CNC laser/router combo

General discussion of laser machines

CNC laser/router combo

Postby qwerty » Mon Dec 16, 2013 9:49 pm

Hi,

after reading many posts and seeing all your beautiful machines, I would like to ask you couple of questions and to receive opinions on idea in my mind.

Seeing pros/cons/possibilities of both CNC laser cutter/engraver and CNC router it looks like a natural choice to have both of these machines available. Two independant machines mean twice the footprint and many doubled parts as they work on the same principal.

I was not able to find a DIY laser/router cutter/engraver combo. I am wondering why.

My vision is pretty straightforward - if you have fuctional Z axis, does it matter if there is a laser head or spindle attached? Or, you can have static laser head and working Z axis with spindle on the same gantry. Or, two independant X axis - one light for laser head, other sturdy for Z axis with spindle...

I doubt about these things:

- what controller can handle this setup (in order to have available vector laser cutting/engraving, raster laser engraving, fully working router)? What software?

- how to precisely align laser beam and router bit?

- considering the Z axis + spindle weight, will laser head move fast enough for laser work? Stronger steppers? Belts? Threaded rods?

- static spindle/laser head and motorised table?


Is it possible to build such working machine on DIY basis? Any conceptual problems? Any ideas?

qwerty
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Re: CNC laser/router combo

Postby cvoinescu » Mon Dec 16, 2013 10:35 pm

The reason you didn't find one is that a machine that's a good CNC router makes a lousy laser cutter, and the other way round.

Laser cutter:
  • Fast movement;
  • Extremely fast movement on one axis (e.g. X) for raster engraving;
  • No load;
  • Extremely lightweight carriage;
  • No requirement that Z moves preserve horizontal position accurately;
  • Optics sensitive to contamination;
  • Optics and tube potentially sensitive to vibration;
  • Enclosed volume for safety;
  • Bed can't be solid, or the laser would cut it, or reflect back onto the underside of the stock and mess it up;
  • Stock does not need to be held down.

Router table:
  • Moderately fast movement;
  • X and Y need the same speed;
  • Heavy cutting load;
  • Heavy spindle to move around;
  • Z movement must be accurately perpendicular on X and Y, and no coupling of Z movement into X and Y positioning;
  • Dusty, even with dust collection;
  • Intense vibration;
  • Need access from sides and top (overhanging stock, access to clamps, dust extraction hose);
  • Bed needs to be stiff, flat and rigid to take the weight of the stock and cutting forces;
  • Hold down facilities required (clamps, vacuum, fixtures etc).

A couple of these aren't showstoppers (the enclosure, and the Z movement), but most are essential differences between the two kinds of machine.
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Re: CNC laser/router combo

Postby qwerty » Tue Dec 17, 2013 7:07 am

Quite impressive list of reasonable arguments, thanks. Giving up on making plans to build such machine...

I am still curious. In theory, with modified requirements and presumptions:
- laser used only to cut; no engraving function,
- no engraving with router neither,
- materials limited to soft plastic or wood,
- laser tube not attached to xy stages to reduce vibration stress on it,
- routing never exceeds workpiece thickness,
- safety, optics protection, dust collection - all managed somehow,
would it even possible to control such combo machine with any of existing controller boards and existing software?


When you consider this very simple 2.x laser custom part (B17015) and imagine, there is extra rectangular opening/notch somewhere on it or there are some salient angle shapes, what are the options to make such part? Router for that double diameter round opening. Laser for rectangular/salient angle shapes/openings. With two dedicated machines, you must move the workpiece between them. Is it even possible to align it precisely in the other machine? With machines having resolution of e.g. 0,02 mm I think there is no chance to achieve such precision when manualy positioning the workpiece, even with some right angle bracket and workpiece temporarily cut to rectangular outer shape for the purpose of utilizing that bracket.

What is the reliable way of doing such two phase workpiece processing in home environment having dedicated CNC laser and router machines?
qwerty
 
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Re: CNC laser/router combo

Postby cvoinescu » Tue Dec 17, 2013 12:36 pm

qwerty wrote:would it even possible to control such combo machine with any of existing controller boards and existing software?

Yes, most CNC controllers and firmware would work, e.g. GRBL, TinyG, and even Marlin and other 3-D printer firmware. Still, not a good idea -- both your laser and your CNC router have compromised functionality, and with all the extra engineering to take care of dust and vibration, the combined machine will cost more than either a better, separate laser, or a better, separate CNC milling machine.

Your piece can be done entirely on a CNC milling machine, no need for a laser. Even if you prefer a two-step process, CNC milling machines have very accurate and repeatable positioning, so all you need is a simple fixture (or some registration pins) to get it perfectly aligned every time (it's much more difficult going from the milling machine to the laser cutter). If you need a rectangular opening, you think about it when designing the part and avoid the need for sharp corners, either by leaving them rounded, or by using dogbones or bisect lines if you need the clearance (e.g. for finger joints). If you really need sharp inside corners (although that's a dubious requirement, and a starting point for cracks in many plastics, including acrylic), you can sometimes machine the part on its edge in a secondary operation (that's how finger joints are sometimes done); or you can file them by hand.
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Re: CNC laser/router combo

Postby qwerty » Tue Dec 17, 2013 1:50 pm

OK, I see your point. Thanks for this valuable input. That part I have used was only an example to illustrate my point. Agreed, many things can be solved out or simplified by their correct design with respect to used machine.


When you pointed out the vibration issue, my first idea was to change the laser tube placing - not to be fixed in enclosure running parallel with X axis, BUT put it completly out of the enclosure (no physical contact with enclosure) and fix it to a garage wall parallel to Z axis. You need to rotate the first mirror of course and position/fix the table to catch the beam. When I think about it,
- you can use any tube length without modifying the existing enclosure (not talking about power supply neither optics; limited by garage ceiling height)
- water hoses can be placed far away from electronics, incl. the high voltage part,
- not the safest build IMHO.

Why there are no builds using this layout? Which important aspects do I miss again?
qwerty
 
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Re: CNC laser/router combo

Postby cadd » Mon Aug 25, 2014 8:12 am

qwerty wrote:Hi,

after reading many posts and seeing all your beautiful machines, I would like to ask you couple of questions and to receive opinions on idea in my mind.

Seeing pros/cons/possibilities of both CNC laser cutter/engraver and CNC router it looks like a natural choice to have both of these machines available. Two independant machines mean twice the footprint and many doubled parts as they work on the same principal.

I was not able to find a DIY laser/router cutter/engraver combo. I am wondering why.

My vision is pretty straightforward - if you have fuctional Z axis, does it matter if there is a laser head or spindle attached? Or, you can have static laser head and working Z axis with spindle on the same gantry. Or, two independant X axis - one light for laser head, other sturdy for Z axis with spindle...

I doubt about these things:

- what controller can handle this setup (in order to have available vector laser cutting/engraving, raster laser engraving, fully working router)? What software?

- how to precisely align laser beam and router bit?

- considering the Z axis + spindle weight, will laser head move fast enough for laser work? Stronger steppers? Belts? Threaded rods?

- static spindle/laser head and motorised table?


Is it possible to build such working machine on DIY basis? Any conceptual problems? Any ideas?

qwerty


is it similar to 3d printers which does 3d printing job ?
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Re: CNC laser/router combo

Postby Guldberg » Mon Aug 25, 2014 7:10 pm

Eurolaser can be equipped with both an knifecutting tool and a router. Its only 1,5kw if I recall correctly. Its mostly meant for cutting pockets in acrylic and for cutting alubond material.
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