$120 Mill DRO

[gte718p]

I guess it should be $180 DRO oops. You get a nice garage table out of it also. You can use the camera to document your projects or surf the web when you are not using the mill.

I'm building up a RF 31 mini mill. The end state is going be a three axis CNC, but it is a slow build.

In the interim, having a mill is proving to be quite useful. I hate counting turns thought. I loose count and my precision *****. At DRO is an incredibly useful tool.

I wish I could claim credit for the design, but I mainly copied Yuriy Krushelnytskiy's design and am using his Android program for the display.

Parts:
3x Igage DRO scales - $100 (Ebay)
Kindle Fire 7in - $50 (Amazon)
Ardunio UNO - $7 (Amazon)
Arduino Protoshield - $4 (Amazon)
HC-06 Bluetooth - $8 (Amazon)
Project box - $4.5 (Radio Shack)

Step One: Fix the Kindle Fire.

The Kindle comes with Amazons custom version of the Android Operating system. It also displays adds on the lock screen which is annoying. Unfortunately Amazon does not include the googleplay apps store or a decent browser. You need googleplay to download Yuri's DROTouch software.

I used instructions from RootJunkie to load Google Appstore. The files you need can be found on here. If you use a PC there is a single click option. Unfortunately I'm a Mac guy so I had to do it manually. It is not hard thought.
1. Download drivers.
2. Place Fire in developer mode by tapping serial number (under device options) multiple time.
3. Under developer tab enable ADB
4. Download files from RootJunky
5. In terminal change directory to the directory you saved the files to
6. Place Fire in
7. at the command line enter:
adb start-server
adb install com.google.android.gms-6.6.03_(1681564-036)-6603036-minAPI9.apk
adb install GoogleLoginService.apk
adb shell pm grant com.google.android.gms android.permission.INTERACT_ACROSS_USERS
adb shell pm hide com.amazon.kindle.kso
adb kill-server
-I hade to remove the parentheses from the first file name to get it to work on a MAC.
8. Download DROtouch from Google Play Appstore.

2. Step Two: Build the circuit.
Yuriys instructions are pretty good. The only thing I think needs to change is the HC-06 is not 5v tolerant. As a result you need another voltage divider for the output to the bluetooth.

Another thing that caused me problems it you wire the transmit pin (TX) on the arduino to the RX on the bluetooth module.

I chose to cut the USB connecter of the gauges. There are five wires in the USB wire. Red, Black, Green,Blue, Yellow.
Red - +3V
Black - Ground
Yellow - Signal

On two of my scales the clock wire was blue. On the third one clock was green. That took a long time to figure out.

Step Three: Eat Bacon

 

[laser3kw]

Uber cool project!
I have a fondness for the digital (and analog)

 

[bdk1976]

Uber cool project!

I have a fondness for the digital (and analog)

X2

I have an older 6x26 import mill I'd like to put a DRO on someday- something like this might be the ticket.


Sent from my iPhone using Tapatalk

 

[nine4gmc]

Sweet!!!

 

[kkroger]

I paid a skosh more for individual items..... But it does work well.

 

[ND80]

Great project.

Love Arduino stuff.

 

[zkling]

Awesome! Have you tested the accuracy and precision?

 

[gte718p]

Awesome! Have you tested the accuracy and precision?

I've been using the scales for a month or so with the factory read outs. I don't have hard numbers, but accuracy is fairly good and precision is very good with the stock gauges.

Over an inch there is a .001 difference between my dial indicator and the scales. The dial indicator is not the best and I'm not also not 100% sure it is perfectly perpendicular to the travel. Something is off a little, either the dial indicator is off, or I have cosine error on the dial indicator or the scales.

The DRO program has the ability to adjust for errors. If my scale is not perfectly level, IE it is creating a little cosine error, the program can correct for that. For what I do, and the mill I have a thousandth is not horrible.

In the limited experiments I have done, repeatability is good. For my accuracy test, repeatability was within .0005 over 9 cycles. I also did a huge layout of holes and the alignment is perfect.

The only problem I have had is the update rate on the the factory gauges was not great. It tended to jump during rapid transits.

 

[gte718p]

I might add when doing this type of work, an Oscope is essential.

I have this little one, DSO Nano.

Worth its weight in gold. You can get the genuine one from Adafruit or directly from SEEED. Like most electronics you can by a pretty good knock off on eBay or Alibaba.

Just a shout out for an awesome little tool Now off to find a much better set of small needle nose pliers and better small crimpers. My no name Chinese ones have served me well for many years, but are no longer up to the task.

 

[Spudland_Dave]

Awesome Project!
Little related side question for ya...why did you elect to go with a Fire and hack it, vs just buying one of the many "non name brand", straight Android tablets off eBay/Amazon/etc which are in the same $$ ballpark?

 

[kf4zht]

Planning on doing this very soon to my new mill. Just curious why you did the arduino over the MSP430? The 430 looks like it can support more stuff for the same money and less soldering

 

[Guster]

Planning on doing this very soon to my new mill. Just curious why you did the arduino over the MSP430? The 430 looks like it can support more stuff for the same money and less soldering

MSP430 is needed if you want to use quadrature encoded scales.

I just managed to source some from RS after I found a set of decent Easson scales for my lathe. All that is left to do is making the voltage splitter inputs and mount it all in an enclosure. Will probably take longer to fit the scales to my lathe.

 

[Guster]

I might add when doing this type of work, an Oscope is essential.

I have this little one, DSO Nano.

Thanks for the link. That is nifty. Didn't know they existed.

 

[gte718p]

Awesome Project!
Little related side question for ya...why did you elect to go with a Fire and hack it, vs just buying one of the many "non name brand", straight Android tablets off eBay/Amazon/etc which are in the same $$ ballpark?

Doing a little research the Fire is a better quality tablet then the no name brands. They used good quality components in the production of their tablet and they stand behind their hardware.

The no name brands are just to much of a gamble. The QA isn't there and you never know what chip manufacture they are using. One tablet could be the best thing ever, the next three identical ones could be total ****. Amazon is a known quantity. For the price, it wasn't worth the gamble to save $1.

Planning on doing this very soon to my new mill. Just curious why you did the arduino over the MSP430? The 430 looks like it can support more stuff for the same money and less soldering

The difference in the amount of soldering is trivial. I mainly went with it because I have several Arduinos and am familiar with them. I have used them for quite a few projects including drones, LED displays, and the RFID keys for my motorcycle.

 

[gte718p]

I just ran across a single chip solution for Arduino and Bluetooth in a nice small form factor.

http://www.seeedstudio.com/depot/Bl...mailchimp&utm_medium=edm&utm_campaign=EDM1113

SEEED makes really cool stuff at reasonable prices. The only problem is everything ships from Singapore or Hong Kong and it is slloooooooooow.
to late for me, but maybe for someone else, or.maybe the lathe needs a readout ??

 

[RogueFab]

Holy cow. What a cool idea. Nice that the amazon gizmo just dropped in price too! I am going to have to consider that baby O scope as my next tool purchase.

 

[laser3kw]

RogueFab? you wouldn't AKA Boss3.0 from another site long, long ago?