosity, how many passes did you need for that 10mm oak? And at what mm per second?

 

[akirk]

Just out of curiosity, how many passes did you need for that 10mm oak? And at what mm per second?

5 passes
speed 360
power: 100%

 

[JoeNinety]

That's not 360mm per second surely? That would be crazy fast. Anyway, does that give you fairly straight edges, without much of a chamfer?

 

[akirk]

Mm per minute I think…
And yes - gives a pretty good edge