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Saturday, 27 August 2016

Progress on Chairs

There's been some movement on the chair project. I have used the CNC3020 to make joints, which makes a very neat joint and parts that are more or less interchangeable. 

Both mortices and tenons are done with custom gcode programs. I have finished all the parts for the first (trial) chair and have glued it up.

The chair is pretty solid so far, the seat needs fixing now and some covering with fabric. Some foam is also needed as these won't be wooden seats, the thickness of the foam needs to be determined.

The seat blocks were originally going to be wooden, but with the 4 degree sides and three screw holes, I have decided to 3d print them.

They really are much neater and are very strong. Also, I get to do something else while they are being printed (I can probably print a chair set at a time if it'll fit on the print bed) and I can have almost any colour I want.

Saturday, 13 August 2016

Finally Got DRO Touchscreen Working

I rewired a few GPIOs to move them away from the JTAG interface and the
XPT2046 touchscreen is now working:

I now have all the hardware working and can start on fleshing out the firmware a bit. Then I'll put the DRO back on the lathe and try it for a bit.

Tuesday, 9 August 2016

Ah ha! The TFT Lives!

The breadboarded ARM DRO can finally get the TFT display to display something over the SPI interface. I've used the same x*y colour map:

This is good news as it's a movement forwards. It turns out that I wired the JTAG signals to some of the TFT interface signals and the JTAG was turned on by default. As I want to keep the JTAG debug facilities I'm going to rewire the interface on the PCB. I will mill another PCB at some time, so it doesn't matter too much.

I now need to get the touch screen controller talking, then all the hardware will be talking. Then on to make some more complex firmware to do DRO type stuff.

Saturday, 6 August 2016

More Tenons on the CNC3020

I've done some more joints on the CNC machine. Here's one at a fairly accurate 4 degrees:

This is for the seat of the chair. It's a pretty accurate 4 degrees, set up using wedges that I 3D printed at various angles. This is the joint being machined. It's a fairly simple tool path but fairly efficient. It takes about 25 minutes for a tenon (mortices are quicker), but that time isn't dead time, I can do something else while the machine is working.

And the final result (these are test pieces):

Lathe DRO 

I've mounted the ARM based DRO on the wall and attached two gauges to the lathe. The Y axis isn't attached and the code mirrors the X axis, but apart from that it's working:

The gauges are here:

I've re-cased one PCB but left the other one with a display. I'm not sure what I'll do with the next ones, it depends on the space I have available. There's only two channels of gauge decoders plugged in at the moment, both decode the cheap Chinese gauge data streams (24 bit). For some reason I've not worked out I have a signal problem with the channel that attaches to the more expensive gauge that outputs the 2x24bit data stream. I need to build some more gauge channels and attach gauges to the mill and the third gauge to the lathe.

The TFT display isn't working at the moment, I have to get the SPI protocol working, I'm going to do that on a breadboard.

I'm going to try the DRO out as it is for a while and see how it goes.

Tuesday, 2 August 2016

Mortice and Tenon Test Pieces

These are some more mortices and tenon test pieces. They fit nicely but I think there's enough room for glue.

I now need to make some angle plates so I can machine these at the angles I need for the chairs.
I think you could make the tenons and mortices different shapes if required, which is an interesting option where multiple joints want to be in the same space, such as where two rails attach to the same upright.