Chinese Scales and DRO

[Doug]

I brought some scales for my lathe a few months back, they are the cheap iguage time with remote readout

They were ok but had an annoying habit of switching off in powersave mode when least expected. However last week my x axis readout died while I was using it. I swapped for the z axis reader and that worked so I know it’s the readout unit at fault. I tried emailing the shop I bought them from (I won’t mention who cos they still haven’t replied) to ask if I could buy a new reader head unit. While searching I. Discovered “TouchDRO “ a project posted on the web for using all sorts of scales with a tablet to produce a full featured DRO. So I set about making up the circuit on an Arduino programmer

It’s not very complicated and the instructions are very good on Yuri’s toys website the results are better than I could ever have hoped for the DRO on my lathe is now awesome well worth the effort of upgrading,
Total cost was not that crazy either
Google tablet £40
Arduino Uno £2.60
Arduino prototype shield £2.80
Bluetooth module £2.80
Resistors £1.80
USB breakouts £2.30
The result is this;


www.yuriystoys.com/p/arduino-basic-dro-controller.html?m=1

I just need a bracket to hold the tablet and tidy up the installation.
Definitely worth doing

[Roger]

That's really neat Doug. This should work with any make of linear or rotary encoder. I can see it having uses in lots of other applications

[Doug]

Dec 2, 2018 13:16:55 GMT Roger said:

That's really neat Doug. This should work with any make of linear or rotary encoder. I can see it having uses in lots of other applications

I have been using it today and I especially like the fact I can type in the size of material so when I take a cut it shows the remaining material size. I am going to add a “w” axis too to the tailstock so I can register accurately the drill depths.
Very useful little project indeed.

[jon38r80]

Yuri's website is very interesting, gives some ideas how to overcome some of the unreliability of if Igaging scales as well as well as the more sophisticated stuff that Doug has discovered.
You don't need to buy a tablet if you already have a smart phone as it will run on that too, I tried it before I bought a 'proper' DRO to fit to my mill. One of the problems I had with the scales was that the shielding and earthing on the cables was a bit iffy. Made up some new cables as Yuri suggested, made a lot of difference to reliability and they stopped jumping most of the time.

[Roger]

Another thought is to add a multi-tool feature like I have with the Newall DRO. With that you can set any number of different offsets against tool numbers. That's useful when you set up several tools that you can swap into quickchange tool holders and then instantly get back to the correct DRO reading without any further measuring. It's a real time saver on repeat work, but of course, as soon as you move the compound slide or the tool post, the settings all go out the window.
It ought to be dead easy to change the program and add a couple of buttons to the interface to do that.

Mine remembers the settings even when you turn the power off. I did a similar thing with my PIC interface for the weighbridge, I'm sure you can do that with the Arduino too.

[Doug]

Dec 2, 2018 19:43:21 GMT Roger said:

Another thought is to add a multi-tool feature like I have with the Newall DRO. With that you can set any number of different offsets against tool numbers. That's useful when you set up several tools that you can swap into quickchange tool holders and then instantly get back to the correct DRO reading without any further measuring. It's a real time saver on repeat work, but of course, as soon as you move the compound slide or the tool post, the settings all go out the window.
It ought to be dead easy to change the program and add a couple of buttons to the interface to do that.

Mine remembers the settings even when you turn the power off. I did a similar thing with my PIC interface for the weighbridge, I'm sure you can do that with the Arduino too.

It does have the multi tool feature already in the app, I can set tool and workspace offsets, I don’t have a QC tool post so I can only benefit from the workspace offsets, it can save any number of points so fairly useful for complex shafts. 
I haven’t switched off the tablet fully but the positions are saved if the Arduino looses connection or is switched off and back on (the app saves the position) the interface is just to send pulses to the app so is fairly dumb.
oh and the app has plusecoder input for a tacho and an input for probing points too. Pretty cleaver stuff, but I doubt I will need that lot.

[DX-SFX]

My experience of these cheap scales, certainly the early ones, is that they're unreliable and prone to failure. I bit the bullets and paid for proper DRO scales (optical on the milling machine, magnetic on the lathe) and don't regret that decision one bit. I found even the slightest condensation on the cheap ones had them fail along with the seriously flimsy wiring and plug/sockets.

[Doug]

I have expanded the DRO to include the tailstock I now have measurement on all the lathe axis, have used them quite a bit and found I am now accurately machining to 0.01mm so pretty happy with the result. It would be nice to get better resolution which I may do in the future, the system allows for glass scales so I may add them one day.


I have a good 6” of travel on the tailstock and the scale can read just over that.

[Doug]

Have done a bit of an update and added rpm to the spindle motor that now has a vfd (variable speed three phase motor)


The pickup is super simple hall-effect sensor from eBay for a couple off £
The only thing left is to connect the x axis via a couple of rose joints and a rod as this will hopefully improve the accuracy as I think it’s loading up a tiny bit and it will allow me to bolt the head to something more substantial.
Anyway after some serious amount of use it’s really worth the effort and a cheap alternative to buying a full set of scales and a readout.

[JonL]

What a fantastic project, I love it. Keeping the swarf out of the hall effect sensor might be fun though.

My biggest issue at the moment with programming Arduino is a suitable interface. I went over to a Chromebook a while ago which does almost everything I need, but for some reason I can't get to talk to Arduino (via Linux). I can't load anything on to my work laptop as the MoD don't like that sort of thing, so I may have to buy a second hand laptop just for programming.