30 Sep

Polargraph @ The Old School House

On the 24th Sept 2015, we met for the first time at the Old School House in Boscombe. I brought along my Polargraph and did a short ‘Show and tell’ on connecting and setting up the software and hardware, image calibration and the various plotting options (at least that’s how it went in my head, I was probably rambling and jumping from topic to topic without explaining anything properly ūüôā

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We plotted Donald Duck and some vector shapes on the night.

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Some of my previous Polargraph plots hastily hung around the room.

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20 Sep

Measure twice, cut once!

ahhhh…the power of hindsight!

I could have hidden this and pretended that my next job was my first. But no. The job was to cut a pocket into one side of the ply, and then a profile cut, to cut the shape from the stock. This was going to be a wireless charging dock (thanks Mark!).

I had to cut it fine to get the power to pass through the stock, it will lose voltage / amps or whatever as it passes through the material, so keeping it thing was important.

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The less; Don’t use a crap ruler, then assume what your looking at is 18mm as that’s what it said on the listing! A tolerance of +/- 0.5mm is enough to ruin your project, and render your stock useless!

I have since re-measured, and it is 17.5mm in thickness. So that, along with something I must have done wrong with the setup (ahem!) I managed to cut through this block.

 

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I’ve had tools fly out of collets before, and certainly had endmills snap and fly across the room before (well it would have, had it not been for the cages around the machine). ¬†So looking at this crap thing, I thought a make shift guard was in order, queue a useful box lid and clamp.

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OMG its doing it! I ran the job cutting at 1mm passes, a combination of reasonable depth without putting to much strain on the machine / our ears having to listen to it for a few hours as the thing cuts out!

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Another shot of the process, running the pocket . The feed rate has been a bit of a chore – I think I set the firmware to go as fast as 1500mm/s, which is pretty decent! but the web has said it tops out and binds at around 400mm/s, 400mm/s is very slow. I’m sure I have seen vids on youtube of it running faster.

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Lots of dust. I wont be running this machine frequently! I think I have to create a cage to go over it, but that will take up more desk space, which I don’t have! I look forward to a nice workshop or something for it to go in. The air was rather smelly, I liked it, but the woman was moaning – a lot! I filled the vacuum twice!

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The money shot

It has completed the profile and now  is the time I see the nice scar in the pocket! Nooo!

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Maybe I can convince the other half to let me have another go at running the same job in the house, again.

I have to figure out how to set the endstops and home settings. Its pretty straight forward without the endstops but it would allow me to set a basic start position for most jobs, and in the future to let me cut on both sides of the stock. I also need to get the thing cutting faster, it took around 2.5 hrs to cut this job, I’m confident I could cut this in 1, that being said, it would be rather loud – and also requiring more, or any, extraction!

I also need a slot cutting for a cable to come out the side…

18 Sep

Polargraph Los Dios Muertos

All the cool kids dig¬†the Mexican Day of the Dead festival make up these days… and what with Halloween just around the corner this seemed apt.

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If I remember rightly, this was plotted with grid size 12, sample size 18, pixel scaling @ 1 and the usual 0.35mm pen tip for a 0.4mm Stabilo Point 88. This took over 24hrs!

The original image can be found here

15 Sep

Polargraph Einstein

The latest plot from the Polargraph. Tweaked the pixel scaling here (0.98), but I think it is slightly too much for the chosen grid size as there are gaps between some of the pixels. This was grid size 16, sample size 18 and pen tip size 0.35 on the usual 0.4mm Stabilo.IMG_20150914_212112

Try looking at the picture from a distance or squinting and see how much detail your brain adds to the image!

 

09 Sep

Polargraph prints

Some more recent prints from the Polargraph. This is still running with the original PCB. I haven’t yet updated the software to account for the pin out changes on v2.1.

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I’ve seen the Bruce Lee picture plotted on other Polargraphs and it comes out really well, so wanted to see how it compares when plotted on my Polargraph. This was plotted with grid size @ 18 and sample area @ 20 with a Stabilo Point 88 Fineliner 0.4mm with pen tip size set to 0.35mm in software.

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Sir Terry Pratchett plotted from a colour photo with grid size @ 12, sample area @ 18 and the same pen and pen tip size as above.

The new gondola design seems to be working really well now.

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New Gondola design plotting Albert Einstein.

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All three points of force are acting (more or less) around the centre of the pen. Two of the arms require support when printed and were rough when they came of the printer and even after cleaning up they would get stuck from time to time which cause glitches in the plot. The parts were assembled and spun on a drill and manually manipulated for a while and with the addition of some silicone grease they seem to work well now.

The removable pen holder thread dimensions are still wrong. I need to get my 3d printer running again so I can test any changes I make. In the mean time I turned the pen holder down on a lathe and it is currently a press fit, which seems to work really well. I’m tempted to get rid of the thread and redesign both parts to be press fit. That would make them quicker and easier to print.

This design also uses a lot less plastic than my previous version and also allows visibility of the pen tip so you can see exactly what is being plotted. Previously I had to wait a while for the gondola to move on to see if the pen was plotting correctly.

One additional part I need to design is the pen depth setting tool. The idea of the removable pen holder was that I could load it into a jig, drop in a pen which would then correctly set the depth of the pen in the pen holder. Tighten the screw and fit to gondola! That would allow me to do quick pen changes which would be handy if I ever get round to trying plots with multiple colours.

 

04 Sep

Kossel – some months in

I think a holiday was what I needed to get my head in the right place for this stupid printer!

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Turns out the current Marlin forks have removed the probe feature, as its being reworked. I figured this out in the longest way possible – after around two days of calibrating my z offsets with software. I go to probe, nothing happens. I re compile my old firmware, i get the probe, but no soft end stops. Two weeks later, I just accept that, and use my screws as end stop offsets, and I have the probe back.

Other mods have been a new fan bracket thing for the hot end¬†– it kept colliding into the X and Y towers – now they’re at an offset and fits well – what it hits now though, is the probe pillar, the little thing that puts the probe away after it completes its 22 point calibration!

Maybe I should go to FSRs, but that would mean that I have to undo / redo a lot of work – not happening anytime soon!

The fans are too good though, and my stupid heater cannot manage to keep temps. it got to around 180 despite the target being 210. I reached for my e – z fuse tape, and applied it – now its lovely and insulated, looks pretty decent also.

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I’m running new filament, after printing a new spool holder, the thing can be left, I’ve gone shopping to return home to completed prints, its a good feeling! The filament looks good, I have printed around a third of the spool so far, and its been trouble free.

http://www.thingiverse.com/thing:992116

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http://www.amazon.co.uk/dp/B00ERCEAGW/ref=sr_ph?ie=UTF8&qid=1441382224&sr=1&keywords=filament

I did have some prints go bad, what looks like the z axis got some skipped steps (on a delta that looks like steps skipped in x / y), not sure why, I did some oiling, and then decided its due to the belts being a bit too tight. When the effector was dancing around doing small infills, it would be quite graunchy, so I slackened off the belts a little and that appears to make it nice and smooth. I ran some prints very slowly last night and the loudest thing was the fan on the hot end – its a very quiet machine.

I also got around to printing and installing the LCD cover – which makes things nice and tidy – it isn’t the nicest of models though…

http://www.thingiverse.com/thing:320117

I also had a go at using meshmixer to generate some rather intelligent support structures – unfortunately it fall off mid way through the structure – but due to the wonders of reprap, it somehow fixed itself when it counted!WP_20150831_17_13_42_Pro WP_20150831_17_38_46_Pro

I doubt i’ll get time for many more mods to be honest, but the list is still there

Images:

I know Mark uses this model on his i3 so thought i’d do the same.

http://www.thingiverse.com/thing:37327

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Some more Grasshopper generate forms  Рusing the same two profile rails, I was able to modify the amount of divisions of the curve, then draw an arc between the two curves along the sub division. Data MAtching Arc with loft

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These guys were printed flat, at 0.2mm and 0.3mm

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I then re oriented them vertically – spiral vase mode. 0.2mm approx 10mm/s!

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Grasshopper vase, worked really well – apart from the undersides of the wibbly bits. I think I will re print, but at a much slower speed – you can see the errors just building up from a previous blip.

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