Unknown Domain

More plastic stuff

I received these samples from theplasticshop.co.uk today and I am very impressed with the speed with which they replied and the lengths they went to for just one small order. I am not happy with the material however, not their fault. It’s just it has a gloss/satin like finish when I really just want a light grain both sides which is the same both sides.

I am going to harass the VitaSheet people again as they have not gotten back. I also spoke to a guy at RapidformRCA who advised agains styrene which Cut laser Cut recommended because of the carcinogenic fumes caused by laser cutting the styrene plastic.

Quick jot down of my ideas before bed

Polypropylene nightmares…

I looked into the eSheet company and they only sell the same BLACK9170 (aka BK9170) from VitaSheet Group, however I emailed to see if they can supply a G01 finish both sides or recommend someone. There minimum order quantity (MOQ) is £35 which is good for me so I asked them to quote how many sheets for that price but I am okay with buying it from Sea White at the moment for prototyping.

I also spoke to Cut Laser Cut in Vauxhall who said PP (Polypropylene) only comes in a two grain finish, which despite their great laser knowledge shows how much they know, but they said to look at styrene, but styrene is what Plasticard is, and although it’s smooth it has a tendency to snap as I mentioned in my post about Twitter Display V2 however I may pop in to take a look.

I have also spoken to a few suppliers in China but they will only supply smooth black 0.8mm in 1 tonne MOQ while they will supply natural (milky white) in single sheet MOQ.

Very annoying, I can’t use PVC in the laser cutter either so there is one less material. I need to find a solution as I am not happy with PP having two tone, I also need to investigate screen printing some PP at some point, I will speak with Rose Thomas about this, the screen printing tech at UCA where I work.

Research dump over, whats next?

I am still keen to build a unit and try to find a way to fund and fabricate my original idea. My skills in laser cutting are much better, I have had a chat with someone who is a bit of an engineering hobbiest and even spoken with a water jet cutting company who told me to make it in plastic not metal as I was thinking.

Drive system

I asked for a stepper motor for my birthday last year so I now have a nice 1.8º stepper motor from Cool Components. I also have an EasyDriver and coupler from FreeDay 2011.

I am keen to try a timing gear and belt assembly this time however I think it will turn out to be cost prohibitive. I also know I need to use spring loaded screws to stop the stepper from rattling free and I need to use opto-switches to detect flaps passing.

Structure

I also know that 3mm acrylic is plenty strong enough and that I should buy Tensol to glue it rather than superglue like last time.

Flaps

I am still looking for a supplier of polypropylene sheets for the flaps, I spoke to Sea White who provided the original material and they told me that it is VitaSheet BLACK9170 which is sold by the VitaSheet Group, I contacted Jed Brutes who has promised to contact a supplier who can provide a G01 (smooth) finish to both sides in low volume as they can’t deal with me directly, pending a call still, will follow up next week.

I have also contacted The Plastic Shop who are working with their supplier to get me a sample of 1mm natural finish and a 3mm black so I can see what the 1mm thickness is like, however the Sea White was perfect at 800 micron (0.8mm) thick. I also just remembered I had some samples sent from a site called eSheet and I am going to pursue buying some from them again as it was actually a really good finish.

Laser cutter

I’ve gone from no laser cutter to having access to two, one at UCA where I work which is on campus not far from where I live and one at RCA which is large format where I am a student until the end of the year, however the UCA one is better and I can use it myself now I am a laser trained staff member there and want to keep the project bubbling over until summer when I will go for it rather than distracting me too much during my last term at RCA.

Next steps are to continue sourcing the materials and especially the timing belt and gears.

Thingiverse Split-Flap Display

I’ve tried not to be critical of anything but this really is crap, although nice if you have time to make it to see the principal of how it works…

http://www.thingiverse.com/thing:1175

Split-flap pixel array

Not much info about this but looks like another split-flap prototyper at ITP…

http://itp.nyu.edu/shows/thesis2011/sean-fitzgerald/

Wikipedia: Split-flap display

The wikipedia article was the most useful resource in the V1 design as it has a patent drawing which explains how it works.

http://en.wikipedia.org/wiki/Split-flap_display

It also links to the patent on Google Patents which gives you a closer look, and it appears to be barrel timed (for lack of an engineering vocabulary).

http://www.google.com/patents?vid=3501761

Twitter Display V2

Unfortunately almost all the files about this model were lost however it featured 3mm thick clear acrylic, with gears which were made using the Adobe Illustrator star tool and then capping the ends with the circle tool to make them less sharp and wearing.

I do have some images from the train back from the laser cutter and they used the same flaps as the original. The biggest improvement was the use of a stepper motor (from RS), connected via a ULN2003A to an Arduino and the accuracy despite the rush job was near 100%.

I do however have some images from the files I used to plan in, the first of which is an image showing (to scale) the stepper on the right, with a gear attached to its shaft, and connected to two more gears, providing clearance of the flap even at full extension.

This image shows how the gears and the stepper relate, and the flaps at the front at full extension (left).

The side panel where the gears were kept was originally designed to be two sheets of 3mm acrylic with a 5mm piece in the middle and 3mm gears such that the middle piece was to be cut with these three circles to make a space for the gears to sit in whilst holding them in a confined space to prevent too much wobble, in the end it ended up being a complete void to avoid any problems and reduce material count.

I think this is from version one but it ended up in version two’s design files, it shows how the flap attaches into the sprocket wheels and shows a not to scale axel in the middle.

This final piece was used to measure the cap between the outer edge of the stepper hosing and the centre of the sprocket wheel axel, not sure why, presumably at the time I know how much clearance was needed to ensure the flaps didn’t hit the motor and cause a jam.

With this design I also tried using Plasticard material which is styrene sheet material however the little legs snapped off from heat stress in about 1 second, while the polypropylene sheets didn’t snap off unless forced or after 2 weeks of use, one in my degree show (v1) and one in the emerge graduate showcase (v2) where it died.

Twitter Display V1

The following is almost all the details you would need to manufacture the original display, including the original files, these are licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License, however I would suggest not building this except if you realise it won’t work as anything more than an ornament, the accuracy of a servo motor is not suitable.

Speaking of servo motors it was supplied by Maplin, and was a generic model however it was hacked for continuous rotation. I used an Arduino Diecimila to run the motor for a random period of time and stop to make it look like it might if it worked.

The following is the vector PDF of the file used to cut the main structure on the laser cutter, the material used is 5mm acrylic from a supplier called Plastic Online, there is an error in the design which meant the servo mounting plate was useless and I replaced the square with the round hole for the axel.

The following is the vector PDF of the file used to cut the flaps on the laser cutter, the material used is polypropylene from a supplier called Sea White of Brighton.

The following is the vector PDF of the files cut on the Craft Robo which made the vinyl appliqués, materials from this site: MDP Supplies

More images of the unit in progress and after, and in action…

More4 Rebrand

In the past couple of weeks More4 did a rebrand and one of my favourite studios (Jason Bruges Studio) were involved. I cannot help but see the resemblance to Rebecca Baumann’s work however the technique is the only real similarity. Although the technique in this case is my interest.

A great making of video, disappointingly little technical info but great video none the less.