Chinese DROs: Accuracy?

Hi,

I just got an offer for Chinese DROs (to fit onto a mill or a lathe), that are quite cheap. I _would_ prefer Heidenhain, Sony or Mitutoyo, but not my wallet! These cheapos seem to have a resolution of 1/100mm, but what's their accuracy?

I do have a Tek TDS waiting for some waves to sample, a programmer for uCs, a laptop willing to cycle through some C-code and the knowledge to put all the things together ...

Nick

Reply to
Nick Müller
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. Nick, is this an offer that OTHERS might take advantage of? If so, can ya share the info? TIA Bill

Reply to
BillP

I don't know.

What do you want to know? I only know, that there is a documentation about the protocol of the Chinese scales and that there must be a way to convert it to V24 AKA RS232. That's what the uC is for. Also I know, that I have done something like this before. I further know, that this would not be my first C-program. I would not be to declined to make the info/code/etc PD.

If I would be a cop, I would say: "I ask the questions!" :-)

So anybody knows something about accuracy?

Nick

Reply to
Nick Müller

You might want to look at:

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before reinventing the wheel.

Pete C.

Reply to
Pete C.

Thanks, I know that. But I don't want a dedicated board with uC + display for that. Just a uC for the conversion DRO V24.

Nick

Reply to
Nick Müller

In numbers? :-)

Good to know! Do you have the shumatech board or just his "dongles"? When out of sync, was the display of the DROs confused, or "just" the box doing the processing? OK, the connectors will be a problem (I've read the articles), but I guess that can be done mechanicaly healthy. So, are you sure that it was only a mechanical problem?

Nick

Reply to
Nick Müller

You really need to solder the leads (or a header) directly to the board, don't use the slide-in connectors. I used the 4 pin header listed in the Shumatech optional list, but you could just as easily solder the wires right straight to the board.

DT

Reply to
DT

the scale. I suppose this is why they won't work when wet. However, the Mitutoyo water resistant calipers use inductance as the measuring method. ERS

Reply to
Eric R Snow

I just came across this text. It might help you:

"Anyway, among other things, it was discovered that, if the scales were left connected to the DRO-350 when its power supply was unplugged, the DRO-350 would drain the batteries in the scales. There was then a procedure that had to be followed to get the scales to work correctly again (remove the battery, leave it out for a minute, put in a new battery, bury a dead cat under the big oak tree...). And on it went."

The solution is to leave out the batteries.

Nick

Reply to
Nick Müller

The best prices for optical scales are offered at the ShumaTech Yahoo user group at

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They have been tested by the users of the displays.

Regards,

Tim LMSC

877-376-4373

Reply to
LMSC

And what is the price range? Also, I hate to subscribe to Yahoo.

What I have found here is abot 5..10 times the price of the Chinese scales.

Nick

Reply to
Nick Müller

I got the answer of the dealer now: He claims +/- 0.03mm on a 300mm scale?!

A Mitutoyo caliper, 300mm long, has +/- 0.04mm. Now would anyone trust the +/-0.03 of the Chinese crapmanship ... er ... craftmanship?

Nick

Reply to
Nick Müller

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