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Saw horses

Having just bought a house, I'm back in full DIY mode again. And as everyone knows, DIY requires saw horses! So knowing that I would be needing a couple in the near future, I sat down with AutoDesk Inventor and quickly drew up a simple design, based on timber that was in cheap and plentiful down at The Ply Guy.

And a few minutes later I had a set of plans ready to go:

Timber used:

1x 2410x300x23mm industrial ply shelving4x 2700x65x40mm reject grade LVL timber (LVL = Laminated Veneer Lumber, a super strong engineered wood, basically thick ply)Small length of 150x10mm ply

$20 of wood later and I was ready to get building. First up I ripped the 300mm ply shelving into 150mm wide bits 800mm long for the top of the saw horses. Table saw made short work of that.

Then I made the brace under the top of the saw horse from the LVL. Next up some legs... these were a little fiddly with all the angles, but...

3d Printer - part 9

You might think I've completely forgotten about my 3d printer, but rest assured it is still receiving attention.

My main complain so far with the machine is that some of its prints were not very square. Often successive layers that should be on top of each other, ended up on a diagonal, getting more and more off axis. I didn't have much luck tracking down why this was happening, but I suspect it is a quirk of either the microcontroller not being powerful enough, or the firmware (Teacup) having a subtle bug.

So I decided to redo the electronics. I ordered a parallel port breakout board off ebay for a few dollars, same as I'd used on my CNC machine. This arrived and was duly installed:

These aren't designed to drive 3d printers so a little fiddling was required to make it work. X, Y, and Z on the machine matched up with the respective outputs on the board. The extruder was hooked up to the A axis, and the limit switches plugged straight in.<...

Wedding seal

As part of sending out our wedding invites, I wanted to do something a little special. Somewhere along the line we got the idea of making up our own seal for the envelopes. I fancied the idea of using my CNC machine to make up a stamp, and it didn't seem like it would be too hard to do.

First step was to make up a drawing. This was more work than I imagined, as there were a number of requirements:

Must contain no details smaller than the size of the end mill. That means fancy fonts with thin ascenders are a no-no. Thick block sans-serif only please.Can't be too big. The bigger it is the more wax that will be used and the harder it will be to machine.Must look good!

In the end I came up with a design that incorporated a bit of both of us:

M and R are our initials obviously. Below my initial we have a lump of railway track... again distorted and "chunked up" due to the above requirements. Then below Rachel's initial we have a daisy, the ...

MrCNC - part 5

My CNC machine has been receiving a bit of attention lately. It's been sitting a little forgotten for a while with a couple of problems:

No stepper motor drivers – I used them all on my 3d printer, and then blew them all up!The spindle doesn't run very well – something is slightly out of alignment and so the whole thing makes a lot of noise and draws a lot of power.

The stepper motor drivers have been replaced so that part is fixed. While I was at it, I decided to clean up the controller board. Here is what it looked like beforehand – wires and hot glue all over the place.

I decided to mount the board to the end of the machine. This would keep the controller off the bench  and the wires nice and tidy. I also opted to add a small control panel to hold the power switch, emergency stop button, a power LED, and two speed control knobs: one for the spindle speed, and one for the feed rate (how fast the machine runs through its program).

3d Printer - part 8

Progress continues on my 3d printer.

A lot of research and learning has been done, the learning curve with 3d printers is very steep! However my fifth print came out very well, with only a few minor flaws:

It seems that Printrun sometimes pauses on OS X, unless it is always in the foreground. In other words, you can't really do anything else on the computer at the same time. For a modern powerful computer and multitasking operating system this seems odd.

Extruder improvements

I quickly discovered that even my improved grippy roller for the extruder wasn't up to snuff. The sandpaper gripped the filament quite well, but then just sanded it smooth, clogging up the sandpaper and leaving it smooth! So I went back to the drawing board and dug out the Dremel.

I made up a jig out of spare wood, cable ties and masking tape which holes the steel rod in position, and allows me to position a spinning cutting disk at righ...

3d Printer - part 7

Progress continues on my 3d printer...

Power Supply

Meters for my power supply arrived a few weeks back, but I only just got around to installing them. I had to drill out a 38mm hole for the mechanism to fit inside of, but I only have 45mm+ hole saws and 32mm spade bits, which made things a bit complicated. If only I had a CNC machine, this would be a piece of cake! For some reason that did not occur to me and instead I used a 32mm spade bit followed by a few minutes on the Dremel with a sanding disk. Did the job pretty well, even if it did cover the garage in MDF dust.

A couple of hastily drilled mounting M3 holes and a whole lot of epoxy leaves this:

I wired the voltmeter in parallel, and the ammeter in series with the output. Nice and simple, works a treat. Completed power supply was reassembled and tested on an RCD protected output, just in case. All tests passed and the meters were even wired up correctly.

Printer

Testing showed that t...

3d Printer - part 6

Progress continues slowly on my 3d printer. While waiting for the increasingly erratic Chinese postal system, I set about getting the extruder and hot-end working.

The hot-end is responsible for turning the plastic filament into a model, by melting it and squeezing it out of a tiny hole. The filament looks a bit like white spaghetti, or like the cutting cord used in line-trimmers in the garden.

The extruder grabs the filament and pushes it down a tube to the hot-end. The hot-end has a large block of metal with a heater and temperature sensor built into it; these work in concert to keep the metal block at a constant temperature, about 180°C for melting the PLA plastic that I have.

So I sent about making sure it was all going to work. First test was to ensure that the temperature sensor worked correctly. The hot-end I'd purchased had a thermistor built into it, which is a type of resister that changes its value as its temperature rises and falls. I did some tests an...

3d Printer - part 5

Continued from part 4.

My linear bearings finally arrived, just under a month in transit. I wasted no time at all in putting them to use. First I added some supports to mount them by; these are just my usual 1mm thick sheet of styrene, epoxied to the bearing with a couple of supports on each side.

Y axis limit switches were then added:

And then the Y axis was joined to the Z axis. I used some MDF spaces to ensure the Y axis was level with the rest of the machine and glued the whole lot in place.

I then clamped it with whatever heavy objects I could find. It may be a mess, but it worked!

While that was setting up, I started building the electronics. I used a similar approach to my CNC machine, using female mating sockets and some self adhesive copper strip to form bus bars. The various components then get soldered up into sub-assemblies that plug into the female headers.<...

3D Printer - part 4

Progress continues on my 3d printer. This week I have been continuing to work on the Z axis. With the rails and bearings ready I needed needed to make something to connect the threaded rod to carriage. I decided to use my tried-and-tested method of casting a white-metal block directly around the threaded rod.

To do that, I fixed up my previous mold and found some white metal. I melted it on the stove (thanks for the tip sis!) and poured it into my mold, tapping it a few times to get rid of any bubbles. Then I pushed a block of wood down on the top and waited for it to cool. I destroyed the mold to remove my item, but never mind. I don't anticipate needing to make any more for a while. I gave it a quick clean with a file and used my drill on grunty-mode to remove the threaded rod. I gave it a zap with CRC and drove the rod through a few dozen times to clean out the thread. Here is the finished block:

I threaded it on to the rod and wondered how I was ...

3D Printer - part 3

Just a quick update: my stepper motors have arrived!

Of course now I realise that there was quite a bit I could've done without the stepper motors :)

I've wired up limit switches for both the X and Z axes:

And I've made bearing blocks for the Z axis, seen here with the motor on the wrong side. I have also made up the brackets and support for the Z axis.

A quick test fit of the various bits to see how it all fits together:

Now I need a 5-to-8mm shaft coupling (although as I've learnt I am capable of making them myself) for the Z axis leadscrew, and a 2 sets of linear bearings for Y axis. I ordered the bearings nearly a month ago, but they must be taking the scenic route to get here as they still haven't arrived. In the meantime there is plenty I can do, e.g. wiring the whole thing up.

Still, exciting progress :-)