Monday, 6 May 2013

Printing - More And Maker Faire UK...

Last week we went to the Maker Faire in Newcastle (England). It was fantastic and my youngest really enjoyed building a flashing LED name badge. There were quite a few 3D printers with one guy demonstrating a 3D router built out of 3 old flat bed scanners and a Dremmel type device. The whole thing was held together in a retired PC case. Hacking at its best! There were a few Makerbot devices, a Cup Cake and a guy in the throws of building a Rostock. There was good STEM support and Daleks to boot. You could have spent all day there, we did! The people were fantastic and the food was good value for money. For once we were not ripped off by a venue, thanks Centre For Life.

I went ready to buy filament but found none for sale and no 3D printers for sale either, but plenty of working printers and lots of people ready to talk to about 3D printing.

I managed to post our Minecraft Creeper derivative this week as we have not been twiddling much with

Huxley #710 - First Print
Huxley #710, having had so much fun at Maker Faire. I also managed to find a picture of Huxley #710 in completed form. This picture was taken during Huxley #710's first print of a whistle, Thing 1046.

The Minecraft Creeper shown here is a derivative of Thing 11825. The boys wanted a version that had improved facial features (no drooping) and a swivel head. So I created a clip that fits into the body and head. We have printed around 10 of these now, as the boys friends wanted some. At Maker Faire UK (Newcastle), Creepers were seen hanging out on top of the Printcraft computer monitors. But yours could look around! (The leg pitch is just over 11mm).

The clip arms are designed to compress together completely and be a snug fit into the holes in the head and body. If your printer produces blobs on parts you may have to clean up the clip to avoid issues assembling the clips. The images shown are how Huxley #710 prints parts, no clean up was required or performed. Similarly if your holes are too small or too large then you might have issues. I posted STEP files so you can tweak things if you prefer.

Minecraft Creeper - Thing 83942
Design For Manufacture
By removing the head from the body, the head can be printed without distortion. Tthe drooping seen in the green creeper (our first, whose head does not move). The mating features are designed to locate and allow rotation. The clearance between the head and body bearing location diameters and the clip centre locating diameter is 0.20mm by design. To accommodate the slightly out of round holes manufactured in FDM layer manufacture. The clip deformation assumes a non brittle material in this case Faberdashery PLA. As the clip is significantly deformed on insertion into the head and body. The part was printed as three elements as a clip on the head or body might have needed material support. The clip is intended for use in other assemblies and allow for repair, if required. Which would be more of an issue with parts having integrated clip features. At the time the clip was designed, there were limited versions on Thingiverse. A redesign might use one of the clip designs on Thingiverse.

Minecraft Creeper - Thing 83942

This item has small parts and is not suitable for young children as a result. With some effort our Creeper head could be removed, unlike Lego Duplo characters for example.

Sample Part Manufacturing Technical Documentation
Printer : Huxley #710 (RepRap Pro)
Firmware : Marlin 1.0.0 RC2 - 15 Feb 2013
Software : RepRap Pro Software 811708f - Pronterface
Material : PLA - Faberdashery - Arctice Whilte - Village Green
Material Dia. : 1.75 mm (Msd 1.80 mm )
Nozzle : 0.50 mm
Layer height : 0.25 mm
Layer width : 0.6 mm
Extrusion T : 198 C
Bed T : 60 C
Feed Rate : 28 mm/s
Perimiter rat. : 0.5
Infil pattern : Hexagonal
Infil solidity : 0.15
Cooling Fan : Yes
Bed material : Borosilicate Glass
Over hangs : Yes
Support : No
Design For Manufacture Parameters
Model : Absolute dimensions
Scale : 1:1
Holes : Yes
Layer height : 0.30 mm
Layer width : 0.6 mm
Over hangs : Yes
Support : No

Model Tools
Function: Model Fix up
Tool: NetFab Studio Basic
Version: 4.9

Utility cabinet lock

The item below is intended only for a Utility Cabinet which has no service equipment fitted.

Unique Utility Box Key And Lock
This week I designed a new lock for a spare utility box outside our house. I suspect the gas utility supplier told the builder they could not use the original location due to its proximity behind the central heating system and directly below the exhaust flue!

So I have re-tasked the cupboard as an external water tap box. This will keep the tap warm in winter and secure. The water already runs on the other side of the wall to the central heating and there was even a hole through the wall for a water pipe.

To be able to use the Utility Box in this way we had to prevent any accidental entry to the wrong boxes. So we could not allow the standard Utility Box key to be used for this box. A custom key was required.

I designed a new key and lock based on the current lock and Thing 88,  created by Nophead. Using the STL to STEP conversion program to allow easy modification and a new key element to be added. I then measured the original elements, having removed the spring washer and parts from the box.

In the original design, the lever has a moulded triangle and uses a spring washer to retain the moulded part in place. This could simply have been inverted but would have meant the key would be very unique and annoying if lost. Additionally the standard cabinets may be opened by utility company service personnel. Any implementation should not be mistaken as simply a key they may not seen before even if they were inexperienced. Despite there is nothing dangerous inside the box.

There are two parts to the lock, the barrel which has a square drive to mate with the lever. The whole assembly is kept together with a stainless steel screw inside the box. Holding the lever against the barrel through the cabinet door via the square drive. The key shown at the top of the image fits from the outside as if its a normal key but will not open the standard utility cabinets. As it can't drive the triangle form used on a standard cabinet. Printing used the parameters shown above. The Key prints in one piece (upside down from that shown in the image).

'Hey - Presto' new key and no risk of people going in the wrong box. A unique solution for a unique situation. If we loose the key, the unit can be opened with a standard Allen Key. In the event we move, no issues for new occupants either, although I will leave the original parts in the box.

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