[chbot] Laser cutting at Fab Lab XCHC

[Volker Kuhlmann]

On Fri 05 Dec 2014 09:22:57 NZDT +1300, Michael Field wrote:

I got 3mm acrylic cut today. The design is in inkscape, using the ponoko
templates because I thought at first I'll have to use them.

The fab lab laser cutter's software is unable to load svg files. Export
dxf from inkscape, ansure "base unit" is set to mm (the px default won't
work). I turned off preview and left all other settings as pe default.

Luckily we noticed just in time that the laser machine file import
reduces the design by 20% exactly. As we couldn't find the cause (anyone
knows?) we scaled up by 25% on the laser machien software.

Cutting width was defnitely more than 0.15mm, more like 0.3-0.4mm,
with the finest lens available.

Cutting burns off molten plastic vapour, especially when hitting the
honeycomb grill underneath, leading to cloudy deposits on both sides.
The choice is to leave the bottom backing paper on, giving a clean
surface at the expense of having to peal it off gazillion little pieces
(which was my design). Carl said leaving the backing paper on the top
could spread its burned deposits over the plastic, so we didn't try
that.

I'll try to clean in hot water with dish wash first before trying meths.

The cutting edges are acceptable but much rougher than I was expecting.
No clouding, but pretty uneven reflection.

Because it's all new there was a bit of mucking around setting up the
machine. The DIY course for the laser cutter isn't set up yet so DIY
isn't yet possible.

The fume protection needs improving, the laser machine has lousy fan
control. A bit of re-wiring and a timer relay will fix that.

Booking was a bit haphazzard, I don't find Carl particularly responsive
and the required info isn't on the website. No doubt things will settle.
It's very good to have the facility in town because one can get jobs
done at 1 day turnaround.

I ended up getting the plastic from Mulford Plastics. Good service. They
optionally sell the acrylics in all colours by a m² price, and the price
is pretty OK although they didn't mention cutting fee to me and the m²
price was higher than they told me.

Thanks muchly to Winston and others who posted the sources for plastic
sheeting, it helped heaps.

Volker

-- 
Volker Kuhlmann
http://volker.top.geek.nz/	Please do not CC list postings to me.