Engraving

In preparation for producing a ‘token’ present (not shown here as it’s a surprise!) I did some trial engraving cuts in 3mm red acrylic. 200mm/s engrave seemed to give a good result using Newlydraw’s 4 line enhance option (no idea what that does, but it seemed to come out better).

Image

Nevertheless, the engraved text wasn’t that readable as-is, so I thought about trying candle wax and boot polish fillers. I’d read about others using wax crayons, but didn’t have any handy – a candle is still wax so I thought I’d try it.

Image

Aesthetically, I was expecting to prefer the white, but I’ve actually used black on my finished piece (and my fingers – nasty boot polish).

Hearts

A friend enquired about the viability of laser cutting hearts into 6mm ply. I’d only got 3mm ply to hand, so gave it a go.

Unfortunately, I forgot to take any photos which is a shame as it was my first attempt at etching an image too. These were cut on top of some previously failed cuts. It would be nice to have a bit less muck visible (the other side is fairly clean) so will have to sort the ventilation out better.

DSCF0625

I also had a go at cutting some mirrored red acrylic. The idea with this is that you cut with the underside upwards. It didn’t work too well. The metal layer sparked a lot and while it was well charred after a 1mm/s attempt, it didn’t cut all the way through.

Another attempt a week later (after fixing the power knob) I managed to cut a heart out on the second attempt. The first didn’t cut all the way through. I had to do a 2mm/s pass followed by a second at 6mm/s (both with an accurate 90% power setting). Results were okay, but not super:

DSCF0630

Loose power control

Earlier experiments had found inconsistent cutting. Although it initially appeared to be cutting differently in different areas of the bed, I also found it inconsistent in the same area between different cuts. Thinking it through, I realised that the ‘digital’ counter mod was rolling round from 999 to 000 more than once and probably shouldn’t. I couldn’t find anything about this mod except for a forum post which at least linked to the part and datasheet at Rapid Electronics.

DSCF0585

There was only one thing for it. I prised the case off (friction fit) and found that the two grub screws holding the original knob were loose. Lo and behold, the original pot has ten turns and the ‘digital’ counter also has ten turns from 000 to 999. Once tightened, the power control now goes correctly from 000 to 999.

DSCF0592

Here’s hoping for more consistent cutting. The mA meter power reading now goes significantly higher than it was doing and seems to be reasonably consistent with the power selected.

Bottle puzzle

Some time ago I posted this rather rough and ready wine bottle puzzle on Instructables.

FBPXI1UGHFK7KSX.LARGE

I’ve been meaning to CAD it up ever since and with the availability of the laser cutter thought it about time.

Unsure where to start, I had a play with Sketchup. After a reasonable learning curve and following a tutorial on Instructables I came up with the following:

sketchup-bottle-puzzle

The faces were then extracted to an SVG file using the sketchup-svg-outline-plugin and processed in Inkscape to produce a DXF for the cutter. I had some trouble getting Newlydraw to recognise the DXF on occasion, so did have to resort to an HPGL PLT file once.

I didn’t catch any pictures of my first attempts, but I had a bit of trouble as some of the pieces didn’t cut fully through in places. I was also surprised at how long the cut took – about half an hour. The inconsistent and long winded cutting is another story which I’ll blog about later.

As I found that the pieces meshed well without worrying about the kerf of the laser beam, I decided to arrange appropriate pieces adjacently such that I only needed to cut once. This involved importing the DXF file from Inkscape into a CAD package (DraftSight) and moving the pieces about. The final step was to remove any duplicate lines as the laser cutter is dumb and would still go over each twice. This was rather fiddly, and prone to a couple of mistakes. I’m sure there must be a script out there for DraftSight or LibreCAD or something which would do this for me. Even highlighting double lines would be a godsend.

draftsight-bottle-puzzle

Now, just a gratuitous action shot of the cutter in action. I used Newlydraw’s ‘optimum cutting order’ option which has a bit of crazy idea of ‘optimum’. It works though I found it left some of the pieces in the centre until after it had cut the whole of the outside out which is not ideal.

DSCF0583

Some of the pieces dropped straight out:

DSCF0593

Others steadfastly remained in place and hadn’t cut through. With judicious use of a craft knife I was able to recover most of the stuck bits:

DSCF0595

A second attempt at a later date faired, well, differently. More stuck, but only slightly and most snapped out:

DSCF0591

Glueing:

DSCF0596

Finished (I must take a better shot of this):

IMG_6147

Detail of the locking mechanism:

DSCF0601

The puzzle locking/unlocking spoiler is not included.

Coolant troubles

We’ve toyed with a number of ideas for coolant containers. Constrained by the space we’ve got to put the cutter in, I was after something taller rather than wide, but not likely to topple over.

We’ve got 3.33 L of coolant (we sold 1/3 of the 5L we bought) so mixed with deionised water at 4:1 that gives us 16.5 L or so in total.

Looking around town for the best I could find I came across the following ’14L box & lid':

DSCF0624

So I got that set up, poured in what I thought was about eight litres of coolant/water mix and found that it reached the top of the box. Hmmm! Rough dimensions of the box are 0.30m x 0.20m x 0.13m = 0.0078m³ = 7.8L. Somewhat less than the claimed 14L.

So, don’t believe what you read on a sticker on a box! Maybe 14L is the model number…

Materials

I’m not really sure why I’m blogging about the initial material stock we purchased for the Northackton laser cutter, but I have photos so thought I might as well use them…

5L of Laserscript Coolflow anti-freeze from HPC. I’m sure we could have found something similar that we could have picked up locally instead of paying £15 for a delivery (and still having to fetch it 15 miles from the delivery depot). Mixes 4:1 with de-ionised water.

DSCF0564

Ten sheets of 3mm and ten sheets of 1.5mm ply from Hobarts. Each sheet will need cutting into three to fit the 275x217mm bed of the laser. Incidentally, that’s the cuttable area, but sheets up to 326×260 will just fit in the recess. Also a sheet of laserable rubber to play with (which was fun previously).

DSCF0566

And some acrylic offcuts to get us started:DSCF0565

I can’t see that lot lasting that long, but it should last us long enough to know what we need to order more of.

Laser cutter

Thanks mostly to a generous benefactor, Northackton bought a laser cutter. Until we make sufficient space for it at the hackspace it’s temporarily in my garage. Inevitably, I’ve been ‘testing’ it in the meantime so thought I’d blog some of my experiences. With some inspiration from a post to the Nottinghack list by Martin Raynsford, I coined the term ‘Lasiverse’.

Initially, I had a lot of trouble getting the drivers recognised on my Windows XP netbook. I never did get to the bottom of it suffice to say it now works on another computer. Adrian (a friend from Northackton) and I eventually got it going on another laptop while it was still in my living room.

DSCF0580cropped

Being inside with a broken laser cutter was handy while it was sub-zero outside, but once we’d got some anti-freeze it was time to shift it to the garage for both space and fumes.

DSCF0586