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Latest Threads
Kids Monkey Bars
Forum: Projects
Last Post: admin
2020-08-17, 10:12 AM
» Replies: 0
» Views: 92
Gordon's OrgMOT Spot weld...
Forum: Projects
Last Post: Org
2016-10-23, 09:07 PM
» Replies: 3
» Views: 3,719
MOT Spot Welder
Forum: Projects
Last Post: admin
2016-10-14, 10:47 AM
» Replies: 19
» Views: 13,994
Org's MOT Spot Welder
Forum: Projects
Last Post: Stevo
2016-10-04, 03:58 PM
» Replies: 5
» Views: 4,919
Lido - Electrical Cabling...
Forum: Recommended Suppliers
Last Post: admin
2016-09-27, 10:59 AM
» Replies: 0
» Views: 1,840
Reactive LED Table
Forum: Projects
Last Post: admin
2016-09-15, 04:24 PM
» Replies: 0
» Views: 1,526
Printed Circuit Boards
Forum: Recommended Suppliers
Last Post: admin
2016-09-15, 11:15 AM
» Replies: 0
» Views: 1,591
Sieg C2 Mini Lathe CNC Co...
Forum: Projects
Last Post: Stevo
2016-09-13, 03:09 PM
» Replies: 2
» Views: 6,476
Wheels and Casters
Forum: Recommended Suppliers
Last Post: admin
2016-09-13, 02:39 PM
» Replies: 0
» Views: 1,491
Mobile Shoe Rack
Forum: Projects
Last Post: Stevo
2016-09-13, 01:57 PM
» Replies: 1
» Views: 2,584

 
  Kids Monkey Bars
Posted by: admin - 2020-08-17, 10:12 AM - Forum: Projects - No Replies

The kids wanted some Monkey Bars as an addition to their Jungle Gym and I thought it would be a nice excuse to dust of my welder after quite some time. 

I got the kids involved in the paper design and deciding on the colour scheme, afterwhich a trip to steel shop to get some round bar 32mm x 2mm thick 4 pieces at 2.5m length and 25mm x 2mm thick 16 pieces cut to 750mm

After measuring a kid or two, we decided on a height of 1.9 - 2m and a length of 10 bars spaced 30cm apart. A local metal tube bending company helped me bend in a 200mm radius on the top sections of the frame. After which some notching of tubes and welding together and we were done with the frame. The metal work took about a day as it was really straight forward. High level costs: Metal R1500, Paint R600, Grinding 3 hours, Welding 4 hours.

Unfortunately I forgot to take pictures of the construction but here are a few from the installation:

1. Get frame in position to check where to dig holes:
   

2. Red Oxide undercoat:
   

3. Concrete in place:
   

4. Paint
   

Final thoughts:
1. A 10 bar length works out around 3m long, from a weight bearing point of view it would be stronger in the middle with less bars, maybe 8.
2. The 750mm width is overkill 500mm-600mm would have sufficed.

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  Gordon's OrgMOT Spot welder
Posted by: Gordon - 2016-10-14, 11:40 PM - Forum: Projects - Replies (3)

   
   
   
   

Put it in an old ABS box I've had laying around for years. Not very well done just mostly hot glued in. The port above the power inlet is for the foot pedal (Still to be built.)

The boards are a bit of a mess as I'm learning to read and use fritzing and electronics and also the first time I've put something like this together so Org has probably lost  a lot of hair trying to help me get this done. Was a good exercise regarding the learning I have gotten out of it though so a big up to Org for designing the timer which is awesome! and helping me through it. Its adjustable and dual pulse or I guess as many pulses as you want. Next is to activate it remotely from smartphone.... lol.

I got 95mm2 cable from Lido which I had to eventually strip the insulation off of where it coils in the transformer in order to get it to fit. It is quite a large transformer but the cable is really thick. All coiled and the primary is back in and everything is clamped for re-welding tomorrow. Hoping this puts out huge amps.

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  Org's MOT Spot Welder
Posted by: Org - 2016-09-29, 10:56 AM - Forum: Projects - Replies (5)

Hi all,

I finally registered. I do not want to make the post too long, so I will add my progress over a few posts.

I bought a second-hand MOT from an appliance repair shop. For those in Centurion, you can buy it from Ryk's electrical (just google them) for R150. New ones is from R400 upwards.

I first cleaned the transformer, by using a hacksaw to cut through the secondary windings on the transformer, as close to the metal as possible.
   
   

Then I used a punch (or a bolt in my case) to punch the windings out of the metal.
   
   

The final result:
   


Next up: Choose the secondary wire size!

I first tried normal 2.5mm2 household wire.
   

Then I tried my inverter welder's earth cable which is 16mm2.
   
   

Next I tried a piece of cable from my old Oil-bath-welder. This is a bit thicker than the 16mm2 wire I tried previously, but I do not know the exact spec.
   

All of these wires were only 2 windings.

As can be seen, the thickness of the wire makes a big difference.

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  Lido - Electrical Cabling and Components
Posted by: admin - 2016-09-27, 10:59 AM - Forum: Recommended Suppliers - No Replies

Lido Electrical is a nice medium size company with a branch in Randburg. They stock a lot of electrical hardware like lights, electrical boxes, switches and tools. They also stock a large range of Electrical cabling, including the nice and thick "welding cable" that I have purchased in the MOT Spot Welding build.

Strydom Park
14 Langwa StreetStrydom Park
Tel: +27 (0) 11 791 6070
Fax: +27 (0) 11 791 6101
Email: lidostrydom@icon.co.za

[Image: RedLidoLogoSmall-300x68.png]

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  MOT Spot Welder
Posted by: admin - 2016-09-25, 06:24 PM - Forum: Projects - Replies (19)

This thread will detail the Microwave Oven Transformer (MOT) Spot Welder Build.

A MOT can instead of converting to high voltage be re-purposed to deliver high Current (400-1000A) @ low voltage (1 - 3V). This high current can be used to melt metal and form the basis of a spot welder. 

The build is still in progress and will be updated as progress is made:

The original plan is as follows:
   

Firstly we start of with a nice big Mother of a Transformer (MoT):
The primary loop resistance measured 1.6Ohms with the secondary loop measuring 75.9Ohms 
       

In order to re-purpose the MOT we need to remove the "secondary" coil which can be identified by the thin wire it is made off. This coil is then replaced with a thick wire of 1-3 loops.

The transformer with secondary removed:
The availible space with the Shunt removed 19mm wide by 39 height.
   

And that is where I am now.

A word of caution, I wanted to proceed using wire from a vehicle "Jumper Cable". I actually found a nice thick 16mm (diameter) jumper cable at MIDAS rated 1000A. However please be cautioned when I examined the actual wire core was only 3mm or 4mm in diameter with the plastic insulation being the majority of the cable. I do not believe this cable is suitable for this purpose and will continue my search for actual AWG 2 to 4 cable. 

In the meantime I will continue work on a Triac based driver circuit.

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  Reactive LED Table
Posted by: admin - 2016-09-15, 04:24 PM - Forum: Projects - No Replies

You know those YouTube videos that make you think “Awesome… I want one?” well check this reactive LED table out:

YouTube LED Reactive Table

Now,… to build an improved version:

Requirements:

Multiple Modes:
Clock Mode showing digital clock
X&O Game
Snake Game
Sound Equalization’s
Ping Pong Game
More LEDs!!!
Finer Resolution
Fade Effect, Variable brightness Control
Yes the list may be ambitious, but lets see how it goes.

First up, Based on my unsuspecting donor table size: 
   
I can accommodate 48×27 (1296!!!) White LEDs Driving this array will require some thinking. I stumbled across the DADDY of all LED drivers made by TI the TLC5955. This bad boy can drive 48 LEDs using a single chip.

Hmmm… I have 27 Rows of 48 LEDs, I wonder if this one chip can be multiplexed to drive all 1296 LEDs! Let the games begin.

A breakout board was created as these (TLC5955) buggers only come in teeny tiny surface mount packages.
   

The TLC5955 is interfaced over serial communications, It has a single input register of 769 bits that must be written and latched.

If the MSB is 0 then the remaining bits are used to code the brightness of each LED using 2 Bytes (16bits) per LED. This means 0×0000 is off and 0xFFFF is full on.

If the MSB is 1 then when latched data is transferred to the “control” register, this needs to be done only once in most cases as this register sets global brightness and features.

Implementing the Arduino Code (Why Arduino you ask?… because I got out voted by my team(I like PIC)):
There exists a library for the TLC5940 that I tried to use initially but soon after abandoned that Idea for code from scratch, come on how hard can it be to write serial data?

Turns out there are multiple ways of achieving serial communications

Using the standard Serial.begin(); <-- maximum 115.2kHz
Using software based bit bang, toggling a digital pin <-- CPU intensive
Using SPI library on MOSI,MISO,SCK,SS pins <-- Can reach speeds of Fosc/2 (10Mhz for the ATmega2560)
It was easy enough to setup a new Arduino project that imported the SPI library. This can then be used to transfer data byte by byte. This was the problem… byte by byte? The guys over at TI have made my life hard by firstly not having a register that is a multiple of 8bits, forget that, each setting in the control data is either 3,5 or 7 bit combinations???

We therefore need a way to build up the bytes to be transferred. The register of 769bits in code was increased to 776bits (97bytes) with the first byte left padded 0000 000X where X is the control bit of the 769 bit register.

Using this method, the Control data was first written once on bootup followed by LED control data.

Now for the challenge… Can we multiplex this one IC to drive all 1296 LEDs? I got hold of a few 74HC595 serial in parallel out shift registers and have interfaced them to the arduino. each output of this shift register will enable a 48LED line therefore I need 4 of these ICs (8*4=32 >> 27).

Lets get some peg board to serve as the frame and populate a few rows of LEDs:
   

A viola, I'm able to drive two rows:
   

I've populated 5 rows thus far and that is where I current am in this project.

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  Printed Circuit Boards
Posted by: admin - 2016-09-15, 11:15 AM - Forum: Recommended Suppliers - No Replies

Hi Guys, 

If you looking for small/medium quantity PCBs I would recommend a Roodepoort home based company run by Mr Frik called PCB International.

Last I ordered they charge R200 for setup, plus R25 for a negative image (looks like an xray picture) But the coolest part is that they then charge around R1/cm^2. So if you need 3+ boards it works out cheap in my opinion. You will also need to draw a thin rectangle around your board and specify the size in mm he will then use that boarder to ensure correct size. 

I used Mr Frik for simple single sided boards but he says he can do double sided and as small as 20mil trace size. 
Word of caution: use him only if there is NO urgency for the board, turn around time is up to a month. Also I do not think he does silk screening so its just basic rough PCBs.

Contact Details:

Frik Nel
PCB International cc 
082 565 5419
011 762 7271
http://pcbint.com/contact.html

Here's an example of a recent "breakout" board I got made for a surface mount "HTSSOP56" package:
   
   

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  Wheels and Casters
Posted by: admin - 2016-09-13, 02:39 PM - Forum: Recommended Suppliers - No Replies

Gauteng Trolley and Wheels is one of those small rustic businesses that have survived around 20 years. They sell all types of wheels and build all types of trolleys using their wheels. 

If you need some wheels for a project or experienced advise, be sure to check them out.

They are located in Westdene very close to NJR steel at:

25 Perth Road, Westdene, Johannesburg, Gauteng, 2092
(011) 477-0757/9925/2073
http://www.gautengtrolley.co.za/

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  Mobile Shoe Rack
Posted by: admin - 2016-09-13, 01:51 PM - Forum: Projects - Replies (1)

I had a request to build a "large" mobile shoe rack and came up with this simple design based on 25x25mm square tube frames with 10mm square bar inner bars:

1. The Original Plan (Did I mention I love SketchUp?):
   

2. Tack Together the outer frames (deviated from original plan in terms of size and levels):
   
   
   

3. Join Frames, tack weld everything together:
   
   

4. Add Wheel Box for wheel bolt support and aesthetics:
   

5. Weld all joints and grind back

6. Red Oxide Paint:
   

7. Black Gloss Top Coat:
   

8. All done:
   

I have not tested it yet but I'm sure it can hold at least 48 pairs of shoes!

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  Sieg C2 Mini Lathe CNC Conversion
Posted by: Stevo - 2016-09-13, 12:56 PM - Forum: Projects - Replies (2)

I have had this mini lathe for a while now and finally got going on the conversion.

So to start with I cut the spindle encoder wheel on the cnc mill, then made the optical sensor, still need to make another 2 sensors and then do the electronics behind that, that will plug into my cnc controller and a few changes to LinuxCNC. I got my ballscrews from Hobbytronics (http://www.hobbytronics.co.za/c/809/ball-screw) very good pricing and I they arrived quickly.

Image of Encoder attached.

I would suggest that you guys enable image pasting into this forum, http links suck.

   

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