New pressies

Super fast shipping brought me more goodies today, 1 x PCB Heatbed from Denmark and 3 x GT2 belts from the US. The most awesome part is that the belts are an exact match for the gears already on the motors. (I didn’t know what profile the gears were when I ordered the belts, only that they had a 2mm pitch on them)

The 2mm pitch on the belts should offer decent improvements over the standard 5mm pitch, The profile on these belts is also specially designed for linear motion as apposed to the profile on the T5 belts, apparently this helps reduce backlash?


Got me some motors

Pressies in the mail this morning, An army of beautiful stepper motors.

Removable rubber noise / vibration dampener and heatsink. 42N/cm which should apparently be enough to run the Extruder on the machine. .85A in Bipolar config which is well below the max 2A of the drivers. The best part is the gear on the end, hopefully I can find a belt that fits on it so I don’t have to worry about making a new gear.

Only average part is that I’m now stuck at work for the next 8 hours and can’t install them on the frame (pics to come)

GPS Puzzle Box

The following photos are the reason why there hadn’t been much progress of late on the other projects. I initially came across a website by a guy called Mikal Hart who made a “Reverse Geocache” for a friend for a wedding present. The idea is based around a locked box that will only open on one place on earth. James decided that he liked the idea and wanted one…

BOOM! Finished project, Solid Aluminum case, all screws soldered or glued, MK1 of the impenetrable GPS puzzle box.

Press the button on the front and the box comes to life. There is a limited number of times you can press the button however, once used up the box will refuse to open at all. If you still have tries left however and if the box can get a GPS fix then it will give you a distance to your destination and then power off. If you are within a certain distance of your destination then it will open.

A couple of coolish parts to the circuit;

High Sensitivity GPS receiver, 15 sec warm start time in tests, RTC with battery backup, built in Data logger, 5v safe inputs and cool flashing red LED.

On the Left, Pololu 5v boost regulator. Will take input voltages from 0.8V up to 5v and provide a 5v output with a current varying depending on the input voltage. At 3v in it will give you 200mA.

On the Right, Pololu pushbutton power switch. Toggles output on and off at the press of a momentary pushbutton switch. Draws under 0.01 μA in standby mode, also provides a OFF input that when brought high will cause the switch to turn off. This means that the Arduino board is able to effectively switch off (but not on) its own power supply. Because of the low standby current, the box running on 3 x AA batteries should last a couple of years before the batteries need changing.

I do have to say a BIG Thank You to Peter for his help, time and machining skills in designing and making the locking mechanism for the box, without it this project would have been much more hillbilly and nowhere near as precise.

Not a Time Machine – Part 4

So there hasn’t been an update for a while, a lot has been happening however both on the Hot Tub and on other projects. A couple of weekends ago saw a lot of progress with the Hot Tub, including firing it up and soaking in it for the first time.

On Saturday Tim and I hired a pipe bender from the local Hire shop and proceeded to embark on a 3 hour pipe bending marathon with the help from William and Mark. The first bend went horrifically averagely with the pipe turning slightly egg shaped and dented on the outside where the rollers pressed against it. Filling the pipe with sand and capping the ends with gaffa tape and placing some patches of carpet around the rollers seemed to solve most of these problems.

The other issue that we had was that we were trying to bend 4m of pipe with a pipe bender that was designed to be mounted upright on the ground with very little ground clearance. The solution to this was to tip the whole thing on its side and spiral the pipe out and around the frame of the bender as it was bent.

Bending angles etc were all done by guesswork but the result seemed to work out pretty smooth.

Once the pipe had been coiled the required amount we then had to address an issue that because we had had to coil the pipe through the frame of the bender, we had ended up with a coil that was about 10cm too tall to fit inside the gas bottle.  After much jumping up and down on it, squeezing it in the bench vice and taking blurry pictures of it we managed to compress it enough to fit.

From here we cut slots in the sides of the LPG tank and then took it out to Reub’s farm for some late night Arc Welding.

Later that night we fired up the Tub at about 6pm for a test run to see how it would heat. Minor success but nothing soakable was achieved.

Next day (Sunday) a better planned approach was devised, wind shields protected the boiler, a chimney and blower helped with airflow and half an old mattress helped insulate the top of the tub.

In this next photo you can actually see the flames coming out of the holes at the bottom of the boiler because of the volume of air coming from the fan.

During the week Reub and I put some more work into the boiler, Reub finished welding up the sides of it and I cut down an umbrella stand and turned it into a boiler stand.

The next weekend we spent Friday night and Sat camping in the Coromandel, On Sunday however we decided that the Tub needed another outing so we dragged it out to Reub’s parents place and set it up in a couple of fireplaces in the reserve. Doing so meant that we had to join 5 garden hoses together, run them down through some bush, over a mangrove mud flat and then up through a gorse bush.

Even after getting the hose down there however we still needed to get the water down, this involved pumping it from one tank to a second and then gravity feeding it from the second to a third.

Several hours of heating produced semi acceptable results, Reub’s Shrub (TM) heated up a lot faster but the size meant that it was only approved for Dual Occupancy.

Whilst not exactly up to standard yet this project may be shelved for a while in favor for other projects. Going forward we need to look at improving the efficiency of the boiler by cutting more vent holes in it and trying to get it to burn better on just wood. We also need to look at insulating the tub better so less heat is lost to the open air. The only other change that needs to be made is the inclusion of a wooden rim around the top of the tub, mostly for aesthetic reasons.