Wednesday, 19 April 2017

All Gauges Attached to DRO

The remaining gauges have been attached to the DRO. There's now 3 gauges on the lathe and three on the mill. All of the gauge channels are now populated and attached:

Each card has a PIC on it that converts from the gauge serial protocol to I2C. The main ARM processor then interrogates each of the relevant gauge channels over I2C and displays the values.

Each of the gauge channel PCBs is identical, the firmware is almost identical, the only difference is the I2C slave address, which is 0x30 and 0x40 for each pair of PCBs on the same I2C bus. There's three I2C busses.

The main DRO PCB has an ARM processor on a commercial LPExpresso card:

The TFT screen is a touch screen and there's a menu system running on it. The DRO can be set to display the lathe channels or the mill channels. The smaller OLED displays then show the appropriate axis tags. When running in lathe mode the two X axis values can be added together.

The gauges have been attached with 3D printed plastic mounts. I may re-make them in metal if they aren't rigid enough.

The gauges are held in clips that can have screws clamping them from the sides:

 I've removed the buttons from the gauges if they were presse dby the clips. The buttons aren't needed and you also don't need to read the displays as the DRO does that.

The batteries aren't needed either as the DRO channels all have a 1V5 power supply. The gauges run from that and are powered all the time the DRO is powered. The power down of the gauge display doesn't stop the serial data stream, either, which is nice.
 The mill X gauge is mounted in a similar way:

The Y as well:

And the Z gauge:

The lathe bed gauge was one of the more complicated mounting arrangements.

I've started to use the DRO and it certainly makes measuring things much easier. I need to check that the gauges are working correctly by comparing with a dial indicator.

Friday, 7 April 2017

Picture Frames

Three picture frames were required for a significant day. I thicknessed some offcuts of scaffolding board and mitred the corners. Some glass from our old windows was cut down. An old box was used as a backing sheet.

I normally glue frames and hammer sprigs in for support, but this time I used proper V nails manually hammered in. They worked well, so much so that I didn't need to clamp the frames as the glue dried.