Friday, 24 November 2017

Broken Keyboard

To control the Maslow I use a wireless keyboard, which is very useful as I can operate the Maslow at close quarters rather than being tethered by a keyboard cable to the control computer. Unfortunately I was using it recently and dropped it on the floor. This has happened beofre but this time when I picked it up and tried to use it, it wasn't working. It looked like the supply wasn't connected any more.

I took the keyboard apart and there was a dodgy looking inductor from the batteries to the PCB. I checkd with a multimeter and it was open circuit. I replaced it with a wire and checked. The keyboard started up and the keys worked, but the trackball didn't work and the low battery LED filckered. So it looks like the inductor is necessary to smooth out the supply voltage or help with transients. I didn't have any inductors, at least 100uH ones.
I chipped the paint off the inductor and found a ferrite core. The problem was the connection to the windings. The core seemed sound so I got some wire (the same wire I used when connecting the eMMC chip to the USB adapter) and rewound the inductor:

This fixed the keyboard, the trackball now works well.

Saturday, 28 October 2017

More Maslow

More Maslow

I tried a test cut on the Maslow recently and had a problem. The plywood circles I cut out before for the filament reel were cut fine. The new test part was a chair leg cut from scaffolding board. As the board is 36mm thick many passes are required to cut the part as I didn't fancy a full depth cut. The problem showed itself as a dropped USB connection. This stops the cut and I had to re power the arduino to get a link back. After some experimentation it looked like the router is generating noise that kills the USB connection. It also seem to very comprehensively kill the WiFi too.

I tried a main filter on the Maslow and computer but that didn't work. Trying to use an old-ish laptop also didn't work as the ubuntu was too old for the software, so that was out. next stop was the purchase of a proper line filter.

This allowed me to cut the entire part (which took about an hour) without a dropped USB connection. I'm pretty happy that this has gone a long way towards fixing the problem, this part took a long while to cut and is one of the biggest ones in the chairs. I may want to cut an entire kit of parts in one go, which would be two of these and some other parts, but I may be able to do that with a deeper cut (especially if I buy a new cutter).

The  sled had to have outriggers added so that it could be stable across the entire board. This worked pretty well too. You can just see them in this photo:

I'm not sure what I'll do if I try to cut from full width boards, this was a smaller board cut from a larger one. I may need outriggers over the top of the sled, or maybe the wider board won't require outriggers on the sled. We'll see.

Wednesday, 4 October 2017

Maslow Update

Maslow Update

The Maslow is now together:

This morning I moved the motors forwards so that the chains are more parallel to the work surface. Hopefully this will stop the chains jumping on the sprockets when I start cutting thicker material.

The router I am using is quite top heavy and this causes the sled to tend to tip backwards, especially if the router bit it out from the work surface. at the moment I'm putting a rod of steel on the top of the sled as a sort of counter weight. It works, so I'm happy at the moment.

I have made the first 'thing' using the machine:

Well, OK, it's the parts for a thing, not a thing, but this is the sort of thing the Maslow was for. Big plywood things. At first anyway, maybe big scaffolding board things later. These parts are going to be a filament reel for the 3D printers. I've made them manually before and this was way quicker. And I can do something else while the parts are cut out.

The calibration was a bit out before I moved the motors. I'll have to re-calibrate now the motors have moved, but hopefully I can get the calibration back to something as good as I had before. Those discs I made are slightly oval, but I'm hopng I'll be able to manually adjust that out on the next calibration.

The Z axis mount works remarkably well, considering the wood isn't actually attached to anything, it's just wedged in there.

I may have a go at 3D printing a replacement for the wooden version, but this works, so I'm in no hurry.

Tuesday, 26 September 2017

Prototype X-Y Table

 The new microscope came with a nice XY stage, but the slide holder was missing. I made one from a cheap XY table. The XY stage is manual, which is fine for adhoc looking at dies, but for photographing dies and then stitching photos there's a lot of photos. It's tedious doing it manually. So I prototyped an XY table from DVD drive stepper motor assemblies.

I had an arduino and two stepper drivers, so connected it all up;
The result is here, the two stepper drivers are being driven with the same signals.

And another view.

I'll have to make a stage block with a dovetail to mount this on the microscope. I may also remove material from the top table as it could do with being a bit lighter.

Wednesday, 20 September 2017

New Microscope

I've been looking at a lot of ICs under my microscopes recently, and realised that it was a way that I could do better reverse engineering. This will let me look at the ICs on a PCB without datasheets, so the PCB could possibly be re-used.
Reverse engineering the IC is an interesting thing in itself, as well.

So, I had a look on ebay and bought a metallurgical microscope. This has a lighting system that can illuminate a subject from the top, so it works on opaque samples like ICs.

It came with no objectives, so I'm now hunting for decent objectives for it. It has a proper X-Y table which is good for moving samples about. This is especially useful for die-shots which are large arrays of photos.

The USB microscope is still useful for soldering and so on, as this microscope has a working distance from objective to sample of between about 0.5mm and 10mm. That's not a lot of room for soldering!

The X-Y table didn't have a slide holder so I bought a cheap X-Y table mechanism on ebay and used some melted down food trays cast into an ingot :

After machining into a block, I drilled some holes and mounted the slide holder from the cheap XY mechanism:

So I now have a nice spring loaded slide holder:

It's not perfect, and has a bit of a broken drill in it, but it's decidedly better than my first attempt:

Thats a bit of sheet metal bent into a holder shape. It's much better now.

Next projects are a camera mount and an LED based illumination source.

Saturday, 2 September 2017

Maslow L298 Failure

Maslow L298 Failure

My Maslow motors stopped working, so I removed the IC from the PCB, decapped it and had a look. One of the transistors has overheated, maybe shorting some rails out:

For reference, the full chip looks like this:

Tuesday, 29 August 2017

From Scrap to Rings...

Starting with some leftover wood, I found some circles inside, using the bandsaw:


 It turns out that there were quite a few circles in that bit of scrap:

The circles stack quite nicely too...

I found some holes in the middle of the circles, as well...

We chose some colours and bought some sample pots

and went multicolour.