Gemmasta Encoder Mod Thread

[Orange Pirate]

Looks like club membership just halved . And you answered a question I had about the clock. Something I've been pondering. I bought a heap of those Real Time Clock modules before and couldn't get them to work.
I've been looking at screens from 'Nextion'. A 2.5" is $13. A 3.2" $20. The GUI is not so hot as 4D systems but for $20 you can't go wrong. There is also loads of Arduino software out there for them, unfortunately nothing for Microchip and it's not open source software so....... But I still bought one. Serial data is the way to go.

[MakkyBrown]

Yeah I was pretty happy  , thought I had blown it up but lucky it was just the mega that died and they are only about $12.
The screen I'm using is about 3inch usable area but the pixels are pretty chunky. 128x64. Might have a look on ebay to see if I can find one about the same size so I can use the same enclousure.
The clock I used was dead easy, vcc,gnd and the two i2c wires. Included the library and pretty much just copied/changed a few lines of code and it was done.

[MakkyBrown]

Those nextion screens look pretty good where did you buy them from?
There is this cheap one on ebay but I wonder if it's a dodgy seller.
http://www.ebay.com.au/itm/3-5-Nextion-HMI-TFT-LCD-Display-Module-For-Raspberry-Pi-2-A-B-Arduino-Kits-/152236980404?hash=item237207f8b4:g:bnYAAOSwFdtX1ECG

[Orange Pirate]

I bought it direct from Nextion. The price works out the same as ebay by the time postage is applied and I also bought the the USB to UART converter for $6. I don't no if it is necessary, it is on the 4D systems screens along with the SD card. I've a feeling you can program the Nextion screen with SD only but it makes debugging way easier with the converter.


Cheers
Op

[Orange Pirate]

FINISHED 



The board showing the micro controller (big chip at 9 o'clock) The tricoloured LED (the bright one). The encoder connector at 12 O'clock. The micro controller programming cable below that. RPM counter connector centre and at the bottom the ribbon cable to connect the scree. The whole of the bottom right corner is a power supply circuit including a 5V regulator (12V to 5V), a diode to prevent reverse polarity stuff ups, a crow bar circuit (including the little chip) and a quick blow fuse to avoid over voltage situations - again. At two o'clock is the chip that converts the differential signal from the encoder to a single ended signal for the micro controller. This was used to stop the effect of electrical noise causing problems. But knowing what I now know I would consider taking another, cheaper approach.







Finally finished. And it works way better than anticipated. A long time getting here. When version’s three smoke escaped, it meant reordering everything with almost every order went astray. Also, because I had been doing the design on the fly, it meant I had to reinvent it the circuit again.
Also since the smoke had escaped once I had no intention of letting it happen again, so I added a failsafe circuit (crowbar circuit) as well. Being pretty clue less about electronics meant it all went at a snail’s pace.
Also, added a tri-coloured LED that turns on and off depending on what the encoder is doing. A sort of diagnostic tool as I found in previous builds not knowing what the processor was seeing was always a problem when debugging. And it looks cool too.
The encoder has a resolution of 0.0225* .The screen is a touch screen which displays the actual angle as well as the target angle, it also shows RPM numerically as well as graphically and is accurate to +/-3 RPM from 10 – 2000+ RPM. I aim to have a keyboard on it to at least put in the target angle. Once the actual angle approaches the target angle the screen will change colour, this is so I don’t have keep checking the figure and as long as it’s in my peripheral vision I’ll know when the cut is near done. A kind of ‘Cut to Depth Indicator’ I guess. The yellow wire is a switch wire from the screen to the microcontroller to signal a mode change. The better way to do it would have been through serial data but my programming abilities are a bit to basic.
So far, I a very impressed by its performance and hopefully it will make angle adjustment a lot quicker, certainly easier on the eye, and repeatability should be many times more accurate. My only complaint is my graphics design is a bit rudimentary slash crap, if I was a bit artier it could look really cool also. But this can all be played with and adjusted a bit further down the road.
I have to say a big thanks again to Makkybrown as without his designs and idea’s this would never of happened. It’s been a great learning curve also. I’m looking forwards to my test cuts to see what it can produce.


Cheers
OP

[MakkyBrown]

Congrats OP  ,

When I cut with mine, I cut until the target angle I want is constant no flicker. The last bit when it's almost showing the target angle constantly I'll let the stone run on the lap with no hand pressure till target angle is constant. This works really well for me.

[Quentin]

And another successful Encoder build... This time on a Halls Xtra. Detailed by Tom Herbst in his Faceting Book, and with the genorous
help of Makky Brown who adapted his code to suit updated components, I started the build a little after Xmas.


A little bit fiddly, but within the reach of anyone who has the patience and the drive to cut a good stone.
Makky B was generous with his help and sugested I use the same components as his build which made the puzzle easyer to
nut out.


I have to say that I am delighted with the result...You've heard it all before if you have been following this thread,
speed, acuracy, repeatablity, etc... Its a quantun leap from the bog standard Xtra. I've even got a clock (for assessing
temporal distance between tea brakes) and an RPM Counter.


Main parts from Ebay and US digital and the rest from Jaycar, fitting the encoder to the machine requires a little thought
though I suspect its easier than on the Gemmaster.
Eternally great full to MB ...he gave me everything I asked for...albeit NOT on a silver platter... I had to sort the puzzle...a great learning curve.
But thats OK! I had to read the program a hundred times, make a circuit diagram and parts list to make sense of it all...a bonus! and in the spirit of the help
that came my way from others, I'm more than happy to share the experience of my build. Don't be scared of it... its not that
difficult... others have done the hard yards and you WILL be happy with the result.
Q
PS First time on a forum, i've attached the pics in a PDF file ...Hope it works

[Aussie Sapphire]

great work Quentin and shows the power of the community in forums such as these.


Can I suggest you post your photos in the Gallery - there is a relevant album for stuff like this (Faceting Machine Modifications):


http://aussielapidaryforum.com/forum/index.php?action=gallery;cat=86


If you do it as a pdf attachment, it runs the risk of being deleted as the attachments folder fills up.


Cheers
Leah

[MakkyBrown]

Well done Quentin and welcome to the forum, the xtra looks like a nice solid machine. It also looks a lot easier to fit an encoder than the gemmasta. Thanks for uploading the pics etc.

[Orange Pirate]

Very cool Quintin.  Well done. Can I ask a few questions? Whats the controls on the display do? What sort of encoder did you settle for? And one more, which I should ask Andrew as well. How do you enter the 'target angle'?


With both you and Andrew having real time clocks fitted and having a third decimal place. I can feel an update coming. 


Cheers
OP

[MakkyBrown]

The target angle is entered pushing/hold the button when at the desired angle but it's useless imo as I never use it. You use the same button to access the second screen which stores your last 10 target angles. Or did I change it to 12, it been that long since I used it I can't rememer lol.

[Quentin]

Hi OP,
Ended up using an E5 Encoder from US Digital 2000 CPR.I too had noise from the DC motor but fixed it with an external plug pack. The switch just isolates the encoder and the knob is the speed controller mounted in the same box (hence the noise) All good however.
Must say that i'm impressed with your build. Love the colour screen.
Q

[Orange Pirate]

Thanks Quentin. That's interesting what you have mentioned about the noise. As you probably know MakkyBrown had the same problem. I've yet to complete a proper run with mine but it makes me think the differential option I chose for the encoder may have been the right choice.
The colour screen was easier than it looks. In the screen GUI (graphics user interface) software just cut and paste images or numbers. Manipulate them, chose a colour and assign a number. Then with the micro-controller, using that GUI, it was just a case of sending value X to screen item Y.
Literally as easy as that.


Cheers
OP

[MakkyBrown]

My noise is probably gone now, removing the DOC circuit and wires fixed it. I should pull of the last couple of ferret magnets and test it.

[MakkyBrown]

I've got my encoder turned on all the time atm as the screen is playing up and it doesn't like cold starts so...
I've just ordered a new screen. Same size as the old one but I can wire it in serial to get rid of the wires birds nest. And cheap only about $7 delivered No need for a mega now will use a nano with connector shield.
http://www.ebay.com.au/itm/ST7920-128x64-12864-LCD-Display-Green-Backlight-Parallel-Serial-Port-for-Arduino-/191981783250?hash=item2cb30188d2:g:A6oAAOSwiDFYNYe0