Digital Chinese Scales

[NarrowGauge]

I recently fitted a scale to the carriage of my lathe and was so impressed, that I then proceeded to fit them to the x and z axes of my mill.

With the lathe I was able to fit both the scale and head well away from the cutting action. The Z axis of the mill is also well clear of swarf etc. The x axis of the mill has been fitted with a perspex cover to offer some protection, as I consider it to be quite vulnerable. All of the scales are the cheaper e-bay derived scales.

Can I ask, what precautions do group members take to protect their own scales and are there any particular pitfalls to avoid?

I am now thinking of fitting a scale to the y axis of the mill, but of course this is in the most messy area of the machine with little scope to provide a clean mounting.

Your experiences and thoughts would be welcome.

Thanks

Dave.

[SteveW]

Dave,

I bought some scales and am still trying to solve your last problem. I got them from Chronos over a year ago, they were cheap and sold as not suited to external displays. I have since had the battery replacement problem (see another thread). While looking at the battery compartment I noticed there were lands for an external connector. This has to be the answer to both our problems but unfortunately I've yet to find any details of the connection.

[Allan Waterfall]

I've got a Shumatech set up on my mill,it uses Chinese scales.

www.shumatech.com/

There is a British agent for the DRO.

I got my scales from Arceurotrade,prices seem reasonable.I just used a normal horizontal scale on its side on the quill,it's a lot less bulky than the vertical ones.There are no problems if you cut one to shorten it.

Allan

[NarrowGauge]

Steve, if you require further information about the decoding protocol used on the chinese scales, this can be found on the schumatech site that Allan mentions. I believe most chinese scales allow for remote reading, by use of a plug in lead and slave display.

I bought my scales from P J Tooling, through their e-bay shop. They were slightly cheaper than ArcEuro, but I have found both suppliers to be both helpful and prompt in their dispatch. Both suppliers offer the remote slave display and cables. I consider this to be a 'must' for the y axis on a mill. At least this allows for more protection to be placed over/around the scale, but just how susceptibile to oil etc are these scales?
Dave.

[SteveW]

Allan,

BRILLAINT! I've just visited that URL and saw the DRO I bought.

Last night , after adding the piece above, I spent a couple of hours looking but getting nowhere.

The next head scratcher is whether to make a connector or solder directly (yuk!) to the unit.

[Allan Waterfall]

I sodered mine direct into the reader on the scale,a bit fiddly and of course it voids any warranty.
On the plus side it stops the"plug worked loose" problem.

If you go with a Shumatech set up,use the capacitor in place of a battery if you can.I just hollowed a dead battery out and soldered the capacitor in it.

If you stick with a battery make sure you electrically insulate the scales and reader from your machine or you will find the battery goes flat in a matter of hours and gives unsteady dro readings.

Allan

[Doug J]

Anybody interested in using the Chinese scales should look at the Shumatech web site that has been mentioned. I have recently built this DRO and had no problems with it, it really is so much easier than trying to read the small display on the scales. There is a user group dedicated to this DRO with loads of useful information on it. The added bonus is that the scales can be completely covered since you do not need to read the individual scales - the unit is also quite cheap to build.
Doug J

[SteveW]

Guys,

I just ordered a ShumaTech reader @£135. There is also an item on it in MEW Trade Counter but the man on the phone doesn't accept orders, must be via the web.

Here you're given the option of red or green LEDs but no chance of selecting which so it'll be pot luck.

The hardest bit was PayPal... KIN NIGHTMARE. I had an old account which they told me had expired, certainly my cards details had.

Would PayPal simply let me branch from the ordering process to update them? NO!

Much messing about later I get to update my details. Was I successful? NO!

The whole paying process seems to have been designed by a thirteen year old using a ZX81 so it barfs easily. Even the close account went wrong. Why was I closing? Well half way though explaining I get timed out.

Am I happy? What do you think?

[NZoldun]

Porbably old news to most, but here goes:-

There is a complete article in the latest MEW (Feb-March 2005, English) on an english developer who has a system for coupling to a computer (pp50-51)

[SteveW]

NZ Oldy,

Yea I saw that. Looks intersting especially if you haven't pushed the boat out already on higher end DROs.

There has been a few previous articles on the subject of position readouts and the cheap end simply recycles the inards of a computer mouse, a pulley and a bit of fishing trace. My reservation with this cheaper route is that it does require an investment of time and a little money. Having done so and then realised how useful DRO equiped kit is you're straight in the worry of is what you've got good enough/robust enough. Chances are that it won't be.

Re my previous posting on the colour of the LEDs from the Shumatech UK supplier. He emailed me the following day and its' all sorted. Why didn't I think of that?

Having looked at both, i.e. cheap Chinese linear scales and optical encoder and then seeing how the Shumatech system connects it occured to me the best route would be to use Chinese scales on the front and a computer for the readout at the back. Given the £135 (inc UK VAT p&p) I've just paid for the box and given my techy background I could have made a gizmo to connect the scale directly to one of my many PCs. Another idea was construct a video source directly and plug a monitor into it. The trouble with this is that: 1. I ain't got the room for a PC/monitor, 2. I'd never get around to it & 3. Its 'only' 135 quid and it'll all be going a couple of days after getting the bits.

[NarrowGauge]

Steve

I would be interested to hear how you get on with the ShumaTech kit. It has certainly caught my eye too, not only for the practical functionality, but also, for the pleasure of building the device.

Technical support looks to be very good.

Dave.

[SteveW]

NarrowGauge,

Watch this space....

[henryspringer]

[quote author=SteveW li

There has been a few previous articles on the subject of position readouts and the cheap end simply recycles the inards of a computer mouse, a pulley and a bit of fishing trace. around to it & 3. quote]

Can you point me to any of these articles please. It's something I have tried in the past and would like to see other ideas on how to do it. The pc display is the main problem.

[Staffordshirechina]

Henry,
A couple of articles were in the Model Engineer a year or two back.
The system was called 'Rodent Rules' you can download the free PC software from compucutters website at

ourworld.compuserve.com/homepages/compucutters

Regards
Les

[SteveW]

Re. Budget DRO

see Model Engineers Workshop No 87 page 40. Dec '02.. Jan '03.

The article on using the bits of a mouse is tacked on the end of a series on "Enhancements to Compumill".

[SteveW]

All,

I thought it about time I updated you guys on my Shumatech DRO kit as promised.

The first thing to realise it that it is a kit. By this I mean a load of bits, a PCB and some pre-made cable assembles. I also found it necessary to go and get a copy of the assembly details from the web as I didn't opt for this on the order.

I also went for the pre-drill plastic case. I would rate this as essential unless you are super tight and prepared to spend a morning drilling all the holes, round and oblong. Details for this are provided but for an extra tenner no way.

The components arrived taped individually onto a parts list where these were unique or in simple strips of resistors and capacitors where there were loads of the same item. Either way is was a doddle finding the components and I didn't need to look up any resistor codes. The IC were laid out in order on conductive foam. The UK supplier has put a lot of thought into what he supplies making assembling the kit is a relatively easy step by step process. The PCB is very good quality double sided with silk screen and coating. I does have some very fine copper traces and these are quite close to pads so care is required.

However, I should also add that I'm suppose to be a bit technical and have the cored solder, precision pliers, cutters, temperature controlled iron and static free location to put it all together. I used to make a living at it. At 53 now I just needed good light and my magnifying hat on. Remember that you'll be working on a 0.1" pitch for all the chips. Also read the instuctions a couple of times, the display go on one side the rest goes on the other side of the board. The supplier will "mend" a kit for a fee if you don't feel up to this. If you have no experience of assembling complex electronics AND you're getting on a bit I urge you to explore this route.

I bought a little plug-in power supply from Maplins for £13 and some S-Video cables that fit the sockets provided. The Maplin cables are twin coax and not the four discreate wires I've seen described on the web. Using the coax cables simply requires easing the inner out about an inch and a half back from the end. This gives four insulated ends.

Did it all work? Once completed the kit burst into life without a hitch. The manual describes quite well what to do to set it up, covering both lathe and mill versions. Note that the software IS different for Lathe/Mill.

Unfortunately I have also discovered there a TWO types of Chinese scales. If anyone has, like me, bought the ones from Chronos at the Harrowgate MEX a few years back at around £22 you will find that they don't work. Arrgh!

Although the connections are identical mine only has two buttons and appears to provide what looks like BCD output with bursts of clock instead of the staight 20bit value and clock that the unit expects. BUGGER!

To be investigated further.

[davetaylor]

Hi, I am new to the model engine game and at present I am setting up my workshop. I have tried to find the "Rodent Rules" software on compucutters website but it is missing. Does anybody have a copy for me?

[mmaidnz]

This appears to be a similar setup to Shumatech's.:http://www.yadro.de/dro/diy.html.
A bit cheaper,so perhaps worth looking into.No connection blah blah blah.

[jones]

mmaidnz, I was just about to post that same link. You beat me to it. I was wondering if anyone had tried it as it looks to be cheaper and more flexible than any other similarly priced DRO.

yadro.de/

[Chris Kelland]

Hi All,

Have a look at the Shuma Tech Yahoo Group for all the info you could possibly need! I have fitted my mill with a complete set of remote readouts. I did have a look at the shumatech kit and decided not to use one. Whilst there are two types of scale, 2 & 3 button they are the same, the 2 button are auto start and finish and have protected pcb's. As far as batteries are concerned alkaline cells last just a few days, silver cells seem to last about a year. From info I have found short battery life is due to only the readout being turned off - the pcb and the memory stay live. On my set up the readout does not come on at all, only the remote display unit comes on.


To date it has performed well.

Chris.