Lathe Centre Height Finder

I got fed up with fiddling with tool heights on the mini lathe, so I cobbled together this

It's not hugely pretty, but it works and is adjustable. I like the base, as it's a bit of metal I picked up while walking somewhere, on the off chance I could use it, and I have, excellent. The brass and base are polished, but you can't see that in this picture very well, so there's some shiny bits.

Main DRO PCB 2.0

I've decided to put the entire Lexpresso card onto the DRO main board as it saves me the hassle of laying out a processor board, and I get the debugger/programmer half of the card as well. I can lay out a processor card later if I want to. The card also has nice 0.1inch holes for mounting on a PCB, which the Arduinos don't I thought about using and Arduino Mega, but mounting it was just too difficult.

New main PCB being milled:

I'm doing two passes, the first with a 0.6mm bit and the second with a 0.2mm bit. The first pass gives me more clearance around the tracks and pads and th eseocnd does th efine isolation. This should make it a bit easier to solder without shorts like I had on the first PCB. Of course, it means two 7 hour milling sessions, not one, but it's probably worth it.

Change of DRO Direction

 I've spent a lot of time recently trying to get the PIC16F18875 working as the main controller on the DRO. It's sort of working but there's problems. Whenever I make a simple code change (something like changing a /1000 to a /10) the code sometimes just fails to run. This would be fine, as it's probably a bug, well maybe, but as the Microchip debugger also doesn't seem to work, it's all a bit of a disaster. Looking on the web it seems this is a fairly common experience. It's a shame as I've used PICs a lot in the past and they were useful little devices. Anyway, I've decided to ditch the PIC and try something else. At the moment he plan is to use an LPC1114 ARM based device. This has the added advantage of more flash (32K), similar clock speed and lots of GPIO. Unfortunately it is a 3V3 device and that means I will have to deal with level shifting and add a regulator.  Anyway that's all OK, just a bit more complexity and if it works I can lay out a mostly 3V3 PCB with the LPC on it.

The other thing about the LPC chips is that they don't come in any DIP packages. Not that are available to buy anyway. So I have tried to mill a QFP48 footprint that is one of those used by the LPC1114. Once I used a 0.1mm cutter and a shallow depth of cut, I managed this:

It's not perfect, there's a bit of copper that hasn't been milled away. I think I may be able to sort that with either a second milling or slightly more depth. Anyway, it looks to be possible, so that's the plan.
Those pads are 0.5mm between centres, by the way.

Spindle Camera Mount

I made a quick little bracket for mounting the spdinle camera on the CNC milling machine while it is operating. I can then see what's happening without having to look at the spindle directly.

The shiny red bit is a mount off a cheap magnetic base from ebay. It works well, I may get some more. Unfortunately the base isn't very strong.

Here's a picture of some PCB milling going on:

here's a video of the same.

Nuts

I've been looking for 12mm T nuts with an M6 hole for a while, to use with my very small vice. I finally decided to make some as I couldn't find any. Some steel arrived and off I went.

The one on the left is the 12mm T nut with an M10 hole. Mine are on the right. They work nicely. I think I'll have to cut some bolts down to a useful length though. The mill pretty easily cut these out too, I managed to make the cuts in a single pass, which made it easier.  One I get the DRO going I'll be able to take multiple cuts more easily, I just couldn't be bothered this time.

DRO Display Running

The main display PCB has now got some firmware that does something. The code can talk to all three OLED displays and also to the three LED readouts.

It can also get pixels on the TFT, but the range of co-ordinates seems limited in some way. There's also some spurious pixels on the OLED displays, but it seems deterministic so I don't think it's noise.
I need to get the touch screen code in a fit state to register keypresses.

I've also routed a couple of gauge channel daughter boards:

The bottom one is milled using a 0.2mm bit as I have done with most of my PCBs so far. After the problems with shorts on the display PCB (which turned pout to be soldering problems, as there's no solder resist), I have tried a double stage milling process in the second PCB. The first stage is a mill with a 0.6mm bit, followed by one with a 0.2mm bit to cut away the final detail. This leaves a larger gap around most of the tracks, which I hope will act as a sort of solder resist.

Here's a populated gauge channel PCB:

The socket is for the PIC12F1822 which reads the gauge data stream. The transistors are used for level shifting the data to 5V and also for driving the data and clock lines in order to put some gauges in to fast mode.
There's also a 1V5 supply generated with a simple voltage divider.

First DRO PCBs

 I've routed the first DRO PCBs. This is the main display PCB with one gauge interface daughter board:

There's the three LED axis displays and the OLED axis label displays. The larger display at the bottom is the TFT that I want to use for diagrams etc.

This is the gauge interface board:

it plugs in like this:

The partially populated display PCB from the rear:

Unfortunately I have a short between the supply rails on the display board, so I'm going to remove the excess copper to try to isolate it.