Laser Cutter Things

[Dave Chanter]

FYI to folks working on the Laser Cutter,

I dropped off 5 Metres of 150mm diameter PVC ducting for the exhaust system, feel free to use it. ;) There is still some work to do around fitting a suitable bracket to the exhaust chimney in the ceiling to hold and extraction fan and plumbing the whole thing together, but that should help get us on the way. I wont be around until next Tuesday so if someone is feeling capable and enterprising on Saturday feel free to start the work.

Maybe we can laser cut some collars/connectors for the ducting?

Let me know if you need anymore supplies in this thread, I'm sure the membership can scrounge up whatever else we need and failing that we do have a modest budget to finish this project off.

Cheers

DC

[Darren Freeman]

On Thu, 2013-05-16 at 00:59 -0700, Dave Chanter wrote:
> FYI to folks working on the Laser Cutter,

Turns out I'm now one of them :)

> I dropped off 5 Metres of 150mm diameter PVC ducting for the exhaust
> system, feel free to use it. ;) There is still some work to do around
> fitting a suitable bracket to

Thanks! I've also set aside some flexible aluminium duct that would
probably go the whole distance, but it's less wasteful to just use it
for the last leg up to the machine.

> the exhaust chimney in the ceiling to hold and extraction fan and
> plumbing the whole thing together, but that should help get us on the
> way. I wont be around until next Tuesday so if someone is feeling
> capable and enterprising on Saturday feel free to start the work.

I have also put aside an *awesome* blower for this purpose. At this
stage I'm just lending it long-term as I have nothing else like this for
my own projects. It should be mounted inside the flue to keep the
ducting at negative pressure, and it will also reduce the noise.

So hold off on committing anything until I've had a chance to drop it
off. It will need some wiring done once I've located a suitable variable
speed controller. (Which I'm sure I have already in the pile.) I'll do
all the wiring if someone wants to start on a plywood plate that fits
snugly on the end of the flue and can hold up about 1 kg of fan. This
means putting screws through the side of the flue to hold it firmly in
the up position. (As opposed to the exploded into millions of pieces on
the ground position.)

The plate should have a hole in the centre for the PVC to fit snugly
into, again without falling out. The fan is a centrifugal type with a
circular intake that mounts flush against the mounting surface.

> Maybe we can laser cut some collars/connectors for the ducting?

Yes, I was thinking that. But I believe we are having trouble generating
G-code from sensible design formats. A jigsaw and some random bits of
wood would do.

Do we have a jigsaw?

> Let me know if you need anymore supplies in this thread, I'm sure the
> membership can scrounge up whatever else we need and failing that we
> do have a modest budget to finish this project off.

A step down transformer, 240:120 V, about 150 VA on the output, would be
nice, if anyone has such a thing lying around. But we can live without
it.

Have fun,
Darren

[Luke Weston]

As a proof of concept mounting plate (and mainly to test a relatively large laser cut job after Darren and myself realigned the laser optics, and to test the abundant smoked grey 4.5mm polycarbonate in the laser.) I cut this duct adapter plate for a 120mm PC-style fan.

It came out pretty good. What you would need here is some sort of cylinder or tube 110mm in diameter that fits into the 110mm hole and is glued into the hole. A bit of plastic pipe a few inches long would do it - then you plug your flexible duct on over the end of it.

But this is just a proof of concept. I will design and fabricate a new larger one that fits onto the side of the machine and has a 150mm hole. Does anyone have a <= 100mm long bit of 150mm dia PVC drainpipe or anything similar?

Tapping and countersinking the (laser-cut) 4mm screw holes accounted for most of the work!

Now the entire bed area in the machine can be used successfully because we aligned the optics properly the other week, meaning large objects can be cut. :)

The smoked grey 4.5mm Lexan (from Rob B) cuts great, although I did run it slow (250mm/min).

These guys reckon clear polycarbonate (at least the particular material they used) discolours and generates lots of soot when cut, but this does not happen with this material. 

http://support.ponoko.com/entries/20189761-Can-Ponoko-cut-Polycarbonate-plastic- 

Cheers,

  Luke

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[Rob Gannon]

>Yes, I was thinking that. But I believe we are having trouble generating
G-code from sensible design formats.

The generating gcode is all sorted. I have created a plugin and a profile
for Cura to generate the gcode from a .stl file. It just needs to be setup
on a laptop at the space and put onto github. I'll do that next chance I
get, probably next Tuesday. I can send you the files if you need it before
then, or send me your design and I'll send you gcode.

Rob.

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[Dave Chanter]

Do we have a workflow for DXF or SVG files?

I'm curious because that would be far more standard than STL and they are very easy to produce.

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[Andy Gelme]

hi Darren,

On 2013-05-16 22:53 , Darren Freeman wrote:
> I have also put aside an *awesome* blower for this purpose. At this
> stage I'm just lending it long-term as I have nothing else like this
> for my own projects.

That is a kind offer ... thanks.

However, since the laser cutter is a piece of equipment that is likely
to be very important at the space ... we should put in place a solution
that we won't have to worry about returning part of it (at a time out of
our control).

Maybe this helps us quickly get going ... and that should happen.

But, I don't think we should stop until the permanent (non-removal)
solution is in place.

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[Angus Gratton]

1;3400;0cOn Thu, May 16, 2013 at 05:40:52PM -0700, Dave Chanter wrote:
> Do we have a workflow for DXF or SVG files?
>
> I'm curious because that would be far more standard than STL and they are
> very easy to produce.

Is the Lasercutter's controller board running Lasersaur firmware? (that's what the
Wiki page says it was designed to run.)

If so how does the LasaurApp shape up? It's supposed to support SVG
and a subset of DXF. https://github.com/stefanix/LasaurApp

Or is that the program that was generating invalid gcode?

(FWIW I've also used the gcode export plugins for inkscape with other tools
in the past, but with limited success.)

- Angus

[John Spencer]

The Lasersaur firmware is a modified version of grbl, and is more than a couple of revisions behind the current.  I think it does some non-standard laser-on-off stuff.

the LasaurApp seems ok.  I haven't exhaustively tried the gcode generation.  I definitely think it's worth going down that path as it's VERY easy to use.

John

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[Rob Gannon]

The laser cutter is running Marlin, 3D printer firmware which is why we are
using 3D printer software to create gcode.

It uses the extruder fan on and off codes to turn the laser on and off.

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[John Spencer]

Marlin is also a variant of grbl.

I keep forgetting what the fan/laser on off codes we're using are.  Someone email me here so I can look it up later.

[Luke Weston]

M106 on, M107 off. Must be preceded with M400 to finish the buffer first.

Cheers,

  Luke

[Dale Goddard]

Also on that note by "mounting in the flue do you mean the pvc pipe running up to the vent or inside the roof vent itself?

I would be hesitant to mount anything inside the vent as we don't know whether or not it has the support in the roof, and honestly, it probably doesn't.  I have been scouting around for an extraction fan we can mount directly beneath the PVC pipe running up to the vent so at minimum the laser cutter is negatively pressured. We may be able to mount a small fan inside the vent, but I wouldn't put anything heavier than a bathroom vent fan in there.

[John Spencer]

I bought a fan for it today. It's just a 250mm extraction fan. I'll
drop it at the space tomorrow.

John

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[Luke Weston]

Slightly off topic...

When I send it the following G-code file, I get a square plate measuring about 205x205mm.

Not 250x300mm. Why?

Is there some sort of maximum dimension limit where the firmware is falling over?

M400
M107
G92 X-22 Y-22
G00 X0 Y0
G01 F250
M400
M106
G01 X300 Y0
G01 X300 Y250
G01 X0 Y250
G01 X0 Y0
M400
M107


Cheers,

  Luke

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[Stuart Young]

If it's using Marlin, then yes, there are usually maximum dimensions defined in the firmware. They should be set to the max dimensions of movement for the machine minus about 5mm for safety.

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[Luke Weston]

We really should tweak that.

FYI the machine's usable area is 445 x 285mm. If I write that down here I know where to find it for future reference :)

[Darren Freeman]

On Sat, 2013-05-18 at 00:27 -0700, Dale Goddard wrote:
> Also on that note by "mounting in the flue do you mean the pvc pipe
> running up to the vent or inside the roof vent itself?

I mean, stick a plywood plate over the opening at the end of the
existing metal pipe. Run a PVC pipe up to the plywood plate. Mount the
fan on top of the plate.

> I would be hesitant to mount anything inside the vent as we don't know
> whether or not it has the support in the roof, and honestly, it
> probably doesn't. I have been scouting around for an extraction fan
> we can mount directly beneath the PVC pipe running up to the vent so
> at minimum the laser cutter is negatively pressured. We may be able to
> mount a small fan inside the vent, but I wouldn't put anything heavier
> than a bathroom vent fan in there.

I think it would be a good idea to negative pressure as much as
possible, since then any air leaks will result in clean air rushing in,
not smelly air rushing out. But the highest risk of leaks will be in the
flexible section, so at the bottom of the PVC would work if we're
confident about the joins after the fan outlet. The fan I have in mind
is quite noisy when blowing hard, so that's another reason for mounting
it up higher and surrounded by pipe.

Just from briefly looking up into the flue, I thought it would hold the
fan, but maybe it requires a bit more support. Since there is apparently
enough PVC available, I was thinking we should run the PVC all the way
to the ground and block off the end. That way, the PVC becomes a support
structure running up to the flue, and the flue itself only has to locate
the assembly so that it doesn't fall over. Then it can hold a heavier
fan.

Since the pipe I've just described is blocked off, this necessitates
putting joiners in it where the inlets are required. We could fashion
some vane or gate valves, and then have two inlets for future expansion.

Again, all rigidly mounted in place to the one piece of PVC running up
from the floor. Possibly secured using dynabolts. (Somebody will
eventually run something into this.) We could also use some lengths of
wood in place of the PVC as a support. (I really am convinced somebody
will run something into this at some point!)

Have fun,
Darren